常压至高压下砂土强度、变形特性试验研究

发布时间：2018-06-04 10:52

本文选题：土力学 + 高压　；参考：《岩石力学与工程学报》2016年11期

【摘要】：砂土材料常压至高压下的强度、变形特性是构建砂土模型的首要问题。开展3种粒组砂土8 MPa围压范围内的等向压缩试验以及0.2~6.4 MPa围压范围内的三轴剪切试验,将砂土常压至高压范围内的力学特性进行系统分析,以获得能够将常压至高压范围内的强度、变形特性进行统一描述的力学参数。通过研究发现:(1)砂土在高压下出现一定量的颗粒破碎,改变了砂土的剪切耗能机制,使得砂土三轴压缩剪切由剪胀软化特征向剪缩硬化特征转变;(2)砂土材料的三轴压缩剪切峰值应力比受砂土粒径、围压共同影响,M-C强度准则在高压条件下不再适用;而残余应力比则基本不受粒径、围压的影响,是典型的无黏性摩擦型岩土力学参数,应作为砂土基本力学特性指标;(3)砂土材料在常压至高压范围内的剪切过程中存在较明显的临界状态现象,临界状态曲线与等向压缩曲线形态相同均呈指数衰减型并在高压条件下产生交叉,两者共同构成砂土材料的状态区间能够体现常压至高压范围内的剪胀与剪缩特征。
[Abstract]:The strength and deformation characteristic of sand material under pressure and high pressure is the first problem to construct the sand model. The isotropic compression test and the three axis shear test within the confining pressure range of 0.2~6.4 MPa are carried out in the confining pressure range of 3 kinds of sand soil in the confining pressure range of 8 MPa, and the mechanical characteristics of the sand soil under the pressure range are systematically analyzed in order to obtain the normal pressure. The strength and deformation characteristics are uniformly described in the high pressure range. Through the study, it is found that (1) a certain amount of particle breakage occurs under high pressure, which changes the shear energy dissipation mechanism of the sand, making the three axial compression shear from the dilatancy softening characteristic to the shear hardening characteristics; (2) the three axis compression shear of the sand material. The peak stress ratio is influenced by the sand particle diameter and confining pressure, and the M-C strength criterion is no longer applicable under high pressure, but the residual stress ratio is basically not affected by the particle diameter. The influence of the confining pressure is the typical non viscous frictional geotechnical parameters, which should be used as the basic mechanical characteristic index of the sand soil; (3) the shear process of the sand material in the range of atmospheric pressure to high pressure. There are obvious critical state phenomena, and the critical state curves are exponentially attenuated with the ISO compression curves and intersecting under high pressure conditions. The state interval of the sand material can reflect the dilatancy and shear shrinkage characteristics in the range of atmospheric pressure to high pressure.
【作者单位】：苏州科技大学土木工程学院;中国矿业大学深部岩土力学与地下工程国家重点实验室;
【基金】：江苏省高校自然科学研究面上项目(15KJB170017) 住房和城乡建设部科技计划资助项目(2015 K4 034) 国家自然科学基金面上项目(51378327)~~
【分类号】：TU441

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