滩涂极软地基托板桩法处理技术研究

为研究滩涂极软地基上托板桩的工作特性,开展了现场试验和有限元分析.现场实测了地表沉降及土压力,并据此建立了二维平面应变模型,进而对不同时期的地基土超孔隙水压力、土压力、沉降、水平位移等问题进行了研究.研究结果表明:随着填土高度增加,桩顶与桩间土差异沉降增大,产生土拱效应和拉膜效应,桩身轴力、桩体荷载分担比和桩端附近土体超孔压增大;填筑完成后超孔压消散,地基土逐渐固结,桩间土与桩顶差异沉降增大后趋于稳定,桩体荷载分担比逐渐稳定在80％左右;土工格栅拉力较小,传递荷载的能力有限;浅层地基土对桩体有负摩阻力,桩身轴力沿深度先增大后减小;托板桩法可有效控制地基土水平位移.

Research on Treatment Technology of Cap-pile Method in Extremely Soft Ground

In order to study the working characteristics of cap-pile method on the extremely soft foundation in mud flat, this paper carries out the field test and finite element analysis. According to the measured ground surface settlements and earth pressures, the two-dimensional plane strain model is established. Furthermore, excess pore water pressures, earth pressures, and settlements of foundation soil in different periods are examined. The results show that the differential settlements between piles and surrounding soils increase with the increasing filling height. The differential settlements lead to the occurrences of soil arching effect and tensioned membrane effect, which increase the axial force of the pile as well as the load sharing ratio of the pile and the pore water pressures of the soil at the pile bottom. After the completion of the construction, the excess pore water pressures dissipated and the foundation soil gradually consolidated. The differential settlements between piles and soils increase and then tend to be stable. The pile load sharing ratio gradually stabilized at about 80%. The geogrid has low tension and limited ability to transmit loads. Since the shallow foundation soil has negative frictional resistance to the pile, the axial force of the pile increases with the growing depth in shallow area and then decreases as the depth increases. Finally, the cap-pile method can effectively control the horizontal displacement of foundation soil.