Emergency treatment method for sudden gushing of high confined water stratum foundation pit

Abstract

The invention discloses an emergency treatment method for sudden gushing of a high confined water stratum foundation pit. The method is characterized by comprising the steps that the water gushing condition is proved, a steel casing is arranged on the water gushing point in a covering manner to serve as an energy-releasing relief well, a simple back pressure platform is arranged at the bottom of the steel casing, the height of the steel casing should be 1 m above the static water level, water gushing kinetic energy can be guided into the steel casing, then, the water head pressure is released, and the water level in the steel casing depends on the pressure difference to be balanced; and meanwhile, the top face of the casing is sealed, communication of internal gas pressure and external gas pressure of the casing is prevented, the backpressure backfilling sealing grouting condition is simulated, a WSS double-tube non-shrinkage two-fluid grouting technology is adopted for carrying out advancing type segmented grouting, and therefore the aims of rapidly controlling water gushing of the foundation pit and reducing the risks of the foundation pit are achieved. According to the method, the number of emergency treatment materials and machine tools is small, the source is convenient, a construction technology is simple, the workload is small, and the construction cost is low; the emergency treatment time is short, and the dangerous omen can be rapidly controlled; and the method is suitable for treating water gushing of the foundation pit in various foundation pit excavation processes, and is particularly best in sudden gushing treatment effect of the high confined water head stratum foundation pit.

Description

technical field [0001] The invention relates to an underground structure, especially a method for treating inrush water of foundation pits in highly confined water formations. Background technique [0002] Guangxi Nanning City Rail Transit Line 2 project was constructing the 6-7 axis of the main foundation pit of the road station station. When the excavation was about 1m above the design bottom elevation of the foundation pit, water gushed out suddenly, and the water gushing volume reached about 300? / h. The designed excavation depth of the main foundation pit of this section of the station is 17.817m, mainly passing through silty mudstone, and the basement is underlying moderately weathered breccia. The silty mudstone is a semidiagenetic rock that has been consolidated into a rock shape. Most of the core is columnar. The rock is soft and the sound of hammering is hoarse. It is continuously and stably distributed and is an impermeable layer. Moderately weathered breccia is f...

AI Technical Summary

Problems solved by technology

The advantage of this method is that the water blocking is fast and can be implemented immediately. The disadvantage is that the workload of backfilling and secondary excavation is large, and it cannot fundamentally solve the problem of foundation pit inrush. It must be combined with grouting or well replenishment to prevent secondary inrush Chung

Although the construction period of grouting plugging is short, the disadvantage is that the effect is not easy to guarantee, especially for highly confined water; the advantage of replenishing wells and dewatering is that the effect is good, but the construction period is long, the selection of well locations is easily restricted, and the displacement is large, which is not conducive to protection. Groundwater resources, and large-volume precipitation is likely to cause subsidence of surrounding strata, resulting in secondary disasters

Images