Treatment method for large-thickness collapsible loess

Abstract

The invention provides a treatment method for large-thickness collapsible loess. The treatment method comprises the following steps: 1) sinking small-diameter steel casing into soil to form pile holes each having a depth equal to or smaller than the thickness of the collapsible loess stratum; 2) inserting (1) 1-6 drain boards or (2) hollow water pipes with a plurality of drain holes or (3) hollow steel pipes with a plurality of nozzles into the pile holes to bottom ends thereof; 3) repeating the steps 1) and 2) until the pile holes with the water injection fittings are formed everywhere in the field; 4) injecting water or injecting water under pressure into the water injection fittings in the pile holes to cause self-weight collapsible settlement of the collapsible loess after immersion; 5) observing and recoding the collapsible settlement amount of the soil mass in a foundation until the collapsible deformation of the soil mass in the foundation is stable; and 6) reinforcing the top-layer soil mass of the foundation by use of a filling compaction method or a dynamic compaction method. The treatment method has the characteristics and advantages of high construction speed, remarkable effect of eliminating loess collapse, dry operation, high bearing capacity, and the like.

Description

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

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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

Moreover, the above-mentioned processing methods, when faced with loess layers with a large thickness of more than 30 to 40 meters, all have the difficult problem that the construction is difficult or even impossible, or the construction cost is very expensive.

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