| This paper is based on the project of Xiema tunnel in Chongqing city.Chongqing Xiema tunnel is the key engineering in expressway system in Chongqing city.The tunnel is a two-way three-lane municipal highway tunnel,whose geological conditions are extremely complex.In the construction process,there are many kinds of bad geological disasters such as mud,water inflow,high pressure.After several rounds of engineering construction,the groundwater and the surrounding ecological environment became fragile.How to protect the fragile water environment is a difficult problem in engineering construction under the complicated geological conditions.According to the construction status of Xiema tunnel,studys are carried out on the key technologies of long tunnel constructions in complex geological conditions in city.The research contents are as follows:1 The key technology of rich water construction in karst areaAiming at the construction problem of karst water-rich section in the crescent tunnel,the paper mainly studies the improvement of tunnel support,waterproof layer and control grouting technology to ensure the safety and quality of water-rich construction.(1)High strength support structure of large cross section soft surrounding rockThrough the analysis of large section soft rock deformation mechanism and supporting structure calculation analysis of Xiema tunnel,it puts forward the new support structure.The supporting ideas of the “first make anti rigid and soft”,increase the toughness and stiffness.The original tunnel lining of the structure is reduced.(2)Shotcrete technologyIn view of the traditional concrete technology with the characteristic of jet dust,high resilience,or high cost of raw materials,complicated process,Xiema tunnel adopts high toughness modification of sprayed concrete reducing the amount of concrete backfill and improving the performance of concrete.(3)Construction technology of strong viscous jet waterproof layerTraditional waterproof roll can not be rolled and concrete tightly,and easily leading to concrete waterproofing system failure in the extrusion process of lining.Xiema tunnel adopts waterproof technology of spray membrane waterproofing system,ensuring the reliability of the technology.There is no special requirement for the construction of environmental non-toxic,no pollution to the environment.(4)The key technology of grouting in karst water rich sectionThe innovation of Xiema tunnel free grout stopping wall back grouting hole and subsection control based on containment.Control grouting,and the base pipe type water gushing grouting reinforcement technology.With that,the safety of construction of more than 2000 meters of water rich karst section are guaranteed,the environment of underground water and surroundings are protected,the construction of tunnel are carried successfuly.2 Controlled blasting technology of large cross section tunnel under complex geological environmentXiema tunnel improves the utilization ratio of explosive energy saving explosives,improves the efficiency of construction to speed up the construction progress and improve the economic benefits of saving construction cost through controlling blasting technology.Blasting vibration velocity was reduced from 8cm/s to 0.4cm/s,the blasting vibration is far less than the specification and approval of the Public Security Bureau allowed value,protecting the surface buildings and the surrounding ecological environment.3 The comprehensive monitoring management system of water-inrush in construction of karst tunnelA set of real-time intelligent monitoring system used in tunnel in complex geological conditions was designed and applied in Xiema tunnel.With this system,multi-source precursory information focused on tunnel disaster are monitered,and the safety of the tunnel are guaranteed. |
PDF Full Text Request