Collapsible foundation immersed tube pile forming treatment method

Abstract

The invention belongs to the technical field of foundation treatment construction, and relates to a collapsible foundation immersed tube pile forming treatment method. When a collapsible loess foundation is treated through immersed tube compaction piles, when shrinkage cavities occur after immersed tubes are pulled out, a long spiral drilling machine is adopted for conducting rotary excavating on retracted soil in holes for secondary soil discharging, and the beneficial effects of being good in hole forming effect and high in construction work efficiency are achieved. Meanwhile, due to secondary soil discharging after shrinkage cavity treatment, the compaction degree of soil between the piles is reduced, foundation soil is wet and soft and large in water content, and in order to make up for the compaction effect of the soil between the piles and improve the water content of the foundation soil, a filler ramming scheme of the next procedure is adjusted into a pile forming construction method including lime soil backfilling, heavy hammer ramming, layered filler filling and layered ramming. Due to the fact that lime is used for filler adding, the cost of the pile forming method is properly increased compared with a plain soil backfilling ramming pile forming scheme, the construction efficiency of the pile forming method is the same as that of the plain soil backfilling ramming pile forming scheme, and meanwhile the beneficial effects of being good in pile forming effect and effectively improving the foundation soil property are achieved. Compared with the scheme I, the scheme II and the scheme III in the prior art in the third part of the invention, the secondary hole forming and pile forming scheme has the beneficial effects of being economical, efficient, safe, environment-friendly and applicable.

Description

technical field [0001] The patent of the invention belongs to the technical field of foundation treatment and construction, and relates to a treatment method for collapsible foundations by sinking pipes and forming piles. Background technique [0002] For the situation of severe shrinkage and failure of the immersed tube in the wet and soft ground in the collapsible loess area (see the background of the invention in part 4 of this article for details), the usual treatment options are: one is to directly change to replacement The treatment plan is to dig out all the collapsible soil layers, backfill the qualified soil materials layer by layer and compact them until the collapsible foundation soil is completely replaced. This plan is suitable for shallow collapsible soil layers and small soil thicknesses. Obviously, due to the thick collapsible soil layer of the proposed site, full replacement has the disadvantages of great safety hazards in deep foundation pit operations, lar...

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Problems solved by technology

[0002] For the situation of severe shrinkage and failure of the immersed tube in the wet and soft ground in the collapsible loess area (see the background of the invention in part 4 of this article for details), the usual treatment options are: one is to directly change to replacement The treatment plan is to dig out all the collapsible soil layers, backfill the qualified soil materials layer by layer and compact them until the collapsible foundation soil is completely replaced. This plan is suitable for shallow collapsible soil layers and small soil thicknesses. Obviously, due to the thick subsidence soil layer of the proposed site, the full replacement of the site has the disadvantages of great safety hazards in deep foundation pit operations, large replacement and high cost, and uneconomical disadvantages, so the replacement plan is not applicable

The second is to directly change to the dynamic compaction treatment plan, but the environment in which the project is located is not suitable for the dynamic compaction plan, and the construction noise of the dynamic compaction is large, the tamping energy per unit area is small, and it is difficult to achieve the effect of compaction in the deep layer, and the reinforcement depth is limited. Applicable dynamic compaction program

The third is to use Luoyang shovel to excavate the shrinkage hole of the immersed tube. This solution has the disadvantages of low work efficiency, long construction period and high cost, and the Luoyang shovel is also easily absorbed by the hole wall soil. The Luoyang shovel that sinks into the hole cannot be pulled out, and the Luoyang shovel is not suitable for the excavation scheme of this working condition

[0007] However, when the ground treatment construction was carried out according to the above-mentioned treatment construction method at this site, serious shrinkage cavities were found after the tube was pulled out during the process of the immersed tube forming holes, and the hole was difficult to form. The immersed tube reached a depth of 8.7m. It was found that the hole wall soil squeezed out of the pipe diameter quickly retracted, and the hole diameter after shrinkage could no longer meet the construction conditions for heavy hammer tamping and filling. The heavy hammer driven into the hole cannot be pulled out

Part of the shrinkage cavity is serious and all the holes have been blocked, and the holes cannot be seen below 1m of the working surface, and the holes have failed, so it is impossible to carry out the filler ramming construction in the next process normally

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