Study On Genetic Mechanism And Pile-soil Contact Effect Of Anti-slide Piles Of Xinyan Landslide

The expansive soil high-filled embankment landslide in Xinyan section whichbelongs to the Wangqing-Yanji highway is named Xinyan landslide. With theresearching lack on the genetic mechanism, it always slides again after itsreinforcement which threatens the highway’s normal operation and opening to trafficheavily. By the detailed field investigations and laboratory tests, the engineeringgeological conditions and characteristics of deformation and cracks of Xinyanlandslide has been studied well. So are the physical and mechanical characteristics.The shear strength of the swelling soil of Xinyan landslide is low.The progress of deformation is affected by many factors including expansivesoils with low shear strength, the unreasonable load by filling on the surface of oldlandslides, the space for lateral deformation, the groundwater and so on. Finally, theprogressive failure has occurred in the low shear strength of expansive soils.According to the genetic mechanism and characteristics of the landslide, threeschemes which include anchor cable, anti-slide pile and slope toe backfill are putforward. The results show that they all can be satisfied with the requirement that makethe slope stable. Thus the system coordinating the drainage of surface andunderground must be designed for guaranteeing that Xinyan landslide will not slideagain.With using the numerical analysis software of FLAC3D, the two-dimensionalgeological model has been made up for researching the formation process of Xinyanlandslide. It’s shows that the horizontal displacements of the slope increase by filling on the surface of old landslides. The soils in the toe of slope have the phenomenon ofstress focus. Shear failures spread from the toe to the inside of the slope. When thefilling completes, the slip mass through the slope appears meaning the Xinyanlandslide happens.The influence on the arching effect from the cross section shape of single-rowpiles and layout style of double-row anti-slide piles has been studied by numericalsimulating through the software of FLAC3D. The results show that compared withcircular piles, the arching effect surrounding square piles is much better and itsdisplacement of piles is smaller. The load-sharing ratio of square piles and soils ishigh and uniform distribution along the mechanical part of square piles. Comparedwith parallel laying-out piles, Quincunx laying-out piles is beneficial to promotingsoil arching effect. And the bearing load of soils between double-rows piles is smaller.So the residual sliding-resistance force of soils between double-rows piles can beserved as emergency capacity, which improves the stability of landslide.