水位下降对库岸陡坡地基稳定性影响分析  

Analysis of the Influence of Water Level Drop on the Foundation Stability of the Steep Slope of the Reservoir Bank

作　　者：胡惠华 方强 张奇华 刘文连 陈昌富[4] 马德青 HU Huihua;FANG Qiang;ZHANG Qihua;LIU Wenlian;CHEN Changfu;MA Deqing(Hunan Provincial Communications Planning,Survey and Design Institute Co.,Ltd.,Changsha,Hunan 410200,China;Badong National Observation and Research Station of Geohazards,China University of Geosciences,Wuhan,Hubei 430074,China;Kunming Prospecting Design Institute of China Nonferrous Metal Industry Co.,Ltd.,Kunming,Yunnan 650051,China;College of Civil Engineering,Hunan University,Changsha,Hunan 410083,China)

机构地区：[1]湖南省交通规划勘察设计院有限公司,湖南长沙410200 [2]中国地质大学(武汉)湖北巴东地质灾害国家野外科学观测站,湖北武汉430074 [3]中国有色金属工业昆明勘察设计研究院有限公司,云南昆明650051 [4]湖南大学土木工程学院,湖南长沙410083

出　　处：《公路工程》2023年第3期97-103,131,共8页Highway Engineering

基　　金：国家自然科学基金面上项目(52079129);湖南省交通运输厅科技进步与创新计划项目(201003,202120)。

摘　　要：思澜高速公路某桥梁位于糯扎渡水电站库岸,桥梁施工期间,桥梁下侧的库水位变动区的风化岩陡坡出现浅层失稳滑移。陡坡地基的稳定是桥梁基础和上部结构安全的前提。因此,分析桥梁陡坡地基的稳定性是必要的。采用数值模拟分析了库水位下降作用下陡坡地基的渗流场,基于岩土现场大型剪切试验与陡坡浅层滑坡反分析结果,采用极限平衡方法,分析了库水位下降作用下该陡坡地基的深层稳定性变化趋势。结果表明:库水位下降对该陡坡的稳定性影响显著;随着库水位的持续下降,陡坡地基的深层稳定系数出现先降低后升高的趋势,潜在滑动面的剪出口位于动态水位以下10~20 m;库水位维持在最低水位时,陡坡内地下水作用的程度减弱,陡坡稳定系数升高。在暴雨工况且库水位下降作用下,陡坡地基稳定系数小于1.1,岸坡总体处于欠稳定状态,因库水位下降作用,从水中出露的全风化岩坡体将先行衰变失稳,是斜坡失稳源,并将牵引整个库岸陡坡失稳。建议对陡坡地基进行加固。A bridge on the Silan Expressway is located on the bank of the Nuozhadu Hydropower Station.During the construction of the bridge,a shallow instability and sliding occurred on the weathered rock steep slope in the reservoir water level fluctuation area below the bridge.The stability of steep slope foundation is aprerequ isite for the safety of bridge foundation and upper structure.Therefore,it is necessary to analyze the stability of the steep slope foundation of the bridge.This article uses numerical simulation to analyze the seepage field of steep slope foundation under the effect of reservoir water level drop.Based on the results of large-scale shear tests on site and back analysis of shallow landslides on steep slopes,the limit equilibrium method is used to analyze the trend of deep stability change of the steep slope foundation under the effect of reservoir water level drop.The results indicate that the decrease in reservoir water level has a significant impact on the stability of the steep slope;as the water level of the reservoir continues to decrease,the deep stability coefficient of the steep slope foundation shows a trend of first decreasing and then increasing.The shear outlet of the potential sliding surface is located 10 m to 20 m below the dynamic water level;when the reservoir water level is maintained at the lowest level,the degree of groundwater action on steep slopes weakens,and the stability coefficient of steep slopes increases.Under the rainstorm condition and the drawdown of the reservoir water level,the stability coefficient of the steep slope foundation is less than 1.1,and the bank slope is generally in an unstable state.Due to the drawdown of the reservoir water level,the fully weathered rock slope exposed from the water will decay and become unstable first,which is the source of slope instability and will lead the whole reservoir bank to instability.It is recommended to reinforce the steep slope foundation.

关 键 词：库水位下降 陡坡地基 渗流场 斜坡失稳源 稳定系数 

分 类 号：U416[交通运输工程—道路与铁道工程]