Stratum Deformation And Process Control Of Large Cross-section Tunnel With Shallow Tunnels Construction Method

It is predicted that a great deal of urban underground engineering will be constructed at early-middle period in the 21st century based on flourish civil engineering foreground nowadays, and at one time many geotechnical problems will also come forth. As far as complicated geologic condition with weak watery strata, complex construction condition with multi-tunnel system and complex environmental condition with adjacent to building and pipeline are concerned, difficulty and risk of construction are very great and the mechanism of ground settlement and its distribution are also very complex. Large land subsidence value induced by construction of large cross—section tunnel can lead to that road surface, buried pipe lines and buildings and so on are damaged. Furthermore, bad economic loss and social effect can be brought about. As a result, it is an urgent realistic problem that land subsidence induced by tunneling is forecasted and controlled so as to realize information and dynamic construction and ensure the safety of close-by building and buried pipeline.Based on vast literatures and extensive practices, the construction technology and the stratum deformation prediction and controlling theory in large cross—section tunnel construction with multi-hole was investigated , by local experimentation, theory analysis and numerical simulation. Its application was carried thoroughly, and a series of results were obtained.Firstly, it is very important that construction process of excavation and support and mechanical effect of supporting structure are simulated reasonably as far as land subsidence induced by tunneling is forecasted.Secondly, by a series of sites test, the earth responded rules which tunneling face of SCTM passed through observation main-transect during its frontage, backside and same position were studied systematically. The distributing characters of the earth stress and its distortion were analyzed in an all-round way.Thirdly, to study of land subsidence on complex multi-tunnel system engineering, in virtue of nonlinear characteristic of construction route in underground engineering, mathematical model of optimal excavation sequence aiming to land subsidence is built on basis of dynamic programming theory. Furthermore, the optimize theory is applied in large cross—section tunnel construction with multi-hole.Fourthly, in order to ensure land subsidence by excavation is less than settlement control standard, this paper presents the stratum deformation prediction and controlling theory, realizing information and dynamic construction...