基于土极限应变的建筑物纠倾方法模拟与工程应用

Simulation of rectification method based on soil ultimate strain for leaning building and engineering applications

水平掏土法是建筑物纠倾常用方法之一,确定临界掏土孔间距是建筑物安全平稳回倾的关键,其与土体性质、上部荷载等因素有关,目前主要依靠工程经验确定。针对建筑物掏土纠倾法,采用有限元极限分析方法,将土体极限应变作为破坏准则,并通过立方体模型数值分析得到土体极限应变值,超过极限应变定义为土体破坏。在此基础上,通过数值分析研究了工程中常见的粉土和黏土在不同土体参数、上部荷载和掏土孔间距等情况下,掏土孔周边土体应变达到并超过极限应变的演化过程,得到孔间土体的破坏面首先在孔侧边出现而后在孔间土体发展,将掏土孔间土体破坏面贯通作为纠倾极限状态,得到了不同土体参数和上部荷载情况下掏土孔间距建议值。最后将上述方法应用于对3个实际纠倾工程的掏土孔间距进行计算,结果表明,分析所得孔间距与实际工程的掏土孔间距较为接近。

Underexcavation is one of the most commonly used procedures for the rectification of leaning buildings.The determination of the limit hole spacing is the key process of the safe and steady rectification.The hole spacing is related to the soil properties and upper structural loading etc.and mainly determined by the engineering experiences at present.Finite element limit analysis method was adopted to simulate the building rectification.The ultimate strain criterion was taken as the failure criterion of the soil,and the ultimate strain was obtained by numerically loading the test cube.The failure area of the soil was determined based on the idea that the soil strain is larger than the ultimate strain.Further,numerical analysis on the silty and clay soil which are common in practice was done,and the evolution of the failure areas related to the different soil parameters,upper loadings etc.,were studied.It was found that the soil failure surface first appeared at the side of the hole and then developed between the holes.The failure area breaking through the soil between the holes was defined as the limit state of the rectification,and values of the hole spacing were suggested for different soil parameters and upper loadings.Finally,the research method was applied to three engineering projects.The results show that the hole spacing obtained from the finite element limit state method agrees well with the practical used values.