大型输水渠道膨胀土(岩)渠段边坡稳定分析

Analysis and Study on Slope Stability of Expanded Soil Channel Section of Large Water Pipeline

膨胀土(岩)工程特性特殊,易造成边坡失稳、滑塌,因此对膨胀土(岩)渠坡的稳定性进行分析尤为重要。针对膨胀土(岩)渠段不同的破坏模式提出了相应的边坡稳定分析方法,并给出了边坡稳定分析时参数取值的经验方法:对于有明显裂隙面的裂隙强度控制下的渠坡滑动采用极限平衡法中的摩根斯坦-普拉斯法(Morgenstein-Price Method)进行计算(滑裂面为裂隙结构面),对于无明显裂隙面的渠坡采用极限平衡法中的毕肖普法(Bishop)进行计算(搜索最危险滑动面)。以南水北调中线工程干渠某膨胀土(岩)渠段为例进行渠坡稳定分析,指出:对于南水北调中线工程土体参数,弱膨胀土黏聚力取峰值强度,中、强膨胀土(岩)体强度采用分带选取原则,在大气影响带(0~2.5 m)范围内取残余强度,在过渡带(2.5~4.5 m)范围内黏聚力按峰值强度的0.5~0.7倍取值、内摩擦角按峰值强度对应内摩撑角的0.7~0.8倍取值,4.5 m以下非影响带黏聚力取峰值强度。

The canal slope or bottom of the trunk canal of the South⁃to⁃North Water Diversion Project involves about one⁃third of the open channel section of the expansion rock(soil),and the engineering geological conditions are complex.Due to its special engineering character⁃istics,expansive rock(soil)is prone to slope instability and collapse,and the problem of expansive rock(soil)encountered in waterconser⁃vancy projects(especially channel engineering)is more and more difficult to deal with.In addition,the amount of engineering,processing in⁃vestment and processing are also more difficult.Therefore,the stability of the expansion rock(soil)slope is one of the key problems in the design of the expansion rock(soil)channel.In this paper,the corresponding slope stability analysis method was proposed for the different failure modes of expansive rock(soil)channel.The empirical method of the parameter value of slope stability analysis is given:For the chan⁃nel slope sliding under the control of the fracture strength with obvious fissure surface,Pulasifa(Morgenstein⁃Price Method)in the limit equi⁃librium method is used to calculate(sliding surface is fracture structure surface)for drainage slopes with no obvious fissure surface,Bixiaop⁃ufa in the limit equilibrium method is used to calculate(search for the most dangerous sliding surface);The strength of the soil body in the middle line of the South⁃to⁃North Water Diversion takes the peak strength of the weak expansion soil,and the principle of band selection is a⁃dopted for the strength of the medium and strong expansion(rock)soil body:The residual strength is taken within the range of the atmospher⁃ic influence zone(0 to 2.5 m);In the transition zone(2.5-4.5 m),the C value is 0.5 to 0.7 times the peak strength,and theφvalue is 0.7 to 0.8 times;4.5 m below non⁃effect band peak strength.