| China is the country with the widest distribution of karst areas in the world.With the rapid development of the national economy,the traffic network has been constantly improved,and more and more karst tunnels have been built.The diseases of operating karst tunnels under the action of long-term karst water pressure have become increasingly prominent,which seriously threaten the safety of tunnel operation.However,the current research mainly focuses on the advanced geological prediction,construction safety and treatment technology of karst tunnel after the karst is revealed during the construction period,and there are relatively few studies on the diseases in the operation of karst tunnel.Through the operation of karst tunnel disease research,such as rainfall caused by mutations in the water pressure is the main factor of karst tunnel diseases,therefore,zheng wan railway karst tunnel rich water tunnel as engineering background,developed a set of simulated high water level of groundwater,rock type,pipe cavity device,waterproof and drainage system,such as lining structure model test system.Based on this,this article will through the methods of numerical simulation and model test research of tunnel in karst region,operating process,the karst water burst,rich water karst tunnel in filling type and tube type cavity in different water head,different drainage conditions of rock-salt cavity are located in different location,high water pressure under the action of seepage water pressure behind the lining effect of the size and distribution of change rule and the internal force of tunnel lining.Its main contents and achievements are as follows:(1)by filling type cavity model test,on the basis of ? level of surrounding rock,and consider the buried depth of surrounding rock,karst water of different initial water head height,waterproof and drainage pattern,etc.,karst tunnel lining under different working conditions,the operations behind the water pressure distribution,is obtained,and conventional drainage circumstances edge water pressure in the corner of the tunnel has significantly reduced effect,optimize drainage circumstances of inverted arch tunnel center water pressure is significantly lower.At the same time,it is concluded that the annular blind pipe can also reduce the pressure of tunnel lining.At the same time,the failure model test of the filled karst tunnel was carried out.In the case of no drainage,the failure occurred 1.8m away from the vault,and the maximum invert displacement was 3mm.(2)the influence law of the duct-type concealed karst cave on the internal force of tunnel lining was studied by means of the duct-type dissolved cavity model test.Test on the basis of ? level of surrounding rock,according to the karst cave is located in the middle of tunnel lining vaults,sidewall,side corner and inverted arch center four conditions.For each situation,the different effects of the size of the cave and the change of the water pressure in the cave on the tunnel structure were analyzed.Generally speaking,the larger the diameter of the cave,the greater the water pressure in the cave,the greater the impact on the tunnel lining near the cave,and the more unfavorable the lining structure was.(3)through the establishment of a three-dimensional seepage model with Midas and the simulation and comparison of the filling cavity model test,the simulation results show that in the case of conventional drainage,the water pressure at the back of the tunnel lining is reduced,the wall corner is significantly reduced,and in the case of optimized drainage,the water pressure at the center of the inverted arch is significantly reduced.The water pressure near the annular blind pipe and far away from the annular blind pipe were extracted and compared.Under the condition of no drainage,when the distance from the arch is greater than 1.6m,the tunnel lining does not meet the safety standards,the safety coefficient k<1,and the maximum invert displacement is 2.7mm.(4)through the establishment of three-dimensional load structure model with Midas,the simulation and comparison of the tubular cavity model test,the simulation results and the numerical calculation results are compared,the results of the two research methods basically reflect the same law,for the same kind of tunnel design,construction and research to provide useful reference and reference. |
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