碎石桩处理饱和砂土坝基地震响应离心模型试验  

Centrifuge shaking table tests on stone column-improved saturated sandy dam foundation

作　　者：黄俊清 黄晓实 颜业敢 汪玉冰 周燕国[1,2] HUANG Junqing;HUANG Xiaoshi;YAN Yegan;WANG Yubing;ZHOU Yanguo(College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,China;MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering,Zhejiang University,Hangzhou 310058,China;Center for Hypergravity Experiment and Interdisciplinary Research,Zhejiang University,Hangzhou 310058,China)

机构地区：[1]浙江大学建筑工程学院,浙江杭州310058 [2]浙江大学软弱土与环境土工教育部重点实验室,浙江杭州310058 [3]浙江大学超重力研究中心,浙江杭州310058

出　　处：《中南大学学报（自然科学版）》2023年第12期4848-4859,共12页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51988101)。

摘　　要：为了研究坝体与坝基相互作用下饱和砂土坝基的地震响应规律及碎石桩的抗液化效果,首先,设计和开展了2组超重力振动台试验,研究了碎石桩处理前后饱和砂土坝基不同位置的加速度、孔压和位移等地震响应规律;然后,评估了坝基液化的可能性及碎石桩的抗液化效果;最后,通过反演方法探究了坝体和碎石桩对坝基不同位置土体的动剪应力-剪应变响应的影响。研究结果表明:未处理坝基的加速度放大系数在坝体正下方随高程增加而逐渐减小,在坝趾下方和坝外自由场随高程增加而先减小后增大;碎石桩处理坝基具有更大的刚度和更小的阻尼,加速度放大系数整体比未处理坝基的大;坝体能够增强下方土体的抗液化能力;碎石桩处理能够降低超静孔压的累积速率和峰值,加速震后孔压消散,但在遭遇强震时处理区外土体仍会发生液化。坝基土体的动剪应力-剪应变响应受初始围压和超静孔压影响,坝体下方土体的剪切模量更大,碎石桩能够通过抑制超静孔压的发展来缓解处理区内土体剪切刚度的退化。In order to study the seismic response of the saturated sandy foundation and the effectiveness in mitigating liquefaction of stone columns under the interaction between the dam and the foundation,firstly,two centrifuge shaking table tests were designed and conducted,the acceleration,pore pressure and displacement at different locations of the saturated sandy dam foundation were comparatively studied before and after the treatment with stone columns.Secondly,the possibility of liquefaction of the dam foundation and the effectiveness in mitigating liquefaction of stone columns were assessed.Finally,the influence of the dam body and stone columns on the dynamic shear stress-shear strain response of the soil at different positions of the dam foundation was investigated through back-analysis methods.The results show that the acceleration amplification factor of the untreated foundation decreases with elevation under the center of dam,and it decreases firstly and then increases with elevation under the toe of dam and at free field.The stone column-improved foundation has greater stiffness and less damping.The acceleration amplification factor of stone column-improved foundation is generally greater than that of the untreated foundation.The dam can increase the liquefaction resistance of the soil below.Stone columns can reduce the accumulation velocity and peak of excess pore pressure,accelerate the dissipation of excess pore pressure,but the soils outside the treatment area will still liquefy during strong earthquakes.The dynamic shear stress-strain response of the foundation soil is affected by the initial confining pressure and excess pore pressure.The soil beneath the dam body has larger shear stiffness.Stone columns can mitigate the degradation of shear stiffness of the soil in the treatment area by inhibiting the development of excess pore pressure.

关 键 词：坝基 液化 碎石桩 地震响应 离心模型试验 

分 类 号：TU411[建筑科学—岩土工程]