考虑桩土局部分离的饱和土体中桩基水平动力响应分析  

Horizontal Dynamic Response Analysis of Pile Foundation in Saturated Soil Considering Partial Pile-Soil Separation

作　　者：时昆鹏 丁肇伟 宋春雨[1] 陈龙珠[1] SHI Kunpeng;DING Zhaowei;SONG Chunyu;CHEN Longzhu(School of Navy Architecture,Ocean&Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学船舶海洋与建筑工程学院,上海200240

出　　处：《结构工程师》2022年第4期141-150,共10页Structural Engineers

基　　金：国家自然科学基金资助项目(51678361)。

摘　　要：采用有效应力的方法,根据不排水过程中的土体应力应变关系,计算孔压变化,并利用UMAT子程序模块进行二次开发,实现考虑孔压生成的修正Mohr-Coulomb本构模型在数值模拟上的运用。结合桩土接触面条件,研究考虑桩土局部分离的饱和土单桩及群桩的水平动力响应。将本文结果与已有文献进行对比,验证了本文方法的有效性和正确性。通过参数分析,研究桩土局部分离、桩间距、加载频率对桩基动阻抗及孔压分布的影响。研究结果表明:水平动力荷载作用下,桩土分离显著地降低了桩基水平动阻抗,土体塑性和超孔压对桩基动阻抗也有相应影响,高频荷载作用时,其影响更大;循环加载后,桩周上部土体产生超孔压,削弱了土体有效应力和桩基水平承载力。Based on the method of effective stress,the change of pore pressure is calculated according to the stress-strain relation of soil in the process of non-drainage,and the UMAT subroutine module is used to realize the application of the modified Mohr-Coulomb constitutive model considering the formation of pore pressure in numerical simulation.Combined with the conditions of pile-soil contact surface,horizontal dynamic responses of single pile and pile group in saturated soil with partial pile-soil separation are studied.The results of this paper are compared with the existing literature,which proves the effectiveness and correctness of the proposed method.Then the effects of pile separation,pile spacing and loading frequency on dynamic impedance and pore pressure distribution of pile-soil foundation are studied by parameter analysis.The results show that:under the action of horizontal dynamic load,pile-soil separation significantly reduces the horizontal dynamic impedance of pile foundation,soil plasticity and excess pore pressure also have corresponding effects on the dynamic impedance of pile foundation,and the influence is greater under high-frequency load;after cyclic loading,the upper soil around the pile produces excess pore pressure,which weakens the effective stress of soil and the horizontal bearing capacity of pile foundation.

关 键 词：局部分离 修正Mohr-Coulomb模型 水平荷载 群桩 超孔压 

分 类 号：TU473.1[建筑科学—结构工程]