软层对土质边坡破坏模式及稳定性影响的数值分析
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摘要
为了研究软层对土质边坡破坏模式及其稳定性的影响,运用FLAC~(3D)建立多分层(坡体分4层,坡基分2层)土质边坡模型。将软层分为由内摩擦角φ控制的软层(内摩擦角φ较小的软层),以由黏聚力c控制的软层(黏聚力c较小的软层)。考虑工程实际选取4种常见的软层分布方式:①软层在边坡顶部、②软层在边坡底部、③软层在边坡顶部和底部、④软层在边坡中部,采用强度折减法分析了不同软层分布和不同软层性质边坡的滑动面和安全系数。结果表明:(1)内摩擦角φ控制的软层分布不同时,分布②边坡表现为圆弧+直线型破坏,其余分布则表现为圆弧型破坏;(2)黏聚力c控制的软层在不同分布时,分布②呈明显的圆弧型破坏,其余分布表现为一定程度的圆弧+直线型破坏;(3)位于边坡中部的软层显著降低其稳定性,其中以黏聚力c控制的软层不利影响最为显著;(4)随层间参数差异值的增大,不同的软层黏聚力c与内摩擦角φ对于滑动面上边缘距坡顶距离作用效果相反,而对于安全系数的影响表现一致;(5)针对软层位于边坡中部的情况,软层自身性质相较于其周围土层的性质对边坡稳定性影响更为显著。在相关施工中应主要对软层进行加固,并适当对其周围土层进行补强,可实现经济合理的支护方案。
In order to study the impact of soft layer on failure mode and stability of soil slope, the model of multi-layer stratified soil slope with body of 4 layers and base of 2 layers is simulated by FLAC~(3 D). The soft layer is divided into soft layer controlled by internal friction angle φ(the soft layer with a smaller φ) and soft layer controlled by cohesion c(soft layer with a smaller c). Considering the engineering practice, 4 common soft layer distributions are chosen, including ① upper soft layer, ②lower soft layer, ③upper and lower soft layers, and ④middle soft layer. The slip surfaces and safety factors of soil slopes with different soft layer distributions and properties are analysed by strength reduction method. The result shows that(1) for the soft layer controlled by φ in different distributions, the slope of distribution ② shows mixed failure mode of arc and beeline, and the rest of the distributions are obviously arc failure modes;(2)for the soft layer controlled by c in different distributions, the distribution ② is obviously arc failure mode, and the rest of the distributions show mixed failure mode of arc and beeline to some extent;(3) the stability of the soft layer in the middle part of slope is significantly reduced, and the soft layer controlled by c is the most adverse;(4) with the increase of the difference of interlayer parameters, the effects of c and φ on the distance between the upper edge of slip surface and the slope top are opposite, but their effects on the safety factor are the same;(5) for the soil slope with soft layer in middle part, the property of the soft layer has more significant influence on the slope stability compared with that of the surrounding soil layer. In the construction, the soft layer should be mainly reinforced, and the surrounding soil layers should be reinforced appropriately, so that an economical and reasonable support scheme can be realized.
In order to study the impact of soft layer on failure mode and stability of soil slope, the model of multi-layer stratified soil slope with body of 4 layers and base of 2 layers is simulated by FLAC~(3 D). The soft layer is divided into soft layer controlled by internal friction angle φ(the soft layer with a smaller φ) and soft layer controlled by cohesion c(soft layer with a smaller c). Considering the engineering practice, 4 common soft layer distributions are chosen, including ① upper soft layer, ②lower soft layer, ③upper and lower soft layers, and ④middle soft layer. The slip surfaces and safety factors of soil slopes with different soft layer distributions and properties are analysed by strength reduction method. The result shows that(1) for the soft layer controlled by φ in different distributions, the slope of distribution ② shows mixed failure mode of arc and beeline, and the rest of the distributions are obviously arc failure modes;(2)for the soft layer controlled by c in different distributions, the distribution ② is obviously arc failure mode, and the rest of the distributions show mixed failure mode of arc and beeline to some extent;(3) the stability of the soft layer in the middle part of slope is significantly reduced, and the soft layer controlled by c is the most adverse;(4) with the increase of the difference of interlayer parameters, the effects of c and φ on the distance between the upper edge of slip surface and the slope top are opposite, but their effects on the safety factor are the same;(5) for the soil slope with soft layer in middle part, the property of the soft layer has more significant influence on the slope stability compared with that of the surrounding soil layer. In the construction, the soft layer should be mainly reinforced, and the surrounding soil layers should be reinforced appropriately, so that an economical and reasonable support scheme can be realized.
引文
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[16] 张常亮,李萍,陶福平,等.黄土强度指标对边坡稳定性的影响研究[J].公路交通科技,2011,28(3):20-25.ZHANG Chang-liang,LI Ping,TAO Fu-ping,et al.Research of Effect of Strength Index on Loess Slope Stability[J].Journal of Highway and Transportation Research and Development,2011,28(3):20-25.
[17] 柴佳乐,张拥军,李博,等.开挖条件下软弱夹层对岩质边坡稳定性的影响[J].工程建设,2017,49(2):1-6.CHAN Jia-le,ZHANG Yong-jun,LI Bo,et al.The Influences of Weak Interlayer on Rocky Slope Stability under the Condition of Excavation[J].Engineering Construction,2017,49(2):1-6.
[18] 张鲁渝,郑颖人,赵尚毅,等.有限元强度折减系数法计算土坡稳定安全系数的精度研究[J].水利学报,2003,34(1):21-27.ZHANG Lu-yu,ZHENG Yin-ren,ZHAO Shang-yi,et al.The Feasibility Study of Strength-reduction Method with FEM for Calculating Safety Factors of Soil Slope Stability[J].Journal of Hydraulic Engineering,2003,34(1):21-27.
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[21] 陈祖煜,汪小刚,杨健,等.土质边坡稳定分析:原理·方法·程序[M].北京:中国水利水电出版社,2003.CHEN Zu-yu,WANG Xiao-gang,YANG Jian,et al.Soil Slope Stability Analysis:Theory,Methods and Procedures[M].Beijing:China Water and Power Press,2003.
[2] JANBU N.Slope Stability Computations Embankment Dam Engineering[M].New York:John Wiley and Sons,Inc.,1973.
[3] SARMA S K.Stability Analysis of Embankments and Slopes[J].Geotechnique,1973,23(3):423–433.
[4] ZIENKIEWICZ O C,HUMPHESON C,LEWIS R W.Associated and Non-associated Visco-plasticity and Plasticity in Soil Mechanics[J].Geotechnique,1975,25(4):671-689.
[5] LIU S Y,SHAO L T,LI H J.Slope Stability Analysis Using the Limit Equilibrium Method and Two Finite Element Methods[J].Computers and Geotechnics,2015,63:291-298.
[6] CHEN X,WU Y,YU Y,et al.A Two-grid Search Scheme for Large-scale 3-D Finite Element Analyses of Slope Stability[J].Computers and Geotechnics,2014,62:203-215.
[7] CHEN Z Y,MORGENSTERN N R.Extensions to the Generalised Method of Slices for Stability Analysis[J].Canadian Geotechnical Journal,1983,20(1):104-119.
[8] 张社荣,谭尧升,王超,等.多层软弱夹层边坡岩体破坏机制与稳定性研究[J].岩土力学,2014,35(6):1695-1702.ZHANG She-rong,TAN Yao-sheng,WANG Chao,et al.Research on Deformation Failure Mechanism and Stability of Slope Rock Mass Containing Multi-weak Interlayers[J].Rock and Soil Mechanics,2014,35(6):1695-1702.
[9] 刘怡林,黄茂松,袁伟,等.斜坡含软夹层地基路堤离心模型试验与数值模拟[J].岩土力学,2013(增2):22-34.LIU Yi-lin,HUANG Mao-song,YUAN Wei,et al.Centrifugal Model Test and Numerical Simulation of Embankments on Sloping Ground with Weak Interlayer[J].Rock and Soil Mechanics,2013(S2):22-34.
[10] 李龙起,罗书学,魏文凯,等.降雨入渗对含软弱夹层顺层岩质边坡性状影响的模型试验研究[J].岩石力学与工程学报,2013,32(9):1772-1778.LI Long-qi,LUO Shu-xue,WEI Wen-kai,et al.Model Tests of Rainfall Infiltration Effect on Bedding Rock Slope with Weak Interlayer[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(9):1772-1778.
[11] 蒋水华,姚池,杨建华,等.考虑参数空间变异性的非均质边坡可靠度分析[J].防灾减灾工程学报,2016,36(4):572-579.JIANG Shui-hua,YAO Chi,YANG Jian-hua,et al.Reliability Analysis of Heterogeneous Slopes Considering Spatially Variable Soil Properties[J].Journal of Disaster Prevention and Mitigation Engineering,2016,36 (4):572-579.
[12] 刘怡林,宁兆轲,姜瑞清,等.抗滑桩加固含软弱夹层边坡三维弹塑性数值分析[J].岩土工程学报,2013,35(增1):216-221.LIU Yi-lin,NING Zhao-ke,JIANG Rui-qing,et al.3D Elastoplastic Stability Analysis of Slopes with Weak Interlayers Reinforced by Piles Based on FEM[J].Chinese Journal of Geotechnical Engineering,2013,35(S1):216-221.
[13] 汤祖平,李亮,赵炼恒,等.含软弱夹层边坡稳定性的极限分析上限解析[J].铁道科学与工程学报,2014,11(2):60-64.TANG Zu-ping,LI Liang,ZHAO Lian-heng,et al.Stability Analysis of Slopes with Weak Interlayer Based on Upper Bound Limit Analysis[J].Journal of Railway Science and Engineering,2014,11(2):60-64.
[14] 宋子岭,杨添,赵立春.含多层软弱夹层的顺向岩质边坡稳定性评价方法对比分析[J].中国地质灾害与防治学报,2016,27(2):20-25.SONG Zi-ling,YANG Tian,ZHAO Li-chun.Application of Combination Algorithm in Stability Analysis of Rock Slope with Contains Multilayer Weak Bedrock Layers[J].The Chinese Journal of Geological Hazard and Control,2016,27(2):20-25.
[15] 陈玮,简文彬,董岩松,等.某含软弱夹层花岗岩残积土边坡稳定性研究[J].水利与建筑工程学报,2014,12(6):107-112.CHEN Wei,JIAN Wen-bin,DONG Yan-song,et al.Stability Study of a Granite Residual Soil Slope with Weak Interlayers[J].Journal of Water Resources and Architectural Engineering,2014,12(6):107-112.
[16] 张常亮,李萍,陶福平,等.黄土强度指标对边坡稳定性的影响研究[J].公路交通科技,2011,28(3):20-25.ZHANG Chang-liang,LI Ping,TAO Fu-ping,et al.Research of Effect of Strength Index on Loess Slope Stability[J].Journal of Highway and Transportation Research and Development,2011,28(3):20-25.
[17] 柴佳乐,张拥军,李博,等.开挖条件下软弱夹层对岩质边坡稳定性的影响[J].工程建设,2017,49(2):1-6.CHAN Jia-le,ZHANG Yong-jun,LI Bo,et al.The Influences of Weak Interlayer on Rocky Slope Stability under the Condition of Excavation[J].Engineering Construction,2017,49(2):1-6.
[18] 张鲁渝,郑颖人,赵尚毅,等.有限元强度折减系数法计算土坡稳定安全系数的精度研究[J].水利学报,2003,34(1):21-27.ZHANG Lu-yu,ZHENG Yin-ren,ZHAO Shang-yi,et al.The Feasibility Study of Strength-reduction Method with FEM for Calculating Safety Factors of Soil Slope Stability[J].Journal of Hydraulic Engineering,2003,34(1):21-27.
[19] Itasca Consulting Group,Inc.Flac 3D User Manuals[M].Minneapolis:Itasca Consulting Group Inc.,2005.
[20] 孙书伟,林杭,任连伟.FLAC3D在岩土工程中的应用[M].北京:中国水利水电出版社,2011.SUN Shu-wei,LIN Hang,REN Lian-wei.Application of FLAC3D in Geotechnical Engineering[M].Beijing:China Water and Power Press,2011.
[21] 陈祖煜,汪小刚,杨健,等.土质边坡稳定分析:原理·方法·程序[M].北京:中国水利水电出版社,2003.CHEN Zu-yu,WANG Xiao-gang,YANG Jian,et al.Soil Slope Stability Analysis:Theory,Methods and Procedures[M].Beijing:China Water and Power Press,2003.