土石坝坝基液化土层置换材料关键参数优化  

Key parameters optimization of seismic liquefaction replacement materials for earth-rock dam foundation

作　　者：陈莹波 李明超[1] 任秋兵 杨琳[1] 赵宇 CHEN Yingbo;LI Mingchao;REN Qiubing;YANG Lin;ZHAO Yu(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300354,China;Tianjin Water Investment Group Co.,Tianjin 300200,China)

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300354 [2]天津水务投资集团有限公司,天津300200

出　　处：《水力发电学报》2022年第10期140-151,共12页Journal of Hydroelectric Engineering

基　　金：国家自然科学基金面上项目(51879185,52179139)。

摘　　要：土石坝地震液化可能会引起结构失稳、地基失效等问题,严重威胁工程安全,需要设计采用土层挖除置换的抗液化措施。现有土层置换方案往往根据工程经验进行设计,缺少置换材料的定量化优化分析。本文提出了考虑地震作用下土石坝坝基液化土层的置换材料关键参数优化分析方法,基于实际工程数据,通过数值仿真对土层置换材料进行了优化分析,揭示了置换材料孔隙率、密度、体积模量与剪切模量、黏聚力与内摩擦角四组参数变化对液化的影响规律。结果表明,在土体参数常见取值范围内,孔隙率与密度过小或过大的方案的抗液化效果均较差,模量、内摩擦角较大的方案抗液化效果更好;通过方案比选优化,获得了抗液化效果关键参数的优化数值。随后基于优化参数进行模拟分析,实际工程坝体竖向位移总体得到有效改善,下游坝坡坡率优化率达53.9%,动力计算末液化体积残余值优化率达69.6%。所提出的方法为土石坝置换材料的优化分析提出一种可行手段,对于提高土石坝抗液化性能具有参考意义。Seismic liquefaction of earth-rock dams may cause structural instability,foundation failure or other problems,severely threatening the safety of dam projects.New anti-liquefaction measures of soil removal and replacement should be designed,as the previous design of soil replacement schemes was usually based on engineering experiences,lacking quantitative optimization analysis of the soil replacement materials(SRMs).This paper presents an optimization analysis method of the key SRM parameters,considering the liquefaction of earth-rock dam foundation under earthquake action.Based on real project data,numerical simulations and optimization analysis of SRMs are carried out,revealing variations in seismic liquefaction under the influence of the four groups of SRM parameters,i.e.,porosity,density,bulk modulus and shear modulus,as well as cohesion and internal friction angle.We find that in the common range of soil parameters,the anti-liquefaction effect is poor for a scheme using too small or too large porosity and density,while it is better for a scheme using a large modulus and a large internal friction angle.The key SRM parameters can be optimized through a procedure of comparison,selection,and optimization of the schemes.This can achieve a significant improvement in the vertical displacement of a dam body,as shown in our case study:an optimization rate of 53.9%for the downstream dam slope ratio,and 69.6%for the residual liquefaction volume at the end of dynamic analysis.This demonstrates our method is effective and applicable to optimization analysis of earth-rock dam replacement materials,along with its great significance for improving anti-liquefaction performance of earth-rock dams.

关 键 词：地震液化 土石坝 土层置换 材料参数 优化分析 

分 类 号：TU45[建筑科学—岩土工程]