砂土剪胀软化、剪缩硬化统一本构的显式计算  

Explicit calculation of sand unified model combining shear dilatancy softening and shear shrinkage hardening

作　　者：陆勇 周国庆[2] 杨冬英[1] 宋家庆 LU Yong;ZHOU Guo-qing;YANG Dong-ying;SONG Jia-qing(School of Civil Engineering,Suzhou University of Science and Technology,Suzhou,Jiangsu 215011,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining & Technology,Xuzhou. Jiangsu 221116,China)

机构地区：[1]苏州科技大学土木工程学院,江苏苏州215011 [2]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116

出　　处：《岩土力学》2019年第3期978-986,共9页Rock and Soil Mechanics

基　　金：江苏省高校自然科学研究面上项目(No.15KJB170017);江苏省建设系统科技项目(No.2017ZD204);苏州科技大学科研基金自然科学项目(No.ZL2873);国家自然科学基金项目(No.51508369)~~

摘　　要：密实砂土通常表现出常压下剪胀软化特性、高压下剪缩硬化特性,不同的力学特性对岩土体受荷力学行为的演化有着重要影响。构建能够反映剪胀软化、剪缩硬化特性的本构模型并且实现其数值模拟计算,则是分析剪胀软化材料的受荷响应特征以及完善岩土体渐进破坏理论所要解决的一个重要科学问题。研究中首先对已构建的能够反映密实砂土相关力学特性的砂土统一本构模型进行描述,分析该模型的数值计算关键问题。基于显式方法进行模型应力积分程序的二次开发,应力积分过程中采用应变空间中的加卸载准则并对模型破坏面进行光滑处理以满足计算过程中的加卸载判断以及塑性应变方向的确定。通过计算实例验证了显式方法能够克服剪胀、软化问题的计算难点,可以实现对剪胀软化、剪缩硬化材料的力学行为分析计算。Dense sand normally exhibits shear dilatancy softening under normal pressure and shear shrinkage hardening under high pressure. Therefore, unified model of sand and its numerical implementation is an important scientific problem for describing the loading response of dilatancy softening material, and it will also promote the progressive failure theory. In this study, the unified model of sand which reflects the mechanical properties of dense sand under normal and high pressure is firstly described, and then the key problem of numerical calculation for the model is analyzed. By using the explicit method, the secondary development of stress integration program is carried out. In the process of stress integration, loading-unloading criterion within strain space and smoothed failure surface are used for satisfying the judgment of loading condition and determination of plastic strain direction. An example is given to prove that the explicit method can overcome the difficulties in calculation for dilatancy and softening. This method shows a good way to analyze the mechanical behavior for materials with dilatancy softening and shrinkage hardening characteristics.

关 键 词：砂土 剪胀 软化 显式积分 

分 类 号：TU441.4[建筑科学—岩土工程]