Research On Settlement Of Shield Construction In Expansion Rock And Soil

Shield Tunneling is the main method of subway construction,which may cause large ground surface settlement or uplift and easy to be mud cake in the difficult ground conditions,such as in the Expansion Rock and Soil. Paper takes Expansion Rock and Soil of LangBai shield zone with the Nanning Metro Line 1 for the research object, using mathematical statistics, finite element analysis and other methods, making some related studies for ground settlement and deformation of tunnel segment according to shield construction.(1)Teasing out the engineering properties of expansive rock and soil in Guangxi area and it influence law with the surrounding environment changes by the collations of previous literature.(2) Based on collations analyze of massive monitoring data with shield construction process in the expansive mudstone Lot, which the results showed that transverse settlement of ground surface with shield construction in expansive rock and soil approximate match the Peck formula's normal distribution curve. The maximum settlement is not in the center of the tunnel axis but deviates from the line center a distance with 1 ~ 3m; The ground began to be affected when the distance between measuring points and excavation face is 3D(D=6.3 shield excavation diameter),and the most of the vertical ground surface settlement concentrated in the later settlement the shield tail pass through the measure points. Segmental lining deformation caused by shield tunneling is mainly uplifting and values are between 5mm and 8mm.(3) Make curve fitting for the stability monitoring data of transverse settlement of ground surface in the expansive mudstone by applying the Gauss Peak Value Function, and the correlation coefficient more than 0.9.(4) Take the analysis of Temperature field equivalent to Humidity field, simulating hygroscopic expansion effect of expansion mudstone, which taking effect on segmental lining deformation and ground surface settlement in the process of shield tunneling, and according to corresponding geotechnical parameters of the construction site, using ABAQUS finite element analysis software to establish three-dimensional dynamic model of shield excavation, by comparing the calculated results and the monitor data shows that the calculated results can fit measured values very well, which explained the finite element analysis method can be used in the simulate shield excavation with the expansive rock and soil.(5) Through the expansion of mudstone formation shield tunneling parameters 95% confidence interval statistics, getting the value range of Nanning expansive mudstone shield tunneling parameters, and binding the range of parameters, summing up effective measures to shield construction settlement in the expansive rock and soil.