Construction Scheme of Ground High-pressure Pre-grouting in Water Rich Soft Rock Stratum of Long Inclined Shaft with Large Longitudinal Slope
Tai'an No.2 construction support tunnel(inclined shaft)of the Dianzhong Water Diversion Project is located in a fractured fault zone and the remaining tunnel section has a long distance of occurrence,facing the dilemma of"no water deformation,slag slip,water deformation,and sudden mud"composite geological disasters.The pumpability of the broken powder rock is poor,and the use of"advanced reinforcement inside the tunnel"for treatment is time-consuming and expensive,posing a great risk of adverse geological safety.To break the deadlock,directional drilling technology from the petroleum industry and high-pressure pre grouting technology from the coal industry were introduced.Combined with the implementation effect of this technology in the deep hole high-pressure pre grouting of water inrush and mud burst in the project,as well as the experience of preventing and controlling water in the complex wellbore of the newly added vertical shaft at Shenzhen University,classified treatment was adopted to simplify complex problems.The comprehensive treatment requirement of"advanced reinforcement+advanced water blocking"in the tunnel was simplified to"advanced water blocking",reducing the difficulty of treatment.It sets up drilling sites on the surface to construct L-shaped boreholes,and conducts advanced grouting and water blocking reinforcement on the surrounding strata of the target tunnel section,forming a curtain consolidation circle.Based on the excavation exposure,advanced grouting is supplemented inside the tunnel,and further targeted grouting reinforcement is carried out inside the curtain circle to strengthen the surrounding rock and improve the efficiency of tunnel excavation support,so that the construction period and investment can meet the engineering requirements.
adverse geologyadvanced water blockingadvanced reinforcementground pre-groutingL-shaped drillingcurtain circle
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