三板溪水库南孟溪堆积体演化机制与稳定性评价  

Evolution Mechanism and Stability Evaluation of Nanmengxi Colluvial Deposit in Sanbanxi Reservoir

作　　者：柏威伟[1] BAI Weiw&(China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China)

机构地区：[1]中铁第四勘察设计院集团有限公司,湖北武汉430063

出　　处：《安全与环境工程》2023年第3期161-170,共10页Safety and Environmental Engineering

基　　金：国家重点研发计划项目(2021YFB2600400);中铁第四勘察设计院科技研发重点项目(2020K114)。

摘　　要：水库运行过程中库水位频繁变化是导致库岸边坡变形失稳的重要因素之一。以我国西南地区三板溪水库南孟溪堆积体岸坡工程为研究对象,在前期现场调查、地质勘察和室内试验的基础上,分析了南孟溪堆积体成因机制及形貌演化过程,并结合岸坡渗流场分析,通过极限平衡分析方法对该堆积体在不同工况条件下的稳定性进行了评价。结果表明:南孟溪堆积体是斜坡表层岩体在两组陡倾节理、顺坡向缓倾层面和顺坡向断裂的不利组合作用下产生崩塌破坏的结果,其形成过程大致可分为6个阶段;正常运用条件下,库水位下降过程中,该堆积体边坡稳定性系数呈先降后升的趋势,且在库水位约为464.9 m时边坡稳定性系数达到最小值,而在水库蓄水期,边坡稳定性系数呈先保持基本稳定后逐步下降的规律;非正常运用条件下,在库水位降低20%~30%时边坡稳定性系数达到最小值;堆积体边坡在部分工况下不满足规范要求的边坡最小安全系数标准,设置重要构筑物时需要采取加固措施。The frequent fluctuation of water level during reservoir operation is one of the important factors leading to the deformation and instability of bank slope.Taking the Nanmengxi colluvial deposit of Sanbanxi Reservoir in Southwest China as an example,based on the preliminary field investigations9geological explorations and laboratory tests,the formation mechanism and morphological evolution process of the deposit are analyzed.Combined with the analysis o£seepage field of the bank slop,the slop stability under different working conditions is evaluated by the limit equilibrium analysis method.The results show that the Nanmengxi colluvial deposit is formed by the collapse failure of the slop surface rock mass under the adverse combination of two groups of steep joints,along-slope gently inclined layers and along-slope faults,and the formation process can be roughly divided into six stages.Under normal operating conditions,the slope stability coefficient tends to decrease first and then increase during the decline of reservoir water level,and reaches the minimum value at the water level of about 464.9 m.During the water storage period,the slope stability coefficient first maintains stable and then gradually decreases.Under abnormal operating conditions,the stability coefficient reaches the lowest value as the water level declines by about 20%—30%.The colluvial deposit slope in reservoir bank does not meet the safety standard under some working conditions,and reinforcement measures should be taken when setting important structures.

关 键 词：库区堆积体 库水位变化 边坡稳定性评价 堆积体成因 三板溪水库 

分 类 号：X43[环境科学与工程—灾害防治] P642.22[天文地球—工程地质学]