下伏空洞地基极限承载力与破坏模式上限有限元法

发布时间：2018-03-21 17:44

本文选题：空洞　切入点：上限法　出处：《岩土力学》2017年01期 　论文类型：期刊论文

【摘要】：地基极限承载力的确定对于下伏空洞地区基础设计和施工具有重要意义。采用上限有限元法对地基破坏时的极限状态进行数值模拟。首先,简要介绍上限有限元法的基本原理与计算过程;进而提出合理的计算假定,建立可考虑多种影响因素的计算模型;其次,利用上限有限元法计算出多种工况下的地基极限承载力上限解,按Tergaghi建议的地基承载力公式,得到承载力系数N_c、N_q、N_g,并对其影响因素进行分析;最后,根据大量的能量耗散图及速度场图提出3类典型的破坏模式,并对其影响因素进行分析。研究表明:随着内摩擦角j的增大,N_c和N_q均增大,而当j较大时,N_g才出现正数,且随着j增大而增大;随着空洞顶板厚度与基础宽度之比H/B的增大,N_c和N_q均增大。而当j较小时,N_g随着H/B的增大而减少;当j较大时,N_g随着H/B的增加而增加。N_c、N_q和N_g均随着D/B的增大而减少。下伏空洞地基存在3种典型的破坏模式:冲切破坏模式、冲切剪压破坏模式和Prandtl破坏模式。
[Abstract]:The determination of the ultimate bearing capacity of the foundation is of great significance for the design and construction of the foundation in the underground cavern area. The upper bound finite element method is used to simulate the limit state of the foundation when the foundation is destroyed. The basic principle and calculation process of the upper bound finite element method are briefly introduced, and the reasonable calculation assumption is put forward, and the calculation model which can take into account many kinds of influence factors is established. Secondly, Using the upper limit finite element method to calculate the upper limit solution of the ultimate bearing capacity of foundation under various working conditions, according to the formula of foundation bearing capacity suggested by Tergaghi, the bearing capacity coefficient of NCX / NQ / T / N / G is obtained, and the influencing factors are analyzed. Based on a large number of energy dissipation diagrams and velocity field diagrams, three types of typical failure modes are proposed, and the influencing factors are analyzed. The results show that: with the increase of the internal friction angle j, both C and N _ Q increase, but when j is larger, the positive number appears. With the increase of j, the ratio of the thickness of cavity roof to the width of foundation, the ratio of cavity roof thickness to the width of foundation, the ratio of cavity roof thickness to the width of foundation increases, but when j is smaller, the NG decreases with the increase of H / B, and the ratio of H- / B increases with the increase of the ratio of cavity roof thickness to base width. With the increase of H / B ratio, the number of NSCC / NQ and NG decreases with the increase of D / B. there are three typical failure modes: punching failure mode, punching shear failure mode and Prandtl failure mode.
【作者单位】：湖南大学岩土工程研究所;
【基金】：国家自然科学基金项目(No.51278187)~~
【分类号】：TU470

【相似文献】