Study On Ling Design And Reliability Of Shallow Tunnel Structure

Based on application of reliability theory and implementation probability limit design method, establishing corresponding design criterion is a tendency in national and international engineering design, and is an effective means in improving the level in national engineering design. Main uncertainty varies are quantified; empirical method is substituted by statistical mathematics; explicit design concept is substituted by implicit design, that is the essence of reliability design, therefore, engineering design becomes more scientific and rational.For complexity of environment where tunnel structure is built in, so the stochastic factors for example, load value on tunnel structure, property of wall rock and calculation mode etc are hard to determine; at present in design of tunnel structure, the probability design theory only applied to deep tunnel. And in order to study the probabilistic design of shallow tunnel, in this thesis, based on the light of monolithic ling of tunnel structure, statistical parameters of basic stochastic variable related to "load-structure" model are analyzed; interaction between ling and wall rock is considered in calculating, and Monte-Carlo method is applied in calculating the statistical characteristic of inner force, and JC method is applied in calculating reliability index.Considering the succession of ling design method, main factors including load, ling calculation mode, and ultimate bearing ability of concrete component, which play important role in achieving probabilistic design from the light of monolithic ling, are analyzed in this thesis. Particularly the statistical characteristic of break-angle which is important to calculating the load of shallow tunnel is studied by using Monte-Carlo method; the method of calculating the load of shallow tunnel and the method of calculating the inner force of ling etc are generalized in this thesis. The calculating model is built and calculated in FEM, and elastic link is used to simulate the interaction between ling and wall rock. Routine which is compiled in FORTRAN language by author is used to identify, remove tension link and loop computing. By associating with Monte-Carlo method, the input random varies including load, material young's modulus, lateral pressure coefficient, and calculating mode etc are sampled...