A Study On Treatment And Collapse Mechanismanalysis Of Speedway Tunnel In Wuzhuling

The speedway tunnel is a necessary part of the express highway, it has a widespread availability in the international community nation especially those developed countries. In the construction of speedway tunnel, the collapse is the most common typical accident. Collapse once occur, not only delay time of project, significantly increase engineering expenses, but also will imperil the builder and technical personnel's safety even life. If the treatment to these accident is not appropriate, there will leave engineering quality concealed to suffer from, make it very difficult that maintenance and repair even normal use, Various quality problem emergenced in speedway tunnel engineering is overwhelming majority because those quality incipient fault concealed in construction process. Therefore, research the generating mechanics of tunnel collapse, investigate treatments more reasonable is valuable.Generating reason of collapse is complicated, there have reasons of geology qualification and construction level, meanwhile, have a reason of the related personnel's understanding problem. Collapse hazards tremendous, to a certain extent, it's the one of the casualties of the accidents which the largest construction threatened and most easily produce casualties; Collapses governance is difficult, if not right under specific circumstances, it is very difficult to cure it completely, and vulnerable in collapsing follow governance, furthermore, if the treatment is not complete, it will seriously affect the safe use of the whole project. For the collapse been reasonably governanced, we must first clearly understand generating mechanics of collapses, then take corresponding measures for prevention and treatment of collapses against the influencing factors,to make a reasonable treatment. This paper based on speedway tunnel in Wuzhuling of Zhuyong expressway project, research the generating mechanics of tunnel collapse and caving accident from geology, hydrology and human factors aspects, and raise orresponding treatment methods in view of its physical circumstances, and use three-dimensional finite element method to establish the actual geological model, explain the causes of collapses and caving through numerical method. Simulate the tunnelling construction after real treatment and analyse the rationality and security of this treatment method through the results of numerical calculation.The summary of factors which cause the collapse and caving of speedway tunnel in Wuzhuling: 1, the influence of the vicinity region of fracture, rock been compresso-crushed, layered, poor interlaminar cohesion; 2, shallow depth, rock weathering is high-intensity, assume soil or cloddy pulverescent structure; 3, in the collapse region, the tunnel is three-driveway widening, the span length is wide and the depth is shallow, resulting in the relaxation of the influence to the saddle surface; 4, under the influence of structure and depth, the rock in collapses region have very developed joint fissure, and rich of groundwater; 5, continuous rain, confluenced and infiltrated the saddle surface, is the principal inducing factor of collapse and caving accident; 6, the actual construction failed to timely changes in the initial scheme against the situation changes; 7, the disturbance to adjacent rock by the blasting in tunnelling construction.Against the actual situation collapses and caving, and the influencing factors, adopt reasonable means treatment: 1, in view of the tunnel adjacent rock grade is low, the quality is poor, pipe-roof+ advancing pipe grouting technology should be used to collapses region advancing support; 2, in view of the tunnel span length is wide, cross-section is big, rock cracking, the tunneling of sub-section, short footage, timely support should be adopted; 3, secondary lining should be timely constructed, increased the lining thickness, for enhancing its supporting capacity; 4, adopting surface drilling grouting technology, the seiling surface collapse cavity, control surface subsidence; 5, construct catchwater and discharge ditch in collapses areas, strengthen prevention measures.Establish the mountain geological three-dimensional FEM model, according to the actual ground stress in the region imposed boundary conditions to model, solve the initial stress field of tunnel collapse section, analyse this accident with numerical method. Simulate tunnel actual excavation and support after collapses been cured, analysis through of the numerical results, the advancing support to collapses by pipe-roof+advancing pipe grouting technology and the increment of the thickness of the lining, they do good in controlling of the deformation of rock, greatly reduced the appearance of the plastic zone, make tunneling safely pass the saddle in adverse geological conditions.The collapse and caving of speedway tunnel in Wuzhuling have compared more influencing factors, to a great extent, they contain most of the other tunnels collapses factors, which have a certain universality, this paper have done a comprehensive analysis of these factors; raise a number of collapses and caving treatment methods, and verify the method's security through numerical calculation results. The analysis to generating mechanics to collapse and caving of speedway tunnel in Wuzhuling and the corresponding treatment methods could provide some reference for the prophylaxis and treatment to other tunnel collapse in the future.