Study On Failure Mechanism And Stabilization Technology Of Expansive Red Sandstone Cut Slope

The red sandstone slopes collapse a lot on Hunan Liu-Li Highway, and the morphologyand charecteristics of their failure are different from the ordinary red sandstone slope. Normaltreatments such as arch skeleton protective structure and cutting down the slope are noteffective to these slopes, which produces difficulties to highway construction. In order tosolve this problem, this paper carried out study on the failure mechanism and treatmenttechniques of expansive red sandstone slopes through field research, indoor experiments,theoretical analysis, numerical simulation and practical project construction, which couldprovide some reference to similar slope project.Firstly, the lithologic characters of red sandstone from different layers of the collapsedslope were studied through indoor experiments, and types and charecteristics of the slopefailure were analyzed by field research. Typical failure modes of expansive red sandstoneslope was proposed with a character of facial tractive successive developing, since it wascontolled by weathering disintegration of the rock and mechanical property of the structuresurface. Then, the interfacial strength of weak structural surface, saturated shear strength andhydraulic characteristics of weathered soil and shear strength of reinforced soil were studiedthrough Large Direct Shear test, Direct Shear test, Tri-axial test, Penetration test and SoilWater Characteristic Curve test, which offered parameters to the failure mechanism studywith numerical simulation anlysis. After that, the influence of geotechnical strength andboundry water condition to the slope stability were analyzed through Finite Element methodand Limit Equilibrium method with a strength criteria of Generalized Mises criterion and aslope stability analysis of Finite Element Strength Reduction method. The results showed thatpore water pressure of soil was pushed up and shear strength was cut down by external waterpressure, which resulted in collapsion of slopes. Last, the flexible protective structure wasdesigned to stabilize red sandstone slope in connection with its failure mechanism, and thereinforcement mechanism of the structure was analyzed. The structure effectively drained thewater in the slope and controlled the pore water pressure in safe range, which eliminated theweaken influence from outside water and improved the stability of the slope. The technologywas applied in treating a collapsed slope and a favorable effect was achievedThe failure mechanism of expansive red sandstone slope was studied from theperspective of its distensibility, and its typical failure modes was proposed, which revealedthe process of such slope collapsion. A new kind of treatment technology was used to treat the collapsed slope and the collapsion problem of red sandstone slopes was solved, which couldprovide guidance to relative theory study and practical application.