考虑土拱效应的疏排桩-土钉墙组合支护基坑桩身内力和变形分析

Analysis of Internal Forces and Deformation of Pit Excavation Supported with Scattered Row Piles and Soil Nailing Wall Considering Soil Arching Effect

采用中型岩土离心机进行了8组疏排桩-土钉墙组合支护基坑的离心机模型试验,基于试验结果,研究了土拱效应的存在条件,探讨了采用规范方法计算疏排桩-土钉墙组合支护基坑桩身内力与变形的适宜性,并提出了考虑土拱效应的桩身内力与变形的计算方法。研究结果表明:有土拱效应存在时,采用规范法计算得到的桩身内力及变形,与离心机模型试验临界破坏时的试验结果比较接近;桩间不能形成土拱效应时,规范法计算结果与离心机模型试验结果偏大;与规范方法相比,采用研究的计算方法计算疏排桩支护基坑桩身内力与变形更为合理。

A series of centrifuge model tests of pit excavation supported with scattered piles and soil nailing walls were carried out.Based on the results ,the presence of soil arching effect was investigated.The suitability that use the specification method to calculate the internal forces and deformation of pit supporting structure with scattered row piles and soil nailing wall was explored.In addition,a calculation method of internal forces and deformation of piles considering soil arching effect was created.The results showed that when the soil arching effect can formed between piles,the results of pile internal forces and deformation by specification method was similar to the results of centrifuge tests which the structure in a critical damage state.Otherwise,the results of pile internal forces and deformation by specification method larger than the results by centrifuge test.Furthermore,the pile internal forces and deformation of pit supporting structure with scattered row piles was calculated by the proposed calculation method of model test was more reasonable.