Based On The Rainwater Infiltration Coupling Of Hydraulic Tunnel Portal Construction Disturbance Stability Study

The hydraulic Tunnel portal section of general under surface water erosion,weathering fracture slope surface,and embedded depth of the hole section tend to be shallow,supporting the upper structure is difficult to form bearing structure in geotechnical engineering.So the hole section after excavation disturbance surface highly vulnerable to pull crack,if during the construction and is in the rainy season,rain infiltration by the surface weathered layer or crack,it is easy to cause the hole section of the collapsed roof caving,so the construction disturbance-rainwater seepage coupling under the action of tunnel portal stability study has very important significance.In this paper based on the engineering support of a shallow buried tunnel entrance section on the basis of existing research results,based on the rain infiltration in the tunnel engineering and construction disturbance problem using numerical simulation and theoretical analysis,field monitoring method are studied,such as the concrete research content is as follows:(1)the project has carried on the induction summary inverse analysis for rock mass,and established the displacement analysis of the results of inspection methods;Crushing weathered rock mass under the rain infiltration of various physical and chemical process was analyzed,and explained the broken rock mass strength changes under the rain infiltration and the function of the pore water pressure in the form.(2)reference for domestic related specification and combined with the actual situation of a shallow buried tunnel entrance section,corresponding monitoring plan,on a certain tunnel entrance section of the forced deformation of the surrounding rock and supporting structure of condition monitoring,analysis of monitoring data after research;Advance geological forecast for tunnel entrance section at the same time,combined with detection data of the hole section of engineering geology were analyzed.(3)based on the monitoring data,combined with the golden section optimization method to establish a numerical model of tunnel surrounding rock mechanical parameters(deformation modulus E,cohesive force c,internal friction Angle ?)to the inversion,the inversion results of inspection.(4)the displacement back analysis of surrounding rock parameters as the periodof the surrounding rock analysis,numerical simulation model is set up,with different rainfall duration,different construction methods when the rain infiltration-coupling under the action of tunnel entrance construction disturbance of surrounding rock and the stability of the supporting structure for numerical simulation of the research shows that: the rain as time continued down gradually in the soil permeability,saturation of tunnel surrounding rock mass shows the law of change of gradient,under the action of rainfall wetting front step by step down,the rain infiltration increases the tunnel vault,the weight of the overlying soil seepage force produced by its impact on the stability of the tunnel to weak to increase the influence of gravity;-the rain under the action of seepage coupling tunnel construction disturbance stability is the worst,the effect of rain infiltration to weaker than the role of the construction disturbance.