| Road construction on soft soil foundation often takes the form of pile composite foundation subgrade. Most of the application of pile composite foundation of soft-soil subgrade form case was successful, but there are also many diseases in embankment such as cracks, the excessive settlement and lateral cases, and even sliding accident project. Parts of the engineering by drilling holes in the embankment after adding pipe pile mode of treatment for the cracking or excessive lateral embankment reinforcement again, in order to improve its stability.This article relies on the Xinhui-Taishan highway south line near K63+500 to test the compation effect of the embankment reinforcement project of pipe pile construction, and put forward the stability analysis method for the Reinforcement such as cracking, the excessive settlement and lateral diseases of embankment. The main work is as follows:(1) Choose two pieces of particular areas as test area in the reinforcement treatment engineering section,laying equipment such as pore water pressure gauge, inclinometer tube, settlement plate before construction of Pipe, monitoring and analysis the compaction effects of soil when piles piling, including changes in pore water pressure subgrade soil at different depths, and subgrade soil depth along the lateral as well as subsidence of the embankment, etc. The results of the above analysis of the monitoring data show that:the compacting effect is obvious when reinforced pipe pile foundation with pile after drilling holes.(2) Latera curves were obtained in accordance with inclinometer tube buried in the hole of pile and another inclinometer tube buried in the soil near the very pile. After analyzing and comparing, conclusions are as follows:horizontal displacement between piles and Soil between piles are basically the same; The minimum radius of curvature along the depth of the latera curves measured by inclinometer buried in piles and another inclinometer buried in soil next to pile are basically the same.(3) The results of the maximum bending moment calculated according to the pile curve, then compared with the crack moment and the ultimate moment of the pipe pile, to judge whether the pipe pile is produced crack or break. Camera is carried out on the part of the pipe pile to detect the crack of the pile, the results was basically the same to results of pile cracking obtained by the projected curve.(4) The pile segment which was imposed in the embankment is called "pile in embankment", including the construction of cast-in-situ section on the upper of the pile. According to stress analysis of piles and soil in the embankment, pile load calculation formula is derived, then precast pile top load formula of buffer layer control. Analysis shows that the dam in the piles and piles interval, embankment height, embankment load of pile length, embankment soil shear strength index and so on.(5) On the basis of the main sliding mode of the composite foundation of the pipe pile, the characteristics of flow sliding and pipe pile are mainly through the pile top reaction and the pile side friction to improve the stability of the roadbed, proposed " the secondary correction density method" to analysis the stability of pile composite ground reinforcement with pile after drilling holes. The method takes the original piles and guiding-hole piles into two levels to consider, after twice subgrade soil density correction, we can use the existing conventional stability analysis software to analyze the stability of the concrete embankment composite foundation. Select number of cross-sectional to analysis its stability,the results showed that the analysis results of "the secondary correction density method" is in accord with the situation of practical engineering. |
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