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7. Undrained cyclic triaxial testing on sand with non-plastic fines content cemented with microbially induced CaCO3

Author

Sasaki, T and Kuwano, R

Subjects
Civil Engineering, Soil Sciences, Other Engineering, Geological & Geomatics Engineering
Abstract

Sandy materials with or without a non-plastic fines content, including sand recovered from Urayasu City after the 2011 Great East Japan Earthquake, were employed and solidified with CaCO3 produced by a bacterial species named Sporosarcina pasteurii in a study. The solidified materials were prepared in a triaxialcell and then subjected to undrained cyclic loading. The results were analyzed to provide insight into the effectiveness of MICP to sand with a non-plastic fines content in mitigating the liquefaction potential.

Published
2016

32. Estimating stress wave velocity in granular materials: Apparent particle size dependency and appropriate excitation frequency range

Author

Dutta, TT, Otsubo, M, Kuwano, R, and O'Sullivan, C

Subjects
0403 Geology
Abstract

There is a lack of consensus in the literature on the influence of the median particle size on stress wave velocity in cohesionless soils. For assemblies of spherical particles with Hertzian contacts, the stress wave velocities should not depend on particle size. However, a link between particle size and stress wave velocity has been reported in laboratory experiments. In this study, to identify the reasons for the discrepancies, wave velocity measurements were performed using planar piezoelectric transducers on four different sizes of alkaline glass beads and natural silica sands. The experimental results indicate that shear and compression wave velocities are independent of the median particle size. In accordance with dispersion theory, both the experiments and discrete element simulations demonstrate that the maximum frequency that can propagate through a granular assembly (i.e., the lowpass frequency) reduces with increasing median particle size. The relationship between the lowpass frequency and the input signal frequency determines the quality of the received signal and hence the accuracy of the interpreted stress wave velocity data. To accurately estimate shear wave velocities, the selected input frequencies should match those frequencies which exhibit the largest gain factors and input frequencies should not exceed the half of lowpass frequency. To determine the compression wave velocity, it is suggested to adopt the start to start method and to choose an input frequency which is slightly lower than the lowpass frequency.

Published
2019

40. Characterization of soil stiffness anisotropy at small strains based on phase velocities of shear waves measured by novel testing apparatus

Author

Liu Junming, Otsubo Masahide, and Kuwano Reiko

Subjects
granular soil, small-strain stiffness anisotropy, phase velocity, soil testing apparatus, Environmental sciences, GE1-350
Abstract

For the characterization of soil stiffness anisotropy at small strains and the calculation of soil elastic constants derived from the cross-anisotropic model, it is important to obtain stress wave phase velocities of soils in both principal and oblique directions. This study developed an original eight-prismatic shape apparatus equipped with disk-shaped shear plates to measure shear (S-) wave phase velocities (Vphase) in multiple directions, and four granular materials of various shapes were tested by this apparatus under isotropic confinement. Experimental results confirm the capability of the new apparatus and reveal that both S-wave propagation and oscillation directions are sensitive to soil inner fabric, i.e., Vs changes with the variation of either S-wave propagation or oscillation direction. Based on the experimental observations, it is suggested to keep the same S-wave oscillation direction when measuring Vs in multiple propagation directions so that the corresponding shape of the S-wave surface (polar plots of Vs in arbitrary propagation directions) is more precise to reflect the small-strain stiffness anisotropy of soils.

Published
2024
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41. Sensitivity of G0 and stress-strain relation of geomaterials to grain shape and surface roughness

Author

Otsubo Masahide, Li Yang, and Kuwano Reiko

Subjects
grain shape, surface roughness, stiffness, strength, Environmental sciences, GE1-350
Abstract

It is empirically known that the packing property and mechanical responses of cohesionless granular materials are influenced by grain shape. For example, the attainable range of void ratio depends on grain shape; angular materials tend to exhibit greater friction angles. Besides, shear wave velocity (Vs ) and small-strain shear modulus (G0 ) of sphere assemblies are affected by surface roughness. However, consensus has yet to be reached on the combined effect of grain shape and surface roughness on G0 and stress-strain relation. This contribution aims to evaluate the shape-roughness combined effect on the strain-dependent mechanical responses of granular materials. Three groups of glass beads having different grain shapes and a silica sand were used, and their grain surfaces were roughened through a systematic procedure using a milling machine. In total, eight materials were subjected to triaxial compression after measurement of Vs. The experimental results reveal that the stress-strain relation of angular particles is remarkably affected by the surface roughness, whereas the roughness effect on the stress-dependent variation in G0 is limited for angular particles.

Published
2024
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42. Contractancy and shear behavior of extremely loose structure soils with particle breakage in saturated and unsaturated conditions

Author

Sato Itsuki, Kuwano Reiko, and Otsubo Masahide

Subjects
volcanic pumice, particle crushing, particle breakage, unsaturated, triaxial test, Environmental sciences, GE1-350
Abstract

Pumices with high pore voids of volcanic origin are distributed throughout Japan and are the causal layer of slope failures. In many cases of surface failures, it is difficult to assume that the resulting layers are fully saturated. The high waterholding capacity of the pumice suggests that they were deposited in an unsaturated state with a high degree of saturation. In this study, saturated triaxial compression tests and fully undrained unsaturated triaxial compression tests were conducted on artificially produced pumice and natural pumice while measuring the amount of crushing. This is to clarify the relationship between the crushing and mechanical properties of pumice with porous particles, which are often the cause of such disasters, and their behaviour under unsaturated conditions. The results showed that the pumice stones have an ultra-high pore structure. Moreover, pumice with porous particles reached a steady state under both saturated and highly saturated unsaturated conditions, and the amount of crushing increased under highly saturated unsaturated conditions.

Published
2024
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43. Candidate genes in panic disorder: Meta-analyses of 23 common variants in major anxiogenic pathways

Author

Howe, A.S., Buttenschøn, H.N., Bani-Fatemi, A., Maron, E., Otowa, T., Erhardt, A., Binder, E.B., Gregersen, N.O., Mors, O., Woldbye, D.P., Domschke, K., Reif, A., Shlik, J., Kõks, S., Kawamura, Y., Miyashita, A., Kuwano, R., Tokunaga, K., Tanii, H., Smoller, J.W., Sasaki, T., Koszycki, D., De Luca, V., Howe, A.S., Buttenschøn, H.N., Bani-Fatemi, A., Maron, E., Otowa, T., Erhardt, A., Binder, E.B., Gregersen, N.O., Mors, O., Woldbye, D.P., Domschke, K., Reif, A., Shlik, J., Kõks, S., Kawamura, Y., Miyashita, A., Kuwano, R., Tokunaga, K., Tanii, H., Smoller, J.W., Sasaki, T., Koszycki, D., and De Luca, V.

Abstract

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case–control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel–Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15–1.40, P=2.49 × 10−6), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53–0.79, P=1.81 × 10−5) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14–1.42, P=2.49 × 10−5) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07–1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14–1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07–1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07–1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate lar

Published
2016

44. Candidate genes in panic disorder:meta-analyses of 23 common variants in major anxiogenic pathways

Author

Howe, A. S., Buttenschön, Henriette N, Bani-Fatemi, A., Maron, E, Otowa, T, Erhardt, A, Binder, Elisabeth B., Gregersen, N. O., Mors, O, Woldbye, D. P., Domschke, K, Reif, A, Shlik, J., Kks, S., Kawamura, Y, Miyashita, A., Kuwano, R., Tokunaga, K, Tanii, H., Smoller, J. W., Sasaki, T., Koszycki, D., De Luca, Vincenzo, Howe, A. S., Buttenschön, Henriette N, Bani-Fatemi, A., Maron, E, Otowa, T, Erhardt, A, Binder, Elisabeth B., Gregersen, N. O., Mors, O, Woldbye, D. P., Domschke, K, Reif, A, Shlik, J., Kks, S., Kawamura, Y, Miyashita, A., Kuwano, R., Tokunaga, K, Tanii, H., Smoller, J. W., Sasaki, T., Koszycki, D., and De Luca, Vincenzo

Abstract

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15-1.40, P=2.49 × 10 -6), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53-0.79, P=1.81 × 10 -5) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14-1.42, P=2.49 × 10 -5) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07-1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14-1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07-1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07-1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorpora

Published
2016

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