膨胀土边坡失稳特征及其防治技术标准化

Failure characteristics of expansive soil slope and standardization of slope slide prevention by geotextile bag

膨胀土吸水膨胀、失水收缩,产生裂隙,导致膨胀土边坡出现“逢堑必崩、无堤不塌”的现象。本文通过分析膨胀土的水力作用机理,揭示膨胀土边坡的失稳特征;根据极限平衡分析法所得膨胀土边坡稳定性分析结果,提出“减小膨胀土边坡坡率不足以提高膨胀土边坡稳定性”的观点;建立裂隙膨胀土的剪切强度理论和膨胀土边坡稳定性分析方法。针对膨胀土边坡具有浅层性、牵引性、平缓性、反复性、长期性、成群性、季节性和方向性等失稳特征,提出膨胀土滑坡和工程边坡防治的隔、挡、固3类技术;揭示聚苯乙烯泡沫(EPS)板的减胀机理和减载效果,建立土工编织袋防治技术的标准化设计方法和施工工法,并介绍土工编织袋技术标准化的应用示范工程。

Expansive soil swells and shrinks due to water absorption and water loss,forming unique mechanical properties of swelling-shrinkage and fissure,which leads to the phenomenon that expansive soil slope will collapse with cutting and all dike will collapse.The slope failure characteristics of expansive soil slope were revealed through analyzing the hydraulic action mechanism of expansive soil.Considering that the limit equilibrium analysis method is not suitable to calculate the stability factor of expansive soil slope,the shear strength theory was put forward to calculate the stability factor of expansive soil slope.It is found that reducing the slope ratio can not effectively improve the stability of expansive soil slope.Expansive soil slope failure is characterized by shallow,tractive,gentle,repetitive,long-term,clustering,seasonal and orientational properties.According to the failure characteristics of expansive soil slope,three kinds of methods,i.e.,separating,retaining and stablizing(SRS),were proposed for prevention and control of expansive soil slope slide.The reduction mechanism of swelling pressure and load reduction effect of expanded polystyrene(EPS)plates were revealed.The standardized design method and construction method of soilbag prevention technology were established,and the typical engineering application of soilbag in prevention of expansive soil slope were introduced in detail.