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将饱和黏性土中静压沉桩过程近视看作柱孔不排水扩张问题,在充分考虑土体三维强度特性的条件下采用SMP准则改进的修正剑桥模型,推导得出柱孔扩张引起超孔压的基本解答。在此基础上,考虑桩周土竖向和径向固结,建立空间轴对称固结方程的定解条件,采用分离变量法求得桩周超静孔隙水压力消散的级数解答。分析桩周土体超静孔隙水压力随时间和空间的演变规律,揭示应力历史、径向和竖向固结系数以及剪切模量等因素对初始超孔压的产生和随后的固结速率的影响规律,并通过实例验证本文解答的合理性和适用性。通过与现场实测对比,本文解答较好地反映了静压桩周土体超静孔隙水压力的演变规律。此外,桩周土体的超静孔隙水压力随距桩侧径向距离增大呈对数衰减。剪切模量和竖向固结系数对桩周土体固结速率影响较小,而土体超固结比和径向固结系数对固结速率影响较为显著,表明超孔压消散主要发生在径向。研究成果对静压桩承载力的确定具有一定的指导意义。
Considering the myopia of saturated cohesive soil during static pressure pile-sinking process as the problem of undrained expansion of column bore, the modified Cambridge model improved by SMP criterion is used under the condition of fully considering the three-dimensional strength characteristics of soil, The basic solution of pressure. On this basis, taking into account the vertical and radial consolidation of the soil around the pile, the solution conditions for the axial symmetry consolidation equation are established. The series solution to the excess pore water pressure dissipating in the pile circumference is obtained by the method of discrete variables. Analysis of the evolution law of the excess pore water pressure with time and space in the soil around the pile reveals that the generation of the initial excess pore pressure and the subsequent consolidation rate, such as stress history, radial and vertical consolidation coefficient and shear modulus, The law of influence, and verify the rationality and applicability of the solution by examples. Compared with the field measurements, the solution of this paper reflects the evolvement law of the excess pore water pressure around the static pressure piles. In addition, the excess pore water pressure of the soil around the pile decreases logarithmically with the increase of the radial distance from the pile side. The influence of shear modulus and vertical consolidation coefficient on consolidation rate of soil around the pile is small, while over consolidation ratio and radial consolidation coefficient of soil affect consolidation rate significantly, which indicates that dissipation of excess pore pressure occurs mainly In the radial direction. The research results have certain guiding significance for determining the bearing capacity of static pile.