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根据静载荷试验和数值模拟的结果,研究垫层厚度对水泥土搅拌桩复合地基沉降的影响规律。针对珠海地区广泛存在的淤泥质土,进行了天然地基和4种垫层厚度的水泥土搅拌桩复合地基现场静载荷试验。在地基中预埋沉降管和沉降磁环,利用带刻度的探头感应加载过程中沉降磁环位置的变化,获取地基的分层沉降量,据此分析复合地基的沉降规律。在现场试验的基础上,对水泥土搅拌桩4桩复合地基进行了数值分析,将数值计算得到的不同垫层厚度复合地基中桩、土的分层沉降进行比较,结果表明垫层的设置减小了桩的沉降量,但过厚的垫层不能够有效地提高复合地基的承载力,反而会增大沉降。建议对褥垫层厚度的选取,除了要综合承载力和沉降两方面因素之外,还要考虑实际的地质条件。垫层厚度可取20～40cm,当淤泥层位于桩身中部以下取高值,位于桩身中上部取低值。
Based on the results of static load test and numerical simulation, the influence of cushion thickness on the settlement of cement-soil mixing pile composite foundation is studied. For the widespread muddy soil in Zhuhai area, the static load field test of the composite foundation of cement-soil mixing pile with natural foundation and four kinds of cushion thickness was carried out. The subsidence pipe and settlement magnet ring are embedded in the foundation. The position of the subsidence magnet ring is sensed during the loading process by using the graduated probe. The settlement of the foundation is obtained, and the settlement law of the composite foundation is analyzed. Based on the field test, the numerical analysis of 4 composite foundation with soil-cement mixing pile was carried out. The layered settlement of pile and soil in different thickness of composite foundation with different cushion thickness was compared. The results show that Small pile settlement, but too thick cushion can not effectively improve the bearing capacity of composite foundation, but will increase the settlement. It is suggested that the thickness of mat should be selected in addition to comprehensive bearing capacity and settlement factors, but also consider the actual geological conditions. The cushion thickness of 20 ~ 40cm, when the silt layer is located below the middle of the pile to take high value, located in the upper part of the pile to take low value.