Research On Side Friction Performance Of Precast Pile With Notch On Pile Surface

The ultimate bearing capacity of pile foundation is an important indicator of pile foundation performance.The surface of the prefabricated pile is notched to increase the friction between the pile and the soil.This method can effectively improve the ultimate bearing capacity of the pile without destroying the performance of the pile.This paper discusses the influence of surface notches on the friction resistance of the pile body through direct shear test and finite element analysis.The main work and conclusions are as follows:(1)Using indoor direct shear test equipment,we conducted experiments to study the shear resistance of the concrete-soil interface with nicks on the surface.Taking into account the different impacts of different nick types on the shear performance of concrete slabs,a fourth test was carried out.Shear test of concrete slabs and soil with different types of notches(recessed cuboid,recessed cylinder,recessed triangular pyramid,raised hemisphere).The test results show that: scoring on the surface of the concrete slab can increase its shear strength;the shear strength of the four different types of concrete slab-soil interface with scores on the surface is greater than that of the traditional concrete slab-soil contact Shear strength of the surface.(2)Use finite element software to simulate the process of direct shear test,and compare the numerical simulation results with the results of direct shear test.The comparison results are as follows: the results of numerical simulation and direct shear test fit well.With the increase of normal surcharge,the change trend of numerical simulation and direct shear test is the same;when the shear stress of the concrete slab-soil interface reaches a stable shear displacement The size is basically the same,and the difference between the peak shear stress is controlled by about 5%.(3)In the test of four types of notches,the shear strength of the concrete slab-soil interface is sorted from large to small: concave cylinder notch> concave cuboid notch>concave triangular pyramid notch> convex Compared with the simulation results of the direct shear simulation test,the scoring of the shaped hemisphere is consistent with the two conclusions.(4)Select the concave rectangular parallelepiped notches with better effect of enhancing the shear strength of the contact surface,establish the pile-soil model through finite element software,and study the friction resistance at different notch densities,different pile types,and different vertical loads.performance.From the load-settlement curve graph,it is concluded that the pile with notched surface is larger than the traditional pile with a higher limit pile side friction resistance.The specific conclusions are as follows: After the surface of the pile body is scored,the ultimate friction resistance of the pile foundation increases,and the ultimate friction resistance with a higher score density is higher;the ultimate friction resistance of the end-bearing friction pile is higher than that of the pure friction pile;The ultimate friction resistance of end-bearing friction piles is higher than that of traditional end-bearing friction piles,with a maximum increase rate of 16.504%,and the ultimate friction resistance of scored pure friction piles is higher than that of traditional pure friction piles,with a maximum increase rate of 14.326%.