钢围堰结构下软土地基固结沉降分析

Consolidation settlement of soft clay ground with steel cofferdam structure

外海人工岛由插入不透水层的钢围堰组成岛壁,内部填砂成岛,软土地基采用堆载排水预压进行处理。为了解该特殊结构软土地基的沉降特性,采用有限差分数值计算方法进行分析,并通过与实测数据相比较后的反分析,调整计算参数,使数值计算结果更可靠。分析表明,钢围堰约束软土地基的侧向变形,阻碍了软土地基滑动面的形成,施工期地基的沉降速率远大于相关规范的规定,所以类似这样的特殊结构沉降控制标准应突破规范规定;同时,计算可知该软土地基工后沉降为9 cm,并指出由于堆载作用,工后2 a地基主固结沉降即可完成,为后期运营提供了参考。

The artificial island outside of a sea is composed of steel cofferdam and sand filling in the island. The steel cofferdam inserts the impermeable soil layer. The soft clay ground of artificial island is treated by surcharge preloading with PVDs. In order to know the settlement of soft clay ground with steel cofferdam, the numerical analysis is adopted. The results of numerical analysis are compared with the field monitoring data. Through back analysis of the calculated and monitoring data curves, the parameters are modified, and more reliable results are achieved. From the results, the steel cofferdam restrains the lateral deformation of soft clay ground. The failure plane of soft clay ground is hard to form. The settlement velocity is farther greater than that defined in the relative code. So the settlement velocity rule of the relative code should be broken for such special structure. At the same time, the residual settlement is calculated by means of the numerical analysis method, and its value is 9 cm. The consolidation settlement is completed two years later after the project completion. The calculated results may provide reference for the period of its use.