Impact Of Slope Construction On Bearing Capacity Of Framework Wharf Pile

As the steep land and complex terrain conditions of reservoir river pier,the establishment of wharf in large water-level fluctuations areas often face large construction features such as gravel backfill,in which case the pile force becomes more complicated.This project comes from Subject 4 called" Key Technology Research on the shipping of the Three Gorges Reservoir"(2012BAB05B04),which is the national" 12th Five-Year Plan about "key technology in development of shipping in the upstream of the Yangtze River".In this paper,laboratory model experiments and Finite Element Analysis are used to analyze pile deformation at different slope construction orders.To sum up,the main results of this study are as follows:1.In this paper,two sets of experiments were done and the foundation is consist of sand or the mixture of sand and shale with the mass ratio 8:2respectively.The laboratory static load test of pile was carried out by prefabricating two sets of reinforced concrete pile(the diameter is 10cm and the length is 100cm)with a total of 12.Sand is selected as the first set of test foundation to research the pile bearing behavior characteristics by applying vertical force on piles.While the foundation slope of the other group of test was set as 1:3and sand-shale mixture was chosen as the foundation to research the pile bearing characteristics by means of applying vertical force and horizontal force respectively.2.Under vertical load,the Q-S curve showed a clear steep drop under sand foundation and sand-mudstone foundations,and their failure mode are obviously,they are the foundation damage.The distribution of shaft axis force descends rapidly along the depth,and the axial force value in the lower part is much smaller than the upper part of the pile.While the lateral friction resistance distribution is more complex along the pile depth,as the load increases,the lateral friction resistance increases from top to bottom gradually.Besides,pile bending moment decreases rapidly with depth of the pile after the first increase to the maximum under the action of horizontal force,and it is approximately equal to zero at a distance of 20cm at the bottom of the pile,which indicates the pile has reached the embedded depth.3.This paper takes advantage of finite element software PLAXIS to simulating the construction sequence of pile and backfilling,it discovers that backfilling slope earlier is more conducive to bearing capacity of piles,and thickness of backfill slope has the greatest effect on the pile bearing capacity under this construction sequence,followed by backfill material weight,angle of internal friction and the slope angle,while the impact of depth of rock-socketed pile is negligible.4.Based on Chongqing Guoyuan Port II Extension Project,this paper makes models of construction sequence about pier structure and backfilling slope,the data shows that it is negative for the wharf structural forces by backfilling slope later than the construction of wharf structure.To build the first one to two pier structures and then backfill slope is more reasonable for the stability of structures.In this way the wharf structure has become an entirety not merely to resist itself deformation,but also resist the slope deformation to increase the slope stability,which,after all,is a feasible construction sequence.5.Considering the factors,such as thickness of backfill slope,slope angle and pile diameter,the model is set up by using finite element software ABAQUS to simulate the construction of cast-in-place bored piles on slopes.It comes to a conclusion that concrete casing distortion is significantly affected by the slope backfill,and construction factors and wall deformation curve are obtained from the data to provide guidance for the construction of cast-in-place bored piles.