JPS585328B2 - How to improve soft ground - Google Patents

Description

[Detailed Description of the Invention] The present invention attempts to significantly improve the conventional point-type soft ground improvement method such as the sand drain method by forming a lime-mixed soil column of a desired diameter in the soft ground. It is something.

Embodiments of the method of the present invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 1 denotes an injection tube with a number of injection holes 2 formed horizontally and vertically on the circumferential surface of the tip, and this is inserted into a desired position of soft ground 3 to a desired depth by vibration or jet water injection (Fig. 1). ).

Then, a slaked lime aqueous solution (3%) is mixed with a small amount of gypsum, and is forced into the injection pipe 1, and is sprayed horizontally and vertically at high pressure into the surrounding soil from the injection hole 2, and mixed with the surrounding soil. Stir.

That is, the injection pipe 1 is intermittently pulled up several times, for example, by 50 cm, and pulled down once as necessary in between, to repeatedly mix and stir the slaked lime aqueous solution and the surrounding soil, thereby achieving the required depth from the ground surface. A lime-mixed soil column 4 having a desired diameter, for example, a radius of 5 m, is cast into the soft ground 3.

By performing overcasting on the soft ground 3 at required intervals, for example, a plurality of lime-mixed soil columns 4 adjacent to each other are sequentially formed.

Next, a sand drain body 5 is provided by directly filling the hole of the lime-mixed soil column 4 from which the injection pipe 1 has been pulled out, or by inserting a casing (not shown) into the lime-mixed soil column 4. (Figure 2).

As a result, the soil quality of the soft ground 3 is stabilized by the action of slaked lime and gypsum in the lime-mixed soil column 4, and water permeability is increased, so that drainage by the sand drain body 5 is promoted.

In addition, although the case of the sand drain body was shown in the said Example, the drain body is not limited to sand, but may be made of paper or chemical drain material.

In addition, although the case where gypsum is added to a 3% slaked lime aqueous solution is shown, it is not necessary to add gypsum, and the concentration of the slaked lime aqueous solution is not limited to 3%; Just adjust it.

As is clear from the above description, according to the present invention,
A lime-mixed soil column of the desired diameter can be easily formed by ejecting slaked lime aqueous solution into the surrounding soil from the injection hole at the tip of the injection pipe inserted into soft ground while moving it up and down as necessary. Compared to sand drain construction methods, this method can stabilize the soil over a wider area and improve water permeability.

Moreover, since a drain body such as sand is provided in the lime-mixed soil column with increased water permeability, drainage can be further promoted.

Therefore, it is possible to improve the ground much more efficiently than in the case of point type methods such as the conventional sand drain method.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view for explaining the process of forming a lime-mixed soil column in soft ground, and Figure 2 is a cross-sectional view showing a sand drain body installed in a lime-mixed soil column. …Soft ground, 4…Lime mixed soil column, 5…Sand drain integrated, 1…Injection pipe

Claims (1)

[Claims] 1. While pulling out the injection pipe inserted into the soft ground while moving it up and down as necessary, the slaked lime aqueous solution is ejected into the surrounding soil from the injection hole at the tip to form a lime-mixed soil column of the desired diameter. A method for improving soft ground characterized by providing a drain body of sand or the like in a lime-mixed soil column.