地铁基坑SMW工法桩变形实测及数值模拟分析

Measurement and Numerical Simulation Analysis of SMW Piles Deformation in Subway Foundation Pit

以天津某地铁深基坑工程SMW工法桩支护结构为研究对象,进行变形实测分析及有限元数值模拟研究。根据实测数据得出不同工况下的变形曲线,提出最大水平侧移(δh,max)与最大地表沉降(δv,max)的幂函数拟合公式。分别建立二维“桩-土”和三维“刚性墙体”模型,三维模型将不规则形状的SMW工法桩简化为刚性墙体,墙体宽度取SMW工法桩直径。得到如下结论:桩体弹性模量为30 GPa,土层弹性模量取4倍压缩模量时,二维模型结果与实测接近。在三维模型中,基坑外侧基底上部、基坑外侧基底下部、基坑内侧所受横向外力等效于相同土层深度静止侧向土压力的4.20、2.16、2.00倍,模拟结果较为符合监测变形结果。模型结果验证了刚性墙体简化形式的可行性。

Herein the SMW pile retaining structure in a subway deep foundation pit engineering in Tianjin was taken as the research object to carry out the deformation measurement analysis and the finite element numerical simulation.According to the measured data,the deformation curves under different working conditions were obtained,and the power function fitting formula of maximum horizontal displacement(δh,max)and maximum surface settlement(δv,max)was proposed.The two-dimensional"pile-soil"model and three-dimensional"rigid wall"model were established respectively.In the three-dimensional model,SMW piles in irregular shape were simplified into a rigid wall,and the width of the wall was taken as the diameter of the SMW pile.The conclusions were obtained as follows:when the elastic modulus of pile is 30 GPa,and the elastic modulus of soil layer is 4 times of the compression modulus,the result of two-dimensional model are close to the measurement.In the three-dimensional model,when the lateral external force on the upper and lower part of the base outside the foundation pit,and inside the foundation are equivalent to 4.20 times,2.16 times and 2.00 times of the static lateral earth pressure at the same soil depth,the simulation result is consistent with the result of deformation monitoring.The modeling results verify the feasibility of the simplified form of rigid wall.