Research On The Influence Of Deep Overlying Soil In The Three Gorges Reservoir Area On The Lateral Bearing Capacity Of Overhead Vertical Wharf Structures With Large Water Level Difference

The thick overburden is widely distributed in large rivers and rivers in China,and the thickness of overburden is generally large.Due to the poor geological conditions and loose structure of the deep overburden,when the port and wharf project is built on the deep overburden,the geological problems such as uneven settlement of soil mass,landslide,leakage and liquefaction of sand are easy to occur,which can further have great impacts on the bearing capacity of the port structure built on it.As a result of the deposition of a large number of weathered materials and upstream deposits in the deep channel,there are also a large number of bank slopes with deep overburden in the Three Gorges Reservoir area.On the other hand,the large cyclic change of water level in the Three Gorges Reservoir Area indirectly affects the bearing capacity of the wharf structure by influencing the strength parameters of the bank slope.In order to explore the influence of deep overburden and water level circulation on the lateral bearing capacity of the overhead vertical Wharf in the Three Gorges Reservoir area,this paper establishes the finite element model of the interaction between the wharf structure and the soil mass of the bank slope based on the actual project,and makes a systematic research and analysis.The main research contents and conclusions are as follows:(1)Based on the single factor analysis method,this paper studies the effect of the change of physical and mechanical properties of rock and soil on the safety factor of slope stability and the deformation of soil mass in the deep overburden layer.The results show that the stability safety factor is sensitive to the cohesion c value and the internal friction angle φ value,while the change of the elastic modulus E and the Poisson’s ratio μ will have a great influence on the deformation of the soil and the formation and width of the plastic zone.(2)Considering the nonlinear interaction between pile and soil,the finite element software ABAQUS is used to study the numerical modeling of the structure of the overhead vertical wharf.At the same time,the influence of soil deformation on the lateral bearing capacity of the structure is analyzed and explored under the condition of deep overburden.The research and analysis show that: when the pile length exceeds a certain length,that is,when the whole stability sliding surface of the pile passing through the deep overburden soil slope is deep enough,the squeezing effect of the lateral deformation of the soil on the pile foundation becomes the main factor affecting the lateral bearing capacity of the pile foundation,which cannot be ignored.(3)Based on the numerical method,the influence of soil parameters,the size of rear surcharge,the thickness of overburden and other soil factors on the lateral bearing capacity of the wharf structure,as well as the influence of ship load and the external load of the upper surcharge on the lateral bearing capacity of the overhead vertical wharf structure are studied by using the finite element software ABAQUS.The research shows that,mainly through the single factor analysis method,taking the safety factor of pile body and the relative displacement of pile foundation as the important discrimination conditions,the influence of each factor on the lateral bearing capacity of the overhead vertical Wharf on the deep overburden layer is analyzed.Finally,the following conclusions are obtained: compared with the general high pile wharf,under the condition of deep overburden,the soil deformation has a greater impact on the lateral bearing capacity of the wharf structure,while the impact of external load is relatively small.(4)Based on the finite element strength reduction method,the influence of lateral resistance of wharf pile foundation on the stability of bank slope and the change of bearing capacity of wharf structure in the process of bank slope instability and deformation are analyzed.On this basis,the influence of water level cyclic change and degradation evolution of soil strength parameters on the lateral bearing capacity of wharf structure is studied.The research shows that the stress-strain of the wharf slope and the bearing capacity of the structure still meet the requirements of the design operation with the influence of the water level cycle and the degradation of the soil strength parameters over the years,but the bearing capacity of the wharf structure is greatly reduced in this process,which is unfavorable to the long-term operation of the wharf.