Computation Theory And Experimental Researches Of Anti-slide Pile With Prestressed Anchors

The anti-slide pile with prestressed anchors is a new active anti-slide supporting structure which develops on the basis of the ordinary anti-slide pile. In recent years, the anti-slide pile with prestressed anchors has been widely used, but its calculation theory is not perfect and there are no correlative specifications to make the unification to its calculation method yet. So it will take important theoretical and practical significance to develop theoretical and experimental study of the anti-slide pile with prestressed anchors. Basing on the Western Project of Communication Ministry (200631880237), this thesis has studied internal force calculation method and optimum design method of the anti-slide pile with prestressed anchors, and the related conclusions have been analysed and validated by the laboratory model test. The main results and conclusions are as follows:(1) Laboratory model tests of anti-slide pile and anti-slide pile with prestressed anchors have been accomplished, and reinforcement mechanism of anti-slide pile with prestressed anchors system has been analyzed and discussed. This paper has studied the distribution regularity of landslide thrust and soil resistance in front of anti-slide pile as well as stress characteristic of anti-slide pile when different landslide thrust force act on anti-slide pile and anti-slide pile with prestressed anchors.(2) The anti-slide pile with multi-row prestressed anchors uses many in the high slope engineering. Based on the principle of the foundation coefficient method in calculating the internal force of the ordinary anti-sliding pile, considering the deformation consistence between multi-row anchoring cables and pile body, the finite difference method is presented to calculate its internal force and a computation example is validated by this method.(3) In view of present calculation of the anti-slide pile by single-parameter method, the deflection and slope at the ground of the pile, the maximum bending moment and its position can not agree well with the measured values simultaneously. The principle of composite stiffness and bipaprameter method has been introduced to internal force calculation of the anti-slide pile with prestressed anchors, and it has given the specific computational method and process. The principle of composite stiffness and bipaprameter method is used to calculate anti-slide pile with prestressed anchors in model test, and the calculation values are fit close with testing measured values, which verifies the reliability of the method.(4) Based on the limiting equilibrium principle and taking the unit length anchor provides the biggest anchorage force as the optimized goal, this paper has derived computation formula of the optimum anchor angle and has proposed the scope of the optimal anchor angle considering construction condition. Considering the deformation consistence between prestressed anchor and anti-slide pile, and analyzing change regularity of internal force of anti-slide pile and anchor tensile force when single-row anchor is in the pile at any position above the load-bearing segment, this paper has proposed computation method of the optimum anchor position which determined by the sum of the largest positive bending moment and negative bending moment (its absolute value) is minimum.