Dynamic Characteristics Analysis Of Gravity Wharf Structure Of Low Pile Cap

With the increasing water level in the reservoir area,the shoreline with good foundation conditions is getting less and less,which makes the dock have to be built on the harsh foundations such as deep overburden,easy-to-draw areas and soft soil areas.The low-pile cap gravity-type wharf combines the advantages of pile foundation and gravity-type wharf,and can be well applied to the construction of ports in soft soil areas.The importance of seismic performance is self-evident.The main work of this paper includes:(1)On the basis of reviewing the current status of seismic research on gravity wharfs at home and abroad,it points out the inadequacies of existing research and puts forward the research points of this paper.(2)The three-dimensional finite element model of a low-pile platform gravity wharf was established by using ABAQUS.On the basis of verifying the correctness of the calculation model,the dynamic time history analysis of the gravity-type wharf with different stiffness and low pile caps was carried out.The research shows that under the action of earthquake,the horizontal displacement of the superstructure is always greater than that of the substructure.The overall horizontal displacement of the structure decreases with the increase of the pile diameter,decreases with the increase of concrete strength,and decreases with the increase of the number of piles.Small;the absolute value of the peak acceleration of the upper structure is larger than that of the lower structure,the peak acceleration of the structure increases with the increase of the number of piles,and decreases with the increase of the pile diameter;the earth pressure of the pile increases with the increase of the number of piles,with the pile The diameter increases and increases,and decreases as the concrete strength level increases.(3)A comparative study on the structural dynamic response of anchoring and frictional contacts was carried out.The results show that the absolute values of horizontal displacement and horizontal acceleration of the upper structure of the two connection properties are larger than that of the lower structure;at the end of the earthquake,the absolute value of the residual horizontal displacement using the anchor connection property is smaller than the absolute value of the residual horizontal displacement using the friction contact property;The stress of the contact attribute structure and the dynamic pressure of the pile side are always greater than the stress of the anchor connection property structure and the dynamic pressure of the pile side.(4)A comparative study on the seismic design of the Sino-US gravity dock.Studies have shown that the Chinese norms take into account the reduction factor of seismic action when conducting seismic calculations,and the results calculated according to Chinese norms are smaller than those settled according to US regulations;compared with Chinese norms,American norms consider pore water pressure in calculations.And the design is conservative.(5)Based on the Quarry Creek Pier,the gravity-type wharf of the low pile cap was optimized.The results show that under the seismic load of 0.2gEL-Centro,the peak stress,peak acceleration and peak displacement of the structure decrease with the increase of the pile-cap stiffness;the peak dynamic pressure of the pile side with the pile-stay stiffness Increase and increase.