基于环剪试验的复活型低速滑坡活动机理
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摘要
金坪子滑坡是距离金沙江乌东德水电站大坝下游最近的一处巨型滑坡,其Ⅱ区沿底滑带复活后已持续低速蠕滑超过百年,是乌东德水电站枢纽区最大的地质灾害隐患点。为弄清该滑坡复活后的长期低速活动机理以及再次加速蠕变破坏的条件,针对滑带附近土样的力学性质以及特征强度,通过不同剪切速率、不同黏粒含量以及不同应力条件的室内环剪试验进行了测试。研究结果表明,金坪子滑坡Ⅱ区复活后长期低速蠕滑的原因在于滑带土残余强度由初次破坏的负速率效应转变为强度与剪切速率成正比的正速率效应,滑坡的活动是滑带土黏性流变特征的表现。滑坡再次发生加速蠕变破坏需要克服一个比剪切带残余强度略高的峰值强度,否则受滑带土的黏性阻滞效应滑坡将长期处于稳定蠕变的状态。滑坡雨季运动较快的原因是降雨引起滑体容重的小幅度增加,导致低速蠕变活动加快,但不至于进入加速蠕变阶段。
The Jinpingzi landslide is the nearest large landslide in the downstream direction of the Wudongde hydropower station on Jinsha River. Its reactivated zone Ⅱ has been moving slowly for at least one century which makes it the largest threat to the hydropower station. In order to understand its long-term movement mechanism and the condition for accelerated creep failure, ring shear tests under different shearing rate, different clay particles content and different stress conditions were conducted for the soil samples near the sliding zone. Results show that the movement mechanism lies in the transformation from negative shear rate effect to positive effect of residual strength of the slip zone soil from the first failure to the reactivated movement. The movement of the landslide is a viscous rheological phenomenon of the slip zone soil. Accelerated creeping failure can occur only when the landslide overcome a fast peak strength in the residual state, or it would only keep in the steady creeping state due to the viscous resisting effects. The rainfall can accelerate this landslide to a certain degree by increasing the unit weight of the sliding masses, but it can not cause the accelerated creeping failure.
The Jinpingzi landslide is the nearest large landslide in the downstream direction of the Wudongde hydropower station on Jinsha River. Its reactivated zone Ⅱ has been moving slowly for at least one century which makes it the largest threat to the hydropower station. In order to understand its long-term movement mechanism and the condition for accelerated creep failure, ring shear tests under different shearing rate, different clay particles content and different stress conditions were conducted for the soil samples near the sliding zone. Results show that the movement mechanism lies in the transformation from negative shear rate effect to positive effect of residual strength of the slip zone soil from the first failure to the reactivated movement. The movement of the landslide is a viscous rheological phenomenon of the slip zone soil. Accelerated creeping failure can occur only when the landslide overcome a fast peak strength in the residual state, or it would only keep in the steady creeping state due to the viscous resisting effects. The rainfall can accelerate this landslide to a certain degree by increasing the unit weight of the sliding masses, but it can not cause the accelerated creeping failure.
引文
[1] 蒋秀姿,文宝萍.缓慢复活型滑坡滑带土的蠕变性质与特征强度试验研究[J].岩土力学,2015,36(2):495-501.
[2] Bishop A W,Green G E,Garga V K,et al.A new ring shear apparatus and its application to the measurement of residual strength[J].Geotechnique,1971,21(4):273-328.
[3] 洪勇,孙涛,栾茂田,等.土工环剪仪的开发及其应用研究现状[J].岩土力学,2009,30(3):628-634.
[4] Lupini J F.The residual strength of soils[D].London:University of London,1981.
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[7] Lemos L J L.The effect of rate of shear on residual shear strength of soil[D].London:University of London,1986.
[8] Leroueil S.Natural slopes and cuts:Movement and failure mechanisms[J].Géotechnique,2001,51(3):197-243.
[9] Wang G H,Suemine A,Schulz W H.Shear-rate-dependent strength control on the dynamics of rainfall-triggered landslides,Tokushima Prefecture,Japan[J].Earth Surface Processes & Landforms,2010,35(4):407-416.
[10] Wang G,Sassa K.Post-failure mobility of saturated sands in undrained load-controlled[J].Canadian Geotechnical Journal,2002,39(4):821-837.
[11] Alonso E E,Zervos A,Pinyol N M,et al.Thermo-poro-mechanical analysis of landslides:From creeping behaviour to catastrophic failure[J].Geotechnique,2016,63(3):202-2019.
[12] Wang Y F,Dong J J,Cheng Q G.Velocity-dependent frictional weakening of large rock avalanche basal facies:Implications for rock avalanche hypermobility?[J].Journal of Geophysical Research:Solid Earth,2017,122(3):1648-1676.
[13] Scaringi G,Hu W,Xu Q,et al.Shear-rate-dependent behavior of clayey bi-material interfaces at landslide stress levels[J].Geophysical Research Letters,2017,45(2):766-777.
[14] Sassa K,Fukuoka H,Scarasciamugnozza G,et al.Earthquake-induced landslides:Distribution,motion and mechanisms[J].Soils and Foundations,2014,54(4):544-559.
[15] 胡明鉴,程谦恭,汪发武.易贡远程高速滑坡形成原因试验探索[J].岩石力学与工程学报,2009,28(1):138-143.
[16] 汪发武.高速滑坡形成机制:土粒子破碎导致超孔隙水压力的产生[J].吉林大学学报:地球科学版,2001,31(1):64-69.
[17] Hu W,Xu Q,Wang G,et al.Shear resistance variations in experimentally sheared mudstone granules:A possible shear-thinning and thixotropic mechanism[J].Geophysical Research Letters,2017,44:11040-11050.
[18] 汪发武,彭轩明,霍志涛,等.三峡库区千将坪滑坡的高速远程滑动机理与库水位变动条件下树坪滑坡的变形模式[J].工程地质学报,2008(增刊1):536-541.
[19] 胡广韬.滑坡动力学[M].北京:地质出版社,1995.
[20] Miao H,Wang G,Yin K,et al.Mechanism of the slow-moving landslides in Jurassic red-strata in the Three Gorges Reservoir,China[J].Engineering Geology,2014,171(8):59-69.
[21] 缪海波,殷坤龙,王功辉.库岸深层老滑坡间歇性复活的动力学机制研究[J].岩土力学,2016,37(9):2645-2653.
[22] 崔杰,王兰生,徐进,等.金沙江中游滑坡堵江事件及古滑坡体稳定性分析[J].工程地质学报,2008,16(1):6-10.
[23] 蒋树,王义锋,唐川,等.金沙江下游金坪子Ⅱ区低速滑坡活动机理初探[J].工程地质学报,2017,25(6):1547-1556.
[24] GB50021-2001 岩土工程勘察规范[S].北京:中国建筑工业出版社,2009.
[25] Corominas J,Moya J,Ledesma A,et al.Prediction of ground displacements and velocities from groundwater level changes at the Vallcebre landslide (Eastern Pyrenees,Spain)[J].Landslides,2005,2(2):83-96.
[26] Bhat D R,Bhandary N P,Yatabe R,et al.Residual state creep test in modified torsional ring shear machine:Methods and implications[J].Int.J.Geomate.,2011,1(1):39-43.
[27] Bhat D R,Bhandary N P,Yatabe R.Residual state creep behavior of typical clayey soils[J].Natural Hazards,2013,69(3):2161-2178.
[28] Maio C D,Vassallo R,Vallario M.Plastic and viscous shear displacements of a deep and very slow landslide in stiff clay formation[J].Engineering Geology,2013,162(4):53-66.
[29] Wen B P,Jiang X Z.Effect of gravel content on creep behavior of clayey soil at residual state:Implication for its role in slow-moving landslides[J].Landslides,2017,14(2):559-576.
[2] Bishop A W,Green G E,Garga V K,et al.A new ring shear apparatus and its application to the measurement of residual strength[J].Geotechnique,1971,21(4):273-328.
[3] 洪勇,孙涛,栾茂田,等.土工环剪仪的开发及其应用研究现状[J].岩土力学,2009,30(3):628-634.
[4] Lupini J F.The residual strength of soils[D].London:University of London,1981.
[5] Martins J P.Shaft resistance of axially loaded piles in clay[D].London:University of London,1983.
[6] Tika T E.Fast shearing of pre-existing shear zones in soil[J].Geotechnique,1996,49(2):197-233.
[7] Lemos L J L.The effect of rate of shear on residual shear strength of soil[D].London:University of London,1986.
[8] Leroueil S.Natural slopes and cuts:Movement and failure mechanisms[J].Géotechnique,2001,51(3):197-243.
[9] Wang G H,Suemine A,Schulz W H.Shear-rate-dependent strength control on the dynamics of rainfall-triggered landslides,Tokushima Prefecture,Japan[J].Earth Surface Processes & Landforms,2010,35(4):407-416.
[10] Wang G,Sassa K.Post-failure mobility of saturated sands in undrained load-controlled[J].Canadian Geotechnical Journal,2002,39(4):821-837.
[11] Alonso E E,Zervos A,Pinyol N M,et al.Thermo-poro-mechanical analysis of landslides:From creeping behaviour to catastrophic failure[J].Geotechnique,2016,63(3):202-2019.
[12] Wang Y F,Dong J J,Cheng Q G.Velocity-dependent frictional weakening of large rock avalanche basal facies:Implications for rock avalanche hypermobility?[J].Journal of Geophysical Research:Solid Earth,2017,122(3):1648-1676.
[13] Scaringi G,Hu W,Xu Q,et al.Shear-rate-dependent behavior of clayey bi-material interfaces at landslide stress levels[J].Geophysical Research Letters,2017,45(2):766-777.
[14] Sassa K,Fukuoka H,Scarasciamugnozza G,et al.Earthquake-induced landslides:Distribution,motion and mechanisms[J].Soils and Foundations,2014,54(4):544-559.
[15] 胡明鉴,程谦恭,汪发武.易贡远程高速滑坡形成原因试验探索[J].岩石力学与工程学报,2009,28(1):138-143.
[16] 汪发武.高速滑坡形成机制:土粒子破碎导致超孔隙水压力的产生[J].吉林大学学报:地球科学版,2001,31(1):64-69.
[17] Hu W,Xu Q,Wang G,et al.Shear resistance variations in experimentally sheared mudstone granules:A possible shear-thinning and thixotropic mechanism[J].Geophysical Research Letters,2017,44:11040-11050.
[18] 汪发武,彭轩明,霍志涛,等.三峡库区千将坪滑坡的高速远程滑动机理与库水位变动条件下树坪滑坡的变形模式[J].工程地质学报,2008(增刊1):536-541.
[19] 胡广韬.滑坡动力学[M].北京:地质出版社,1995.
[20] Miao H,Wang G,Yin K,et al.Mechanism of the slow-moving landslides in Jurassic red-strata in the Three Gorges Reservoir,China[J].Engineering Geology,2014,171(8):59-69.
[21] 缪海波,殷坤龙,王功辉.库岸深层老滑坡间歇性复活的动力学机制研究[J].岩土力学,2016,37(9):2645-2653.
[22] 崔杰,王兰生,徐进,等.金沙江中游滑坡堵江事件及古滑坡体稳定性分析[J].工程地质学报,2008,16(1):6-10.
[23] 蒋树,王义锋,唐川,等.金沙江下游金坪子Ⅱ区低速滑坡活动机理初探[J].工程地质学报,2017,25(6):1547-1556.
[24] GB50021-2001 岩土工程勘察规范[S].北京:中国建筑工业出版社,2009.
[25] Corominas J,Moya J,Ledesma A,et al.Prediction of ground displacements and velocities from groundwater level changes at the Vallcebre landslide (Eastern Pyrenees,Spain)[J].Landslides,2005,2(2):83-96.
[26] Bhat D R,Bhandary N P,Yatabe R,et al.Residual state creep test in modified torsional ring shear machine:Methods and implications[J].Int.J.Geomate.,2011,1(1):39-43.
[27] Bhat D R,Bhandary N P,Yatabe R.Residual state creep behavior of typical clayey soils[J].Natural Hazards,2013,69(3):2161-2178.
[28] Maio C D,Vassallo R,Vallario M.Plastic and viscous shear displacements of a deep and very slow landslide in stiff clay formation[J].Engineering Geology,2013,162(4):53-66.
[29] Wen B P,Jiang X Z.Effect of gravel content on creep behavior of clayey soil at residual state:Implication for its role in slow-moving landslides[J].Landslides,2017,14(2):559-576.
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