强震损伤格栅墙处理地基抗液化性能离心模型试验研究  

Centrifuge model tests on liquefaction mitigation performance of soil-cement grid-improved ground subjected to earthquake pre-shaking history

作　　者：周燕国[1] 曹渊 石川明 陈云敏[1] ZHOU Yanguo;CAO Yuan;ISHIKAWA Akira;CHEN Yunmin(MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering,Institute of Geotechnical Engineering,Center for Hypergravity Experiment and Interdisciplinary Research,Zhejiang University,Hangzhou 310058,China;Institute of Technology,Shimizu Corporation,Tokyo,Japan)

机构地区：[1]浙江大学软弱土与环境土工教育部重点实验室,浙江大学岩土工程研究所,浙江大学超重力研究中心,浙江杭州310058 [2]清水建设技术研究所,日本东京135-8530

出　　处：《岩土工程学报》2024年第S01期11-15,共5页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51988101,52278374,51978613);高等学校学科创新引智计划(111计划)项目(B18047)。

摘　　要：水泥土格栅墙能有效减缓被围束土体在地震作用下的剪切荷载及变形,已广泛应用为一种高效的抗液化对策。针对其长期服役过程,开展了两组超重力离心模型试验以研究强振历史对水泥土格栅墙内被围束土体液化响应的影响。两组模型均由15 m厚的易液化含黏粒砂土和2.5 m厚的粗砂层组成。其中,一组模型采用水泥土格栅墙对易液化层进行加固;另一组模型则未进行处理,作为自由场地对照组。两组模型均经历振幅为0.15g的振动事件,且在0.15g振动事件前,对两组模型施加振幅为0.4g的振动事件作为强振历史。试验结果表明,格栅墙在强振下主要的损伤模式表现为竖向贯穿型裂缝,并部分伴随有局部斜向裂缝,且外侧格室对于中心格室表现出类似于群桩基础的“遮蔽效应”。强振历史后,格栅墙中心格室内被围束土体的超静孔压显著低于自由场地,损伤后格栅墙仍具有良好的抗液化效果。同时,格栅墙由于强振后整体刚度的削弱,其与下卧粗砂层间的剪切变形显著减小。The soil-cement grid has been widely applied as an effective liquefaction countermeasure due to its capability to effectively mitigate the shear load and deformation of the enclosed soil under seismic loadings.In terms of its long service period,two dynamic centrifuge model tests are conducted to study the effects of strong shaking history on the liquefaction responses of the enclosed soil.The model ground consists of a 15 m-thick liquefiable clayey fine sand and an underlain 2.5 m-thick coarse sand layer.The liquefiable layer is improved by the soil-cement grid in one model,while the other without any improvement affording a contrast.Both models are subjected to a sinusoidal input motion with amplitude of 0.15g.Several more severe shaking events with amplitude of 0.4g are applied to the models prior to this 0.15g event as strong shaking history.The results imply that the damage patterns of the walls are mainly vertical penetrating cracks,partly accompanied by local diagonal cracks,and the outer cells show a"shielding effect"on the center cell similar to that of a group pile foundation.After the strong vibration history,the central cell of the soil-cement grid still has satisfactory anti-liquefaction effects,leading to a much lower excess pore pressure than free field.At the same time,due to the weakening of the overall stiffness of the soil-cement grid,the shear deformation between the soil-cement grid and the underlying coarse sand layer is significantly reduced.

关 键 词：地震液化 水泥土格栅墙 地基处理 离心机模型试验 地震历史 

分 类 号：TU411[建筑科学—岩土工程]