Study On Reliability Method Of Lining Structure For Deep Tunnel

NATM was the most accepted tunnel construction method. Compound liner was the essential part of NATM. Based on this acknowledgement, the safety of compound liner was the fundamental problem of the whole tunnel structure. The complex underground conditions rendered tunnel structures with great difficulties concerning for the security evaluation with so many variables and factors involving the uncertainty of material parameters, the uncertainty of influence factors, the uncertainty of time-related influence and so on. Upon these uncertainties, this essay, for the sake of overcome all those dilemmas and difficulties along the course of acquiring reliability of structures, put forward a new approach in which reliability of structures were obtained by comparing the stress status in consequence of one single variable varies within its acceptable range. However, this essay was trying to make a useful, but challenging attempt to evaluate reliability of tunnel structure, still it offers references and inspiration for the structure engineering. Contents and results are listed as follows:1. Based on the initial support from construction site, stress conditions of it was acquired by virtue of the theoretical model of initial support building on finite element software with stratum-structure computation method. From the result, the distribution of the stress of initial support was revealed, which increases from the climax of tunnel profile till the side wall of tunnel, then starts lowering till the bottom of tunnel. It correlated with tunnel theories, and provided reference for tunnel construction.2. The fact of most of tunnel deformation occurred after ten days of tunnel excavation was discovered by grey theory and regression analysis. In addition, by the outcome of the analysis, tunnel has experienced much of its deformation before the first practical measurement undertaken. Both of these two discoveries would promote the validity of tunnel construction and offer advices for construction workers.3. With all the data coming from finite element software’s computation, the key control element under the most dangerous condition was known. After curve fitting method and multiple linear regression method adopted, stress function expression of initial support under extremely undesirable situation was acquired and then tested. By response surface method, the reliability of initial support was easily achieved including selecting testing factors, which could effectively guide the construction process under limited references.4. Obtaining the reliability of tunnel structure by Monte Carlo method was much more complicated than response surface method when the accuracy was moderate owing to its repetitive iterative calculation. Comparing the outcomes of500-times and1000-times sample, the accuracy of Monte Carlo method was constantly climbing. On the other hand, the amount of calculation was growing rapidly. This feature indicates that Monte Carlo method was strangled to the situation where high accuracy of result was demanded and the ability of handling huge amount of calculation was provided.