Slope Of Highway In Unloading Area Of Alpine Canyon Safety Risk Control Technology Research

Under the effect of complex geological structure,regional metamorphism,deep river depth,alpine freezing and thawing,strong unloading and weathering,etc.,a large scale and wide distribution of unloading areas are formed in the Taihang Mountain alpine valley area.As China’s highway construction continues to expand to high latitude,high cold and high intensity mountain valley areas,the topography and route alignment restrictions inevitably require the destruction or disturbance of the unloading zone.The deformation and destabilization mechanism of the unloading zone is extremely complicated under the coupling effect of various factors such as weathering unloading,rainfall and artificial excavation,which makes the slope have a lot of uncertainty risk during the construction process.Therefore,it is of great engineering significance to carry out research on construction safety risk control technology for slopes in the unloading area.The thesis selects the slope protection and reinforcement project of Huanglongkou section of G234 highway as the basis,takes the construction safety risk control of slope in the unloading area as the core,analyzes the deformation and damage mechanism and destabilization mechanism of slope in the unloading area,carries out the construction safety risk assessment of slope in the unloading area,proposes the slope reinforcement and construction risk control technology,and combines the automatic monitoring with the construction safety risk dynamic control of slope.The main research contents and results are as follows:(1)Through the engineering geological investigation and analysis of the slopes in the study area,the number of fissures and fissure openness are used as quantitative indicators to divide the unloading zone,and the slopes in the study area are divided into Zone Ⅰ to Zone Ⅲ by combining factors such as the change of rock production and weathering characteristics,revealing the control law of its deformation and damage characteristics influenced by the degree of weathering of the rock and the unloading nodal fissures.(2)Based on the deformation and damage mechanism of the slope in the unloading area,the slope unloading characteristics and damage mode in the study area are analyzed.Based on the soft rock slope in the unloading area and the development of joints and fissures,it is pointed out that the potential damage mode is mainly based on the circular sliding inside the fractured and loose rock body and the sliding damage along the bottom surface of the strongly weathered and strongly unloaded rock body.(3)The safety risk of the slope in the study area is identified by macro-geological qualitative analysis,and the stability of the slope is evaluated by a combination of limit equilibrium method and finite element analysis,and the excavation process of the slope is simulated.According to the analysis results,the method of high mountain valley unloading area road slope construction safety risk assessment based on the index system method is proposed.(4)Based on the slope construction safety risk analysis and assessment,combined with the regional division of the study area,the slope zoning and segmental reinforcement scheme of the unloading area is proposed.For the slopes within zones Ⅰ to Ⅱ,the anchor rib plate wall and anchor frame are used as the main risk control means to increase the anti-slip stability of the slopes.For the slopes within zone Ⅲ with high excavation height,many excavation levels and developed unloading fissures,more effective slope reinforcement measures such as anchor pile plate wall and anchor cable frame are adopted,and then targeted risk control countermeasures and suggestions are put forward.(5)Based on the deformation and damage characteristics of the slope in the unloading area,an automated construction safety risk monitoring system was established based on deformation and stress monitoring,and a construction safety risk grading and early warning method was proposed to carry out real-time monitoring of the construction safety risk of the slope in the study area by zoning and segmentation to realize dynamic monitoring of the construction safety risk of the slope.(6)Based on the monitoring of slope construction safety risk in the unloading area,through the monitoring data of slope surface displacement,tilt of supporting structures and other parameters,the safety status of slope can be dynamically analyzed and evaluated,the development of slope safety posture can be predicted,and dynamic control measures can be taken in time to provide guarantee for slope construction safety.