考虑破坏面转移和垃圾坝作用的边坡稳定分析

Slope stability analysis method considering transfer of sliding failure surface and influence of engineered berm

垃圾坝是山谷型填埋场和横向扩建填埋场中常采用的增稳措施;破坏面在衬里结构不同界面间发生转移也是被证实的规律,考虑破坏面转移和垃圾坝作用的垃圾体边坡稳定分析方法尚未见报道。通过将衬里结构中破坏面转移点作为分界点,将滑动垃圾体分成5个楔体,利用极限平衡条件建立了五楔体边坡稳定分析方法。研究结果表明,五楔体极限平衡分析方法能够分析考虑破坏面转移和垃圾坝影响的填埋体稳定性;考虑破坏面转移计算得到的安全系数低于不考虑考虑破坏面转移的计算结果,考虑破坏面转移的计算方法能够发现更危险的情况;填埋场安全系数随垃圾坝高度的增大而增大;垃圾坝的背坡有一最优坡度,垃圾坝的背坡小于这一坡度时,发生"坝背破坏"模式;垃圾坝的背坡大于这一坡度时,发生"坝底破坏"模式;最危险破坏面通过填埋场的背坡和底坡的衬里,再通过垃圾坝的坝背衬里界面或坝底。

The engineered berm is a general measure to increase the slope stability for valley landfills and the horizontal expansion of existing landfills. The transfer of sliding failure surface between different interfaces in composite liner system has been proved. The slope stability analysis method considering transfer of sliding failure surface and influence of engineered berm is not available. A five-wedge slope stability analysis method is established under the limit equilibrium condition using the failure surface transfer point in liner system as the demarcation and dividing the sliding waste body into five wedges. The research results show that the proposed method can be used to calculate the slope stability of waste filling considering the transfer of sliding failure surface and influence of engineered berm. The safety factor from the new analysis method is less than that without considering the transfer of sliding failure surface. More dangerous state can be found by the new method. The safety factor of slope stability increases with the increasing height of engineered berm. There is an optimum gradient. When the back slope of engineered berm is less than this value, the failure of back slope of the berm occurs. Otherwise the failure under the bottom of the berm happens. The most dangerous failure surface is along the back slope and subgrade slope in the landfill and liner on the back slope of engineered berm or the bottom of the berm.