Study On The Design Of Support Lining Structure In Saturated Loess Tunnel

With the rapid development of China’s national economy, the infrastructure construction has been promoted, China is stepping into the phase of construction peak on transportation (such as road, rail, urban subway), and water conservancy facilities, the increasing number of engineering construction illustrates a fact: China has became one of the countries which has the largest scale of underground projects all over the world, and the amount of tunnels in china is the largest, with the uttermost complex geological conditions. China has the fastest speed of technological developme-nt with respect to these projects, and our technical level and economic achievements have been walking in the forefront of the world. However, due to the reasons about the unclear properties of the physical and mechanical properties of rock and soil, the tunnel project’s individual differences, the design theory is not perfect especially for water-saturated loess tunnel, it is theoretically and practically significant to study water-saturated loess tunnel the support lining structure design.Through the introduction of the "Yintao" project15#tunnel project overview, we can realize the relationship between the surrounding environment and the tunnel, with the help of engineering geological exploration data and research results accumulated over the years, we analyzed the special nature of the surrounding rock of the tunnel body and came up with a stability evaluation. The tunnel body surrounding rock is the fourth unsaturated soil, constructed by plastic to hard plastic like heavy silt loam, silty clay and soft plastic-like silty loam, sandy loam, the overall soil very uniform, the rock traits very different. Secondly, we summarize the existing tunnel lining structure design calculation model, pointing out the characteristics and computational theory of each model, and select the means of calculated using two methods respectively. Selecting class horseshoe-shaped and circular cross-section of two different conditions by ANSYS mechanical analysis of the lining structure of the tunnel, found that the force of the circular cross-section is better than the class horseshoe force. However, comparing with a circular cross section, the class horseshoe-shaped cross-section has more using space and greater width. To meet the same clearance requirements, the circular tunnel has lager amount of excavation, and using more lining and reinforcement ring, and it is not as convenient as the construction of class horseshoe section. Summarize various factors, it is recommended to use the class horseshoe-shaped sectional form. Then we used FLAC software to simulate the excavation of the tunnel, calculations show that, in accordance with the original design file support lining structure is conservative, we can largely optimize it. Thinning the lining in the original design file about100mm, decrease4bolt set, analyzing the entire excavation process from the perspective of supporting ago、after supporting、 after setting the bolt, we can conclude that optimization scheme is feasible. Tunnel lining structure mechanical response under earthquake time history analysis to verify the stability of the optimization program lining structure under seismic action also indicates the important role of anchor support system set up in the earthquake. Finally, the regression analysis through the tunnel construction process monitoring data, pointed out that the tunnel support parameters should be adjusted at any time based on the dynamic information of surrounding rock in the construction process, so that we can ensure the construction of safe and smooth.Water diverting project15#water-saturated loess tunnel section, with longer length, very complex engineering geological conditions, and poor nature, is a very strong typical of the tunnel support lining structure design for the construction of similar projects in the future with a strong guiding significance.