降雨入渗条件下内河航道岸坡稳定性分析
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摘要
降雨入渗是引起内河航道岸坡失稳的重要因素。目前降雨入渗条件下岸坡稳定性数值分析中,关于岸坡竖向剖面的饱和度与孔压分布规律,主要针对不同的雨型分布开展研究,而不同的降雨强度、降雨历时和土体饱和渗透系数也会显著影响饱和度与孔压随深度的分布,从而影响岸坡的稳定性;降雨作用下的许多岸坡失稳现象发生在降雨停止后的某一时刻,目前鲜见针对降雨作用停止后岸坡稳定性变化规律的数值模拟研究;当降雨强度与岸坡土体饱和渗透系数较为接近时,对岸坡的稳定性最为不利,已有研究中没有结合降雨强度考虑土体饱和渗透系数变化对岸坡稳定性的影响。基于此,通过建立ABAQUS有限元数值模型,分析降雨作用对岸坡饱和度、孔隙水压力、位移变形和安全系数的影响。结果表明:降雨入渗会使岸坡浅层土体的饱和度与孔压急剧升高;雨水渗流及基质吸力会使岸坡土体产生变形,强降雨会使浅层土体发生严重塑性破坏;降雨强度一定时,随着降雨时长增加,岸坡稳定性降低,土体渗透系数较小时,岸坡安全系数最小值出现在降雨结束后某一时刻;土体渗透系数对于岸坡稳定性的影响需同降雨强度结合起来考虑。
Rainfall infiltration is an important factor that causes instability of inland waterway bank.In the current numerical analysis of slope stability under rainfall infiltration conditions,the distribution of saturation degree and pore water pressure at the vertical section is mainly studied for different rainfall patterns,but rainfall intensity,rainfall duration and permeability coefficient of saturated soil also significantly affect the distribution of saturation degree and pore water pressure along the depth,thus affecting the slope stability condition.Many of the rainfall-induced slope instability events occurred sometime after the rainfall had stopped,currently there are few numerical simulations to study the stability of bank slopes after rainfall stops.When the rainfall intensity is close to the saturation permeability coefficient of slope soil,the stability of the bank slope is the most unfavorable.The current study does not consider the effect of rainfall intensity on the slope stability due to the change of saturated soil permeability coefficient.In view of the above problems,this paper analyzes the rainfall effect on the slope stability,pore water pressure,slope deformation and safety factor through the establishment of ABAQUS finite element numerical model.The results show that the infiltration of rainfall will cause the saturation and pore water pressure of the shallow soil in the bank slope to rise sharply.The seepage of the rainwater and the matric suction will deform the bank soil,and severe rainfall will cause serious plastic damage of the shallow soil.When the rainfall intensity is constant,with the increase of rainfall duration,the stability of the bank decreases,and when the soil permeability coefficient is small,the minimum safety factor of the bank appears at a certain moment after the rainfall ends;The effect of soil permeability coefficient on bank stability needs to be considered in combination with rainfall intensity.
Rainfall infiltration is an important factor that causes instability of inland waterway bank.In the current numerical analysis of slope stability under rainfall infiltration conditions,the distribution of saturation degree and pore water pressure at the vertical section is mainly studied for different rainfall patterns,but rainfall intensity,rainfall duration and permeability coefficient of saturated soil also significantly affect the distribution of saturation degree and pore water pressure along the depth,thus affecting the slope stability condition.Many of the rainfall-induced slope instability events occurred sometime after the rainfall had stopped,currently there are few numerical simulations to study the stability of bank slopes after rainfall stops.When the rainfall intensity is close to the saturation permeability coefficient of slope soil,the stability of the bank slope is the most unfavorable.The current study does not consider the effect of rainfall intensity on the slope stability due to the change of saturated soil permeability coefficient.In view of the above problems,this paper analyzes the rainfall effect on the slope stability,pore water pressure,slope deformation and safety factor through the establishment of ABAQUS finite element numerical model.The results show that the infiltration of rainfall will cause the saturation and pore water pressure of the shallow soil in the bank slope to rise sharply.The seepage of the rainwater and the matric suction will deform the bank soil,and severe rainfall will cause serious plastic damage of the shallow soil.When the rainfall intensity is constant,with the increase of rainfall duration,the stability of the bank decreases,and when the soil permeability coefficient is small,the minimum safety factor of the bank appears at a certain moment after the rainfall ends;The effect of soil permeability coefficient on bank stability needs to be considered in combination with rainfall intensity.
引文
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[3]Ng C W W,Shi Q.A numerical investigation of the stability of unsaturated soil slopes subjected to transient seepage[J].Computers&Geotechnics,1998,22(1):1-28.
[4]程曦,王元战,马殿光,等.基于ABAQUS的内河航道岸坡稳定性分析[J].水道港口,2012,33(2):152-158.Cheng X,Wang Y Zh,Ma D G,et al.Analysis of inland river waterway slope stability through ABAQUS[J].Journal of Waterway and Harbor,2012,33(2):152-158.(in Chinese)
[5]Rahimi A,Rahardjo H,Leong E C.Effect of antecedent rainfall patterns on rainfall-induced slope failure[J].Journal of Geotechnical&Geoenvironmental Engineering,2011,137(5):483-491.
[6]Tohari A,Nishigaki M,Komatsu M.Laboratory rainfall-induced slope failure with moisture content measurement[J].Journal of Geotechnical&Geoenvironmental Engineering,2007,133(5):575-587.
[7]徐晗,朱以文,蔡元奇,等.降雨入渗条件下非饱和土边坡稳定分析[J].岩土力学,2005,26(12):1 957-1962.Xu H,Zhu Y W,Cai Y Q,et al.Stability analysis of unsaturated soil slopes under rainfall infiltration[J].Rock and Soil Mechanics,2005,26(12):1 957-1 962.(in Chinese)
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[9]张华庆,谭佳佳,左殿军.降雨入渗对软土岸坡稳定性影响研究[J].水运工程,2014(4):148-153.Zhang H Q,Tan J J,Zuo D J.Stability study of unsaturated soft soil slopes under rainfall infiltration[J].Port&Waterway Engineering,2014(4):148-153.(in Chinese)
[10]Kim J,Jeong S,Park S,et al.Influence of rainfall-induced wetting on the stability of slopes in weathered soils[J].Engineering Geology,2004,75(3/4):251-262.
[11]荣冠,王思敬,王恩志,等.强降雨下元磨公路典型工程边坡稳定性研究[J].岩石力学与工程学报,2008,27(4):704-711.Rong G,Wang S J,Wang E Zh,et al.Stability analysis of Yuanmo highway slope under intensive rainfall[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(4):704-711.(in Chinese)
[12]殷宗泽.土工原理[M].北京:中国水利水电出版社,2007.Yin Z Z.Geotechnical principles[M].Beijing:China Water&Power Press,2007.(in Chinese)
[13]马殿光.内河航道土质岸坡生态治理技术及应用研究[D].天津:天津大学,2013.Ma D G.Research on the technology of ecological regulation and application about the waterway slope[D].Tianjin:Tianjin University,2013.(in Chinese)
[14]赵尚毅,郑颖人,时卫民,等.用有限元强度折减法求边坡稳定安全系数[J].岩土工程学报,2002,24(3):343-346.Zhao Sh Y,Zheng Y R,Shi W M,et al.Analysis on safety factor of slope by strength reduction FEM[J].Chinese Journal of Geotechnical Engineering,2002,24(3):343-346.(in Chinese)
[15]费康,张建伟.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei K,Zhang J W.Application of ABAQUS in geotechnical engineering[M].Beijing:China Water&Power Press,2010.(in Chinese)
[16]张芳枝,梁志松,周秋娟.非饱和土性状及其边坡稳定性[M].北京:中国水利水电出版社,2011.Zhang F Zh,Liang Zh S,Zhou Q J.Unsaturated soil properties and slope stability[M].Beijing:China Water&Power Press,2011.(in Chinese)
[2]Tai T W,Fredlund D G,Krahn J.A numerical study of coupled consolidation in unsaturated soils[J].Canadian Geotechnical Journal,1998,35(35):926-937.
[3]Ng C W W,Shi Q.A numerical investigation of the stability of unsaturated soil slopes subjected to transient seepage[J].Computers&Geotechnics,1998,22(1):1-28.
[4]程曦,王元战,马殿光,等.基于ABAQUS的内河航道岸坡稳定性分析[J].水道港口,2012,33(2):152-158.Cheng X,Wang Y Zh,Ma D G,et al.Analysis of inland river waterway slope stability through ABAQUS[J].Journal of Waterway and Harbor,2012,33(2):152-158.(in Chinese)
[5]Rahimi A,Rahardjo H,Leong E C.Effect of antecedent rainfall patterns on rainfall-induced slope failure[J].Journal of Geotechnical&Geoenvironmental Engineering,2011,137(5):483-491.
[6]Tohari A,Nishigaki M,Komatsu M.Laboratory rainfall-induced slope failure with moisture content measurement[J].Journal of Geotechnical&Geoenvironmental Engineering,2007,133(5):575-587.
[7]徐晗,朱以文,蔡元奇,等.降雨入渗条件下非饱和土边坡稳定分析[J].岩土力学,2005,26(12):1 957-1962.Xu H,Zhu Y W,Cai Y Q,et al.Stability analysis of unsaturated soil slopes under rainfall infiltration[J].Rock and Soil Mechanics,2005,26(12):1 957-1 962.(in Chinese)
[8]张社荣,谭尧升,王超,等.强降雨特性对饱和-非饱和边坡失稳破坏的影响[J].岩石力学与工程学报,2014,33(2):4 102-4 112.Zhang Sh R,Tan Y Sh,Wang Ch,et al.Influence of heavy rainfall characteristics on saturated-unsaturated slope failure[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(2):4 102-4 112.(in Chinese)
[9]张华庆,谭佳佳,左殿军.降雨入渗对软土岸坡稳定性影响研究[J].水运工程,2014(4):148-153.Zhang H Q,Tan J J,Zuo D J.Stability study of unsaturated soft soil slopes under rainfall infiltration[J].Port&Waterway Engineering,2014(4):148-153.(in Chinese)
[10]Kim J,Jeong S,Park S,et al.Influence of rainfall-induced wetting on the stability of slopes in weathered soils[J].Engineering Geology,2004,75(3/4):251-262.
[11]荣冠,王思敬,王恩志,等.强降雨下元磨公路典型工程边坡稳定性研究[J].岩石力学与工程学报,2008,27(4):704-711.Rong G,Wang S J,Wang E Zh,et al.Stability analysis of Yuanmo highway slope under intensive rainfall[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(4):704-711.(in Chinese)
[12]殷宗泽.土工原理[M].北京:中国水利水电出版社,2007.Yin Z Z.Geotechnical principles[M].Beijing:China Water&Power Press,2007.(in Chinese)
[13]马殿光.内河航道土质岸坡生态治理技术及应用研究[D].天津:天津大学,2013.Ma D G.Research on the technology of ecological regulation and application about the waterway slope[D].Tianjin:Tianjin University,2013.(in Chinese)
[14]赵尚毅,郑颖人,时卫民,等.用有限元强度折减法求边坡稳定安全系数[J].岩土工程学报,2002,24(3):343-346.Zhao Sh Y,Zheng Y R,Shi W M,et al.Analysis on safety factor of slope by strength reduction FEM[J].Chinese Journal of Geotechnical Engineering,2002,24(3):343-346.(in Chinese)
[15]费康,张建伟.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei K,Zhang J W.Application of ABAQUS in geotechnical engineering[M].Beijing:China Water&Power Press,2010.(in Chinese)
[16]张芳枝,梁志松,周秋娟.非饱和土性状及其边坡稳定性[M].北京:中国水利水电出版社,2011.Zhang F Zh,Liang Zh S,Zhou Q J.Unsaturated soil properties and slope stability[M].Beijing:China Water&Power Press,2011.(in Chinese)