A treatment method for massive water gushing and sand gushing in foundation pits of karst foundation underwater caps

Abstract

The invention discloses a treatment method for a large amount of water and sand gushing in an underwater foundation pit of a karst foundation, including: finding out the location of a large amount of water and sand gushing in the foundation pit of the capping foundation pit and the corresponding riverbed subsidence area outside the steel sheet pile cofferdam, throwing and filling From the clay bag to the subsidence area of ​​the river bed, the clay bag is consolidated with rotary grouting piles along the outer side of the cofferdam corresponding to a large amount of water and sand gushing points, and the underwater quick-setting concrete is used to seal the water and sand gushing points of the foundation pit, and the outer layer of steel sheet piles is set up around the edge of the subsidence area. Weir, lower the water level between the inner and outer cofferdams to half the water head, drain the accumulated water in the inner cofferdams, and excavate foundation pits for caps to the design elevation. In the present invention, the double-layer cofferdam outside the foundation pit reduces the water pressure in sections, the external rotary spray piles of the foundation pit consolidate the subsidence area of ​​the river bed, and the underwater quick-setting concrete in the foundation pit seals a large number of water and sand gushing points. The three-pronged approach can realize foundation The pit-dry construction provides guarantee for the smooth excavation of the cap foundation pit to the design elevation, avoiding the trouble caused by design changes.

Description

technical field [0001] The invention relates to a method for controlling a large amount of water and sand gushing in an underwater foundation pit of an underwater cap, in particular to a method for controlling a large amount of water and sand gushing in an underwater foundation pit of a karst foundation. Background technique [0002] Steel sheet pile cofferdams are often used for foundation pits of pier caps. The water in the cofferdams is drained, the foundation pits are excavated to the design cap floor elevation, and cap concrete is poured. When the bridge crosses the karst channel, the pier cap foundation pit is affected by the water level difference inside and outside the cofferdam, and the originally closed solution groove and solution gap may be broken down by water pressure, resulting in water and sand gushing. If there is a large amount of water and sand gushing in the foundation pit, the loose layer of the river bed outside the cofferdam will collapse in a large ar...

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