Performance information

• Strength changes associated with water transport in unsaturated tuff during drying　　　　　　　　　　　　　　　
  Yota Togashi; Haruhiko Kotabe; Masahiko Osada; Shingo Asamoto; Ken Hatakeyama
  International Journal of Rock Mechanics and Mining Sciences, Volume：186, Feb. 2025, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1016/j.ijrmms.2024.105984
  DOI ID：10.1016/j.ijrmms.2024.105984, ORCID：173296072
• A method of determining unsteady air permeability of rock
  Yota Togashi; Masahiko Osada
  Engineering Geology and Geotechnics: Building for the Future, Proceedings of the Conference EUROENGEO 2024, First page：423, Last page：432, Oct. 2024, [Reviewed]
  For geological disposal of radioactive waste and large-scale collapse of rock slopes due to heavy rain fall, it is significantly important to determine the water transport in the rock mass including unsaturated zones. To precisely predict the two-phase flow of air and water in rock pore spaces, both the hydraulic conductivity and gas permeability must be accurately identified. Most existing methods estimate the air permeability from the differential pressure under steady-state conditions. There are still few methods for evaluating air permeability under unsteady state conditions. This study proposes a method of identifying the ever-changing permeability with time and pressure using a linearized governing equation for air permeability in porous media. This method is based on an exact solution of the linear diffusion equation and requires that air pressure be measured at three different coordinates to approximate the second-order partial derivative with respect to the coordinates. To validate the method, we compared the exact solution derived with the results of air permeability laboratory tests on granite and conglomerate in previous studies. After confirming that the exact solution well represented the results of previous experiments, the unsteady air permeability of the rock was estimated from the results of the same experiments using the proposed method. As a result, it was confirmed that not only can the air permeability be identified with the same accuracy as the steady-state method, but also the unsteady air permeability, which varies with pressure, can be identified.
  University of Zagreb Faculty of Civil Engineering, International conference proceedings
  DOI：https://doi.org/10.5592/co/euroengeo.2024.115
  DOI ID：10.5592/co/euroengeo.2024.115
• Fundamental study on slope failures, failure Shapes, and frequency distribution using sandpile experiment
  Weerahannadige Sachintha Fernando; Keita Yanagidaira; Teppei Kato; Yota Togashi
  Japanese Geotechnical Society Special Publication, Volume：10, Number：18, First page：650, Last page：655, May 2024, [Reviewed]
  The Japanese Geotechnical Society, Scientific journal
  DOI：https://doi.org/10.3208/jgssp.v10.os-7-09
  DOI ID：10.3208/jgssp.v10.os-7-09, eISSN：2188-8027
• Unsaturated Strength of Tage Tuff and Its Water Retention Drying Curve　　　　　　　　　　　　　　　
  Haruhiko Kotabe; Yota Togashi; Ken Hatakeyama; Masahiko Osada
  Zairyo/Journal of the Society of Materials Science, Japan, Volume：73, Number：3, First page：212, Last page：219, Mar. 2024, [Reviewed]
  Strength loss of sedimentary rocks due to water content changes is an important issue in the civil engineering field. Assuming disasters associated with rainfall and drying, it is important to identify unsaturated strength properties for gradually varying moisture contents. Water retention curves are needed to describe unsaturated strength properties. The high suction acting in the case of rock presents a challenge in identifying the suction. In particular, identifying the water retention drying path is difficult. This study propose a method to identify the drying paths using uniaxial compressive strength and tensile strength of Brazilian test. Uniaxial compression and Brazilian tests were performed on specimens with varying water content in the drying pass to investigate changes in their mechanical properties. Strength and stiffness were found to be approximately halved in the wet condition compared to the dry condition. Simplified Mohr-Coulomb failure criteria are also identified using uniaxial compressive and tensile strength. The cohesion decreases with increasing water content, while the angle of shear resistance is independent of changes in water content. Suction at each saturation level was back-analyzed using the detected cohesion and shear resistance angles to identify the water retention drying curve. The water retention drying curves identified were compared with the water retention wetting curve identified by another method to confirm the validity of the proposed method.
  Scientific journal
  DOI：https://doi.org/10.2472/jsms.73.212
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85184568571&origin=inward
  DOI ID：10.2472/jsms.73.212, ISSN：0514-5163, eISSN：1880-7488, SCOPUS ID：85184568571
• Experimental study of frictional resistance influences on tunnel face stability　　　　　　　　　　　　　　　
  R. Kawanoue; T. Yagihashi; Y. Togashi; M. Osada
  IOP Conference Series: Earth and Environmental Science, Volume：1124, Number：1, 2023, [Reviewed]
  In recent years, there have been several ground surface collapses due to tunnel excavation in Japan. Although such accident is caused by ground loosening and tunnel face collapses due to excavation, there is no accepted theory for estimating the face stability because this phenomenon is quite complicated and highly influenced by the supports and lining types. Specifically, the loosened area is relatively large for the urban NATM method, which applied in a shallow sedimentary rock layer. Therefore, a method to quantitatively evaluate the tunnel face stability by this kind of mechanical property is essential. In this study, 2D tunnel pull-out test was conducted to observe the influence of frictional resistance on tunnel face failure and loosening area by changing the shear resistance angle using three particle sizes of dry silica sand and different variation of earth covering. The result demonstrated that failure region doesn't reach the ground surface when the shear resistance angle is 46.4° and covering thickness to tunnel height ratio H/D is over 5 or the angle is 55.8° and H/D is over 3. This study considered that there is an arch effect depending on frictional resistance and earth coverings occurred. Furthermore, even with the same earth covering, the smaller the shear resistance is, the earlier the ground surface collapses. Therefore, it could be said that the higher the frictional resistance is, the later the collapse proceeds.
  International conference proceedings
  DOI：https://doi.org/10.1088/1755-1315/1124/1/012103
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85146556639&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85146556639&origin=inward
  DOI ID：10.1088/1755-1315/1124/1/012103, ISSN：1755-1307, eISSN：1755-1315, SCOPUS ID：85146556639
• Numerical approach to evaluate the influence of water saturation on the strength of Neogene Tuff in Utsunomiya city, Japan　　　　　　　　　　　　　　　
  Neranjan Ranaweera; Yota Togashi; Masahiko Osada; Ryo Kawanoue
  IOP Conference Series: Earth and Environmental Science, Volume：1124, Number：1, 2023, [Reviewed]
  Evaluation of the deformation behavior due to drying is crucial in underground construction works. Especially, geological repository for High-Level Radioactive Waste (HLW) shall be carefully selected to act as a natural barrier to prevent radioactive nuclide leaks. Uniaxial Compressive Strength (UCS) is one such governing factors when designing or selecting a suitable location for such underground storage compartments or access tunnels. Since nuclide leakage through geological repositories, intact rocks UCS will vary with the drying conditions. Hence, it is vital to evaluate the behavior of UCS subject to the conditions prescribed. A variety of statistical models has been built to govern the interdependency between UCS and water content. However, there are no significant amount of research have been conducted to emphasize the UCS variation with the degree of saturation under the influence of drying condition. Numerically, Richard's equation exact solution in Neuman boundary condition has been derived to exploit the degree of saturation with respect to time and position. Experimentally, obtain the UCS variation with the degree of saturation pertaining to the Neogene Tuff in Utsunomiya city, Japan. A best fit statistical model was generated for experimental data between UCS variation and the degree of saturation. Then, the experimental saturation degree was replaced by Richard's equation exact solution saturation degree values. Surprisingly, produced graphs for experimental data and numerical analysis data for exact solution were perfectly overlapped. Results point out that change of UCS shows similar characteristics, which exponentially decrease, with both experimental saturation values and exact solution saturation values influenced the drying condition. Moreover, it suggests that UCS value can be predicted subject to the time and position in the sedimentary rocks under drying conditions.
  International conference proceedings
  DOI：https://doi.org/10.1088/1755-1315/1124/1/012121
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85146632350&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85146632350&origin=inward
  DOI ID：10.1088/1755-1315/1124/1/012121, ISSN：1755-1307, eISSN：1755-1315, SCOPUS ID：85146632350
• ボアホールジャッキ試験による異方性岩盤のヤング率解析法　　　　　　　　　　　　　　　
  川久保昌平; 大野宏和; 松井裕哉; 富樫陽太; 谷 和夫; 加藤猛士
  Volume：17, Number：3, First page：393, Last page：400, Sep. 2022, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.3208/jgs.17.393
  DOI ID：10.3208/jgs.17.393
• Method for Measuring Three-Dimensional Strain Tensor of Rock Specimen Using Strain Gauges　　　　　　　　　　　　　　　
  Mamoru Kikumoto; Yota Togashi
  Rock Mechanics and Rock Engineering, 2022, [Reviewed]
  We propose a method for identifying a three-dimensional strain tensor using six or more strain gauges. This purely theoretical method assumes elementary deformation of the target object. To derive the strain tensor, six independent strain components must be measured using six or more strain gauges. The effect of measurement errors of the strain gauges on the strain tensor varies with the arrangement and orientations of the strain gauges. Thus, we also propose a method for evaluating the quality of the arrangement and orientations of the strain gauges. In this evaluation method, the determinant and condition number κ of the matrix obtained from the unit direction vector in the attachment direction of the strain gauge are analyzed. The quality of each strain gauge arrangement is evaluated based on an assumption of 2–4 rosette gauges attached to a cylindrical specimen. The results of the proposed numerical analysis demonstrated that it is disadvantageous to install strain gauges at axisymmetric positions, and that it is better to have strain gauges attached to the sides in different directions. Furthermore, to evaluate one of the methods verified in this analysis, a triaxial compression test of Neogene-period tuff was conducted for comparison. It was determined that the strain tensor can be specified with high accuracy even though the three-rosette-gauge method had a medium accuracy. The accuracy improved as the number of strain gauges increased, and it was demonstrated that the strain tensor could be identified with sufficient accuracy even when only three rosette gauges are used.
  Scientific journal
  DOI：https://doi.org/10.1007/s00603-022-02849-0
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85127547979&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85127547979&origin=inward
  DOI ID：10.1007/s00603-022-02849-0, ISSN：0723-2632, eISSN：1434-453X, SCOPUS ID：85127547979
• Influence of End Restraints on Strain Responses of Anisotropic Tuff During Triaxial Compression　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  Rock Mechanics and Rock Engineering, 2022, [Reviewed]
  In triaxial tests, the rock specimen is often assumed to have an axisymmetric elementary response. However, the axisymmetric condition of deformation is not always satisfied for anisotropic rocks, because the incremental relationships between stresses and strains are not necessarily coaxial. Furthermore, rock specimens often exhibit non-uniform deformation owing to the effect of end restraints. The influence of end restraints on the deformation behavior is significant in anisotropic rocks when compared with that in isotropic rocks. In this study, four types of consolidated drained triaxial tests were conducted on anisotropic tuff under different conditions involving end restraints. All components of the strain tensor were measured using multiple strain gauges attached to the side of the specimen. Although the normal strains were not considerably influenced by the presence or absence of the cap and Teflon sheets at the top end of the specimens, the shear strains and orientations of the principal strains were significantly influenced by the end restraints. These results indicate that anisotropic elastic parameters determined using shear strains vary widely owing to end restraints.
  Scientific journal
  DOI：https://doi.org/10.1007/s00603-022-02793-z
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85124946700&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85124946700&origin=inward
  DOI ID：10.1007/s00603-022-02793-z, ISSN：0723-2632, eISSN：1434-453X, SCOPUS ID：85124946700
• Determination of 12 orthotropic elastic constants for rocks　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  International Journal of Rock Mechanics and Mining Sciences, Volume：147, Nov. 2021, [Reviewed]
  The deformation properties of rocks ultimately become anisotropic depending on the orientations of mineral particles and sedimentary structures. Characterization of deformation anisotropy is important for accurate understanding of the deformation characteristics of structures constructed inside rocks (e.g., rock foundation and tunnel). The simplest anisotropic elastic model is transversely isotropic elasticity, and in recent years, many methods for rationally specifying this elastic constant have been proposed. Although the most general linear elastic model for describing deformation anisotropy is orthotropic elasticity, no efficient method currently exists for determining the orthotropic elastic constants because the number of elastic constants required for the model description is extremely large. A rational determination method for orthotropic elasticity is necessary when considering application at construction sites and coupling with other phenomena such as differences in water content. In this study, a new method was developed for obtaining all 12 constants of orthotropic elasticity by three uniaxial compression tests on specimens sampled in three directions orthogonal to each other. For each specimen, the strain tensor was measured, and the strains in the elastic region were added and analyzed to identify the principal orientation of orthotropic elasticity. Thereafter, nine elastic constants are specified using the stress–strain relationship of each specimen. The methodology is described herein. The validity of the proposed method was evaluated on the basis of results from verification experiments performed with Neogene soft sedimentary rocks.
  Scientific journal
  DOI：https://doi.org/10.1016/j.ijrmms.2021.104889
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85114791470&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85114791470&origin=inward
  DOI ID：10.1016/j.ijrmms.2021.104889, ISSN：1365-1609, SCOPUS ID：85114791470
• Evaluating changes in the degree of saturation in excavation disturbed zones using a stochastic differential equation　　　　　　　　　　　　　　　
  Yota Togashi; Kazuki Mizuo; Masahiko Osada; Tadashi Yamabe; Hiroshi Kameya
  Computers and Geotechnics, Sep. 2021, [Reviewed]
  Wiley, Scientific journal
  DOI：https://doi.org/10.1002/essoar.10507973.2
  DOI ID：10.1002/essoar.10507973.2, ORCID：100827890
• Numerical method of tunnel face pressure estimation considering progressive failure due to excavation　　　　　　　　　　　　　　　
  Yota Togashi; Iguchi Shota; Masahiko Osada; Ryo Kawanoue
  IOP Conference Series: Earth and Environmental Science, Volume：833, Number：1, Sep. 2021, [Reviewed]
  The stability of the tunnel face is a top priority in a tunnel construction. The estimation of the earth pressure acting in front of the face is essential for the stability evaluation of the face, and many model experiments have been conducted to understand the characteristics of face stability. On the other hand, there are many cases in which the stability of the tunnel face is evaluated by limiting analysis assuming a constant slip region by applying the loosening earth pressure derived by Terzaghi as a boundary condition, but the actual slip region is not always constant and expanded progressively accompanying by the collapse of the face. There are few past studies that have considered this phenomenon. In this study, a estimation method of the tunnel face pressure are developed in consideration of the progress of face collapse. The proposed method is a kind of limit equilibrium method. Assuming a slip line with two ellipses with the same center and different radii, the first-order linear differential equation of earth pressure in the tunnel face direction is calculated from the equilibrium for infinitesimal elements in the circumferential direction.
  International conference proceedings
  DOI：https://doi.org/10.1088/1755-1315/833/1/012157
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85115162285&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85115162285&origin=inward
  DOI ID：10.1088/1755-1315/833/1/012157, ISSN：1755-1307, eISSN：1755-1315, SCOPUS ID：85115162285
• Deformation characteristics of sedimentary rock due to continuous changes of moisture content in wetting process　　　　　　　　　　　　　　　
  Yota Togashi; Takanobu Imano; Masahiko Osada
  IOP Conference Series: Earth and Environmental Science, Volume：703, Number：1, Apr. 2021, [Reviewed]
  In recent years, the number of cases where tunnels are constructed in sedimentary rock layers has increased. It is essential to investigate the deformation characteristics of sedimentary rocks for predicting tunnel deformation. The mechanical properties of sedimentary rocks are widely varied due to moisture content. The rocks are dried by tunnel excavation and wetted by groundwater gushing or backfilling. It is necessary to grasp the changes of deformation characteristics of sedimentary rocks due to moisture changes. In this study, soaking tests were conducted on Neogene period Japanese tuff sampled at Utsunomiya, Japan. In the test, the cylindrical tuff specimens are air dried by over 240 hours at first. Then the tuff specimens are taken in pure water with measuring deformations in detail. There are no effective stress increases by soaking and only uniform matric suction are acted on the specimen without any restraints. The results demonstrated that strain tensor was reached to stable state for 2 - 3 days, and the value of the normal strain perpendicular to the bedding plane is greater than the other normal components and shear strains are also observed in both cases. Although the orientation of the maximum principal strain is in the near of the bedding orientation at the initial dry state, the orientation are suddenly rotated to the normal orientation of the bedding plane. It means that the principal orientation of anisotropy are rotated due to continuous moisture changes.
  International conference proceedings
  DOI：https://doi.org/10.1088/1755-1315/703/1/012021
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85105306702&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85105306702&origin=inward
  DOI ID：10.1088/1755-1315/703/1/012021, ISSN：1755-1307, eISSN：1755-1315, SCOPUS ID：85105306702
• Principal strain rotation of anisotropic tuff due to continuous water-content variation　　　　　　　　　　　　　　　
  Yota Togashi; Takanobu Imano; Masahiko Osada; Koichi Hosoda; Koji Ogawa
  International Journal of Rock Mechanics and Mining Sciences, Volume：138, First page：104646, Last page：104646, Feb. 2021, [Reviewed]
  Elsevier {BV}, English, Scientific journal
  DOI：https://doi.org/10.1016/j.ijrmms.2021.104646
  DOI ID：10.1016/j.ijrmms.2021.104646, ISSN：1365-1609, ORCID：86676642
• Determination of anisotropic deformability parameters of tuff by a single triaxial test　　　　　　　　　　　　　　　
  Yota Togashi; M. Kikumoto; K. Tani
  16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019, 2020, [Reviewed]
  A method of determining deformation anisotropy by a single triaxial test was proposed and a new triaxial testing apparatus including a new cap with a slider mechanism and low friction sheets was developed by the authors. In this study, anisotropic deformation properties of a tuff sampled in Utsunomiya, Japan, were investigated by this method. Strain responses of four specimens sampled to different orientation during triaxial compression were observed in detail. The values of anisotropic deformability parameters of the specimens evaluated on each specimen and demonstrated that the Young's moduli in the bedding orientation are 1.5- 3.9 times larger than that in perpendicular orientation.
  Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, English, International conference proceedings
  SCOPUS ID：85084944450
• A study of deep-seated landslide and its deformation behavior due to rock bridge by centrifuge model test　　　　　　　　　　　　　　　
  Togashi, Y; Yuasa, T; Hasegawa, A; Kawagoe, T; Kasuya, Y; Yamada, Y
  Japanese Geotechnical Journal, Volume：14, Number：2, First page：77, Last page：93, Jun. 2019, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.3208/jgs.14.77
  DOI ID：10.3208/jgs.14.77
• Deformation anisotropy of sedimentary rock sampled from deep seabed near subduction zone　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future, YSRM 2019, First page：163, Last page：168, 2019, [Reviewed]
  Deformation characteristics of sedimentary rocks are anisotropic for their sedimentary structures. Such anisotropy further evolves with changes of the structure due to stress conditions. The same phenomena can be observed to sedimentary rocks sampled from near subduction zone because the structure of such rock changes by tectonic movements. To detect the anisotropic properties of such rock is important for predicting the movement of oceanic plate. In this study, to evaluate the deformation anisotropy of subduction zone rocks, consolidated-drained triaxial compression tests were conducted on sedimentary rocks sampled from deep seabed, 1023 m below the seafloor, in the top basement of the Philippine sea plate. The results during isotropic consolidation demonstrated anisotropic deformations because different values of the normal strains were measured in axial and circumferential directions. The orientations of maximum principal strain tend to move toward the normal orientation of Philippine sea plate. The orientations of the plane including intermediate and minimum principal strains almost agree with the dip (subduction) orientation of the plate. Values of these intermediate and minimum strains were similar. The anisotropic behaviors are the results of in-situ complex stresses owing to the tectonic movement of Philippine plate.
  International Society for Rock Mechanics and Rock Engineering, English, International conference proceedings
  SCOPUS ID：85088437637
• Non-axisymmetric and/or non-elementary response of anisotropic tuff in axisymmetric, elementary triaxial test
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  E3S Web of Conferences, Volume：92, First page：02008, Last page：02008, 2019, [Reviewed]
  Specimens of triaxial tests ordinarily response as element in the axisymmetric condition, and it is theoretically correct assumption. However, for anisotropic rocks, the axisymmetric condition is not always satisfied because incremental relationships between stresses and strains are not coaxial. In addition, such rock specimen often shows non-uniform deformation behaviors due to end frictions. As the reason, the influence of end restraints on deformation behaviors of anisotropic rocks during triaxial compression is much greater than that of isotropic one. In this study, the variations in the stress-strain relationships of anisotropic tuff due to the condition of end restraints are investigated. The results of four consolidated drained triaxial tests with measuring the strain tensor demonstrated that the axial and volumetric strains were not influenced by whether sliding mechanism and Teflon sheets are installed at the end of specimens or not; meanwhile, the shear components of the strain tensor and the inclinations of principal strain orientations are widely varied owing to the end restraints.
  EDP Sciences, Scientific journal
  DOI：https://doi.org/10.1051/e3sconf/20199202008
  DOI ID：10.1051/e3sconf/20199202008, eISSN：2267-1242
• Determining anisotropic elastic parameters of transversely isotropic rocks through single torsional shear test and theoretical analysis　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani
  Journal of Petroleum Science and Engineering, Volume：169, First page：184, Last page：199, Oct. 2018, [Reviewed]
  Deformation properties of sedimentary rock is quite important for evaluating the industrial production of shale gas and the effective design of tunnel constructions, deep rock foundations for nuclear power plant and deep geological disposal. Anisotropic sedimentary rocks, such as shale, can exhibit significantly different material properties in different directions. Knowledge of the anisotropic features of such rocks is, therefore, essential. When a hollow cylinder of an anisotropic material such as a sedimentary rock is torsionally-sheared, the axisymmetry is violated and the stress varies in the rotational direction. Utilizing such stress distributions, we propose a method to determine the parameters of the transversely isotropic elasticity of such a material, including the dominant orientation, via a single torsional shear test using a single hollow cylindrical specimen. A newly designed instrumented cap is also employed. Unlike existing methods, the specimen can be sampled in any arbitrary direction. An overview of the method is presented and its validity is checked both theoretically and numerically. The strain and stress distributions in a hollow cylindrical specimen of a transversely isotropic material is first investigated theoretically, and the stress and strain fields (to which random measurement errors are added) are back-analyzed using the proposed method. The results demonstrate that five elastic parameters, as well as the orientation of the transverse isotropy plane, can be determined uniquely via the proposed method.
  Elsevier B.V., English, Scientific journal
  DOI：https://doi.org/10.1016/j.petrol.2018.05.051
  DOI ID：10.1016/j.petrol.2018.05.051, ISSN：0920-4105, SCOPUS ID：85047636174
• Detection of deformation anisotropy of tuff by a single triaxial test on a single specimen　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  International Journal of Rock Mechanics and Mining Sciences, Volume：108, First page：23, Last page：36, Aug. 2018, [Reviewed]
  Rock anisotropy has conventionally been determined by numerous tests using many specimens sampled at several orientations, however, it is both costly and time consuming. The anisotropic deformation properties (transversely isotropic elasticity and its dominant orientation) of a tuffaceous rock sample obtained in Utsunomiya city, Japan, and characterized by a clear bedding plane, were determined by a newly proposed method, namely, a single triaxial test using a single specimen. Using this method, the dominant orientations of anisotropy are determined by the principal orientations of the strain during isotropic consolidation, and the elastic parameters can be determined by stresses and strains during triaxial compression. This method required the implementation of a triaxial testing apparatus with a newly designed cap including a slider mechanism and low-friction sheets. The six components of the symmetrical, small strain tensors of the tuff specimen were measured using nine strain gauges, while the 3D principal strains were evaluated during uniaxial and consolidated drained triaxial tests. To verify the proposed method, the anisotropic properties of four specimens sampled from a cubic block at different orientations, as characterized by the proposed method, were compared with those determined by multiple uniaxial tests using the specimens sampled for different orientations. The strain responses of the uniaxial tests demonstrated that the Young's modulus of the tuff in the bedding orientation is 1.5 times greater than that for the perpendicular orientation. The orientation of the principal strains deviate from the loading orientation due to the orientation of the bedding plane, and the orientations during isotropic consolidation were inclined in accordance with the dip orientation of the bedding plane. Similar values were evaluated for each anisotropic property determined by both a single triaxial test on each specimen and multiple uniaxial tests. The obtained values demonstrated that the Young's moduli for the bedding orientation are 1.5–2.7 times larger than that in the perpendicular orientation.
  Elsevier Ltd, English, Scientific journal
  DOI：https://doi.org/10.1016/j.ijrmms.2018.04.054
  DOI ID：10.1016/j.ijrmms.2018.04.054, ISSN：1365-1609, SCOPUS ID：85047868449
• Anisotropic elastic parameters of soft sedimentary rock by a single triaxial test　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  Zairyo/Journal of the Society of Materials Science, Japan, Volume：67, Number：3, First page：338, Last page：345, Mar. 2018, [Reviewed]
  To confirm applicability of a method of determining anisotropy of transversely isotropic elasticity via a single triaxial test for a sedimentary soft rock specimen in which bedding plane were not clearly observed, anisotropic deformation behavior of soft sedimentary mudstones, which were sampled in Sagamihara and were not sufficiently studied yet, was experimentally investigated by proposed triaxial test in this study. Non-coaxial anisotropic relationships of stresses and strains were evaluated by full three dimensional strain tensor of mudstone measured by nine strain gauges set on the lateral plane of cylindrical specimen. Orientations of principal strains during isotropic consolidation were agreed with that of bedding orientations observed in the outcrop. Anisotropic stiffness of the mudstone was finally determined by a method of determining anisotropy of transversely isotropic elasticity via a single triaxial test.
  Society of Materials Science Japan, Japanese, Scientific journal
  DOI：https://doi.org/10.2472/jsms.67.338
  DOI ID：10.2472/jsms.67.338, ISSN：1880-7488, SCOPUS ID：85044174657
• Assessment of anisotropic deformation properties of tuff by a single test on a single specimen　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani; Koichi Hosoda; Koji Ogawa
  Geomechanics and Geodynamics of Rock Masses - Selected Papers from the 2018 European Rock Mechanics Symposium, EUROCK 2018, First page：591, Last page：598, 2018, [Reviewed]
  In this study, anisotropic deformation properties (transversely isotropic elasticity and its dominant orientation) of a tuffaceous rock, which has clear bedding planes, were obtained via a consolidated-drained triaxial test using a new cap with a slider mechanism and low friction sheets. Strain tensor of each specimen sampled to different orientations from the same cubic rock block was measured by nine strain gauges attached in lateral plane of the specimen during both isotropic consolidation and axial compression. The results demonstrated that non-axisymmetric deformation of the specimen due to the bedding plane and that orientation during the loadings were evaluated.
  CRC Press/Balkema, English, International conference proceedings
  SCOPUS ID：85063614585
• 堆積軟岩の三軸試験と変形異方性の特定方法に与える端面摩擦の影響　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫; 細田光一; 小川浩司
  Volume：74, Number：1, First page：50, Last page：62, Jan. 2018, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.2208/jscejge.74.50
  DOI ID：10.2208/jscejge.74.50
• Determination and its verification of anisotropic stiffness of tuff by a single triaxial test　　　　　　　　　　　　　　　
  TOGASHI Yota; KIKUMOTO Mamoru; TANI Kazuo; HOSODA Koichi; OGAWA Koji
  Japanese Geotechnical Journal, Volume：12, Number：1, First page：123, Last page：134, Mar. 2017, [Reviewed]
  A new cap with a slider structure was implemented to triaxial testing apparatus for measuring elementary behaviors of an anisotropic material. Top of a cylindrical specimen could displace to perpendicular directions against the loading axis and frictionless boundary conditions were given by the cap. Using this apparatus, six small strain tensor components of tuff including bedding plane were investigated during both uniaxial and triaxial compression tests. The results of uniaxial tests, using two specimens sampled in parallel and perpendicular orientations to the bedding planes, demonstrated tangent Young’s modulus in the bedding direction is 1.5 times larger than that in the perpendicular direction. The anisotropy of Tage tuff assuming transversely isotropic elasticity is identified via proposed method by a single triaxial test using each specimen with inclined bedding plane at 15° or 45°. The results demonstrated that the dominant orientation of the anisotropy agreed well with that of the bedding plane, and anisotropic stiffness values obtained from a single triaxial test were close to those by uniaxial tests.
  The Japanese Geotechnical Society, Japanese
  DOI：https://doi.org/10.3208/jgs.12.123
  DOI ID：10.3208/jgs.12.123, CiNii Articles ID：130005519969
• An Experimental Method to Determine the Elastic Properties of Transversely Isotropic Rocks by a Single Triaxial Test　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani
  ROCK MECHANICS AND ROCK ENGINEERING, Volume：50, Number：1, First page：1, Last page：15, Jan. 2017, [Reviewed]
  A novel method is proposed for determining the deformation anisotropy of rocks by a single triaxial test using a single specimen sampled from an arbitrary direction. Transversely isotropic elasticity is assumed for the purpose of application of the test method to sedimentary and metamorphic rocks, and the non-axial symmetric stress-strain relationships of anisotropic rocks are determined by triaxial testing by means of a simple improvement to the cap in the triaxial testing apparatus. Both the elastic parameters and the directions of the transversely isotropic elasticity can be obtained by measuring the shear deformations that occur under triaxial stress conditions. An overview of the method for determining transversely isotropic elasticity is presented in this paper, along with the results of a sensitivity analysis performed assuming simulated strains with random measurement errors. The results show that the directions of anisotropy can be determined precisely using the directions of the principal strains measured during isotropic compression and that the elastic parameters can be determined uniquely from the stress-strain relationships observed during both the isotropic and axial compression processes.
  SPRINGER WIEN, English, Scientific journal
  DOI：https://doi.org/10.1007/s00603-016-1095-9
  DOI ID：10.1007/s00603-016-1095-9, ISSN：0723-2632, eISSN：1434-453X, J-Global ID：201702219191754669, Web of Science ID：WOS:000392293300001
• NON-UNIFORM DEFORMATIONS AND VARIATIONS OF YIELD STRENGTHS OF ANISOTROPIC SOLIDS DUE TO BOUNDARY CONDITIONS DURING PLANE STRAIN COMPRESSION　　　　　　　　　　　　　　　
  Yota Togashi; Mamoru Kikumoto; Kazuo Tani
  Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering), Volume：72, Number：3, First page：283, Last page：293, Sep. 2016, [Reviewed]
   Non-uniform and non-symmetric deformation properties of anisotropic solids are discussed by 2D finite element simulations of both plane strain testing on isotropic and transversely isotropic solids. The results demonstrated that non-uniform deformation, which can not be estimated in isotropic solids, are observed in anisotropic solids due to both the boundary conditions and anisotropic stiffnesses. Then, the apparent yield strength of the specimen which are defined by the local stresses which reach Coulomb's yield criterion is investigated. In the case which anisotropy of Young's modulus is two times different due to the orientation of anisotropy, yield strengths were underestimated by 44%.
  Japan Society of Civil Engineers, Japanese, Scientific journal
  DOI：https://doi.org/10.2208/jscejge.72.283
  DOI ID：10.2208/jscejge.72.283, CiNii Articles ID：130005416211
• Tunnel monitoring system with wireless sensor network　　　　　　　　　　　　　　　
  Tsuno, K; Nakamura, T; Togashi, Y; Kamachi, H; Ooki, Y
  International Journal of the JSRM, Volume：12, Number：1, First page：15, Last page：18, Jun. 2016, [Reviewed]
  English, Scientific journal
  DOI：https://doi.org/10.11187/ijjsrm.12.1_15
  DOI ID：10.11187/ijjsrm.12.1_15
• 線路下横断構造物の施工に関するボルト締結鋼管の実物大曲げ試験と数値解析　　　　　　　　　　　　　　　
  中村智哉; 富樫陽太; 津野究; 岡野法之; 小山幸則
  Volume：72, Number：1, First page：39, Last page：52, Jun. 2016, [Reviewed]
  Japanese, Scientific journal
  DOI：https://doi.org/10.2208/jscejte.72.39
  DOI ID：10.2208/jscejte.72.39
• DETERMINATION OF DEFORMATION PROPERTIES FOR ANISOTROPIC ROCK MASSES BY IN-SITU TORSIONAL SHEAR TESTING　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K; Kikumoto, M
  J. Japan Society of Civil Engineers, Ser. C, Volume：71, Number：3, First page：241, Last page：253, Sep. 2015, [Reviewed]
  Deformation characteristics of rock masses are often significantly anisotropic due to discontinuities e.g. sedimentary planes and joints. Anisotropic properties of rock masses are commonly obtained by several triaxial tests using rock cores sampled to different orientations, but which is costly and time consuming. In this study in-situ torsional shear test for rock masses is proposed by the authors. Anisotropic deformation properties can be obtained by fewer tests than the conventional testing method. In this paper, for developing testing methods, a method of determining constitutive parameters for transversely isotropic rock masses is proposed. In this proposed method, the directions of anisotropy are determined by the strain responses under isotropic consolidation and 5 elastic parameters of transversely isotropic rocks are determined by both strain responses during isotropic consolidation and the distributed stress responses during torsional shearing.
  Japan Society of Civil Engineers, Japanese, Scientific journal
  DOI：https://doi.org/10.2208/jscejge.71.241
  DOI ID：10.2208/jscejge.71.241, ISSN：2185-6516, CiNii Articles ID：130005100281
• A method to identify deformation anisotropy of rock masses by triaxial testing　　　　　　　　　　　　　　　
  TOGASHI Yota; KIKUMOTO Mamoru; TANI Kazuo
  Japanese Geotechnical Journal, Volume：10, Number：2, First page：201, Last page：211, Jun. 2015, [Reviewed]
  Mechanical behaviors of rock masses often become anisotropic due to discontinuities. Mechanical properties of anisotropic rock masses are previously investigated by triaxial tests using boring cores sampled to from different orientations, but which is costly and time consuming. In this study, a new triaxial testing method to characterize deformation properties of anisotropic rock masses is proposed. This method can identify the directions of anisotropy by the directions of principal strains during isotropic consolidation and also can determine 5 elastic parameters of a transversely isotropic rock by the relationships between stresses and strains during both isotropic consolidation and axial compression.
  The Japanese Geotechnical Society, Japanese
  DOI：https://doi.org/10.3208/jgs.10.201
  DOI ID：10.3208/jgs.10.201, ISSN：1880-6341, CiNii Articles ID：130005086572
• 異方性岩盤の変形特性を特定する三軸試験の提案　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫
  First page：204-209, Jan. 2015, [Reviewed]
  Japanese
• Bending tests of the box form roof for underpass tunneling methods　　　　　　　　　　　　　　　
  Yota Togashi; Tomoya Nakamura; Noriyuki Okano; Kiwamu Tsuno
  6th Japan-China Geotechnical Symposium, SJGS 2015, Volume：1, Number：8, First page：16, Last page：21, 2015, [Reviewed]
  Underpass tunnels are often constructed on the bottom of railway. For preventing a relaxation of natural ground by excavation, box form roofs are set around the area in which the underpass tunnel will be constructed. However, in some cases, box form roofs are gradually bended on bolted joints by both an earth pressure and railway load. It is needed for constructing underpass tunnels safely to manage the torque of bolts in the box form roof. Torque managements of bolts are a valuable important theme for various engineering fields. It is difficult to estimate an initials axial force of bolts, because the relationships between applied torque and initial axial force are changed and affected by both mechanical properties of materials between a bolts and the surface condition of bolts. In this study, in order to appropriate manage a torque of bolts in constructional materials bended by external forces, several bending tests for full-size box form roof used for underpass tunneling method are conducted. The results are demonstrated that as the torque of bolt is increased, both deflection and aperture are decreased. Furthermore, new evaluating method using FE analysis for this bending problem is developed.
  Japanese Geotechnical Society, English, International conference proceedings
  DOI：https://doi.org/10.3208/jgssp.JPN-03
  DOI ID：10.3208/jgssp.JPN-03, SCOPUS ID：84959327224
• Non triaxial behaviors of rock masses assuming transversely isotropic elasticity in a triaxial compression test　　　　　　　　　　　　　　　
  TOGASHI Yota; KIKUMOTO Mamoru; TANI Kazuo
  Japanese Geotechnical Journal, Volume：9, Number：4, First page：479, Last page：493, Dec. 2014, [Reviewed]
  Rock masses often show anisotropic mechanical behavior due to discontinuity or sequence of mineral particle. In a triaxial test, the deformations of these types of rock masses show non triaxial behavior because a condition of axial symmetry is not satisfied. In this study, in order to clarify the deformation properties of transversely isotropic body which is applied for sedimentary rocks by some researchers, two cases of analysis of elements for a triaxial test is conducted. The one is the analysis for the condition which the directions of principal stresses are coaxial with the loading directions and the other analysis is for the condition which the directions of principal strains are coaxial with the loading directions. The results demonstrated two main conclusions: in the case of the former type of analysis, the directions of principal strain are inclined from loading direction; on the other hand, in the case of the latter type of analysis, the directions of principal stress are inclined from loading direction.
  The Japanese Geotechnical Society, Japanese, Scientific journal
  DOI：https://doi.org/10.3208/jgs.9.479
  DOI ID：10.3208/jgs.9.479, ISSN：1880-6341, CiNii Articles ID：130004944114
• 面内等方弾性体を仮定した岩が三軸試験で示す非三軸性　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫
  Jul. 2013
  Japanese
• 面内等方性を仮定した岩盤の三軸応力下の変形特性と異方剛性　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫
  May 2013
  Japanese
• PROPOSAL OF A NEW IN-SITU TORSIONALLY SHEAR TESTING METHOD AND ANALYSIS OF TEST RESULTS FOR ANISOTROPIC ROCK MASSES　　　　　　　　　　　　　　　
  Yota Togashi; Kazuo Tani; Mamoru Kikumoto
  PROCEEDINGS OF THE 5TH INTERNATIONAL YOUNG GEOTECHNICAL ENGINEERS' CONFERENCE (IYGEC 2013), Volume：2, First page：387, Last page：390, 2013, [Reviewed]
  Rock masses often show anisotropic mechanical behavior for their discontinuity and orientation of mineral particles. However, it is rather difficult to evaluate anisotropic mechanical properties of rock masses by existing in-situ test methods, e.g. rock shear tests, plate loading tests. Then in this study, a new in-situ testing method for rock masses is proposed. For development of this test method, FE analysis of was conducted assuming transversely isotropy body. The computed results demonstrated that anisotropic deformation properties of rock masses can be back analysed by the test results.
  IOS PRESS, English, International conference proceedings
  DOI：https://doi.org/10.3233/978-1-61499-297-4-387
  DOI ID：10.3233/978-1-61499-297-4-387, Web of Science ID：WOS:000333366000092
• Analysis for variations of test results of rock shear tests　　　　　　　　　　　　　　　
  Yota Togashi; Kazuo Tani
  ISRM Regional Symposium - 7th Asian Rock Mechanics Symposium, ARMS 2012, First page：535, Last page：543, 2012
  The variations of strength properties of rock shear tests are significantly large because of the discontinuous nature of rock masses and the accuracy of loading control. For the purpose of clarifying the latter reason, in this study, the rotation angles of the concrete block of failure about horizontal axis αf and about the vertical axis βf, the horizontal displacement perpendicular to the shear direction lf are investigated. As a result, the average values (αf, av, βf, av, (lf / hf)av) = (0.5o, 4.9o, 0.2). The standard deviations (σα, σβ, σl) = (±12.2o, ±5.6o, ±0.3). Furthermore Shear stress ratio Δτf/τf is decreased especially in the case αf <
  0.
  International Society for Rock Mechanics, English, International conference proceedings
  SCOPUS ID：85056234506
• Relationships between strength proerties obtained by rock shear tests and those by block shear tests　　　　　　　　　　　　　　　
  Yota Togashi; Kazuo Tani
  ISRM International Symposium - 6th Asian Rock Mechanics Symposium, ARMS 2010, 2010
  Two kinds of rock shear tests are performed by two ways in Japan. One is rock shear test (RST) shearing rock mass directly. Another is block shear test (BST) shearing boundary between rock mass and concrete block. There are few studies, however, being conducted to compare the strength properties obtained by RST and BST. Therefore, the purpose of this study is to obtain the relationships between the cohesion and the friction angles obtained by RST and those by BST. The results demonstrated that, for the hard rock masses [H], the strength properties by BSTs are lower than those by BSTs by about 11-26%. On the other hand, for the soft rock masses [S], the strength parameters by RSTs are higher than those by BSTs by about 10-252%.
  International Society for Rock Mechanics, English, International conference proceedings
  SCOPUS ID：85056216140

• Influence of specimen shape on new simple shear test using rock prism specimen　　　　　　　　　　　　　　　
  I. Sato; Y. Togashi; H. Kotabe; K. Hatakeyama; M. Osada
  58th US Rock Mechanics / Geomechanics Symposium 2024, ARMA 2024, Jun. 2024, [Reviewed]
  Rock masses are subjected to simple shear mode deformation during earthquake. Currently, there is no standardized simple shear test method for rocks in Japan. The authors propose a new test method, the simple shear test of a prismatic rock specimen using torsional shearing. In this test, prism specimens are radially installed on the pedestal, the cap is placed on the specimen tops, and then specimens are torsionally sheared by a torque with fixed axial displacement of the cap. In this study, to investigate the influence of radial shear load distribution by the applied torque on stress-strain relationships, proposed tests were conducted by varying the length/width ratio of the prismatic Berea sandstone specimens from 1-2.5. The results demonstrated that the more smooth stress-strain relationship, the shorter specimen length. On the other hand, the longer specimens showed more complex failure modes, and the strain decreased with increasing torque and did not increase monotonically.
  DOI：https://doi.org/10.56952/ARMA-2024-0470
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85201166051&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85201166051&origin=inward
  DOI ID：10.56952/ARMA-2024-0470, SCOPUS ID：85201166051
• EFFECT OF SPECIMEN SIZE ON SIMPLE SHEAR TESTS OF ROCK PRISM SPECIMENS　　　　　　　　　　　　　　　
  佐藤礁; 富樫陽太; 小田部晏彦; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：50th, 2024
  J-Global ID：202402288484194761
• STRENGTH PROPERTIES OF UNSATURATED TAGE TUFF　　　　　　　　　　　　　　　
  小田部晏彦; 富樫陽太; 畠山健; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：50th, Jan. 2024, [Reviewed]
  J-Global ID：202402291066608421
• Application of LiDAR and depth camera in labolatory experiments of face stability and slope failure　　　　　　　　　　　　　　　
  小林祐貴; 富樫陽太; FERNANDO W.S.G; 戸頃真尋; 長田昌彦
  地盤工学会誌(Web), Volume：72, Number：1, 2024
  ISSN：2435-5348, J-Global ID：202402232449975015
• 非対称要素を用いたすべり曲線における切羽安定問題の土圧理論　　　　　　　　　　　　　　　
  小林祐貴; 富樫陽太; 長田昌彦
  Volume：79th, 2024
  J-Global ID：202402220618275624
• NEW SIMPLE SHEAR TEST FOR ROCKS BY TORSIONAL SHEARING　　　　　　　　　　　　　　　
  富樫陽太; 平沢梨帆; 平沢梨帆; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：49th, 2023
  J-Global ID：202302211005617177
• EXPERIMENTS ON TUNNEL FACE COLLAPSE PROGRESSION AND MODELING OF ARCH ACTION　　　　　　　　　　　　　　　
  川之上諒; 富樫陽太; 小林祐貴; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：49th, 2023
  J-Global ID：202302288192429160
• 含水に伴う田下凝灰岩の強度変化と平均応力変化によるモデル化　　　　　　　　　　　　　　　
  小田部晏彦; 富樫陽太; 長田昌彦; 畠山健
  Volume：49th, 2023
  J-Global ID：202302274901382014
• INFLUENCE OF MOISTURE CONTENT ON MOHR-COULOMB FAILURE CRITERIA FOR SOFT SEDIMENTARY ROCK　　　　　　　　　　　　　　　
  小砂子優貴; 富樫陽太; 畠山健; 川之上諒; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：48th, 2022
  J-Global ID：202202251374440600
• INFLUENCE OF THE EARTH COVERINGS AND SHEAR RESISTANCE ANGLE ON THE STABILITY OF TUNNEL FACE　　　　　　　　　　　　　　　
  川之上諒; 八木橋辰紀; 富樫陽太; 長田昌彦
  岩盤力学に関するシンポジウム講演集(Web), Volume：48th, 2022
  J-Global ID：202202290788540589
• Experimental study of unsaturated mechanical properties of Berea sandstone.　　　　　　　　　　　　　　　
  小砂子優貴; 富樫陽太; 畠山健; 川之上諒; 長田昌彦
  土木学会全国大会年次学術講演会(Web), Volume：77th, 2022
  J-Global ID：202302297095817969
• Development of a new friction reduction materials in underpass tunnel construction by R&C method　　　　　　　　　　　　　　　
  平沢梨帆; 富樫陽太; 中村智哉; 井口翔太; 柏井皓登
  土木学会全国大会年次学術講演会(Web), Volume：77th, 2022
  J-Global ID：202302279423833277
• Influence of advection and diffusion on water content changes in tuff deformation during the drying process　　　　　　　　　　　　　　　
  RANAWEERA Neranjan; 富樫陽太
  地盤工学会関東支部発表会(CD-ROM), Volume：19th, 2022
  J-Global ID：202302241441983156
• 切羽崩壊の進行に伴うすべり線の形状変化を考慮したアーチ作用のモデル化と実験的検討　　　　　　　　　　　　　　　
  川之上諒; 富樫陽太
  Volume：19th, 2022
  J-Global ID：202302246610674996
• A METHOD OF DETERMINING ORTHOGONAL ANISOTROPIC ELASTICITY OF SOFT SEDIMENTARY ROCK BY THREE UNIAXIAL TESTS　　　　　　　　　　　　　　　
  佐藤晴海; 富樫陽太; 菊本統; 谷和夫; 細田光一; 小川浩司
  岩の力学国内シンポジウム講演論文集(CD-ROM), Volume：15th, 2021
  ISSN：1883-1486, J-Global ID：202102224245615750
• FACE PRESSURE THEORY AND EXPERIMENTAL VERIFICATION CONSIDERING PROGRESSIVE FAILURE　　　　　　　　　　　　　　　
  井口翔太; 富樫陽太; 長田昌彦; 川之上諒
  岩の力学国内シンポジウム講演論文集(CD-ROM), Volume：15th, 2021
  ISSN：1883-1486, J-Global ID：202102238621071656
• トンネル引抜き実験による地山の摩擦抵抗が切羽安定性に及ぼす影響　　　　　　　　　　　　　　　
  川之上諒; 八木橋辰紀; 富樫陽太
  Volume：18th, 2021
  J-Global ID：202202225749778477
• Description of saturation distribution of EDZ by stochastic differential equation　　　　　　　　　　　　　　　
  水尾華月; 富樫陽太; 長田昌彦; 相澤恵悟; 亀谷裕志
  地盤工学研究発表会(Web), Volume：56th, 2021
  J-Global ID：202202244907828431
• A METHOD FOR DETERMINATION OF ANISOTROPIC PARAMETERS OF ROCK MASSES ASSUMING TRANSVERSELY ISOTROPIC BODY BY IN-SITU TORSIONAL SHEAR TEST FOR ROCK MASSES
  富樫 陽太; 菊本 統; 谷 和夫
  Volume：42, First page：262, Last page：267, 09 Jan. 2014
  Japanese
  ISSN：1880-7623, CiNii Articles ID：40020163228

• 大断面函体推進における摩擦低減材の力学特性とその試験　　　　　　　　　　　　　　　
  梅津 拓未,富樫 陽太,中村 智哉,長田 昌彦
  Jan. 2025
• 田下凝灰岩を用いた角柱供試体の単純せん断試験と供試体寸法が強度特性に与える影響　　　　　　　　　　　　　　　
  佐藤 礁; 富樫 陽太; 小田部 晏彦; 長田 昌彦
  Jan. 2025
  Oral presentation
• 原位置岩盤試験データベースによる岩盤せん断試験の統計解析　　　　　　　　　　　　　　　
  船山稜真; 富樫陽太; 小田部晏彦; 谷和夫
  Nov. 2024
  Japanese, Oral presentation
• Deformation anisotropy of sedimentary rock sampled from deep seabed near subduction zone　　　　　　　　　　　　　　　
  Togashi Y; Kikumoto M; Tani K; Hosoda K; Ogawa K
  ISRM Int. sym. YSRM 2019 & REIF 2019, Dec. 2019, [International conference]
  English, Oral presentation
• Pore air pressure measurement at Mont Terri Rock Laboratory, Switzerland　　　　　　　　　　　　　　　
  Osada M; Takemura T; Togashi Y; Goshima S
  ISRM Int. sym. YSRM 2019 & REIF 2019, Dec. 2019, [International conference]
  English, Poster presentation
• Determination of anisotropic deformability parameters of tuff by a single triaxial test　　　　　　　　　　　　　　　
  Togashi Y; Kikumoto M; Tani K
  Oct. 2019, [International conference]
  English, Oral presentation
• Anisotropic deformation characteristics of soft mudstone via measuring full strain tensor components during triaxial compression　　　　　　　　　　　　　　　
  Togashi Y; Kikumoto M; Tani K; Hosoda K; Ogawa K
  ISRM Congress 2019, Sep. 2019, [International conference]
  English, Oral presentation
• Non-axisymmetric and/or non-elementary response of anisotropic tuff in axisymmetric, elementary triaxial test　　　　　　　　　　　　　　　
  Togashi Y; Kikumoto M; Tani K; Hosoda K; Ogawa K
  Jun. 2019, [International conference]
  English, Oral presentation
• Triaxial and Torsional Shear Tests for Anisotropic Rock Masses　　　　　　　　　　　　　　　
  Togashi Y
  ISRM Int. Sym. 10th Asian Rock Mechanics Symposium, Oct. 2018, [Invited], [International conference]
  English, Invited oral presentation
• Assessment of anisotropic deformation properties of a tuff by a single test on a single specimen,　　　　　　　　　　　　　　　
  Togashi, Y; Kikumoto, M; Tani, K; Hosoda, K; Ogawa, K
  EUROCK2018, May 2018, [International conference]
  English, Oral presentation
• Stiffness anisotropy in sedimentary rocks: New innovation　　　　　　　　　　　　　　　
  Togashi, Y
  One-Day Workshop on Advanced Laboratory Soil Testing, May 2018, [Invited], [International conference]
  English, Invited oral presentation
• 非開削推進工法による地表面への影響を検討するための小型土槽実験　　　　　　　　　　　　　　　
  板谷創平; 富樫陽太; 仲山貴司; 岡野法之
  Jan. 2018, [Domestic conference]
  Japanese
• 端面摩擦が堆積軟岩の応力ひずみ特性に与える影響　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫; 細田光一; 小川浩司
  Jan. 2018, [Domestic conference]
  Japanese
• エレメント推進を模した矩形断面の土槽掘削実験　　　　　　　　　　　　　　　
  板谷創平; 富樫陽太; 仲山貴司; 岡野法之
  Nov. 2017, [Domestic conference]
  Japanese
• A new testing apparatus to excavate rectangular section for under pass tunnel construction　　　　　　　　　　　　　　　
  Togashi, Y; Nakayama, T; Itaya, S; Hondo, T; Okano, N
  GEOMATE2017, Nov. 2017, [International conference]
  English, Oral presentation
• 矩形断面掘削時の地表面変位応答の予測　　　　　　　　　　　　　　　
  西山和宣; 仲山貴司; 富樫陽太; 岡野法之
  Jan. 2017, [Domestic conference]
  Japanese
• 層理を含む凝灰岩の三軸応力下における非軸対称変形と異方剛性の測定　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫; 細田光一; 小川浩司
  Jan. 2017, [Domestic conference]
  Japanese
• 矩形断面掘削時の土圧変化を考慮した応力非一様解放に伴う地表面変位応答　　　　　　　　　　　　　　　
  西山和宣; 仲山貴司; 富樫陽太; 岡野法之
  Nov. 2016, [Domestic conference]
  Japanese
• A method of triaxial testing for determining constitutive parameters of anisotropic rocks using a single specimen　　　　　　　　　　　　　　　
  Togashi, Y; Kikumoto, M; Tani, K
  ARMA 50th US Rock Mech. sym., Jun. 2016, [International conference]
  English, Oral presentation
• トンネル・地下構造物の変状監視における無線センサの活用　　　　　　　　　　　　　　　
  中村智哉; 津野究; 富樫陽太; 蒲池秀矢; 大木裕久
  Jan. 2016, [Domestic conference]
  Japanese
• 異方性岩盤の変形特性を特定する三軸試験　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫
  Jan. 2015, [International conference]
  English
• A method for determining anisotropic parameters for transversely isotropic rocks by in-situ torsional shear test　　　　　　　　　　　　　　　
  Togashi, Y; Kikumoto, M; Tani, K
  ISRM Int. Sym. 2014 & 8th Asian Rock Mech. Sym., Oct. 2014, [International conference]
  English
• 原位置岩盤ねじりせん断試験による面内等方弾性体を仮定した岩盤の変形特性の異方性の特定方法　　　　　　　　　　　　　　　
  富樫陽太; 菊本統; 谷和夫
  Jan. 2014, [Domestic conference]
  Japanese
• Proposal of analysis methods for test results of the new in-situ rock mass test　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K
  14th JSCE Summer Sym., Sep. 2012, [International conference]
  English
• 積層供試体の弾性波速度計測による不連続面での遅延時間の検討　　　　　　　　　　　　　　　
  富樫陽太; 谷和夫; 岡田哲実; 佐藤浩章
  Jan. 2012, [Domestic conference]
  Japanese
• Analysis for variations of test results of rock shear tests　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K
  ISRM Int. Sym. 2012 & 7th Asian Rock Mech. Sym., 2012, [International conference]
  English
• Delay times of elastic waves at discontinuities measured in laminated specimens　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K; Okada, T; Sato, H
  GEOMAT2011, Sep. 2011, [International conference]
  English
• Statistical analysis of strength properties by rock shear tests based on rock mass classification systems of JGS　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K
  4th Korea-Japan Geotech. Workshop, Jul. 2011, [International conference]
  English
• 岩盤せん断試験の粘着力とせん断抵抗角のブロックの挙動を考慮した分析　　　　　　　　　　　　　　　
  富樫陽太; 谷和夫
  Jan. 2011, [International conference]
  English
• Relationships between strength properties obtained by rock shear tests and those by block shear tests　　　　　　　　　　　　　　　
  Togashi, Y; Tani, K
  ISRM Int. Sym. 2010 & 6th Asian Rock Mech. Sym., Oct. 2010, [International conference]
  English, Oral presentation
• 原位置岩盤試験DBに基づく岩盤せん断試験から得られる粘着力とせん断抵抗角の分析　　　　　　　　　　　　　　　
  富樫陽太; 谷和夫
  Jan. 2010, [International conference]
  English

• 2020 - Present
  環境社会デザイン実験
• 2019 - Present
  微分方程式
• 2019 - Present
  数学演習
• 2018 - Present
  建設工学演習（地盤工学担当）
• 2018
  情報基礎

• JAPAN SOCIETY OF CIVIL ENGINEERS
• THE JAPANESE GEOTECHNICAL SOCIETY

• Development of techniques for identifying deformation anisotropy in unsaturated sedimentary rocks, extension to strength anisotropy identification and modeling　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 01 Apr. 2024 - 31 Mar. 2028
  Saitama University
  Grant amount(Total)：18460000, Direct funding：14200000, Indirect funding：4260000
  Grant number：24K00976
• トンネルの切羽安定問題におけるアーチ作用の予測法の開発　　　　　　　　　　　　　　　
  Apr. 2024 - Mar. 2025
  Principal investigator
• Development of face stability theory considering progressive failure due to tunnel excavation　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Early-Career Scientists, 01 Apr. 2021 - 31 Mar. 2024
  Saitama University
  Grant amount(Total)：4680000, Direct funding：3600000, Indirect funding：1080000
  Grant number：21K14238
• Development of a method to evaluate permeability of rock using barometric fluctuation　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), 01 Apr. 2020 - 31 Mar. 2024
  Saitama University
  Grant amount(Total)：18070000, Direct funding：13900000, Indirect funding：4170000
  Grant number：20H02238
• 大断面函体推進における摩擦低減材の性能強化　　　　　　　　　　　　　　　
  Oct. 2022 - Mar. 2024
  Principal investigator
  Grant number：22704167
• ねじりを利用した岩石角柱供試体の単純せん断試験方法の開発　　　　　　　　　　　　　　　
  Oct. 2022 - Sep. 2023
  Principal investigator
  Grant number：22683015
• 降雨に伴う大規模斜面崩壊の予測に資する堆積岩の不飽和強度特性の検討　　　　　　　　　　　　　　　
  Mar. 2021 - Mar. 2022
  Principal investigator
• 函体推進工法による線路下アンダーパストンネル建設 における摩擦低減材の開発　　　　　　　　　　　　　　　
  Nov. 2020 - Mar. 2022
  Principal investigator
• 飽和度の変化に伴う堆積岩の変形異方性と放射性廃棄物の合理的な埋設方法に関する研究　　　　　　　　　　　　　　　
  Oct. 2018 - Mar. 2021
  Principal investigator
  Competitive research funding
• 三軸試験による堆積軟岩の異方剛性およびその卓越方向の特定　　　　　　　　　　　　　　　
  Aug. 2018 - Mar. 2020
  Principal investigator
  Competitive research funding
• Sep. 2013 - Sep. 2013
  Principal investigator
  Competitive research funding

• 地下構造物の施工法に使用する摩擦低減材の材料試験装置と材料試験方法　　　　　　　　　　　　　　　
  Patent right
• 地下構造物の施工法及びそれに使用する摩擦低減材　　　　　　　　　　　　　　　
  Patent right
• 岩石の直交異方弾性の特定方法　　　　　　　　　　　　　　　
  Patent right
• 掘削工法模擬装置　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6498624
• 新設・既設地下構造物の接続構造　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6474653
• 風速計測装置及び変状評価装置　　　　　　　　　　　　　　　
  Patent right
• トンネル内の列車風を利用した風力発電方法　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6437350
• 覆工エレメント　　　　　　　　　　　　　　　
  Patent right
• トンネル内の列車風を利用したトンネル覆工の変形計測方法　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6293691
• 風速計測を用いたトンネル樋の目詰まり計測方法　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6284892
• 三軸試験装置及び三軸試験方法　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6222659
• 原位置岩盤試験方法および装置　　　　　　　　　　　　　　　
  Patent right
  Patent/Registration no：特許6112663
• トンネル掘削機　　　　　　　　　　　　　　　
  Patent right