颗粒形状和中主应力对砂土力学特性耦合影响的真三轴试验研究  

A true triaxial experimental study on the coupled effect of particle shape and intermediate principal stress on the mechanical properties of sand

作　　者：吴杨 容浩俊 王金莲[2] 李能 吴毅航 崔杰[1] WU Yang;RONG Haojun;WANG Jinlian;LI Neng;WU Yihang;CUI Jie(School of Civil Engineering,Guangzhou University,Guangzhou,Guangdong 510006,China;Guangzhou Marine Geological Survey,Guangzhou,Guangdong 511458,China)

机构地区：[1]广州大学土木工程学院,广东广州510006 [2]广州海洋地质调查局,广东广州511458

出　　处：《岩石力学与工程学报》2023年第2期497-507,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51908153,52178322);广东省基础与应用基础研究基金资助项目(2021A1515012096)。

摘　　要：天然状态下,砂土地基处于三维受力状态。经过复杂的沉积和搬运作用,砂颗粒形态各异,进一步影响其在受力状态下的接触形式。砂土的宏观力学响应同样会受到微观颗粒形状的影响。研究针对不同比例石英砂和玻璃圆(碎)珠的混合颗粒试样开展真三轴剪切试验,研究三维应力状态下颗粒形状对砂土力学特性的影响。结合动态颗粒图像分析技术定量识别颗粒形状参数,获得颗粒形状参数伴随玻璃珠掺量增加的变化趋势。查明中主应力与颗粒形状对砂土宏观力学响应的耦合影响机制。试验结果表明:具有规则颗粒形状的玻璃珠-石英砂混合物能有效抑制试样剪胀特性。对于给定的中主应力系数,玻璃珠-石英砂混合颗粒材料的峰值摩擦角随着颗粒形状不规则度的增加而增大,峰值强度对应的大主应变随着颗粒形状不规则度的增加而减小。玻璃珠-石英砂混合物的峰值强度伴随中主应力系数的变化趋势可以较好地通过岩土材料经典的三维强度理论进行预测。Sand grains are under three-dimensional stress condition in natural state.Particle shape varies due to complex physical and sedimentation process,further affecting the contact mode under loading.The macroscopic mechanical properties of sand are influenced by microscopic particle shape.This study carries out true triaxial tests on mixture of silica sand and round(crushed)glass beads,examines the effect of particle shape on the mechanical properties of sand under three-dimensional stress condition.In combination of dynamic particle image analysis technique to quantitatively analyze the particle shape,the varying tendency of particle shape parameters with glass beads content is acquired.The coupled effect mechanisms between the intermediate principal stress and particle shape on the macroscopic mechanical response are investigated.The test results show that the glass beads-silica sand mixture with regular particle shape effectively suppresses the dilation characteristics of the mixture.For a given medium principal stress level,the peak friction angle of the glass beads-silica sand mixture increases with increasing particle shape irregularity,and the large principal strain corresponding to the peak strength decreases with increasing particle shape irregularity.In this experimental study,the varying tendency in peak strength of glass beads-silica sand mixture accompanied by the variation in the intermediate principal stress can be well predicted by the classical failure criterion.

关 键 词：土力学 中主应力系数 真三轴试验 颗粒形状 峰值摩擦角 破坏准则 

分 类 号：TU43[建筑科学—岩土工程]