高土壤电阻率下的地铁车站桥桩土体应力模拟

Simulation of soil stress in bridge piles of subway stations under high soil resistivity

在高土壤电阻率环境下,电气化地铁的供电系统需要考虑土壤电阻对电能传输的影响.面对当前土体应力分析方法忽视高土壤电阻率的相关性影响,导致土体应力模拟与实际情况不符的问题.提出了高土壤电阻率下的地铁车站桥桩土体应力模拟方法,利用vdP法分析高土壤中电阻率的情况,基于分析结果应用FLAC有限元方法进行有限元模型构建.从工程实际出发,利用有限元方法建立了一种由土组成的微分方程,将其表达为位移、孔压两种形式,并在土地x、y、z方向上的单位流量由达西定律求出.在地铁车站明挖工程桥桩土体连续性特征演变情况下,分析单位时间内土地变形量与单元体表面流量之间关系.根据流固耦合计算公式,设计地铁车站明挖工程工序.根据基于有限元模型的土体应力数值模拟过程,分析明挖初期、明挖一段时间后的主应力模拟结果.由实例对比结果可知,该方法土地下沉量与实际测量的数值仅存在0.5 m的误差、水平位移与实际位移数值一致.

In high soil resistivity environments,the power supply system of electrified subways had to consider the impact of soil resistance on energy transmission.Facing the current soil stress analysis methods that neglected the correlation effect of high soil resistivity,which led to the inconsistency between soil stress simulation and actual situation,a soil stress simulation method for subway station bridge piles under high soil resistivity was proposed.The vdP method was used to analyze the electrical resistivity in high soil,and the FLAC finite element method was employed to construct a finite element model based on the analysis results.Starting from engineering practice,a differential equation composed of soil was established using the finite element method,which was expressed in two forms:displacement and pore pressure.The unit flow rate in the x,y,and z directions of the soil was determined by Darcy s law.The relationship between the soil deformation per unit time and the surface flow rate of the unit under the evolution of soil continuity characteristics of bridge piles in the open excavation project of subway stations was analyzed.According to the fluid structure coupling calculation formula,the open excavation process of subway stations was designed.Based on the numerical simulation process of soil stress based on the finite element model,the main stress simulation results during the initial stage of open excavation and after a period of open excavation were analyzed.From the comparison results of examples,it was seen that there was only an error of 0.5 m between the land subsidence amount of this method and the actual measurement value,and the horizontal displacement was consistent with the actual displacement value.