摘要
针对现有扩孔理论无法考虑土体部分排水条件问题,基于ABAQUS,采用修正剑桥模型(MCC)描述土体的应力-应变关系,建立部分排水条件下柱孔扩张数值模型,开展不同扩孔速率条件下的柱孔扩张数值分析。数值模型的计算过程分为初始、地应力平衡、载荷3个分析步,在载荷步中,对模型右边界施加与初始孔压相等的孔压来模拟排水条件,改变模型左边界的位移实现扩孔的过程,修改载荷步的计算时长来控制扩孔速率,并通过将数值解答与完全排水、完全不排水2种极限排水条件下的理论解答做对比,验证了数值模型的可靠性。针对修正剑桥模型5个本构参数(压缩参数λ,回弹参数κ,泊松比ν′,应力比M,超固结比R)开展参数分析,获得了部分排水条件下柱孔扩张后孔壁处土体有效应力和超孔压的变化规律。结果表明:λ仅影响接近完全排水段的土体应力,对超孔压基本无影响;参数κ对于部分排水段的土体应力和超孔压略有影响;当ν′>0.3后,可以明显发现其对有效应力和超孔压的影响增大;M的增加使得完全排水段和部分排水段的有效应力呈现出增大的趋势;考虑土体应力历史R时,在高超固结比情况下,完全排水段附近的有效应力曲线梯度为0的范围随着R的增大而增大,改变排水条件对土体应力的影响较小,同时高超固结比使得超孔压的消散速度更快;将5个独立变量进行对比分析发现,R对超孔压的影响明显大于其他4个参数。
Aimed at the problem that existing cavity expansion theory cannot consider the partially drained condition of the soil, a numerical model of cylindrical cavity expansion under partially drained condition was established through ABAQUS software, combined with the modified Cam clay model(MCC), which was used to describe the stress-strain relationship of the soil. And the numerical analysis of cylindrical cavity expansion under different expansion rates was conducted. The calculation process of the numerical model was divided into three steps: initial, geo-stress balance, and loading. In the loading step, the pore pressure, which equals to the initial pore pressure, was applied to the right boundary of the model to simulate the drained condition, the displacement of the model’s left boundary was changed to realize the expansion process, and expansion rates were controlled by modifying the calculation time of the loading step. The reliability of the numerical model was verified by comparing the numerical solutions with the theoretical solutions under two extremely drained conditions of completely drained and completely undrained. Parameter analysis was carried out for the five constitutive parameters(λ,κ,ν~′,M,R) of the MCC model, and changes of effective stress and excess pore pressure of the soil at the cavity wall after cavity expansion under partially drained condition were obtained. The results show that λ only affects the soil stress, which closes to the completely drained section, and basically has no effect on the excess pore pressure. The parameter κ has a slight influence on the soil stress and excess pore pressure in the partially drained section. When ν~′>0.3, it can be clearly found that the influence on effective stress and excess pore pressure increases. The increase of M makes the effective stress of the completely drained section and the partially drained section show an increasing trend. Considering the soil stress history R, in the case of high over consolidation ratio, the range, which
作者
周航
余昊
王增亮
李籼橙
陈志雄
ZHOU Hang;YU Hao;WANG Zeng-liang;LI Xian-cheng;CHEN Zhi-xiong(Key Laboratory of New Technology for Construction of Cities in Mountain Area of Ministry of Education,Chongqing University,Chongqing 400045,China;School of Civil Engineering,Chongqing University,Chongqing 400045,China)
出处
《长安大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2021年第1期11-20,共10页
Journal of Chang’an University(Natural Science Edition)
基金
国家自然科学基金项目(51978105,51778092)。
关键词
道路工程
数值分析
部分排水
柱孔扩张
修正剑桥模型
有效应力
超孔压
road engineering
numerical analysis
partially drained
cylindrical cavity expansion
MCC model
effective stress
excess pore pressure
