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真空联合堆载预压与混凝土芯砂石桩复合地基相结合是处理深厚软土地基的一种新方法。该方法既能利用预制混凝土芯桩提高地基承载力,又能利用砂石外壳缩短排水路径、传递真空负压,加快固结。根据真空联合堆载预压下混凝土芯砂石桩复合地基的固结特点,将堆载预压和真空预压的固结效应分开考虑,然后再进行叠加,推导出了真空联合堆载预压下混凝土芯砂石桩复合地基的平均固结度解析解,并利用三维数值模拟对平均固结度解析解进行了验证。通过对解析解的参数分析,探讨了置换率、涂抹区大小及渗透系数、混凝土芯砂石桩长径比和芯桩率对混凝土芯砂石桩复合地基固结特性的影响。结果表明,混凝土芯砂石桩复合地基的固结速率随着置换率和芯桩率的增大而增大,随涂抹区和砂石外壳直径之比、未扰动区和涂抹区渗透系数之比、长径比的增大而减小。
Vacuum combination of preloading with prestressed concrete sand core pile composite foundation is a new method to deal with deep soft soil foundation. The method not only can improve the bearing capacity of foundations by using precast concrete core piles, but also can shorten the drainage path with gravel shells, transfer vacuum negative pressure and accelerate the consolidation. According to the consolidation characteristics of concrete-filled sand-gravel pile composite foundation under vacuum combined with preloading, the consolidation effect of preloading under vacuum and preloading under vacuum are separately considered and then superposed, and then the vacuum combined with preloading The analytical solution of the average consolidation degree of the concrete core-gravel pile composite foundation was established, and the analytical solution of the average consolidation degree was verified by three-dimensional numerical simulation. By analyzing the parameters of the analytical solution, the effect of displacement rate, size and permeability coefficient of the coating area, the ratio of the length to diameter of the concrete core-pile and the core-pile ratio on the consolidation behavior of the concrete-filled sand-gravel pile composite foundation are discussed. The results show that the consolidation rate of concrete-filled sand-gravel pile composite foundation increases with the increase of displacement ratio and core-pile ratio. The ratio of the permeability coefficient of undisturbed zone and applied zone , The aspect ratio increases and decreases.