JPH047409A - Soil improving method - Google Patents

Abstract

PURPOSE:To secure an arbitrary ground strength even when the original strength of the surrounding ground is weak by forming sand pillars by using a soil improving agent prepared by mixing such a solidifying agent as cement, lime, etc., into sand in the air at a variable mixing ratio. CONSTITUTION:A soil improving agent prepared by mixing in air an adequate quantity of a solidifying agent such as cement, lime, etc., into sand is used as the soil improving agent where soft ground is improved by a sand compaction method. By using the soil improving agent prepared by mixing cement, lime, etc., into sand at a variable mixing ratio, sand pillars are constructed with a sand pillar construction ship and, even when the original strength of the surround ground is weak, an arbitrary ground strength is secured by adjusting the mixing ratio of the cement, etc. Therefore, a higher ground strength can be obtained as compared with sand pillars composed only of sand and, at the same time, the ratio of the sand pillars to the ground to be improved can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a method for improving soft ground using the sand compaction pile method.

(b) Conventional technology The purpose of ground improvement using the sand compaction pile method is to build sand pillars with good water permeability and a certain degree of strength in soft ground, thereby promoting drainage in the soft ground. The purpose of this project is to bring the ground subsidence to an early end, and to stabilize the ground by making the sand pillars bear a certain amount of load to increase the supporting capacity of the ground and prevent slipping and failure.

However, recently there have been many cases where ultra-soft ground with a very high water content is being improved, and in most cases, sand pillars are used for up to 70 to 80% of the area to be improved.

This is because the strength of the original ground to be improved is extremely weak, and the strength is 70 to 8.
If the sand pillars are not cast at a ratio of 0%, the expected bearing capacity will not be obtained, and if the strength of the original ground is extremely weak, the binding force around the sand pillars will be weak, and the sand will not stand on its own. This is because the strength of the sand pillar is also insufficient.

However, when 70 to 80% of the original ground area is made up of sand pillars, a commensurate heaving phenomenon of the original ground occurs, for example, between the improved ground and the structure to be installed. If there is uphill soil, the bearing capacity will eventually be insufficient. Therefore, after improvement using the sand compaction pile construction method, this mounded soil must be removed, and a treatment plant for this soil will also be required, and the cost of removal will be enormous, leaving many problems unsolved. ing.

(C) Disclosure of the Invention The present invention solves the conventional problems as described above, and when improving soft ground using the sand compaction pile method, not only sand but also an appropriate amount of cement, This is a ground improvement method based on the knowledge that sand pillars with a certain level of strength can be built by using an improvement material that is mixed with a compacting material such as lime in the air.

In-air mixing of sand as an improvement material with a consolidation material such as cement,
In other words, mixing without adding water can be done on land using a known device such as a mixer and then transported to the improvement site, or in the case of offshore construction, the mixing device can be installed on a sand transport ship or sand storage ship. The pile-building vessel itself may be equipped with a mixing device.

(D) Example When sand and cement were mixed in air using a known mixer, a sand pillar was built using a sand pile building boat using improved materials in which the amount of cement added was varied relative to the weight of the sand.

The strength (N) of the sand column 28 days after its creation was as follows.

Amount of cement added Strength 10% N>30 5% N=17-25 0% (sand only) N=15 (e) As shown in the effect statement of the invention, the ground improvement method according to the present invention Jtl! Even if the plate strength is low, because the sand columns are constructed using an improved material made by mixing a cement or other solidifying material with a material such as sand, reinforced columns that always have a certain level of strength can be obtained.

In addition, by adjusting the amount of cement or other solidifying material added, it is possible to obtain any desired ground strength, and at least greater strength can be obtained than a sand column using only sand, so the sand column can be applied to the ground that needs to be improved accordingly. This method has significant economic effects, such as reducing the amount of soil and reducing the construction period, as well as reducing the amount of earth piled up in the original ground and reducing the cost of removing it.

Patent applicant Kokudo Sogo Construction Co., Ltd.

Claims (1)

[Claims] In the method of improving soft ground by driving sand compaction piles, an appropriate amount of cement or other solidifying material is mixed in air with the material such as sand used as the improving material, and the mixed material is used as the improving material to strengthen sand columns. A ground improvement method characterized by creating.