The Research For Frame Bridge Shield Construction Process On Soft Foundation

Generally use the construction of Underpass Bridge jacking method, but with the city road gradually widened, bridge span is also growing, and the original railway line reinforcement maximum reinforcement length of36meters, which greatly limits the construction span tunnel bridge. Bridge type shield method is a new kind of jacking construction technology, is the application of principle of the shield machine in the jacking method. Bridge type shield applications, greatly improving the jacking construction safety and economic benefits, at the same time, more important is to provide technical support to the construction of large span tunnel bridge.Bridge shield it has developed in China for nearly10years, but the existing bridge type shield construction system, only some engineering examples in the non-soft soil foundation area, but in the soft soil foundation has never tried the jacking construction method. The soft soil has high compressibility, high water content, low permeability and high sensitivity and significant thixotropy of the engineering characteristics.Because of its special engineering properties, will give the jacking construction process to bring "head", back problems, also can be in alter work caused great subsidence, resulting in excessive settlement and interrupt line transport even caused the accident.According to the characteristics of the jacking construction and requirement of engineering treatment, mode, various methods of soft soil foundation treatment contrast is proposed:(1) the high pressure jet grouting,(2) the static pressure pile method two ways to deal with the soft soil foundation conditions, using the framework of bridge construction bridge of shield method for ground treatment. And were collected and analyzed for the design of system by load analysis and related specifications, and then use MIDAS/GTS software to achieve without effect after treatment compared with the cost of foundation bearing capacity. Results have been obtained and the cost advantages of comprehensive parameters. And the prediction model contrast the post-construction settlement of soft soil, the predicted curve for soft soil engineering settlement selection with reference.