Quantitative Analysis On The Safety Performance Of Supporting Structure Of Highway Tunnel In The Loess

With the implementation of the western development strategy and highway andhigh-speed rail extending to the mountains in our country, the number and size of the tunnelconstruction has also reached unprecedented heights, but the safety margin of building tunnelssupporting don’t have a clear quantified analysis, supporting design by the confining pressurelevel in the relevant norms, safety margin aren’t detailed description,this paper focuses on thetunnel safety degree on highway tunnel supporting in the loess. Firstly, having done indoorGDS triaxial test and conventional compression test, these tests used the loess in the typicalsection, in order to analyzing the stress-strain behavior of loess and their variations,finding:when the minimum principal stress3is a constant, the principal stress difference curvesand the maximum principal stress ratio curves of appear downward trend with increasinginitial water content, and the greater the initial moisture content, the more significant decline.In the case of certain initial water content, the principal stress difference stress-strain curvedecreases with the weakening of the confining pressure, but the maximum principal stressratio curve decreases with the strengthening of confining pressure. The1~3curve doesnot comply with the hyperbolic model, and it is more like a relatively smooth broken line.Secondly, based on the study of predecessor, this paper proposes the definition of the safetydegree. Following, utilizing the basic principle of concrete and the basic principium ofmaterial mechanics, this paper deduces the formula for calculating the safety degree. Thenadopting means of numerical simulation, by influencing and analysising of single factor, thispaper investigates the influencing factors of safety of the tunnel supporting in loess area andtheir variations, study show: Through the analysis data, in a single factor variable conditions,the safety of the tunnel lining and soil cohesion, internal friction angle and elastic modulus aretested positive relationship overall. As they increase the safety of the lining also showed atendency to increase. In contrast, the bulk density and security is inversely proportional to thedegree of relationship, bulk density increases mean the safety of the lining structure reducing.Finally, combining the results of the field observation, paper determines the minimum safetydegree position in the loess tunnel and rationality of tunnel lining design, providing areference to the design and construction of the loess highway tunnel.