建筑物掏土纠倾法单孔与多孔塑性区特性研究及工程应用

在建筑物水平掏土纠倾工程中，掏土孔间距是影响纠倾工程安全与工期的重要因素。为了快速准确地确定纠倾工程中的水平掏土孔间距，研究了单个掏土孔和多个掏土孔情况下孔周边土体塑性区发展特性。利用土体塑性力学分析计算得到了单孔下的孔周土塑性区半径，而后通过有限元模拟得到孔周土体塑性区半径的数值解，将孔周塑性区半径解析解与数值解进行了对比。并通过有限元数值模型研究了多个掏土孔相互影响情况下的塑性区发展规律，以孔间土体塑性区贯通时的距离作为掏土孔间距。考虑土体参数随机特性的影响，研究不同上部荷载作用下掏土孔间距的取值变化规律，上部面荷载与地基承载力特征值比值用p表示，孔间距与掏土孔直径比值用n表示。研究发现：多孔塑性区半径（孔间塑性区贯通时）是单孔塑性区半径的1.3倍左右;标准化荷载p与孔间距比值n二者呈线性关系;通过不同土体参数及上部荷载的不同情况下的p-n曲线，给出了掏土孔间距建议值。同时，将研究结果与三个实际工程进行对比，发现p-n曲线法与实际结果更为接近。

Study on plastic zone features around holes in underexcavation procedures for leaning buildings rectification and its applications

The hole spacing in the horizontal excavation procedure is the most important factor that affects the safety and efficiency of a particular project. To determine the horizontal hole spacing more accurately and quickly, the plastic zone behavior of the soil around the hole, considering the cases of one hole or multiple holes, were studied. Firstly, the plastic zone radius around a single hole was obtained by plasticity analysis. Then, the numerical solution of the plastic zone radius was obtained by finite element simulation. The numerical solution was compared with the analytical solution. Further, the plastic zone radius was studied for multiple holes through numerical simulations. The holes spacing was determined when the plastic zones cut through the soil between holes. Subsequently, the different soil parameters and upper loads were considered to determine the hole spacing. The dimensionless parameters of upper load to foundation bearing capacity ratio p, and the hole spacing to hole diameter ratio n, were adopted. The research results show that the plastic radius of the multiple holes (when the plastic zone cuts through the soil between the holes) is approximately 1.3 times that of the single hole. A linear relationship exists between p and n, and the p-n curve was obtained for different soil and upper loads. The suggested hole spacing was given. Finally, three actual engineering projects were considered and it is found that the p-n curve method results are closer to the values measured in the project sites.