地震效应和坡顶超载对均质土坡稳定性影响的拟静力分析
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摘要
基于强度折减技术和极限分析上限定理,假定机动容许的速度场破坏面,考虑坡顶超载、水平和竖向地震效应影响推导了边坡稳定性安全系数的计算表达式。采用序列二次规划迭代方法(和内点迭代方法)对边坡安全系数目标函数进行能量耗散最小化意义上的优化计算,与多个算例的对比验证了其方法和程序计算的正确性;对影响土质边坡动态稳定性的一些因素进行了参数分析,分析表明:随着边坡倾角β、坡顶超载q、水平和竖向地震效应影响系数的增大,边坡稳定性安全系数显著下降;随着坡顶超载q、水平地震效应影响系数kh的增大、竖向地震效应影响系数kv的减小,边坡的潜在滑动面越来越深,潜在破坏范围越来越大。竖向地震效应对边坡稳定性也有一定影响,强震条件下的设计计算必须考虑竖向地震效应的影响。
The effects of surcharge and pseudo-static seismic forces on soil slopes were investigated by applying the kinematical approach of limit analysis theory and strength reduction technique. The rotational failure surface was considered and analytical expressions is derived to calculate the safety factor of slope subjected to surcharge and earthquake loading. The upper bound solutions for analytical expression are presented by applying iterative optimization method. From the comparative analysis,it can be seen that the solutions presented here agree well with available predictions both in simple static state and dynamic state. Parametric analysis shows that the safety factor of slopes decreases nonlinearly as the stability condition of a slope deteriorates when an increase in values of slope angle,surcharge and pseudo-static seismic forces occurs. From the numerical results,it also can be seen that latent slide surface moves inward to the slope with the increase of surcharge q and horizontal effect kh and the decrease of vertical effect kv,sliding surface and failure mass becomes bigger. The effect of vertical seismic acceleration on the stability of reinforcement slopes is significant especially for strong motion earthquake; i.e. that the effect of the vertical seismic acceleration should be taken into account in the engineering practices.
The effects of surcharge and pseudo-static seismic forces on soil slopes were investigated by applying the kinematical approach of limit analysis theory and strength reduction technique. The rotational failure surface was considered and analytical expressions is derived to calculate the safety factor of slope subjected to surcharge and earthquake loading. The upper bound solutions for analytical expression are presented by applying iterative optimization method. From the comparative analysis,it can be seen that the solutions presented here agree well with available predictions both in simple static state and dynamic state. Parametric analysis shows that the safety factor of slopes decreases nonlinearly as the stability condition of a slope deteriorates when an increase in values of slope angle,surcharge and pseudo-static seismic forces occurs. From the numerical results,it also can be seen that latent slide surface moves inward to the slope with the increase of surcharge q and horizontal effect kh and the decrease of vertical effect kv,sliding surface and failure mass becomes bigger. The effect of vertical seismic acceleration on the stability of reinforcement slopes is significant especially for strong motion earthquake; i.e. that the effect of the vertical seismic acceleration should be taken into account in the engineering practices.
引文
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[2]年廷凯.桩-土-边坡相互作用数值分析及阻滑桩简化设计方法研究[博士学位论文D].大连:大连理工大学,2005.
[3]赵炼恒,李亮,杨峰,等.加筋土坡动态稳定性拟静力分析[J].岩石力学与工程学报,2009,28(9):1904-1917.ZHAO Lian-heng,LI Liang,YANG Feng,et al.Dynamic stabiliti pseudo-static analysis of reinforcement soil slopes[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(9):1904-1917.
[4]MICHALOWSKI R L.Soil reinforcement for seismic design of geotechnical structures[J].Computers and Geotechnics,1998,23(1-2):1-17.
[5]AUSILIO E,CONTE E,DENTE G.Seismic stability analysis of reinforced slopes[J].Soil Dynamics and Earthquake Engineering,2000,19(3):159-172.
[6]LING H I,LESHCHINSKY D,PERRY E B.Seismic design and performance of geosynthetic-reinforced soil structures[J].Géotechnique,1997,47(5):933-952.
[7]NOURI H,FAKHER A,JONES C J F P.Development of horizontal slice method in stability analysis of reinforced slopes[J].Geotextiles and Geomembranes,2006,24(3):175-187.
[8]NOURIA H,FAKHER A,JONES C J F P.Evaluating the effects of the magnitude and amplification of pseudo-static acceleration on reinforced soil slopes and walls using the limit equilibrium horizontal slices method[J].Geotextiles and Geomembranes,2008,26(4):263-278.
[9]NIMBALKAR S S,CHOUDHURY D,MANDAL J N.Seismic stability of reinforced-soil wall by pseudo-dynamic method[J].Geosynthetics International,2006,13(3):111-119.
[10]KAVAZANJIAN E.Hanshin earthquake-reply[R].California:Geotechnical Bulletin Board,NSF Earthquake Hazard Mitigation Program,1995.
[11]STEWART J P,BRAY J D,SEED R B,et al.Preliminary report on the principal geotechnical aspects of the January17,1994Northridge earthquake[R].Berkeley:Earthquake Engineering Research Center,University of California,1994.
[12]中华人民共和国建设部.GB50011-2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2002.
[13]LESHCHINSKY D,LING H I,WANG J P,et al.Equivalent seismic coefficient in geocell retention systems[J].Geotextiles and Geomembranes,2009,27(1):9-18.
[14]BISHOP A W.The use of the slip circle in the stability analysis of slopes[J].Géotechique,1955,5(1):7-17.
[15]ZIENKIEWICZ O C,HUMPHESON C,LEWIS R W.Associated and non-associated visco-plasticity and plasticity in soil mechanics[J].Géotechnique,1975,25(4):671-689.
[16]DUNCAN J M.Limit equilibrium and finite element analysis of slopes[J].Journal of Geotechnical Eng-ineering,1996,122(7):577-596.
[17]DAWSON E M,ROTH W H,DRESCHER A.Slope stability analysis by strength reduction[J].Géotechnique,1999,49(6):835-840.
[18]赵炼恒,罗强,李亮等.水平浅埋条形锚板极限抗拔力上限计算[J].岩土力学,2010,31(2):516-522.ZHAO Lian-heng,LUO Qiang,LI Liang,et al.Ultimate pull-out capacity of strip anchor plates with upper bound theorem[J].Rock and Soil Mechanics,2010,31(2):516-522.
[19]CHANG C J,CHEN W F,JAMES T P YAO.Seismic displacements in slopes by limit analysis[J].Journal of Geotechnical Engineering,ASCE,1984,110(7):860-875.
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