Effect Of Parallel Shield Tunnel Excavation On The Surface Settlement

With the rapid development of urbanization in China,a growing number of rural population choose to live in cities and towns.Therefore,many cities in China are facing the pressure from population explosion,especially in the aspect of transportation.As the growth of urban population,a large area of urban land is used for the construction of residential buildings,office buildings,and so on,which results in serious shortage of urban land resources.Large cities now generally regard developing public traffic facilities,especially subway,light rail and so on as the best measures to alleviate the pressure of migration of population.However,it is inevitable that the subway tunnel construction will cross the areas with high population density and complex geological environment,so the influence of the subway tunnel construction on the surrounding environment has to be known and controlled.Shield method is the most common method used in subway tunnel construction.We take parallel shield tunnels as the research object,and research content is the influence of parallel tunnels' construction on ground surface subsidence of soil.We independently design a set of indoor sand model test platform,which can effectively simulate the double parallel shield tunnel construction process.The main variables in test are tunnel shrinkage rate and tunnel spacing.Finally,we explore and summarize influence law of the parallel tunnel construction on surface settlementParallel test results show that the ground subsidence caused by single tunnel's shrinkage during the process of parallel tunnel contraction can be fitted well by Gauss curve.In order to study the effect of tunnel shrinkage rate,we control constant tunnel spacing(1.5D),explore and summarize the total and net surface subsidence law caused by tunnel construction based on the condition of three different tunnel shrinkage rate(2.98%?5.18%?8.08%).Besides,for further research,we choose three key points as the typical research object.While studying Research tunnel spacing,tunnel shrinkage rate was controlled to be constant(8.08%).We explore and summarize the total and net settlement law caused by tunnel construction which is based on the condition of three different tunnel spacing(1.5D,3.0D,4.5D).Similarly,three key points mentioned above are also the typical research objects for further exploration.In addition,"volume loss ratio",a new conception defined by myself is used to summarize the influence rule of different shrinkage rate and tunnel spacing on surface differential subsidence.