Design And Calculation For Anti-slide Pile With Vertical Prestressed

In the support engineering of reservoir slopes, landslides and thick layer colluvialdeposit landslide of mountainous area highway, lacking of execution conditions forcutting or slope toe back pressure while surplus sliding force is oversize, the commonlarger size anti-slide pile and the poor corrosion resistance of the anchor cable, forthese questions of support engineering, anti-slide pile with vertical prestressed anchorcan be a good solution. Anti-slide pile with vertical prestressed anchor is one newanti-slide support technique contraposing deficiency of common anti-slide anchor pileand prestressed anchor pile, which has fused the advantages of cantilever anti-slide pileand prestressed anchor pile.The vertical pre-stressed anti-slide pile is studied in thispaper, by combining the theoretical analyses and engineering application, and thecalculation and design method of the vertical pre-stress anti-slide pile is alsoresearched based on the soil mechanics, material mechanics, structural mechanics andreinforced concrete design principle. The main achievements of the research are asfollows:(1) Combined with characteristics of vertical pre-stressed anti-slide pile, thispaper discussed the interaction of pile-soil interface,and consider pile above slipsurface as statically indeterminate structure izod, pile below slip surface as beam onelastic foundation. Based on calculation method for common anti-slide pile,arrangement of pre-stressed steels are determined, and calculation model of verticalpre-stressed anti-slide pile is established, and applicable formulas for internal forcesand deformation of pile is proposed.(2) By setting eccentric pre-stressed tendon into the cantilever pile, the favorableadditional bending moment can be got on the top of the pile which can reduce themaximum moment and the shear force in the pile. By applying vertical pre-stressedforce, the entire anti-bending rigidity of the pile body can be enhanced, thedeformation of the pile body can be controlled effectively and the crack on thetensional side of the pile can be restrained, all of which can make the mechanicalproperty better.(3) It can be indicated that the constant influence on the force-bearing part is gotand the influence on the embedded part is changed by the change of the depth when thepre-stressed force is applying on the pile body. Compared with the concrete pile, the embedded part of the pre-stressed pile is shorter and the sectional dimension is smaller.(4) It can be attained from the internal force situation of the pre-stressed tendonthat it is concerned with the initial effective pre-stress and the ultimate anchorage force.The bigger the effective pre-stress is, the higher starting point of the pre-stressedtendon is. The bigger the ultimate anchorage force is, the bigger the potential of theinternal force of the pre-stressed tendon is. The retaining capability of the concrete andsteel can be replaced and compensated by the effective pre-stress in the pile.(5) Put the landslide in the western part of Lizi Ba in the Three Gorges Reservoiras an example, the design scheme of vertical pre-stressed anti-slide pile has been usedbecause the residual pushing force is large and the engineer is influenced by water. Theinternal force distribution of the elastic pile and the rigid pile have been respectivelycalculated, which is compared with the intrinsic scheme. It can be shown that themoment in the force-bearing part is11.9%smaller than the cantilever pile, themaximum moment in the anchorage part is15.9%smaller than the cantilever pile andis closer to the sliding surface. The shear force is basically the same on the slidingsurface and the place is also unchanged. The maximum shear force under the slidingsurface is8.7%smaller than the cantilever pile. It can be found that the verticalpre-stressed anti-pile is a promising new type in the particular landslide treatmentengineering and is worth popularization and application.