Active inclined dual pile row foundation pit supporting method

Abstract

The invention discloses an active inclined dual pile row foundation pit supporting method. The method comprises the following steps that (1) front-row supporting piles inclined towards the interior ofa pit and back-row supporting piles inclined towards the outer portion of the pit are driven to the pile bottom design elevation along the inner side of a foundation pit edge, and meanwhile a waterproof curtain is arranged behind the back-row supporting piles; (2) a jack is arranged at the pile top of each front-row supporting pile; (3) crown beams are arranged on the front-row supporting piles and the back-row supporting piles, and the crown beams on the front-row supporting piles and the back-row supporting piles are connected into a whole through connecting beams; and (4) the soil definedby the front-row supporting piles is excavated to the pit bottom design elevation, and in the excavation process or before excavation, the jacks arranged in the step (2) are adopted for applying control expansion force to the front-row supporting piles so as to reduce displacement of the soil and the pile tops. By means of the method, the pile top displacement can be reduced to a large degree, thebending moment of pile bodies and the engineering cost can be reduced, the excavation depth can be increased, and the possibility of toppling damage happening to the foundation pit can be reduced.

Description

technical field [0001] The invention relates to a foundation pit support method, in particular to an active inclined double-row pile foundation pit support method. Background technique [0002] Pile row support is one of the most widely used forms of foundation pit support in China. Compared with the underground diaphragm wall, the pile row structure has many advantages such as simple construction technology, low cost, and flexible layout. Pile row support arranged at intervals is suitable for the situation where there is no groundwater or precipitation outside the pit is allowed. It can also be used for weak water-bearing strata when a water-stop curtain is set or a side-by-side continuous wall is formed with other mixed piles. When the excavation of the foundation pit is relatively shallow, the geological conditions are good, and the environmental requirements (especially deformation requirements) are not high, the support form of cantilever piles can be used. The pile r...

AI Technical Summary

Problems solved by technology

[0004] First, the displacement of the top of the pile with the same excavation depth is large, and the internal force is large, which will cause a large deformation of the ground behind the pile and endanger the surrounding environment

[0005] Second, when the strength of the piles is not enough, it is easy to cause the slope protection piles to break and make the foundation pit unstable, and the excavation depth of the foundation pit is small, and overturning damage is easy to occur when the excavation depth is large, so the support structure needs more Large cross section and insertion depth

However, this technology mainly relies on the hydraulic axial force applied by the horizontal support to actively control the deformation of the foundation pit, which takes up a lot of space, is expensive, and is not environmentally friendly or economical.

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