Numerical Analysis Of Deformation And Reinforcement Of High Crustal Stress And Soft Rock Highway Tunnel In Muzhailing

Weiyuan Luyuan to Wuwei Liangshui highway is an important section of Lanzhou to Haikou(G75)national highway,which is the most convenient channel highway connecting the northwest and southwest,also the most convenient highway tunnel of the provincial capital Lanzhou and Longnan region,and it is a skeleton of Gansu road network in the mountain central and southern,and the a national highway system the only barin in the southern Gansu,and transport ationartery of the central and southern Gansu economic belt highway,and it has a special position and role in the provincial highway network.Muzhailing high stress soft rock highway tunnel as nutrient-laden force control of Wei-Wu highway engineering,this paper combined the engineering practice,reference the before results of other researchers,first of all,based on the research achievements of predecessors' thesis research idea was designed: Based the Muzhailing tunnel,the location of high stress soft rock tunnel engineering geology,hydrology and climate are simple introducted,and do something for the after the introduction of high ground stress and the study of soft rock tunnel excavation.Then,based on a brief account of the principle of the hydraulic fracturing in-situ stress measurement prove that the Muzhailing high geostress on the accuracy of the results of the practical and in the soft rock tunnel,and using the method of the tunnel in the Muzhailing measured in-situstress,according to the measured results determine Muzhailing tunnel under high in-situ stress.And then,by using numerical simulation method to the whole section excavation method and the up and down steps excavation method to simulate the Muzhailing high stress soft rock highway tunnel construction process,the surrounding rock deformation and stress distribution,and verify the scene and the rationality of the method of actual excavation steps.Finally,through different advance grouting reinforcement length and thickness of grouting reinforcement of numerical simulation,comparative study and economic reasonable grouting reinforcement parameters,to control the deformation and stress of high stress sof trock tunnel.Through these work above,this paper got the following conclusions:1?Due to large buried depth of Muzhailing tunnel,according to the method of hydraulic fracturing in-situ stress test results: with in the scope of the testing depth greater than 30 m,section three sets of drilling measurement results show that the maximum horizontal principal stress value was 26.22 MPa to 38.38 MPa,and the mean is 33.68 MPa,the minimum horizontal principal stress value of 15.73 MPa to 21.52 MPa,and the average is 19.15MPa;Southern three groups of bore hole survey results show that the maximum horizontal principal stress value was 30.16 MPa to 35.68 MPa,and the average is 32.61 MPa,the minimum horizontal principal stress value of 18.11 MPa to 21.29 MPa,and the average is 19.60 MPa.And think about drilling rock mass under the condition of the integrity is poor,horizontal principal stress is still higher than the same depth and horizontal principal stress under the condition of the same lithology size,so the Muzhialing tectonic stress field in the tunnel belongs to high in-situ stress environment;2?By way of up and down the steps between the results of numerical simulation method of excavation way,combined with the actual excavation way up and down the steps method,deformation based on field testing and numerical simulation results,verifying the rationality of the site up and down the steps of excavation;3?Through the Muzhailing ahead of different length inadvance of high stress soft rock tunnel grouting numerical simulation,according to the results of numerical simulation,available with the increase of grouting reinforcement length inadvance,surrounding rock deformation and stress distribution are decrease,this paper advance grouting reinforcement 1 times,2 times and 3 times inexcavation,the results of numerical simulation of drawn ever advance grouting reinforcement to 3 meters(1 times excavation)inadvance grouting reinforcement,control results of the deformation and stress of surrounding rock is best;4?Through the Muzhailing high stress soft rock tunnel advance grouting reinforcement different reinforcement layer thickness of numerical simulation,according to the results of numerical simulation,with the increase of advance grouting reinforcement layer thickness in advance,the deformation and stress of surrounding rock points roughly showed a trend of decrease,in this paper,through advance grouting reinforcement layer thickness for excavation hole diameter of 0.2 times,0.5 times and 1 times,the results of numerical simulation of drawn ever advance grouting reinforcement to advance grouting reinforcement layer thickness of 2m(when 0.2 times of excavation hole diameter),the deformation and stress of surrounding rock control effect is best.Through the above research and analysis,the Muzhailing high in-situ stress soft rock highway tunnel section of the tunnel and suggest a 3 meters in advance(1 times excavation)reinforcement layer thickness is 2~ 3 meters(0.2~0.3 times excavation hole diameter)for advanced grouting reinforcement,to control the high stress soft rock tunnel surrounding rock deformation and stress development,thus achieve the safe construction of the tunnel.