堆筑期土石坝软土碎石桩复合地基固结有限元分析  

FEM analysis on consolidation of stone-column improved soft soil composite foundation during earth-rock dam construction period

作　　者：闫旭政 应宏伟[1,2,3] 周建 韩华超[4] YAN Xu-zheng;YING Hong-wei;ZHOU Jian;HAN Hua-chao(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,Zhejiang,China;Engineering Research Center of Urban Underground Development of Zhejiang Province,Hangzhou 310058,Zhejiang,China;Key Laboratory of Ministry of Education of Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,Jiangsu,China;PowerChina Huadong Engineering Corporation,Hangzhou 310014,Zhejiang,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]浙江省城市地下空间开发工程技术研究中心,浙江杭州310058 [3]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [4]中国电建集团华东勘测设计研究院有限公司,浙江杭州310014

出　　处：《地基处理》2023年第3期205-214,237,共11页Journal of Ground Improvement

摘　　要：目前工程界常采用碎石与原状土参数按面积置换率叠加的方法获取复合地基参数,以进行碎石桩复合地基承载力及变形的计算,但对该方法在堤坝地基中的适用性研究尚不深入。以卢旺达那巴龙格河2号水电站深厚覆盖层软弱基础处理项目为背景,基于PLAXIS有限元平台,采用桩墙法与复合地基法构建二维数值模型,进行大坝堆筑期固结分析。通过观察施工过程中复合地基变形、超静孔压及桩土应力,得到了不同面积置换率下桩墙法与复合地基法在计算加固区沉降的差异,以及不同面积置换率下土中超静孔压及桩土应力比的变化规律。结果表明,传统参数叠加法低估了软土碎石桩复合地基的沉降,其低估程度随置换率的减小而增大。在相同置换率下,施工过程中大坝心墙下部软土超静孔压积累较大。桩土应力比呈先增大后减小的变化规律,且坝高一半处下方桩土应力比较大;不同面积置换率下,碎石桩最大桩土应力比随置换率增大而减小,趋于稳定时的桩土应力比随置换率增大而增大。When calculating the bearing capacity and deformation of stone column composite foundation,the method of superposition of gravel and undisturbed soil parameters according to the area replacement rate is often used in engineering.However,the study on the applicability of this method in dam foundation is still not in-depth.With the background of the soft foundation treatment project for the deep overburden layer of the high earth-rock dam of the Nyabarongo II Hydropower Station in Rwanda,based on the PLAXIS finite element platform,the consolidation of the dam during the construction period was analyzed using a two-dimensional numerical model constructed by the pile-wall method and the composite foundation method.By monitoring the deformation,excess pore pressure and stress of soft soil reinforcement area during construction,the difference of settlement between pile wall method and composite foundation method,as well as the variation law of excess pore pressure and pile-soil stress ratio in soil under different area replacement rates are obtained.The results show that the traditional parameter-added method underestimates the settlement of the soft soil stone column composite foundation,and the degree of underestimation increases with the decrease of the replacement rate.Under the same replacement rate,the accumulation of excess pore pressure in soft soil below the dam core wall during construction is relatively large.The pile-soil stress ratio increases first and then decreases,and below half of the dam height is relatively large.Under different area replacement rates,the maximum pile-soil stress ratio decreases with the increase of replacement rate,and the stable ratio increases with the increase of the replacement rate.

关 键 词：碎石桩 软土地基 有限元 超静孔压 桩土应力比 

分 类 号：TU74[建筑科学—建筑技术科学]