Experimental Study On Load-bearing Characteristics Of Composite Foundation Of Pipe-pile With Holes & Cap Under Vertical Load

With the development of foundation treatment technology, various kinds of composite foundation technology are emerging. As a new technology of foundation treatment, the composite foundation of pipe-pile with holes and cap has not been used in the construction project. At home and abroad, the report about the technology composite foundation of pipe-pile with holes and cap reports is relatively rare. The load-bearing characteristic research of bearing capacity, settlement deformation, pile soil interaction,axial force of pile, pile side friction resistance, pile-soil load share ratio and pile soil stress ratio are almost a blank. Therefore, in order to promote the application of the technology, this paper will be studied the load-bearing characteristics of the technology.Through the indoor model test, the load-bearing characteristics of the composite foundation of pipe-pile with holes and cap have been studied in this paper, and the test model is simulated and analyzed. The main research work and achievements are as follows:(1) Checking out the literature material at home and abroad, introducing the research status about the load-bearing characteristics of the composite foundation of pipe-pile with cap in experimental research and numerical simulation. According to the previous experience and the expected goal, the model test is designed.(2) Through the indoor model test, the load-bearing characteristics of the composite foundation of pipe-pile with holes and cap have been studied, such as settlement deformation, axial force of pile, soil pressure around the pile, pile side friction resistance, pile-soil load sharing ratio and pile-soil stress ratio. The results show that the pile holes can effectively reduce the settlement of composite foundation, the settlement of bidirectional perforation pile composite foundation is the smallest in the three kinds of composite foundation of pipe-pile with holes and cap. Comparing to the pipe-pile without hole, the pipe-pile with holes can accelerate the consolidation of the soil around the pile, the soil around the pile will share more upper load, so as to improve the bearing capacity of composite foundation, the bidirectional perforation type pile is more obvious. The increase of soil pressure around the pile is mainly occurred in the upper part of the soil, and at the deeper place, soil pressure change is not obvious. The pile friction of composite foundation gradually plays the sole with the increase of the upper load, pile side frictional resistance is larger in the lower part of pile. The variation of pile-soil stress ratio of each composite foundation increases slowly at first, and then decreases rapidly with the change of load. The composite foundation of hole-pile with holes is more conducive to play the role of soil load sharing.(3) The load-bearing characteristics of the composite foundation of pipe-pile with holes and cap under vertical load are simulated by the numerical analysis software. The load-bearing characteristics of the composite foundation of pipe-pile with holes and cap have been analyzed.(4) By comparing the results of numerical simulation and indoor model test, theresults are basically consistent, which verifies the correctness of the model test results.