Geotechnical Centrifuge Model Test Of Chair-Type-Pile Retaining Structure

At present researches on steep embankment is very active, steep embankment retaining structure type also developing to the direction of lightening and combination. composite supporting structure appears in this situation, and the chair type pile is one representative type of the composite supporting structure. The chair type pile is consisting of the long pile, the short pile, the beam and the retaining plate, and it had the advantages load-bearing and retaining function.We have seldom seen the application of the chair type pile in the subgrade support engineering, and the structure stress of the chair type pile is also very different from the other retaining structure. The working mechanism of the chair type pile is very complex, so the engineers cannot make an accurate analysis of the pile-soil interaction. Thus, during the design, many parameters are experiential, and it cannot meet the design requirements.In view of this, the paper has made a comprehensive analysis of the pile-roil interaction, The deformation law and the internal force distribution using a combination methods of theoretical analysis, the geotechnical centrifugal model test and the numerical simulation.The main conclusions are as follows:(1) The earth pressure on the short piles is the landslide thrust which is a rectangular distribution, the earth pressure between the long piles and the short piles is simplified to earth pressure at rest, the earth pressure on front of the short piles is equal to the residual sliding resistance force or one third of the passive earth pressure, the earth pressure on the upper face of the beam is equal to the weight of soil on the top of the beam, and the earth pressure on the under surface will not be considered.(2) The chair type pile is simplified as a plane rigid frame, and the frame is divided into the three parts of the cantilever section, the middle section of door type and the anchorage section to consider. And it uses the method of structural mechanics to calculate it.(3) The dangerous section of the chair type pile is consist of the bottom part of the cantilever section pile, the underpart of the critical position of long pile and beam, the middle of the anchorage segment of the long pile, the left side of the beam, the right side of the beam, the underpart of the critical position of short pile and beam and the middle of the anchorage segment of the short pile. So the Structure design is mainly aimed at the seven cross sections.(4)The numerical analysis shows that, the calculation method of the earth pressure during the theoretical calculations is reasonable and on the safe side. The distribution of numerical results and the theoretical results of the axial force and bending moment are very similar, and the theoretical value of the calculated value is greater than the value.(5)By the comparison of the calculation results, the theoretical calculation and numerical simulation, the distribution of earth pressure and the internal force distribution of the geotechnical centrifugal model test are consistent with the theoretical calculation. Thus the calculation method of the rationality of the theory is verified.