Anti-seepage and drainage measures of ultra-deep buried tunnel and distribution law of external water pressure of lining
High external water pressure is one of the key problems restricting the construction of ultra-deep hydraulic tunnel.The comprehensive water blocking and drainage measures centered on drainage holes are the main methods to reduce external water pressure.In order to overcome the problems of high overall meshing difficulty and low computational efficiency of traditional drainage hole solid element method,firstly,a two-node drainage hole line element model was developed based on ABAQUS platform,and its correctness and effectiveness of the numerical simulation analysis of tunnel engineering was verified.Secondly,a three-dimensional finite element model of surrounding rock and lining considering anti-seepage and drainage measures was established to study the seepage field of the tunnel and the distribution of external water pressure of the lining with various anti-seepage and drainage measures.Finally,the influence of design parameters of anti-seepage grouting ring and drainage holes on the distribution of external water pressure was discussed.The principle of spacing arrangement between anti-seepage grouting ring and drainage holes was proposed.The results show that the developed two-node drainage hole line element has high precision and high efficiency in the model with a large number of drainage holes.The more the number of drainage holes,the greater the depth,the smaller the row spacing,and the lower the external water pressure of the lining.The drainage hole can effectively reduce the external water pressure of the lining,but the anti-seepage grouting ring has limited ability to reduce the external water pressure.There is a certain thickness of surrounding rock between the anti-seepage grouting ring and the end of the drainage hole,which can play the role of reducing external pressure more effectively.
hydraulic tunnelconcrete lininghigh external water pressuredrainage holeanti-seepage grouting ring