Research On Time-Space Effect Of Expressway Multi-arch Tunnel Construction And Its Three-dimension Staged Back Analysis

This dissertation made a profound and extensive research on multi-arch tunnelconstruction techniques, including the time-space effect of surrounding rock,theinteraction between the two tunnels, prediction of the space effect caused by theconstruction of the multi-arch, and the space effect caused by the blast construction,by construction monitoring in the field, rock rheology test in laboratory, numericalsimulation, theory analysis and back analysis; it is very important both in theory andin practice.Carrying on analysis to the data obtained by measurement in the field, divide thedata into two parts,one is time effect,and the other is space effect, get the time effectis about 30 percent of space effect; Comparing with the results of the rheology test inthe laboratory and the results obtained by the in-the-field data, find that the rheologyparameter of rock k is very close, so it is directive to the redesign and construction ofthe project; based on the theory of arch effect and the theory of adding, obtains thestress and the displacement of the surrounding rock, and then obtains the formulas ofthe space effect.The arching in the surround rock, which is caused by the dynamic constructionof the multi-arch tunnel, is calculated by the numerical simulation; comparing thestress by calculation and measured in the field, results obtained by criterion method,put forward the formula of calculating the multi-arch surrounding rock pressure.The blasting construction has two typical conditions, one is near the door, theother is far away from the door; they have different effects on the space effect on itsown tunnel and its adjacent tunnel; according the results of analysis, find that theblast far away from the door of tunnel causes much more damage than the blast nearthe door of the tunnel.According to the measurement displacement timing curve of the tunnel dome,make use of function to fit the measured data, so take back the 'lost' displacement andget the whole displacement of measurement point; and then back-analysis themulti-arch tunnel by whole displacement back-analysis and incremental displacementback-analysis; using the parameters of the rock by the back-analysis, forecast theeffects of the next construction; so we can dynamically carry on construction andredesign. Introducing of random experiment and the method of variance analysis toaccelerate the convergence speed, get the random-ant-algorithm and apply in theoptimization of back-analysis; This method is effective and feasible, and it has thebetter overall searching ability and speed.