扩建城市垃圾填埋场的地震稳定性分析
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摘要
结合现场剪切波速试验、室内常规及动三轴试验结果,给出了扩建城市垃圾填埋场地震稳定性的有限元分析方法,并分析了扩建垃圾填埋体沿填埋体内部圆弧滑动面、新老填埋体交界面及底部和背部衬垫系统的地震稳定性。当填埋场中渗滤液水头较低时,扩建填埋体最易发生沿新老填埋体交界面的滑动。与总应力法计算结果相比较发现,总应力法只适合分析输入地震动较小的情况,而当输入地震动较大时,由于它不能考虑动孔压上升所导致的MSW软化而使得其计算的扩建填埋体沿圆弧滑动面的安全系数偏保守。另外,采用Newmark法分析了不同输入地震动时不同横、竖向扩建方案的永久位移,分析表明:扩建填埋体沿新老填埋体交界面的地震永久位移的对数近似与屈服加速度同最大水平加速度的比值呈线性关系,并给出了其永久位移的拟合公式。
Using the obtained parameters of field shear velocity test,static and cyclic triaxial tests,the finite element method based analysis approach is presented for the seismic stability of extended municipal solid waste(MSW) landfill,and the seismic stability of extended MSW along internal circular sliding surfaces,along interface between extended and existing MSW as well as along back and base liners is analyzed respectively by the finite element method.During the earthquake,the extended MSW more tends to be failure along the interface between extended and existing MSW if the water level of the leachate in extended MSW is low.For the dynamic stability of the extended MSW along internal circular sliding surfaces,the computed dynamic factor of safety of the conventional total stress method will be larger than the real one due to that is cannot take into account the softening of MSW induced by the increasing dynamic pore water pressure during the earthquake.The permanent diplacements of six landfills with different vertical and horizontal extensions are computed by the Newmark method for two kinds of input accelerograms with different maximal horizontal accelerations.Results show that logarithm of seismic permanent displacement of extended MSW along interface between the existing and extended MSW is roughly linear to the ratio of the yield acceleration and the maximal horizontal acceleration.
Using the obtained parameters of field shear velocity test,static and cyclic triaxial tests,the finite element method based analysis approach is presented for the seismic stability of extended municipal solid waste(MSW) landfill,and the seismic stability of extended MSW along internal circular sliding surfaces,along interface between extended and existing MSW as well as along back and base liners is analyzed respectively by the finite element method.During the earthquake,the extended MSW more tends to be failure along the interface between extended and existing MSW if the water level of the leachate in extended MSW is low.For the dynamic stability of the extended MSW along internal circular sliding surfaces,the computed dynamic factor of safety of the conventional total stress method will be larger than the real one due to that is cannot take into account the softening of MSW induced by the increasing dynamic pore water pressure during the earthquake.The permanent diplacements of six landfills with different vertical and horizontal extensions are computed by the Newmark method for two kinds of input accelerograms with different maximal horizontal accelerations.Results show that logarithm of seismic permanent displacement of extended MSW along interface between the existing and extended MSW is roughly linear to the ratio of the yield acceleration and the maximal horizontal acceleration.
引文
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[2]RATHJE E M,BRGY J D.One-and two-dimensional seismic analysis of solid-waste landfills[J].Canadian Geotechnical Journal,2001,38:850-862.
[3]BRAY J D,RATHJE E M.Earthquake-induced displacement of solid-waste landfills[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,1998,124(3):242-253.
[4]刘君,孔宪京.卫生填埋场复合边坡地震稳定性和永久变形分析[J].岩土力学,2004,25(5):778-782.LIU Jun,KONG Xian-jing.Seismic stability and permanent displacement analysis of a solid waste landfill slope containing geomembrane[J].Rock and Soil Mechanics,2004,25(5):778-782.
[5]陈云敏,柯瀚,凌道盛.城市垃圾填埋体的动力特性及地震响应[J].土木工程学报,2002,35(3):66-72.CHEN Yun-min,KE Han,LING Dao-sheng.Dynamic properties and seismic response of municipal solid waste[J].China Civil Engineering Journal,2002,35(3):66-72.
[6]冯世进.城市固体废弃物静动力强度特性及填埋场的稳定性分析[D].杭州:浙江大学,2005.
[7]SEED H B.Consideration in the earthquake design of earth and rockfill dams[J].Geotechnique,1979,29(3):215-263.
[8]MATASOVIC N,KAVAZANJIAN E J.Cyclic characterization of OII landfill solid waste[J].Journal of Geotechnical and Geoenvironmental Engineering,1998,124(3):197-210.
[9]陈云敏,王立忠,胡亚元等.城市固体垃圾填埋场边坡稳定分析[J].土木工程学报,2000,33(3):92-97.CHEN Yun-min,WANG Li-zhong,HU Ya-yuan,et al.Stability analysis of a solid waste landfill slope[J].China Civil Engineering Journal,2000,33(3):92-97.
[10]JONE D R V,DIXON N.Landfill lining stability and integrity:the role of waste settlement[J].Geotextiles and Geomembranes,2005,23:27-53.
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