JPS63277316A - Ground improving work for building - Google Patents

Abstract

PURPOSE:To increase tensile strength as well as compressive strength and shear strength of the ground by a method in which the ground deprived of surface soil is mixed with a solidifying agent by stirring, a reinforcing material is set in the ground, and soil is newly placed and mixed with the solidifying agent by stirring. CONSTITUTION:The base 3 of the ground deprived of surface soil is mixed with a solidifying agent 4, e.g., stabilizer, etc., with stirring and tamped to form a base ground 7. A reinforcing material 8 of a latticed or meshed form is set on the ground 7, and good-quality soil 9 is newly placed on the material 8 and mixed with a solidifying agent 10 with stirring to form the ground 13 for building. The tensile strength, as well as the compressive strength and shearing strength, of the ground can thus be increased, and therefore, no cracks occur in the ground even when unequal subsidence takes place.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for improving construction ground.

(Conventional technology) Conventionally, there has been a method of improving the topsoil of the ground using a cement-based solidifying agent (referred to as conventional example 1), a method of strengthening the ground by adding reinforcing material (referred to as conventional example 2), and a method of strengthening the ground by adding reinforcing material during embankment. There is a construction method (called Conventional Example 3) that strengthens the ground by adding

(Problems to be Solved by the Invention) Conventional Example 1 has high compressive strength but lacks tensile strength, and has problems such as easily cracking the ground when compressive force is applied in a vertical direction to the ground. Ta.

Conventional Example 2 had a problem in that the soil was disturbed when reinforcing material was inserted, which weakened the compressive strength.

Conventional Example 3 had problems such as insufficient compaction of the ground because reinforcing material was inserted into the embankment.

(Means for Solving the Problems) The present invention involves excavating the existing ground over the entire area for construction, removing the topsoil, and scattering an appropriate amount of solidification material on the base bottom of the ground from which the topsoil has been removed. After mixing and agitating the material and the base bottom excavated to an appropriate depth, rolling compaction is performed to form a sub-base, and reinforcing material formed in a lattice, mesh, etc. is placed on top of this sub-base. Construction in which high-quality new earth and sand is laid down to an appropriate thickness on top of the reinforcing material, the new earth and sand are mixed with an appropriate amount of solidification material, and then compacted to form the upper ground, which becomes the ground for construction. This is a ground improvement method.

(Function) By placing reinforcing materials between the ground-improved sub-soil and the upper ground, the compressive strength, shear strength, and tensile strength of the ground are increased.

(Example) The drawings show an example of the construction ground improvement method of the present invention.

First, using an excavator (not shown) or the like, excavate the current ground 1 in the entire area of the construction ground and remove the topsoil 2 to a depth of approximately 300 to 500 feet (see Figure 2).

The thickness of the topsoil 2 to be removed is 200 mm considering the softness of the topsoil 2.
In some cases, a dragon may be sufficient, and in other cases, 700 mm or less is necessary.

An appropriate amount of solidification material 4 is sprinkled on the base bottom 3 of the ground from which the topsoil 2 has been removed in this way (see Figure 3). As solidifying material 4,
Ground stabilization agents, cement, etc. are used alone or in combination. Suitable examples of the ground stabilizing treatment agent include Fujibeton (trade name of Keio Kaken Kogyo Co., Ltd.) and Asatsu Clean Set 1140 (trade name of Nippon Cement Co., Ltd.).

The base bottom 3 with an appropriate amount of solidification material 4 sprinkled thereon is similarly excavated with an excavator to a depth of about 300 mm to 600 mm, and the excavation ±5 and solidification material 4 are mixed and stirred to obtain the first improvement ±6. (See Figure 4).

The surface of the thus mixed and stirred first improvement ±6 is leveled with, for example, a packet of an excavator, and the first improvement ±6 is temporarily rolled.

After the preliminary rolling is completed, the level of the first improvement ±6 is measured, and the operator corrects areas where the level difference is large or where there is uneven mixing.

After correcting this level difference, etc., the first improvement ±6 was applied to the roller etc.
(not shown) is used for main rolling.

After the main compaction is completed, water is sprinkled on the first improvement ±6 to adjust the water content ratio.

The base layer 7 is constructed by taking an appropriate curing period.

A reinforcing material 8 formed in the form of a lattice, a mesh, etc. is placed on the base 7 (see FIG. 5).

As the reinforcing material 8, for example, plastic, reinforcing steel, bamboo, rope, cloth, etc. are used. The reinforcing material 8 is basically formed in a lattice shape or a mesh shape, but may also be formed in a single direction.

On top of the base 7 on which the reinforcing material 8 has been placed, new soil 9 of good quality is laid with an appropriate thickness, and on top of this new soil 9, an appropriate amount of solidification material 10 is sprinkled ( (See Figure 6).

The solidifying material IO may be the same as the solidifying material 4 described above. As new high-quality soil9, well-drained mountain sand, river sand,
Sea sand, masa soil, etc. alone or in combination are suitable.

A second improvement ±11 is obtained by mixing and stirring the new earth and sand 9 with an appropriate amount of solidification material 10 sprinkled thereon using the same excavator (see FIG. 7).

The surface of the second improved soil 11 mixed and stirred in this way is leveled using, for example, an excavating bucket of an excavator, and the second improved soil 11 is temporarily rolled.

After the preliminary rolling is completed, the level of the second improvement ±11 is measured, and the operator corrects areas where the level difference is large or where there is uneven mixing.

Further, the main rolling of the second improvement ±11 is performed using a roller or the like.

After the main compaction is completed, the level of the second improved soil 11 is reconfirmed, and water is sprinkled on the second improved soil 11 to adjust the water content ratio.

Then, by taking an appropriate curing period, the upper ground 12
Configure.

In this way, the construction ground 13 is constituted by the base ground 7 and the upper ground 12 with the reinforcing material 8 interposed therebetween. A foundation etc. is constructed on this construction ground 13.

FIG. 9 shows a state in which the construction ground 13 constructed in this manner is bent due to the unevenness.

In particular, tensile forces are generated at symbols A, B, and C in the figure.

Even if the ground bends in this way, the reinforcing material 8 takes part in suppressing the tensile force of the soil, increasing the rigidity of the ground and preventing cranking.

(Effects of the invention) The existing ground, which is a soft ground from which the topsoil has been removed, is improved to an appropriate depth and used as a base ground, and new soil of good quality is laid on top of this base ground to create an improved upper ground. A reinforcing material in the form of a lattice or mesh is interposed between the base ground and the upper ground. Therefore, it is possible to obtain a construction ground with increased compressive strength and shear strength as well as increased tensile strength.

Because the ground has been improved over the entire area of the building site, the strength of the ground is high not only in the foundation area but also in the area where the gables will be installed.

This ground has tensile strength, so even if uneven settlement occurs, cracks will not form in the ground.

Therefore, buildings built on such ground are stable.

[Brief explanation of drawings]

Figures 1 to 8 show the procedure for carrying out the construction ground improvement method of the present invention, in which Figure 1 is a cross-sectional view of the building site, Figure 2 is a cross-sectional view of the current ground with topsoil removed over the entire area of the building site, Figure 3 is a cross-sectional view of the base of the ground from which the topsoil has been removed, with assimilation material sprinkled on it, Figure 4 is a cross-sectional view of the first improved soil, Figure 5 is a cross-sectional view of the reinforcing material laid on the sub-soil, Figure 6 is a cross-sectional view of new high-quality earth and sand being poured onto the sub-base on which reinforcing material has been laid, and solidification material is sprinkled on top of this new earth and sand. Figure 7 is a cross-sectional view of new high-quality earth and sand and solidification material being spread on top of this new earth and sand. Cross-sectional view of the mixed and stirred second improved soil,
Figure 8 is a cross-sectional view of the construction ground completed by composing the upper ground, and Figure 9 shows the tensile strength of the soil due to the reinforcing material even if the construction ground completed in this way sinks unevenly. FIG. 1... Current ground 2... Topsoil 3...
・Base bottom 4, 10...Solidification material 5...Drilling± 6...First improved soil 7...Substrate 8...Reinforcement material 9...New soil of good quality 11...・Second improvement ±12...Upper ground 13...Building ground A, B, C・
...Tensile force 1x7! ! ff 2nd drawing 3rd straight 4th drawing Y5 drawing! Figure 6 Figure 7 7'1 ゛go θ Figure θ 93

Claims (1)

[Claims] 1) Excavate the current ground over the entire area of the construction site to remove the topsoil, sprinkle an appropriate amount of solidifying material on the base bottom of the ground from which the topsoil has been removed, and mix the solidifying material with an appropriate depth. After mixing and agitating the base bottom excavated in For construction purposes, the new earth and sand of good quality are laid down to an appropriate thickness, the new earth and sand are mixed and stirred with an appropriate amount of solidification material, and then compacted to form the upper ground and used as a building ground. Ground improvement method.