Sublevel retreating type two-fluid composite grouting construction method for deep foundation pit of sandy gravel stratum

Abstract

The invention discloses a sublevel retreating type two-fluid composite grouting construction method for a deep foundation pit of a sandy gravel stratum. The method comprises the steps of determining a grouting reinforcement scheme; conducting field measuring and setting-out; drilling holes, placing double grouting pipes downwards after the holes are formed, then installing pipe pulling devices, and pulling out drill pipes; preparing grouting fluids; conducting grouting in every other hole, conducting two-fluid composite grouting of the cement-water glass grouting fluid and the modified water glass grouting fluid, and comprehensively considering conversion of the grouting fluids according to changes of the grouting pressure, the flow and grouting positions, wherein the grouting pressure reaches 2MPa or exceeds 3MPa at the same time when the grouting quantity exceeds 80% of the designed value; and after the double pipes are lifted, repeating the grouting process till grouting is finished. The method has the advantages that the phenomenon that the grouting pipes can not be installed due to hole collapse can be avoided; advantages of the two grouting fluids are integrated by composite grouting of the two grouting fluids, waterproof curtains are achieved, meanwhile, the permeability coefficient is low, and the setting strength is high; and the problem that the pipes are pulled difficultly due to grouting fluid backflow is solved.

Description

technical field [0001] The invention belongs to the technical field of foundation pit engineering, and relates to a construction method of segmented retreat double-liquid composite grouting for deep foundation pit grouting and waterproof reinforcement projects in sandy pebble formations. Background technique [0002] As far as the current situation of tunnel and underground engineering grouting in my country is concerned, for double-liquid grouting, double-pipe drill pipe grouting method and sleeve valve pipe grouting method are the construction methods that are currently used more and have better grouting effects. . [0003] Existing double-pipe grouting construction generally adopts double-pipe drill pipe, and an in-pipe mixer is installed at the end. Clean water is used as the circulating fluid for drilling, and when the design depth or position is reached, the closed end point is used to switch the lateral injection. Then use a grouting pump to inject the two kinds of s...

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Problems solved by technology

[0007] In order to overcome the disadvantages of the existing double-pipe grouting method, such as grout backflow, difficulty in pulling out the pipe, and a long construction period, the retreating grouting of the sleeve valve pipe is easy to collapse t...

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