地下水动态作用下大型碎裂顺层岩质滑坡变形响应规律分析

Analysis of deformation response law of large cataclastic bedding rock landslide under dynamic action of groundwater

大型碎裂顺层岩质滑坡广泛分布于三峡库区,至今这类滑坡仍持续位移变形,对滑坡体上居民、长江航道甚至三峡大坝造成巨大威胁。借助三峡库区谭家河滑坡GPS监测数据、勘察资料、水文气象资料等,采取多因素综合过程分析和定量分析手段,分析库水、降雨、地下水动态作用下滑坡变形特征及诱发机制。研究表明:(1)库水位消落会诱发滑坡变形,反之,库水位上涨会抑制滑坡变形。在库水位涨落期间,持续强降雨均会加剧滑坡变形。(2)在汛期及蓄水期,降雨会抬升地下水位,当前期月降雨量达到129 mm以上,QSK2地下水位出现1次涨落变化过程,该期间水力促使滑坡变形作用显著发挥。(3)若当日强降雨未引发滑坡变形,降雨入渗补给地下水2 d后,QSK2地下水位上涨达到临界值(≥242.4 m)会诱发滑坡发生剧烈变形,当地下水位由峰值(245 m左右)下降至临界值(≥241 m)后,滑坡变形趋势减弱。(4)QSK2地下水位涨落期间,地下水位抬升高度(≥2.85 m)、平均地下水位(≥242.1 m)、地下水位峰值(≥244.0 m)等相关参数越高,滑坡变形往往越剧烈,相反,地下水位越低,滑坡通常越稳定。该研究成果对碎裂顺层岩质滑坡诱发机制的分析、监测预警及应急抢险处置等颇有借鉴价值。

Large-scale cataclastic bedding rock landslides are prevalent in the Three Gorges reservoir area,and they continue to displace and deform,posing a significant threat to residents,the Yangtze River channel,and even the Three Gorges Dam.This paper analyzes the characteristics and inducing mechanism of landslide deformation under the dynamic action of reservoir water,rainfall,and groundwater,using multi-factor comprehensive process analysis and quantitative analysis methods based on GPS monitoring data,survey data,and hydrometeorological data of Tanjiahe landslide.The results indicate that:(1)the decrease of reservoir water level will induce the landslide deformation,on the contrary,while the rise of reservoir water level can inhibit the landslide deformation.During the fluctuation of reservoir water level,continuous heavy rainfall will aggravate the landslide deformation.(2)During the flood season and storage season,rainfall is conducive to raising the groundwater level.The previous monthly rainfall reaches more than 129 mm,the groundwater level of QSK2 has a fluctuation process,during which the hydraulic power leads to significant landslide deformation.(3)The heavy rainfall on the first day did not cause any landslide deformation.However,after two days of continuous rainfall,the groundwater level of QSK2 rose to a critical value of 242.4 m,which led to severe landslide deformation.As the local groundwater level dropped from its peak value of about 245 m to the critical value of 241 m,the landslide deformation trend weakened.(4)During the fluctuation of QSK2 groundwater table,the higher the uplift height of groundwater table(≥2.85 m),the average groundwater table(≥242.1 m),the peak value of groundwater table(≥244.0 m),and other related parameters,the more severe the landslide deformation tends to be.On the contrary,when the groundwater level is lower,the landslide generally tends to be more stable.The research results can be referenced for analyzing the inducing mechanism,monitoring and providing warning,as well as emergency treatment of cataclastic bedding rock landslides.