软土中静压桩贯入引起的超静孔压力理论分析

根据静压桩在软粘土中贯入的特点,用柱孔扩张理论模拟其贯入过程,引入软化系数和对数应变描述沉桩过程中桩周土体塑性区的大变形和应变软化等特征,推导出柱孔扩张时弹性区和塑性区产生的超静孔隙水压力解析式,与Vesic解进行了比较表明,本文推导的理论解适用范围更广。基于该理论解,结合昆山市某场地地质资料,分析讨论了软化系数、孔径大小和剪切应力对超静孔隙水压力大小和分布范围的影响,同时与现场监测数据对比分析,理论计算和实测结果吻合较好,表明该解析解对预测软土中由静压桩的贯入引起的超静孔隙水压力的大小和分布具有一定实用价值。

Theoretical Analysis of Distribution of Excess Pore Water Pressure Caused by Installing Pile in Soft Clay

According to the characteristics of penetration of jacked-in pile into soft clay,the penetration process is simulated with cylindrical cavity expansion theory.Considering the characteristics of strain softening and large strain in the plastic zone,the softening parameter and logarithmic strain are adopted to describe the stress field around the piles,an analytical solutions for the magnitude distribution and range of excess pore water pressure around the cylindrical cavities are presented and compared with that of Vesic’s,which show that the solutions derived in the paper are more general than Vesic’s.Based on the analytical solutions and soil parameters in Kunshan Site,the effect of softening parameter,cavity radius and shear stress on the excess pore water pressure during cavity expansion is discussed.Additionally,the comparison between calculated result and the measurements in the field indicates that the analytical solutions agree well with that of the in-situ tests,so the proposed analytical solution is valuable for predicating the distribution of excess pore water pressure due to installing pile in the saturated soft clay.