Collapsible loess treatment method

Abstract

The invention provides a collapsible loess treatment method. The collapsible loess treatment method comprises the steps that (1) a drill stem with a spiral drill bit and a high-pressure jetting system is rotationally placed downwards; (2) after the drill stem is downwards placed to a certain depth, water is injected at high pressure, the drill stem is rotated simultaneously, and then high-pressure jet is formed and sprayed to soil rotationally, specifically, the water injection amount is no smaller than the water amount required when the layer of collapsible loess reaches the highest saturation degree; (3) the drill stem continues to be placed downwards, and high-pressure water injection and rotary spraying are carried out till the drill stem reaches the set depth; (4) the operations from step (1) to step (3) are carried out repeatedly at set intervals till the high-pressure water injection operation of deep-layer soil is completed in a whole foundation site; (5) the collapsibility subsidence amount of foundation soil is observed and recorded till collapse deformation of the foundation soil is stable; and (6) a shallow soil layer of a foundation is reinforced through a filler compaction method or a dynamic consolidation method.

Description

technical field [0001] The invention relates to the field of civil engineering, in particular to the foundation treatment of collapsible loess. Background technique [0002] my country's loess covers a large area, and is widely distributed in the loess of northeast, northwest, central and east China, and is mostly collapsible. Collapsible loess is a special kind of soil, its soil is relatively uniform and loose , Pore development. When not wetted by water, it generally has higher strength and less compressibility. When soaked with water under a certain pressure, the soil structure will be rapidly destroyed, resulting in a large additional subsidence and a rapid decrease in strength. At present, in the treatment of collapsible loess foundation, the commonly used treatment methods include pile foundation penetrating the collapsible soil layer, cushion replacement method, and lime soil compaction pile method. However, these methods have certain limitations, such as poor econo...

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Problems solved by technology

However, these methods have certain limitations. For example, the economic efficiency of the pile foundation is poor, the cost is higher when the collapsible soil layer is thick, and the construction is more difficult. The cushion replacement method is only suitable for areas where groundwater does not occur For buildings with raised elevations and small loads, the compaction effect of the lime-soil compaction pile method is poor due to the low moisture content of the soil and the hard soil quality.

At present, there is also a water-soaking consolidation method that utilizes the characteristics of collapsible loess. The process is generally to arrange water-soaking holes in the site and build a dam around it, and then deliver water to the site in the dam to make the foundation soil submerge and then collapse. The pre-soaking method has a certain effect on eliminating the collapsibility of loess, but there are still some difficulties that cannot be solved. First, the soil in the soaking hole is easy to collapse and form silt when it encounters water, which affects the water-immersion consolidation effect of the soil; The effect of immersion in the deeper soil is poor; third, all the water in the site and the evaporation time is too long, which makes it difficult to accurately observe the subsidence of the subsidence and subsequent construction; fourth, only the shallower loess subsidence is eliminated. The bearing capacity of the foundation cannot meet the load requirements of the building

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