Pre-reinforcement And Stability Analysis Of Channel Slope Of Centianhe Fractured Rock Mass

The main canal project of Cen Tianhe Reservoir is the "Water Conservancy Construction No.1 Project" in Hunan Province.The 240 km,channel was excavated through the fissure rock mass slope,encountering rainfall during the initial support,causing dumping damage and seriously affecting the construction period.Investigate the hydrogeological conditions,determine heterogeneous parameters of rock and soil,and construct numerical model of channel slope.Based on the FLAC3D restoration construction process,the design scheme was reviewed,and the failure mechanism of excavation-induced instability was analyzed.According to the damage situation,using the "bottom-up,segmented grouting" process,we proposed the site treatment measures and analyzed the feasibility of the TOUGH2/Gel-module grouting simulation.Considering the action of canal water during operation,countermeasures for the common problems of channel slope.The main contents and conclusions are as follows:(1)Construction of channel slope model of fractured rock mass and determination of heterogeneous parameters.Site investigation and rock and soil samples,considering the engineering experience and analogy,obtain corresponding geotechnical physics and mechanics and heterogeneous parameters of structural surface.The direct excavation matches the actual situation of the overall rock mass on the inside of the channel.It shows that the fine numerical simulation method and heterogeneous parameters are properly set and have high reliability.(2)Re-check the failure mechanism of the slope and the original design.Insufficient estimation of crack rock slope excavation risk,identify slope hydrogeological conditions and damage mechanism,conduct safety evaluation,including slope settlement,excavation disturbance deformation,designed supported slope stability and deformation stress,etc.The review results show that,under natural conditions,the channel excavation slope is stable and fully supported,heavy rainfall,but the slope safety factor does not meet the specification requirements.(3)Analysis and demonstration of treatment measures of the dangerous slope.On the basis of the original design,the department treatment measures were proposed,including excavation after pulse control grouting reinforcement,rubble concrete retaining wall masonry,anchorage hanging network shotcrete,etc.,to treat the dangerous slope,control the instability risk of potential slope and restore the channels.The numerical calculation and the results show that the slope instability treatment measures are effective,the channel slope is safe enough,and the channel section is restored.(4)Demonstration of excavation measures after pulsating grouting pre-reinforcement of channel slope of the fractured rock mass.For different design parameters of pulation control grouting process,combined with the grouting mechanism,pulation control method and controllable control materials,different grouting control parameters are proposed to reflect the influence of unit strength parameters,realize pulation grouting simulation and slope stability analysis and obtain optimized design parameters.The study shows that using 2 rows of 1.5 m hole spacing and 8.5 m scheme,the slope safety factor can reach over 1.83,pregrouting reinforcement excavation,the channel slope is safe enough.(5)Common problems and countermeasures of channel slope during the operation period.According to the characteristics of high-risk channel slope of crack rock mass and common penetration,damage,cracks,propose countermeasures,determine key monitoring parts according to the numerical simulation results,build a low-power remote monitoring system based on the Internet of Things,put forward monitoring scheme and monitoring analysis.