基于CFD-DEM方法的饱和砂土场地液化模拟研究  

Simulation of saturated sand site liquefaction based on the CFD-DEM method

作　　者：许文昊 王志华[1,2] 申志福 高洪梅[1,2] 刘殷强 张鑫磊 XU Wen-hao;WANG Zhi-hua;SHEN Zhi-fu;GAO Hong-mei;LIU Yin-qiang;ZHANG Xin-lei(Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing,Jiangsu 211816,China;Jiangsu Province Engineering Research Center of Transportation Infrastructure Security Technology,Hohai University,Nanjing,Jiangsu 211816,China)

机构地区：[1]南京工业大学岩土工程研究所,江苏南京211816 [2]河海大学江苏省交通基础设施安全保障技术工程研究中心,江苏南京211816

出　　处：《岩土力学》2024年第8期2492-2501,2514,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金面上项目(No.51678300,No.52178336,No.52108324);江苏省高等学校自然科学研究重大项目(No.18KJA560002);江苏省高校“青蓝工程”中青年学术带头人;江苏省研究生科研与实践创新计划项目(No.KYCX22_1354)。

摘　　要：砂土液化是常见的地震灾害,目前应用于研究砂土液化动力特性的室内试验以及模型试验还不能全面反映土体液化全过程。计算流体动力学(computational fluid dynamics,CFD)与离散元法(discrete element method,DEM)耦合模拟方法能够准确地模拟各类水土耦合问题。通过二次开发的CFD-DEM流固耦合模块实现离散元软件PFC3D与计算流体力学软件OpenFOAM之间的力学信息交互,利用颗粒水下自由沉降验证该方法的可行性。利用PFC3D软件模拟室内循环三轴试验标定出具有真实饱和砂土动力特性的数值砂样。根据已有的参数信息以及耦合模拟方法建立了饱和砂土的场地液化模型。模拟结果表明,离散元法能够复现室内砂土液化试验,标定参数可应用于场地液化模拟;单颗粒沉降速度与理论解一致验证了CFD-DEM耦合方法的准确性;峰值加速度0.25g下不同深度处土体均会发生液化,液化时超孔压比无法达到1,超孔压累计值由浅层往深层递增;液化后土体强度自下而上逐渐恢复,再固结的场地土体结构呈现均匀化发展趋势。Soil liquefaction is a prevalent seismic hazard.However,current indoor and model experiments studying the dynamic characteristics of sand liquefaction struggle to accurately represent the actual soil liquefaction process.The computational fluid dynamics(CFD)coupled with discrete element method(DEM)simulation method can accurately simulate various soil-water coupling problems.The CFD-DEM flow-solid coupling module facilitated the exchange of mechanical information between the commercial discrete element software PFC3D and the open-source computational fluid dynamics software OpenFOAM.The feasibility of this approach was confirmed through particle underwater free settling experiments.Calibration of numerical sand specimens with dynamic characteristics of real saturated sand was conducted using PFC3D software through simulated indoor cyclic triaxial tests.Based on the existing parameter information and the coupled simulation method,a site liquefaction model of saturated sand was established.The simulation results indicate that the discrete element method(DEM)can replicate indoor sand liquefaction experiments,and the calibrated parameters can be applied to site liquefaction simulations.The consistency between the settling velocity of individual particles and theoretical solutions validates the accuracy of the CFD-DEM coupling method.Under a peak acceleration of 0.25g,liquefaction occurs at various depths,and the ratio of excess pore pressure does not exceed 1 during liquefaction.The cumulative excess pore pressure increases from shallow layers to deep layers.After liquefaction,the soil strength gradually recovers from bottom to top,and the soil structure in the re-consolidated site shows a trend of homogenization.

关 键 词：砂土液化 CFD-DEM耦合方法 颗粒自由沉降 场地液化模拟 

分 类 号：TU43[建筑科学—岩土工程]