Large Sections Of The Loess Tunnel Stability Analysis

Our country is a mountainous country, and the hilly area is larger loess covering,The construction of the implementation of the western development promoted our highway, railway GanXianWang of continuous improvement, especially in the west to constantly been outspread, make transportation infrastructure construction in loess plateau areas across the road, railway more and more.The tunnel to overcome obstacle flat terrain, shorten the line mileage, avoid bad geological conditions of the adverse impact of the line, effectively improve the standard line: at the same time to protect the natural environment of reasonable, avoid, reduce the damage of cut excavation ground vegetation, soil and water conservation and maintaining ecological balance, and resist natural disasters are very favorable.At present the railway tunnel design rules "(2005), the TB10003 - highway tunnel design rules" (JTG/T the D70-2004) and the latest popularizing the highway tunnel design detailed rules "(JTG/T the D70-2010 of the tunnel in the design of) makes a detailed requirements and standards of the regulations, but the majority is in the mountains, and rock tunnel loess into special geology, design also just in rock tunnel surrounding the basis of level, increase the lower support parameters, do certain supplementary provisions, give some guidance,especially for large sections loess tunnel, the above standards and design rules and were not somewhat.Large sections loess tunnel stability problems: if the fuzzy evaluation, the geological geotechnical materials tunnel constitutive relation, loess soft rock tunnel mechanical mechanism, nonlinear finite element displacement back analysis, the surrounding rock deformation control index, supporting lining strength growth and wallrock deformation relations, the evaluation of retaining structure, this research at home and abroad, research reports little work just started.Based on the new railway lanzhou to chongqing line lanzhou hub van north loop and lanzhou north marshalling yards (more paragraphs tunnel, the longest section chief 23km km), even khodorkovsky non-recurring national AD DJ45) ever (auges wave highway tunnel - ancient (full-length 1.6 km, project for engineering background, seperated) to the stability of large cross-section loess tunnel are investigated, and the main contents in the following aspects:(1) Summarized in the design theory and surrounding rock tunnel collapse mechanism, stability analysis of the general situation of the study method; (2)In the tunnel construction before operation, ahead of geophysical exploration with the TSP bad geological rocks in their forecast; The main engineering geological conditions of the surrounding rock of tunnel excavation, the effect on the stability of the tunnel;(3)In tunnel construction assignments, comprehensive inspection tunnel primary support limit relative displacement, displacement velocity and displacement of the rate of change, speed stability of tunnel; make accurate predictions;(4)In the tunnel support homework, consider surrounding rock stress together with supporting structure characteristics of tunnel deformation, supporting structure as early consideration, constructing series system safety factor considering the function, to analyze the tunnel primary support system reliability;(5)Preliminary discussion of this special soil mechanical properties of rock, combined with the view of damage mechanics, using statistical principles established "transverse isotropic soil" deformation and fracture process of statistical constitutive relationship damage softening.