To use the batter piles foundations in the soft clay, it is necessary to design for the bending moment occurred by consolidation settlement. In this research, we measured the bending moment occurred on the batter piles due to consolidation settlement by centrifuge tests, and proposed an evaluation method of the bending moment. Furthermore, we cleared the variability of the bending moment in seismic situation by cyclic load test and seismic test. Based on these tests results, we proposed the design method for the batter piles on the seismic situation.
Single-well injection-withdrawal tests (SWIW) have the advantage of efficiently method for evaluating insitu solute transport. In order to investigate the effect of some parameters for breakthrough curve, we conducted sensitivity analysis by numerical simulation with ambient groundwater flow. Results showed that SWIW breakthrough curve is determined by lumped parameter (aperture/ longitudinal dispersivity/ total injection volume combined parameter), retardation factor, and ambient hydraulic gradient. Ambient hydraulic gradient must evaluate for specifying tracer transport, our method was available for estimate ambient hydraulic gradient from non-reactive tracer recovery.
Utilization of soil fractions recovered from disaster debris as geomaterials was strongly desirable after the 2011 East Japan earthquake and tsunami because the soil fraction accounted for a third of the approximately 30 million-ton disaster debris and tsunami deposits. Because the quality of recovered soils varied according to treatment systems at each site as well as the characteristics of original seabed sediments, clarification of material properties of recovered soils is important for future catastrophes. In this research, a total of 404 data, which were archived in Iwate Prefecture, were analyzed to verify particularly the following two issues: 1) the properties of the recovered materials as geomaterial and their relationships with treatment methods, and 2) variation in the quality with treatment progress. A series of analysis indicated that the soil fractions recovered from disaster debris mostly satisfy requirements for utilization as geomaterials and have quality equivalent to general geomaterials, regardless of treatment progress. Some of the chemical and physical properties are significantly affected by additive materials, such as crushed concrete and a steel slag-based material, applied for the purpose of improvement.
Crushed particles are obtained by crushing a solidified dredged marine deposit mixed with cement. It is convenient if they can be used as an alternative fill material for such as reclamation behind seawall. However, it is well known that the cement-mixed soil is deteriorated by the calcium leaching in seawater. In the case of the crushed particles, the deterioration might be accelerated with an increase in contact area between crushed particles and seawater, which make a significant negative impact on an internal friction angle of crushed particles. We examined the deterioration effect on mechanical properties of the cement-mixed soil and its crushed particles using the samples exposed under quasi-marine environment. The test results revealed that when the crushed particles are exposed for 50 years in seawater, the influence of deterioration cannot be ignored and if the crushed particles are used as an alternative fill material of sand/gravel, some measures to prevent the deterioration such as increasing cement content are required.
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%.
Mudflow of earthfill composed of volcanic porous sandy soil called Ninohe Shirasu occurred during the 2011 Tohoku earthquake under high water content conditions. After sampling the soil and remolding it, cyclic undrained triaxial tests for liquefaction strength and deformation properties were conducted under saturated and unsaturated conditions. Not only saturated soil but also unsaturated soils were liquefied. The liquefaction resistance of saturated soil was less than that of standard sand. The liquefaction resistance of unsaturated soil was about 1.5 times greater than that of saturated soil, but the safety factor was low value under actual ground condition. The initial equivalent Young's modulus of the soil was about 90 MN/m2.
The stone walls of Takamatsu Castle tower base have experienced serious damages such as bulging and cracks. Therefore, restoring works were carried out from 2007 to 2011. To start the restoring work, first of all, soil properties and simple bearing capacity tests were carried out to understand the compaction condition of embankment soil. Another compaction test by penetrating wood piles into gravely sand ground was carried out by simple dynamic cone penetration tests. Next, vibration characteristics of stone wall were measured by microtremor before and after the restoration works. Finally, self weight and dynamic deformation analysis of the tower base was carried out using the discrete element method (DEM). All the results of above analysis were compared and verified with the measured deformation value.
In the Pneumatic Flow Mixing Method, dredged soil is mixed with chemical binder in a pipeline during transporting by compressed air. In some applications, the stabilized soil is temporary placed at provisional site, and is excavated and reclaimed at the final site. In the cases, the stabilized soil in which the chemical reaction has already proceeded is disturbed during the excavation and transportation processes, which cause considerable decrease in the strength. It is important to investigate the soil disturbance effect for its further applications. The authors investigated the soil disturbance effect on the mechanical properties of cement stabilized soil. The unconfined compression tests were performed on three types of laboratory mixed cement stabilized Kaolin clay; stabilized soil without disturbance and disturbed after 3 or 7 days curing. The study has revealed that the soil disturbance influenced the stress - stain behavior of the soils considerably. In this paper, the soil disturbance effect is presented as well as the microscopic view of the stabilized soils.