| The core of this paper is the study of tunnel safe interval,deducing the formula of the tunnel safe interval considerding the parameters of surrounding rock and the supporting parameters in theory,trying to obtain the theoretical data of the the tunnel safe interval in different levels of surrounding rock.In this paper, the main content includes:1) Introduce briefly the construction methods, the tunnel collapse risk factors and prevention and emergency response measures.2) Deduce the tunnel safe interval formula,referencing the theory of beam on elastic foundation, considering seven influence parameters. Influence parameters including the elastic force coefficient 0k, the level of surrounding rock s, the surrounding rock severe ?,with three parameters of surrounding rock,the elastic modulus of sprayed concrete E, the tensile strength value [ ? ] and the primary support thickness δwith the three initial supporting parameters and the tunnel excavation width D with one geometric parameter of tunnel excavation.3) Combining with engineering cases, Comparative analysis of the safety distance of standard value and the calculated value of this article has carried, and gives some suggestions.4) Research the tunnel safe interval formula, and investigate relationships between forces of elastic coefficient 0k,surrounding rock severe ? and the tunnel safe interval, give method of select parameter in using the the tunnel safe interval formula.The author insist that should be applied the new Austrian Tunneling Method " frequent measurement" thoughtis to judge the tunnel safe interval. Do the whole dynamic process of the tunnel monitoring measurement about the both surrounding rock’ property and the support’ property,and that’results are applied to judge the value of the tunnel safe interval. To ensure the safety of tunnel construction and tunnel engineering quality, or strive for maximum working face of construction,so that can improve work efficiency and reduce the cost maximumly. |
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