Anchor Composite Soil Nailing Reinforcement Of Foundation Pit Optimization Desion Of Parameters And The Analysis Of The Influence Law Of Foundation Pit Displacement

With the development of composite soil nailing technology, bolt composite soil nailing technology has been more and more widely used, because of the characteristics that its lower cost and convenient for construction. But there are numerous problems and accidents in deep foundation pits engineering due to the understanding of the synergy mechanism of anchor and soil nailing is not clear, and the deformation of the deep foundation is not reasonably controlled. The phenomenon that decreasing the stability of foundation pit safety to reduce the project cost in the process of composite soil nailing construction is common. This paper, on the basis of predecessors’ research,analysis and discusses the synergy mechanism of pre-stressed anchor composite soil nailing, study and optimize the angle of the pre-stressed anchor rod, anchor length and so on, and simulating analysis and evaluation the parameters by finite element simulation software. The main research contents are as follows:1. Analyzes the development and mechanism of soil nailing and bolting, and explore the mechanism and failure mode of the synergistic effect between soil nails and pre-stressed anchor synergy2. Optimizing design scheme is given in this paper in view of the present problem that the single anchor and soil nailing incident angle is not reasonable, exist in pre-stressed anchor composite soil nailing technology. Through theoretical derivation and mathematical analysis, found that the anchor can maximum exert its tensile and shear capacity, when the sum of the incident Angle and the slip plane cut anchor angles is 45 °.3. Through the calculation of the of foundation pit slope stability coefficient in a project example. Verify the foundation pit slope stability coefficient in the optimal design scheme of pre-stressed anchor angle suggested in this paper, and the stability coefficient is greater than the foundation pit slope stability coefficient of current common design method.4. In this paper the specific optimized design scheme is given, aiming at the present phenomenon that pre-stressed anchor rod are made into uniform length in the engineering construction. For portions of the anchoring force smaller required is wasteful if design the anchor rod anchor length according to the position of the anchoring force needed for unity, so this paper gives the formula of the optimal anchorage length at any position of pre-stressed anchor, through the formula of the foundation pit slope stability coefficient.5. Combined with one project in Jinan Shandong, the finite element model is established by the finite element simulation software ABAQUS, through the first simulation analysis how the bolt incident angles changing affect the horizontal displacement and vertical displacement of the foundation pit, under the condition of the single anchor rod structure, through the second simulation analysis the effect of other impact factors to displacement of foundation pit.