When existing masonry walls are dry masonry structures, the piled stone and cobblestone layers are not integrated. Therefore, concrete is laid in front of masonry walls as a countermeasure. However, such construction is difficult when immovable equipment is installed in front of masonry walls along railway lines. In this study, we developed a grout filling method using the back of piled stone as a replacement and performed indoor model and field grout filling tests. We observed that plastic grout exhibited high filling performance as grouting because of its low fluidity and low leakage from piled stone joints, and we described the grout filling method. To verify the reinforcement effects of the proposed method, we performed shaking table tests using the model and confirmed that piled stone and cobblestone layers exhibited integrated behavior by backfilling. In addition, we found that the residual displacement of the wall body was inhibited by applying the rod-shaped reinforcing material, resulting in an integrated overturning mode even at a higher vibration acceleration.
Slope failures during rainfall are likely to be induced by an increase in soil water content, an increase in shear stress due to an increase in soil own weight, and a decrease in shear strength due to loss of suction. However, the actual slopes are so complicated that to grasp the process and mechanism of slope failure in detail, which is applicable to predictions or countermeasures, has been a long-standing issue. In the present study, we developed a new centrifugal field rainfall generation system with making a uniform rainfall distribution during centrifugal model experiment, to understand the penetration behavior of rain water into the embankment ground and deformation behavior at the time of collapse by using this system. Moreover, various experiments were conducted to estimate the possibility of predicting the occurrence of slope failure by the data obtained from measuring equipment and the effect of countermeasures. As a result, it was confirmed that groundwater level was generated by infiltration of rainwater and slope failure occurred. In addition, it was revealed that installation of drainage pipes has the effect of suppressing the rise in groundwater level due to the drainage effect.
The property of binary granular mixture, which is one of coarse grained soil, is influenced by the skeletal structure with respect to the content of large particles. For the purpose of evaluating the limit large particle content of small particle skeleton structure we proposed a new microscopic model, conducted angle of repose and void ratio experiment, and evaluated the skeleton structure using the microscopic model. A new parameter introduced to the microscopic model that consider the anisotropy of the shape and arrangement of large particles. From the angle of repose and void ratio experiment, the larger and more distorted large particle and the larger the void ratio of small particle became the lower limit large particle content of the small particle skeleton structure was. From the evaluation of the skeleton structure by microscopic model, it was possible to estimate limit large particle content of small particle skeleton structure by grain size analysis of large particle and minimum density test of small particle based on the estimation formula.
There is a ground improvement technology called the permeation grouting method, which is used as a liquefaction countermeasure for sandy ground. The ground improved by the permeation grouting method, has a large spatial variability in material property such as shear strength compared to natural soil deposits. The spatial variability in the shear strength of the improved ground is anticipated to affect the bearing capacity. Therefore, a bearing capacity evaluation based on the performance specification is required considering the spatial variability of the ground. In this paper, a random field theory is used to represent the spatial variability of shear strength of the improved ground, and a bearing capacity analysis is conducted by Monte Carlo simulation using the finite element method and the shear strength reduction method. The effect of spatial variability of the improved ground on the reliability of bearing capacity, failure mechanism and bearing capacity is discussed stochastically and statistically.