Experimental Investigation On Lateral Bearing Capacity Of Pile Foundation For Zhanjiang Group Structural Clay

The gray clay distributed in Zhanjiang in China has attracted extensive attention of both academic world and engineering circle because of its unique engineering characteristic.Because the soil texture of the overlaying soil in Zhanjiang areas is quite special.The natural foundation is already unable to reach the bearing requirements of the current high-rise buildings.Therefore,the pile foundation has wide applications in that area.As a result of Zhanjiang group gray clay with a strong structural properties,the lateral bearing behavior of pile foundation is complex.However,if the existing design and calculation theory and approach for pile foundation are used for the pile foundation design under lateral loads of the structural clay in Zhanjiang group,there might be more or less calculation errors.Therefore,based on the studies of the mechanical property of the structural clay in Zhanjiang group as well as the studies on the bearing capacity of the pile foundation at home and abroad,this paper is going to conduct a study to the lateral load character of the foundation pile in the structural clay of Zhanjiang group through field model test,thus acknowledging the influence of the lateral load to the working property of the pile foundation,so as to provide reference for the design and construction of pile foundation in Zhanjiang Group structural clay.The main researches and achievements in this paper are as follows:1.Aimed at the condition of soil layer distribution in Zhanjiang,detailed investigation is conducted to the selected general site scope according to the local drilling documents.Then the test result is analyzed to determine the site for the model test.2.It designs and finally confirms a complete set of testing apparatus,including model pile,test loading device and the data collection system.It selects three groups of model piles with the same material and diameter but different pile length.It conducts lateral static load field test to single pile in the structural clay of Zhanjiang group through unidirectional multi-cyclic loading approach.3.Through test data processing,the pile head lateral load-time-pile head lateral movement curve,the pile head lateral load-displacement gradient curve,bending moment of the pile body,shearing force of the pile body as well as the variation of the lateral soil resistance force with the buried depth can be obtained.The analysis result indicates that:with lateral load,both of the lateral critical load H_crr and lateral ultimate bearing capacity Hu in the structural clay of Zhanjiang group,have positive relationships with buried pipe length.The maximum values of pile bending moment,sheering force and lateral soil resistance force increase with the deepening of buried length.The pile bending moment and sheering force mainly concentrates on the upper part of the pile body.The variation of the lateral soil resistance force with the buried depth of the single pile in the structural clay of Zhanjiang group is distributing in an incomplete S shape.4.Through the contrastive analysis between prototype test and model test,this paper conducts a deeper study to the lateral load character of the single pile in the structural clay of Zhanjiang group.Then it comes to a conclusion that the errors of the proportionality coefficient m which is the horizontal resistance coefficient of the foundation soil usually appear at the initial stage of the test.The bending moment,shearing force and the soil resistance force variation of the test pile in prototype test mainly concentrate in the area from the ground line to the 10m buried depth.The lower part of the pile body almost resists no lateral load.The bending moment,shearing force and lateral soil resistance force curve of the prototype test and model test have the basic coincident tendencies.