Construction method for extra-deep foundation pit underground continuous wall

Abstract

The invention discloses a construction method for an extra-deep foundation pit underground continuous wall. Firstly, a grab bucket is used for groove forming, and thus the cost can be saved; after a foundation pit reaches a certain depth, a groove milling machine is used for continuing groove forming, and thus groove forming precision can be guaranteed; further, in the groove forming process, a first hole is formed through the grab bucket and the groove milling machine, then a second hole is formed at a certain distance from the first hole, a partition wall between the two holes is milled, and finally a first-stage groove is formed; in this way, the grab bucket can apply balanced force when excavating each hole, the deviation is effectively rectified, and the perpendicularity of the formed groove is guaranteed; further, after a reinforcement cage is put into the first-stage groove and concrete is poured, the another first-stage groove is formed at a certain distance of the first-stage groove, and finally, a partition wall between the two first-stage grooves is milled through the groove milling machine; preferably, the edges of the concrete in the first-stage grooves in the two sides are milled while the partition walls are milled by the groove milling machine, and accordingly the raw edges are generated, therefore, the bonding tightness of the concrete in the two first-stage grooves and concrete in an intermediate groove can be improved, and the waterproof effect is achieved.

Description

technical field [0001] The invention belongs to the field of underground diaphragm wall construction, and in particular relates to a method for constructing an underground diaphragm wall of an ultra-deep foundation pit. Background technique [0002] The underground diaphragm wall is a kind of trenching machine used on the ground for basic engineering. Along the peripheral axis of the deep excavation project, under the condition of mud retaining wall, a narrow and long deep groove is excavated. After the groove is cleaned, steel bars are hung in the groove Cage, and then concrete is poured to form unit trough sections, and so on section by section, a continuous reinforced concrete wall is built underground as a structure for water interception, seepage prevention, load bearing and water retaining. When the proposed site is a soft soil area, and it is necessary to build an ultra-deep underground diaphragm wall with a depth of more than 70 meters, the distribution of a large ar...

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Problems solved by technology

When the proposed site is a soft soil area, and it is necessary to build an ultra-deep underground diaphragm wall with a depth of more than 70 meters, the distribution of a large area of ​​thick soft soil will bring a series of geotechnical problems to the project construction. Widely distributed thick layer of soft soil , which has the characteristics of natural water content greater than or equal to the liquid limit, natural void ratio greater than or equal to 1.0, high compressibility, low strength, high sensitivity, low water permeability, etc. The anti-seepage ability of the wall directly affects the anti-seepage of the permanent structure. In general, once the wall structure leaks, the permanent structure has a very high probability of leaking at this part, which may cause the surrounding ground to subside and have a non-serious impact on the surrounding environment.

In addition, the ultra-deep continuous wall has high requirements on the accuracy of the underground diaphragm wall groove formation, and the verticality deviation is required to be no more than 1 / 400. If the precision and strength of the mixing pile are insufficient, it will affect the accuracy and stability of the underground wall groove formation

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