| With the continuous development of urban construction,the city subway has become more and more popular way of transportation,and the construction of the subway in Nanning is currently in progress.The building of the subway tunnel is often in the form of double parallel,due to mutual influence behind the second tunnel and the first tunnel between the two parallel tunnel construction,is more complicated than a single hole.The Nanning subway is mainly through expansive mudstone area,also has the most through the gravel layer,such as the surface subsidence caused by construction has an important influence on the surrounding and tunnel construction,It is necessary to study the influence of Nanning metro tunnel construction on the ground settlement,which will provide a reference for the research and analysis of the project.According to the measured data of settlement of Nanning subway interval of several construction surface,using Peck formula and analysis of tunnel construction because of the characteristics and laws of the final settlement of double superposition effect of surface,it is suitable for Nanning basin to the tunnel working face through the gravel layer,and settlement law of parameters of transverse prediction formula of silt strata geological unit.The main research contents include:1.The paper analyzes the principle of ground settlement and the arrangement of measuring points under the influence of double line.2.According to the collected measured data,the characteristics of the surface cross section settlement are analyzed.The Peck formula is used to calculate and fit,and the formation law of the total surface subsidence under the two typical geological units is compared and analyzed.3.Based on the measured data,the vertical settlement data of the tunnel surface are analyzed,and the law of the vertical settlement of the tunnel face passing through the siltstone area in Nanning basin is studied.The main conclusions are as follows:consider the effect of double line stacking,Nanning basin tunnel work face through the round gravel area,the surface subsidence curve shows a single peak feature,in the siltstone area,the surface subsidence curve basically shows the characteristics of double peak,using the Peck formula considering the influence of the two lines,the results of the fitting are good,and the surface lateral prediction formula of these two geological conditions is of practical significance;Considering the interaction of double track tunnel excavation,the vertical settlement law of ground surface under these two geological conditions is analyzed.It is found that the geological condition and relative horizontal coefficient have important influence on the settlement;In the construction of subway tunnel construction lag two,Peck three-dimensional correction formula is not suitable for prediction of the surface in the Nanning basin in subway station construction of gravel and silt rock geological unit conditions caused by the longitudinal settlement. |
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