软土超深基坑端头开挖效应的模拟试验研究

Model tests on excavation effect of deep foundation pit in soft soil

以上海轨道交通四号线修复工程为研究背景,通过离心模型试验提供与开挖施工现场相一致的应力水平和工程特征,使小模型达到与现场相似的条件,研究四号线修复中东侧端头基坑开挖引起的挡墙及周围地层的变化。试验模型比例为1:140,基坑挡墙及支撑均采用铝合金材料,挡墙的抗弯刚度及支撑的抗弯刚度分别按照等效原则进行了换算。试验结果表明,该基坑工程的设计较为合理,在较为复杂的端头段也能基本满足要求,围堰结构起到了阻挡基坑开挖对周围环境的影响的作用。

Based on the repair works of Shanghai Metro Line No.4,centrifugal model tests on the stress level and engineering characteristics similar to the prototype were performed so as to study change of retaining walls and surrounding soil.The model scale was 1 '.140.The retaining walls of the foundation pit and the bracing were designed by use of aluminum alloy materials. The flexural rigidity of the retaining walls and bracings were converted according to the equivalent principle respectively.The test results showed that the design of the foundation pit is reasonable,and it can meet the basic requirements.And the cofferdam plays a great role in holding back effects of excavation of the foundation pit on environment.