The Optimization Test Research For The Ratio Of Concrete Back Fill Grouting The Segment In Shield Tunneling

Shield construction has become mainstream construction method which has been applying to more and more underground engineering as well as tunnels crossing seas and rivers. In the construction of shield tunnel method, shield machine propels forward and tons of heavy segments which has already been installed in cable ejects out at the tail of the shield machine, leaving a lash behind it for the construction work. Simultaneous grouting paste material for shield tunneling is an indispensable step in shield construction. Stratum deformation can be controlled through injecting grout in the lash that has been cut by shield at its tail in order to reach the purpose of controlling stratum settlement and stress release.This article focused on the requires of Suzhou Metro Line 2 simultaneous grouting for shield tunneling, for the purpose of obtaining grout which is suitable for the shield interval in this project, it requires the hardenable grout has the appropriate setting time, easy to be pumped, hard to block the grouting pipe, convenient to proceed the construction management and control, lower construction cost, good mechanical properties and be conducive for the tunnel to bear long-term force. Investigated related documentations on simultaneous grouting for shield construction, and underwent a series of tests on 5 kinds of hardenable simultaneous grouting which were separately compounded by cement, fly ash, bentonite, rivers and and water reducer. According sixteen groups of tests, Test the indicators of performance such as fluidity, bleeding rate, setting time and strength, proceed the non-dimensional regression analysis with the use of SPSS soft, obtained regression equation including the factors of fluidity, setting time, bleeding rate as well as strength which influenced by Water-cement ratio, mortar ratio, water reducing ratio, powder cement ratio and the swelling ratio of water. Analyzing single factor, acquired the function relationship between the indicators of performance and factors mentioned above. Based on the various kinds of parameter indices of perfect grout and the construction cost, and then proceed the regression analysis for every performance index according to the result of testing. Analyzing how the materials of simultaneous grouting influence the performance of grout as well as the intermingled quantity of materials; Set the optimal conditions which the grout satisfied the purpose of minimum cost and maximum performance. Then, based on ideal various index parameters of grout slurry and its minimum construction cost, we came up with optimum proportioning after optimized by MATLAB. Using FLAC3D software we conducted numerical modeling on the effect of two kinds of grout mentioned above that have on stratum settlement as well as on buildings, latter, Verify the two kind of grout that do influence the settlement of ground and buildings.