胶结砂砾石层面直剪试验及破坏行为细观研究

本文采用宏观试验和细观模拟相结合的方法研究胶结砂砾石层面在剪切过程中的破坏行为．首先进行了不同法向应力作用下的胶结砂砾石层面直剪试验，获得了不同的剪切面破坏特征：随着法向应力的不断增加，剪切破坏面凹凸起伏程度、骨料脱落现象越发明显．其次为了深入探究层面破坏现象，按照室内试验采用的骨料级配粒径建立细观颗粒数值模型，结合物理试验对模型进行参数标定，并进行数值模型的层面直剪模拟和细观分析．结果表明，数值模型可以再现宏观直剪试验层面破坏特征；法向应力越大，层面区域颗粒发生错动和翻转的数量越多；层面破坏方式为颗粒间的张拉和剪切混合破坏，裂隙均集中在层面位置，随着法向应力的增加，裂隙的集中区域逐渐由“面”向“带”转变．

Direct Shear Test of CSG Interface and Meso Study on Failure Behavior

The failure behavior of construction interface of cemented sand gravel (CSG) in shear process is studied by the combination of macro test and micro simulation in this paper. Firstly, the direct shear tests of CSG interface under different normal stresses are carried out, and different failure characteristics of shear plane are obtained. It is found that with the increase of normal stress, the profile fluctuation of shear failure plane and the aggregate particle detachment phenomenon become more obvious. Secondly, in order to explore the interface failure phenomenon, a meso particle numerical model according to the aggregate grading particle size used in the physical test is established, the parameters of the model are calibrated based on the test, and the interface direct shear simulation and meso mechanism analysis of the numerical model are carried out. The results show that the numerical model can reproduce the failure characteristics of macro direct shear test. With the increase of normal stress, the number of particles that could dislocate and flip in the interface region increases. The failure mode is a mixed failure of tension and shear between the particles, and the cracks are concentrated in the interface region. As the normal stress increases, the region of crack concentration gradually changes from the “surface” style to the “band” style.