| Our country is a large country, mountains and plateaus account for about60%of thetotal area, with the rapid growth of Chinese economic strength and scientific andtechnological strength, the special structure of small spacing tunnel, can enable theconstruction of tunnel due to technical reasons, special geology, topography, the overall routeline, line and cohesion factors can not be put into construction into reality. So the large spansmall spacing tunnel engineering in recent years become one of the main forms of thehighway construction of tunnel structure in the mountainous area of special geological andtopographical conditions. However, in the case of existing tunnel, accounted for the vastmajority of shallow bias tunnel, surrounding rock in tunnel construction stress interferenceand initial deformation is very complex, two factors plus shallow and bias is exacerbated thissituation. Therefore, it is necessary to large span small spacing tunnel shallow bias sectionresearch, summarize construction technique, which is a large span small spacing many keytechnical problems encountered in tunnel construction to provide a scientific basis andtechnical guidance.This paper mainly based on Tunnel Luwan the actual construction conditions, technologyand Research on construction control of large span bias tunnels with small spacing3Dnumerical simulation and calculation software, the main research work and achievements are:â‘ Through the elaboration, and determine the characteristics of small spacing tunnelsurrounding rock of large span bias stability theory, and then combined with the LuwanTunnel design, engineering and construction technical data about large span bias tunnels withsmall spacing, summarized the construction technology of tunnel with small spacing and largespan bias. Summarizes the construction technology of large span, small spacing tunnel biasinclude: construction management, method of excavation under complex geologicalconditions, construction of blasting technique, bolting and Shotcreting Technology,discrimination and advance geological prediction of surrounding rock, rock reinforcement,surface strengthening, the auxiliary and drainage measures, monitoring and environmentprotection etc.â‘¡The application of ANSYS software, a simulation calculation of shallow biassection construction, dynamic process on the Luwan Tunnel entrance, should be characteristicof deformation force, has carried on the analysis to the surrounding rock, and based on therational analysis of excavation scheme. Under different excavation sequences results of displacement and stress nephogram and supporting internal force calculate, and compared, theconstruction sequence in grade V surrounding rock of large span neibourhood tunneldouble-side heading method reasonable should be outside tunnel after excavation first innerhole, the side heading near the rock excavation after the first excavation of side wall driftaway from the rock.â‘¢Based on the V surrounding rock of large span tunnel double-side heading methodwith small spacing reasonable construction sequence, the3D numerical model of tunnel isestablished by finite element software, simulation analysis of excavation, the reasonableconstruction spacing tunnel with small spacing, after the first hole bias in grade V surroundingrock of large span. According to the analysis results, that the two working face, the reasonableconstruction spacing out2B (B for tunnel excavation diameter), minimum disturbance torock. |
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