A Stability Control Method for Prestressed Advance Excavation in Stratum

Abstract

The invention discloses a method for controlling the stability of stratum pre-stressed excavation in advance, which determines the physical parameters of the stratum and the depth and radius of the borehole; analyzes the distribution of the displacement field of rock and soil corresponding to the length of different grouting textile bags, Determine the length of the textile bag; determine the grouting pressure under specific formation conditions; analyze the maximum horizontal displacement of rock and soil under different drilling spacing, determine a reasonable drilling spacing; drill according to the obtained drilling spacing and drilling depth ; Put the processed grouting pipe covered with textile bags into the drill hole. During the lowering process, attention should be paid to the integrity of the textile bags to avoid grout leakage due to scratches and other reasons; apply horizontal stress: through the textile The bag grouting pipe injects double-liquid slurry into multiple textile bags at the same time to prop up the textile bags. The textile bag propping up process should be carried out at the same time, forming pre-stressed ground around the textile bags, and the compactness of the stratum increases after being squeezed; grouting reinforcement.

Description

technical field [0001] The invention relates to a reinforcement technology applicable to weak and water-rich formations, in particular to a method for controlling the stability of formation pre-stressed advance excavation applicable to weak and water-rich formations. Background technique [0002] During the construction of urban rail transit projects, they often pass through water-rich and weak fracture zones, and water gushing problems in foundation pits frequently occur under the action of engineering disturbance and groundwater. The water gushing area at the bottom of the foundation pit is mainly distributed with miscellaneous fill and silty clay. The grout cap is not strong enough, the rock and soil are weak and compact, and there is a lack of safe and stable grout. During the grouting process, the grouting pipe and the formation The gaps between the gaps are prone to grout leakage, and the grout cannot be effectively injected into the stratum in the treatment area; hole...

AI Technical Summary

Problems solved by technology

The water gushing area at the bottom of the foundation pit is mainly distributed with miscellaneous fill and silty clay. The grout cap is not strong enough, the rock and soil are weak and compact, and there is a lack of safe and stable grout. During the grouting process, the grouting pipe and the formation The gaps between the gaps are prone to grout leakage, and the grout cannot be effectively injected into the stratum in the treatment area; hole collapse and drill sticking accidents are very likely to occur during the drilling process, and it is not suitable for long-distance drilling. Poor, in order to control the diffusion range of grout and improve the effect of grouting reinforcement, it is necessary to adopt the method of ground pre-stress control grouting for grouting reinforcement

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