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Mechanism and Effect Analysis of Surface Deep-hole Sleeve Valve Pipe Grouting Reinforcement in Deep-buried Water-bearing Loess Tunnel
（1. Engineering Management Center of China State Railway Group Co., Ltd., Beijing 100844; 2. Lanzhou University, Lanzhou 730000;3. China Railway First Survey and Design Institute Group Co., Ltd., Xi′an 710043)
Abstract Loess is characterized by "low strength, large deformation, small self-supporting capacity and poor engi? neering properties", and is particularly sensitive to water. Once it meets water, the strength will be significantly reduced, and the engineering properties will deteriorate sharply. Therefore, the construction of the water-bearing loess tunnel is extremely difficult and the safety risk is extremely high. The Shangge Village tunnel on Yinchuan-Xi ′ an High-speed Railway passes through the water-bearing loess stratum, with a buried depth of 102 m. During the conStruction, no obvious dewatering effect can be achieved through the dewatering test, and the surrounding rock of the tunnel is deformed greatly and the progress is slow. In view of this, an experimental study on grouting of surface deep-hole rigid sleeve valve pipe is carried out. The results show that: (1) the grouting of the surface deep-hole sleeve valve pipe can effectively strengthen the stratum and improve its self-stability. The reinforcement mechanism is mainly the filling and water-blocking effect of grouting on vertical primary joints and the spatial skeleton effect of grout stones. (2) After grouting, the accumulated settlement of the tunnel vault is obviously reduced, the deformation rate is reduced, the invert closure time is advanced, and the tunnel excavation progress can reach 60 ~ 80 m/month.The construction schedule has been improved by more than three times compared to that of the ungrouted case. (3)Through grouting, the bearing capacity of the loess stratum at the tunnel base can be increased by more than 3times, thus ensuring the long-term operation safety of high-speed railway tunnels.
Abstract：
Loess is characterized by "low strength, large deformation, small self-supporting capacity and poor engi? neering properties", and is particularly sensitive to water. Once it meets water, the strength will be significantly reduced, and the engineering properties will deteriorate sharply. Therefore, the construction of the water-bearing loess tunnel is extremely difficult and the safety risk is extremely high. The Shangge Village tunnel on Yinchuan-Xi ′ an High-speed Railway passes through the water-bearing loess stratum, with a buried depth of 102 m. During the conStruction, no obvious dewatering effect can be achieved through the dewatering test, and the surrounding rock of the tunnel is deformed greatly and the progress is slow. In view of this, an experimental study on grouting of surface deep-hole rigid sleeve valve pipe is carried out. The results show that: (1) the grouting of the surface deep-hole sleeve valve pipe can effectively strengthen the stratum and improve its self-stability. The reinforcement mechanism is mainly the filling and water-blocking effect of grouting on vertical primary joints and the spatial skeleton effect of grout stones. (2) After grouting, the accumulated settlement of the tunnel vault is obviously reduced, the deformation rate is reduced, the invert closure time is advanced, and the tunnel excavation progress can reach 60 ~ 80 m/month.The construction schedule has been improved by more than three times compared to that of the ungrouted case. (3)Through grouting, the bearing capacity of the loess stratum at the tunnel base can be increased by more than 3times, thus ensuring the long-term operation safety of high-speed railway tunnels.
2023, Vol. 60 