Durability Of Underground Engineering Analysis And Evaluation

In recent years, along with a large number of underground works applied, the problem of underground work's durability has become notable increasingly, and began to attract people's attention. However, because of the particularity and the complexity of underground works'environment, the underground work's durability study has a unique personality. In connection with underground structures' characteristics, this paper does a systematic study in the problem of underground works'durability, the main achievements are as followed:(1) Similarities and differences of the underground and ground concrete engineering are deeply studyed, especially underground structures'particular in the aspect of environmental and construction, and durability factors in four aspects about materials, design, environmental, construction, are generalized.(2)The extended of impaction that rock rheology exert on underground works'durability and security are studied deeply, applying on C++ and ansys software and then do an conducted study by connecting with an actual project, the results show that:rock rheology has a effect on underground works'durability and security, a large displacement occurred in vault of underground tunnel and stress concentration turned out in arch hance and foot of underground tunnel.(3)Based on stress acceleration factor formula about carbonation that have existed are summarized and compared, then more rational and realistic tensile stress acceleration factor formula and press stress acceleration factor formula are determined, which were under experimental data.(4)The factors which effected carbonation are summarized systematicly, these factors are done sensitivity analysis by grey theory, the result shows that:water-cement ratio, cement content, compressive stress, tensile stress, are made sure that have more affection on carbonation.(5)Stress influence coefficient formula about chloride diffusion are summarized and compared, then, tensile stress influence coefficient formula is proposed and compared with a similar formula which has the similar experimental data. The conclusion is that the formula of this paper has a wider application and higher precision, and has a higher reference value in studying of chlorides'erosion in the environment of stress.(6) Durability classification standards are investigated preliminary, then a fuzzy set model for assessing the underground structure durability is proposed and the calculation steps of this model are elaborated in detailed. The actual project shows that using variable fuzzy evaluation model is more reasonable.