苗尾水电站赵子坪岸坡变形失稳的地下水动力作用分析
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摘要
库水位变动是诱发库岸边坡变形失稳的主要因素。为探究库水位变动下倾倒变形岩体破坏后形成的堆积体斜坡的地下水动力作用,以云南澜沧江的苗尾水电站赵子坪滑坡为研究对象,通过现场地质调查和勘探确定了滑坡形态和坡体结构特征;再结合监测数据深入分析了滑坡在地下水动力作用下的变形失稳机制,并基于非饱和土力学理论和有限元法对其失稳机制进行进一步验证。结果显示:赵子坪岸坡为原始倾倒岩体变形破坏后上部强倾倒岩体沿着折断面发生滑动而形成的堆积体斜坡,内部呈层状堆积的片石表明其还保留了部分倾倒岩体的结构特征。水库蓄水后,由于松散的倾倒堆积体为库水渗入坡体创造了良好的条件,地下水位随库水位升高而快速升高,导致孔隙水压力增大而滑坡阻滑段有效应力减小,从而造成稳定性降低,滑坡易沿着由倾倒折断面演化而成的基覆界面发生滑动破坏。
Variation in reservoir water level is the main factor inducing the deformation and instability of bank slopes. In order to explore the groundwater dynamic effect of the slope formed by the collapse of toppling deformed rock mass under the change in reservoir water level,the Zhaoziping landslide near the Miaowei Hydropower Station on the Lancangjiang River in Yunnan was taken as the research object,and the landslide morphology and structure characteristics were determined by field geological survey and exploration. The deformation and instability mechanism of the landslide under the action of groundwater dynamic was analyzed in detail using the deformation monitoring data. They are validated based on the unsaturated soil mechanics theory and finite element method. The results show that the Zhaoziping bank slope is an accumulation slope formed by the sliding of the upper strongly toppled rock mass along the fracture surface after the deformation and failure of the original toppled rock mass. The stratified accumulation of schistose rock in the slope indicates that it retains some structural characteristics of toppled rock mass. After the reservoir impoundment,because the loose toppling accumulation body creates good conditions for reservoir water to infiltrate into the slope,the groundwater level rises rapidly with the reservoir water level rising,which leads to the increase in pore water pressure and the decrease in effective stress in the landslide resistance section,thus the stability of the landslide decreases,and the landslide is liable to slide along the bedrock cover interface evolved from the fracture surface.
Variation in reservoir water level is the main factor inducing the deformation and instability of bank slopes. In order to explore the groundwater dynamic effect of the slope formed by the collapse of toppling deformed rock mass under the change in reservoir water level,the Zhaoziping landslide near the Miaowei Hydropower Station on the Lancangjiang River in Yunnan was taken as the research object,and the landslide morphology and structure characteristics were determined by field geological survey and exploration. The deformation and instability mechanism of the landslide under the action of groundwater dynamic was analyzed in detail using the deformation monitoring data. They are validated based on the unsaturated soil mechanics theory and finite element method. The results show that the Zhaoziping bank slope is an accumulation slope formed by the sliding of the upper strongly toppled rock mass along the fracture surface after the deformation and failure of the original toppled rock mass. The stratified accumulation of schistose rock in the slope indicates that it retains some structural characteristics of toppled rock mass. After the reservoir impoundment,because the loose toppling accumulation body creates good conditions for reservoir water to infiltrate into the slope,the groundwater level rises rapidly with the reservoir water level rising,which leads to the increase in pore water pressure and the decrease in effective stress in the landslide resistance section,thus the stability of the landslide decreases,and the landslide is liable to slide along the bedrock cover interface evolved from the fracture surface.
引文
[1]朱冬林,任光明,聂德新,等.库水位变化下对水库滑坡稳定性影响的预测[J].水文地质工程地质,2002,23(3):6-9.[ZHU D L,REN G M,NIE D X,et al. Effecting and forecasting of landslide stability with the change of reservoir water level[J].Hydrogeology&Engineering Geology,2002,23(3):6-9.(in Chinese)]
[2]尹晓萌,晏鄂川,杜毅,等.库水位下降条件下堆积层滑坡稳定性分析[J].中国地质灾害与防治学报,2017,28(3):8-15.[YING X M,YAN E C,DU Y,et al.Stability Analysis of accumulation layer landslide under the condition of falling Reservoir Water level[J]. The Chinese Journal of Geological Hazard and Control,2017,28(3):8-15.(in Chinese)]
[3]莫伟伟,徐平,丁秀丽.库水位涨落对滑坡稳定性影响研究进展[J].地下空间与工程学报,2006,2(6):997-1002.[MO W W,XU P,DING X L.Research progress on the effect of reservoir water level fluctuation on landslide Stability[J]. Chinese Journal of Underground Space and Engineering,2006,2(6):997-1002.(in Chinese)]
[4]王俊梅,刘海宁.水库蓄水引发的地下水位抬升和渗控措施研究[J].水文地质工程地质,2011,38(5):115-119.[WANG J M,LIU H N. Study on groundwater level uplift and seepage control measures caused by reservoir impoundment[J]. Hydrogeology&Engineering Geology,2011,38(5):115-119.(in Chinese)]
[5]卢书强,易庆林,易武,等.三峡库区树坪滑坡变形失稳机制分析[J].岩土力学,2014,35(4):1123-1130.[LU S Q,YI Q L,YI W,et al. Analysis of deformation and failure mechanism of Shuping landslide in Three Gorges reservoir area[J]. Rock and Soil Mechanics,2014,35(4):1123-1130.(in Chinese)]
[6]向家松,文宝萍,陈明,等.结构复杂滑坡活动对库水位变化的响应特征——以三峡库区柴湾滑坡为例[J].水文地质工程地质,2017,44(4):71-77.[XIANG J S,WEN B P,CHEN M,et al. Activity response of a landslide with complex structure to fluctuation of reservoir water level:a case study of the Chaiwan landslide in the Three Gorges Reservoir[J].Hydrogeology&Engineering Geology,2017,44(4):71-77.(in Chinese)]
[7]张岩,陈国庆,张国峰,等.库水位变化对观音坪滑坡稳定性影响的数值分析[J].工程地质学报,2016,24(4):501-509.[ZHANG Y,CHEN G Q,ZHANG G F,et al. Numerical analysis of influence of water level variation on Guanyinping landslide stability[J]. Chinese Journal of Engineering Geology,2016,24(4):501-509(in Chinese).]
[8]王明华,晏鄂川.水库蓄水对库岸滑坡的影响研究[J].岩土力学,2007,28(12):2722-2725.[WANG M H,YAN E C. Study on influence of reservoir water impounding on reservoir landslide[J].Rock and Soil Mechanics,2007,28(12):2722-2725.(in Chinese)]
[9]赵代鹏,王世梅,谈云志,等.库水升降作用下浮托减重型滑坡稳定性研究[J].岩土力学,2013,34(4):1017-1024.[ZHAO D P,WANG S M,TAN Y Z,et al. Stability studies of buoyancy weight loss landslides under reservoir water level fluctuation[J].Rock and Soil Mechanics,2013,34(4):1017-1024.(in Chinese)]
[10]陶宏亮,范士凯,徐光黎,等.库水位变化条件下堆积体滑坡变形特征及稳定性分析[J].水电能源科学,2014,32(5):96-100.[TAO H L,FAN S K,XU G L,et al. The deformation characteristics and stability analysis of accumulation landslide under the condition of water level change[J]. Water Resources and Power,2014,32(5):96-100.(in Chinese)]
[11]朱继良,黄润秋.某大型水电站水文站滑坡蓄水后的稳定性三维数值模拟研究[J].岩石力学与工程学报,2005,24(8):1384-1389.[ZHU J L,HUANG R Q. Study on the stability of Shuiwenzhan slope in a large hydrostation after impoundment by using 3d numerical modeling.[J]. Chinese Journal of Rock Mechanics and Engineering,2005,24(8):1384-1389.(in Chinese)]
[12]钟登华,安娜,李明超.库岸滑坡体失稳三维动态模拟与分析研究[J].岩石力学与工程学报,2007,26(2):360-367.[ZHONG D H,AN N,LI M C. 3D dynamic simulation and analysis of slope instability in reservoir bank[J]. Chinese Journal of Rock Mechanics and Engineering,2007,26(2):360-367.(in Chinese)]
[13]张旭,谭卓英,周春梅.库水位变化下滑坡渗流机制与稳定性分析[J].岩石力学与工程学报,2016,35(4):713-723.[ZHANG X,TAN Z Y,ZHOU C M.Seepage and stability analysis of landslide under the change of reservoir water levels[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(4):713-723.(in Chinese)]
[14]卢树盛,辛全才,肖诗荣,等.水位骤降下边坡渗流场与应力场耦合数值分析[J].水文地质工程地质,2010,37(6):130-133.[LU S S,XIN Q C,XIAO S R,et al. Numerical analysis of coupling of seepage field and stress field of slope under sudden drop of water level[J]. Hydrogeology&Engineering Geology,2010,37(6):130-133.(in Chinese)]
[15]伍艳,王玮屏,任海平,等.水-土作用对土体渗透系数的影响研究[J].水文地质工程地质,2011,38(6):39-43.[WU Y,WANG W P,REN H P,et al. Study on the effect of water-soil interaction on soil permeability coefficient[J]. Hydrogeology&Engineering Geology,2011,38(6):39-43.(in Chinese)]
[2]尹晓萌,晏鄂川,杜毅,等.库水位下降条件下堆积层滑坡稳定性分析[J].中国地质灾害与防治学报,2017,28(3):8-15.[YING X M,YAN E C,DU Y,et al.Stability Analysis of accumulation layer landslide under the condition of falling Reservoir Water level[J]. The Chinese Journal of Geological Hazard and Control,2017,28(3):8-15.(in Chinese)]
[3]莫伟伟,徐平,丁秀丽.库水位涨落对滑坡稳定性影响研究进展[J].地下空间与工程学报,2006,2(6):997-1002.[MO W W,XU P,DING X L.Research progress on the effect of reservoir water level fluctuation on landslide Stability[J]. Chinese Journal of Underground Space and Engineering,2006,2(6):997-1002.(in Chinese)]
[4]王俊梅,刘海宁.水库蓄水引发的地下水位抬升和渗控措施研究[J].水文地质工程地质,2011,38(5):115-119.[WANG J M,LIU H N. Study on groundwater level uplift and seepage control measures caused by reservoir impoundment[J]. Hydrogeology&Engineering Geology,2011,38(5):115-119.(in Chinese)]
[5]卢书强,易庆林,易武,等.三峡库区树坪滑坡变形失稳机制分析[J].岩土力学,2014,35(4):1123-1130.[LU S Q,YI Q L,YI W,et al. Analysis of deformation and failure mechanism of Shuping landslide in Three Gorges reservoir area[J]. Rock and Soil Mechanics,2014,35(4):1123-1130.(in Chinese)]
[6]向家松,文宝萍,陈明,等.结构复杂滑坡活动对库水位变化的响应特征——以三峡库区柴湾滑坡为例[J].水文地质工程地质,2017,44(4):71-77.[XIANG J S,WEN B P,CHEN M,et al. Activity response of a landslide with complex structure to fluctuation of reservoir water level:a case study of the Chaiwan landslide in the Three Gorges Reservoir[J].Hydrogeology&Engineering Geology,2017,44(4):71-77.(in Chinese)]
[7]张岩,陈国庆,张国峰,等.库水位变化对观音坪滑坡稳定性影响的数值分析[J].工程地质学报,2016,24(4):501-509.[ZHANG Y,CHEN G Q,ZHANG G F,et al. Numerical analysis of influence of water level variation on Guanyinping landslide stability[J]. Chinese Journal of Engineering Geology,2016,24(4):501-509(in Chinese).]
[8]王明华,晏鄂川.水库蓄水对库岸滑坡的影响研究[J].岩土力学,2007,28(12):2722-2725.[WANG M H,YAN E C. Study on influence of reservoir water impounding on reservoir landslide[J].Rock and Soil Mechanics,2007,28(12):2722-2725.(in Chinese)]
[9]赵代鹏,王世梅,谈云志,等.库水升降作用下浮托减重型滑坡稳定性研究[J].岩土力学,2013,34(4):1017-1024.[ZHAO D P,WANG S M,TAN Y Z,et al. Stability studies of buoyancy weight loss landslides under reservoir water level fluctuation[J].Rock and Soil Mechanics,2013,34(4):1017-1024.(in Chinese)]
[10]陶宏亮,范士凯,徐光黎,等.库水位变化条件下堆积体滑坡变形特征及稳定性分析[J].水电能源科学,2014,32(5):96-100.[TAO H L,FAN S K,XU G L,et al. The deformation characteristics and stability analysis of accumulation landslide under the condition of water level change[J]. Water Resources and Power,2014,32(5):96-100.(in Chinese)]
[11]朱继良,黄润秋.某大型水电站水文站滑坡蓄水后的稳定性三维数值模拟研究[J].岩石力学与工程学报,2005,24(8):1384-1389.[ZHU J L,HUANG R Q. Study on the stability of Shuiwenzhan slope in a large hydrostation after impoundment by using 3d numerical modeling.[J]. Chinese Journal of Rock Mechanics and Engineering,2005,24(8):1384-1389.(in Chinese)]
[12]钟登华,安娜,李明超.库岸滑坡体失稳三维动态模拟与分析研究[J].岩石力学与工程学报,2007,26(2):360-367.[ZHONG D H,AN N,LI M C. 3D dynamic simulation and analysis of slope instability in reservoir bank[J]. Chinese Journal of Rock Mechanics and Engineering,2007,26(2):360-367.(in Chinese)]
[13]张旭,谭卓英,周春梅.库水位变化下滑坡渗流机制与稳定性分析[J].岩石力学与工程学报,2016,35(4):713-723.[ZHANG X,TAN Z Y,ZHOU C M.Seepage and stability analysis of landslide under the change of reservoir water levels[J]. Chinese Journal of Rock Mechanics and Engineering,2016,35(4):713-723.(in Chinese)]
[14]卢树盛,辛全才,肖诗荣,等.水位骤降下边坡渗流场与应力场耦合数值分析[J].水文地质工程地质,2010,37(6):130-133.[LU S S,XIN Q C,XIAO S R,et al. Numerical analysis of coupling of seepage field and stress field of slope under sudden drop of water level[J]. Hydrogeology&Engineering Geology,2010,37(6):130-133.(in Chinese)]
[15]伍艳,王玮屏,任海平,等.水-土作用对土体渗透系数的影响研究[J].水文地质工程地质,2011,38(6):39-43.[WU Y,WANG W P,REN H P,et al. Study on the effect of water-soil interaction on soil permeability coefficient[J]. Hydrogeology&Engineering Geology,2011,38(6):39-43.(in Chinese)]