Study On Bearing Characteristics Of Cement Soil Composite Pile With Wedge-Shaped Core

The wedge-shaped Stiffening core soil-cement composite pile technology is a new soft soil foundation reinforcement technology proposed by the research group in combination with wedge-shaped piles and reinforced mixing pile technology.Therefore,this paper investigates the cementation state of the cement,and the load-settlement and inner and outer core load transfer laws of the wedge-shaped Stiffening core soil-cement composite pile through a combination of indoor geotechnical tests,large scale model tests and numerical simulations.1、Changes in cement incorporation and curing stresses on the cemented state of the cemented soil were studied by indoor compression tests.The results show that:the final compressibility of the cement decreases as the cement increases;the application of compressive stresses during maintenance reduces the compressibility of the cement;and the optimal maintenance stress is dependent on the cement admixture.2、In order to study the changes of load-settlement,inner and outer core axial forces and side friction resistance,the model static load test is carried out on the wedge-shaped stiff-core cement composite piles with different wedge angles and cross-sectional average core ratios.The main conclusions are as follows:the load-settling curve of the wedge-shaped Stiffening core soil-cement composite pile is of slow-drop type;increasing the wedge angle and cross-sectional core content ratio within a reasonable range can effectively increase the ultimate bearing capacity of the composite pile and significantly reduce the pile top displacement;the inner core bears the main load,and the load transferred to the outer core is about 10%of the total load at the pile end;increasing the wedge angle has more influence on the side frictional resistance than the cross-sectional average core content ratio.3、Using FLAC^3Dnumerical analysis software,a three-dimensional numerical simulation is carried out based on the model test results to discuss the influence of wedge angle and average cross-sectional core content on the ultimate bearing capacity and load sharing and transfer rules of the combined pile.The results show that the displacement of pile top decreases with the increase of wedge angle and average cross-section core content.A reasonable wedge angle of 1.6°～2.4°and a reasonable average cross-section core content range of 20%～30%are recommended according to simulation research.The average core content of the section has a greater influence on the load sharing ratio between the inner core and the outer core than the wedge angle.