Risk Assessment And Prevention Measures Of Water Inrush In Mountain Tunnels

Water inrush geological disasters are often encountered in the construction of mountain tunnel,which seriously threaten the construction safety.How to carry out risk assessment and control of water inrush disasters in advance is the key and difficult problem in the construction of tunnel engineering.The study on evaluation and prevention and control measures of sudden water inrush in mountain tunnel is helpful to reduce the occurrence probability and loss of sudden water inrush.Based on the FeiXianGuan tunnel project.By means of field investigation and numerical simulation,the causes and mechanism of water inrush disasters in tunnel are studied,and the corresponding prevention measures are put forward.The results not only provide some Suggestions for preventing sudden water gushing in FeXianGuan tunnel,but also provide some references for similar tunnels.The results obtained in this paper are as follows:(1)Through case collection and field investigation,this paper analyzes the basic situation,formation mechanism and treatment measures of typical mountain tunnel water bursting disaster,and summarizes that water bursting disaster is mainly affected by geological structure,stratum lithology,water conservancy conditions and construction factors.On the basis of analyzing the advantages and disadvantages of the traditional evaluation system,evaluation method and calculation model,the mathematical model of two-level fuzzy comprehensive evaluation method is selected as the risk evaluation model of tunnel surge water.Selected the geologic structure,stratum lithology,hydraulic conditions and construction factors as the primary index,forming a sudden surge of water disaster on 16 factors as the secondary impact factor,fuzzy hierarchy structure model is established,the analytic hierarchy process(ahp)is used to determine the weight of the impact factor,then according to the risk matrix method to determine the risk level,set up a complete set of mountain tunnel water risk assessment model.(2)Based on the risk grade of sudden water inrush put forward in the risk assessment of tunnel water inrush,and combined with the main prevention measures of tunnel water inrush disaster,the corresponding risk level of sudden water inrush prevention measures system is developed.At the same time,according to the size and cause of the water inrush in the construction site,corresponding treatment measures are put forward.(3)Based on typical tunnel,the risk assessment of sudden inrush section shows that it is in high risk.Based on the investigation of hydrogeological conditions,hydrodynamic characteristics of water gushing and surrounding rock structure characteristics of the tunnel with field exploration and measured data,this paper analyzes the origin mechanism and basic characteristics of the sudden water inrush in FeiXianGuan tunnel,and puts forward the treatment scheme of "combination of drainage and blocking,limited discharge" according to the specific characteristics of the sudden water inrush section of the tunnel.(4)Using FLAC3 D finite element software to carry out the three-dimensional numerical simulation,studied the stability of surrounding rock in excavation and supporting process and the characteristics of the stress of the supporting structure,the displacement change rule of "radial grouting plugging" measure to the monitored section is compared through the measurement of location,and the measure of "radial grouting plugging" is adopted to ensure that the surrounding rock enters a stable equilibrium state early after the tunnel excavation reaches the monitored section.