Research On The Cutter Selection And Design Of Shield Cutting Large Diameter Pile Directly

With the construction of a large number of subway, and because of the limitation of line selection and buried depth in subway tunnel, more and more obstacles such as bridge and building pile foundation, underground continuous wall are encountered in the construction of shield tunnel. The technology of shield cutting underground obstacles directly has the advantage of saving the project investment, shortening the construction period and reducing the influence to public transport, is gradually accepted in engineering construction.Based on the project of shield cutting14bridge piles with the diameter of1.0-1.2meters in Suzhou subway line2, the research of the cutter selection and design of shield cutting large diameter pile directly was carried by theoretical analysis, and the test of shield cutting reinforced concrete pile was carried out, the performance of cutter was verified and improved by the test. Finally, the transformed shield machine was used for cutting pile foundation of GuangJi Bridge. And the damage and application effect of cutter were analyzed. The main conclusions were obtained as following:(1) The shell cutter of zero back angle and negative front angle with double-side blade was fit for cutting reinforced concrete pile. The critical net cutter spacing of covering cutting plane completely is48.7mm.(2) The wrapped condition of rebar by surrounding concrete is the key factor determining whether rebar could be cut off effectively, so the layout scheme of advancing shell cutter and the concept of cutting rebar with different times were presented correspondingly, then the rebar can be cutted in reasonable length.(3) The advancing shell cutter can protect the adjacent non-advancing shell cutter effectively, the cutting efficiency and the service life of the cutter were improved, the ability of the whole cutter was enhanced.(4) The cutter configuration scheme was successfully applied in the engineering practice, and indicate that shield cutting large diameter piles continuously is feasible.The research on cutter selection and design of this thesis provides theoretical guidance and technical support for the Suzhou shield cutting bridge piles engineering, and have achieved good results in engineering application, which can provide reference for future similar engineering of shield crossing underground obstacles.