Deep foundation pit envelop enclosure and construction method thereof

Abstract

The invention provides a deep foundation pit envelop enclosure and a construction method thereof. The deep foundation pit envelop enclosure is formed by arranging N main piles and N auxiliary piles alternately. The main piles and the auxiliary piles are all cast-in-situ bored piles. A rotary drilling rig or a slewing drilling machine can be adopted, and mud protection wall drilling pore forming isachieved. The auxiliary piles are constructed first, and then the main piles are constructed. Chimeric cavities are reserved in the two sides of the axillary piles correspondingly, and the spaces ofthe chimeric cavities shall be greater than the spaces required for main pile pore forming construction. After main pile pore forming construction, reinforcement cages are lowered, concrete is poured,and the edges of the main piles are tightly embedded into the chimeric cavities of the auxiliary piles correspondingly. Since the chimeric cavities are reserved for the auxiliary piles, the main piles do not need to bite the auxiliary pile concrete during post construction, embedding of the main piles and the auxiliary piles is guaranteed in the mode that the chimeric cavities of the auxiliary piles are reserved, and therefore, the quality problem of failure of bite or insufficiency of bite which frequently emerges during hard secant method construction of secant pile walls is overcome. Sincethe main piles do not need to cut and bite the auxiliary piles, rebars are arranged in the auxiliary piles and are not cut or bit by the main piles during construction, and the auxiliary piles can bealso equipped with the rebars.

Description

technical field [0001] The invention relates to the technical field of construction engineering, in particular to a deep foundation pit enclosure structure and a construction method thereof. Background technique [0002] The foundation pit enclosure structure refers to the enclosure around the foundation pit, and its main function is to retain soil and stop water. The existing foundation pit enclosure structures are common as follows: [0003] ①Steel inserted into the mixing pile (called SMW construction method); ②Stirring pile + support pile; ③Support pile + rotary spraying between piles; ④Occlusion pile; [0004] Among them, the two foundation pit enclosure structures ① and ② are simple in construction and low in cost, but their support strength is not high, and they are usually only suitable for foundation pits with small depths; moreover, they are only suitable for construction of mixing piles. Weaker ground. The third kind of "supporting piles + rotary grouting betwe...

AI Technical Summary

Problems solved by technology

[0004] Among them, the two foundation pit enclosure structures ① and ② are simple in construction and low in cost, but their support strength is not high, and they are usually only suitable for foundation pits with small depths; moreover, they are only suitable for construction of mixing piles. weaker formation

The third kind of "supporting piles + rotary grouting between piles" is relatively simple in construction and relatively low in cost. Its support strength is high but its water-stopping ability is weak. It is usually only suitable for foundation pits with medium depth and low groundwater pressure. And its rotary grouting pile is not suitable for strata with more gravel, pebbles, boulders, block stones, and massive construction waste

④ and ⑤ These two foundation pit enclosure structures have high support strength and strong water-stopping ability, and are suitable for foundation pits with large depth and high groundwater pressure, but the construction is relatively complicated and the cost is high

During the construction of piles, the difference in concrete strength between plain piles on both sides often results in partial holes and inclined holes. It takes a lot of time to correct the pile holes, and it is often difficult to completely correct them, thus affecting the quality of the bite

[0013] In the "hard bite method", the construction speed of plain piles is fast, and the construction speed of meat piles is slow. Because the construction of meat piles and plain piles must be carried out sequentially, the construction of plain piles cannot be carried out too much ahead of time, so the overall construction speed is not fast.

[0014] Whether it is "soft bite" or "hard bite", the plain pile must be cut by the meat pile, so the concrete strength grade of the designed plain pile is relatively low, and it is not suitable for reinforcement, and generally does not participate in the force calculation of foundation pit support , objectively a waste of resources

Images