JP-2026075431-A - Method for evaluating the constructability of ground improvement materials, method for constructing sand piles, and method for manufacturing ground improvement materials.

JP2026075431AJP 2026075431 AJP2026075431 AJP 2026075431AJP-2026075431-A

Abstract

[Problem] To provide a method for evaluating the workability of a ground improvement material, a method for constructing sand piles, and a method for manufacturing a ground improvement material, which can evaluate the workability of the ground improvement material for each moisture content condition from the initial moisture content to the saturated moisture content before actually constructing the sand piles. [Solution] A method for evaluating the workability of a ground improvement material, comprising: a mixing step (step S2); a discharge status observation step (step S3); a discharge status determination step (step S4); a water addition step (step S6); and a workability determination step (step S7) in which workability is determined based on the determination results of the discharge status under multiple water content conditions obtained by repeating the mixing step (step S2), the discharge status observation step (step S3), the discharge status determination step (step S4), and the water addition step (step S6). [Selection Diagram] Figure 2

Inventors

鈴木恭平
角田篤史
小川尚志
粟津進吾
恩田邦彦

Assignees

ＪＦＥスチール株式会社

Dates

Publication Date: 20260508
Application Date: 20241022

Claims (12)

A method for evaluating the constructability of ground improvement materials, The mixing process involves mixing the ground improvement material, A discharge status observation step involves placing the mixed ground improvement material into a hopper and compacting it, and then observing the discharge status when the ground improvement material is discharged from the hopper. A discharge status determination step that determines whether the discharge status is good or bad based on the observed discharge status, A watering step is to add water to the ground improvement material discharged from the hopper and return it to the mixing step, The process includes a workability determination step for determining the workability of the ground improvement material, The workability evaluation method for a ground improvement material is a method in which the workability evaluation step determines the workability based on the results of the discharge status evaluation at multiple water content conditions obtained by repeating the mixing step, the discharge status observation step, the discharge status evaluation step, and the water addition step.
The aforementioned plurality of moisture content conditions include a moisture content condition in which the moisture content of the ground improvement material is the initial moisture content, and a moisture content condition in which the moisture content of the ground improvement material is the saturation moisture content. The method for evaluating the workability of a ground improvement material according to claim 1, wherein in the workability determination step, it is determined that the workability is good if the discharge condition is satisfactory under all of the plurality of water content conditions.
The discharge status observation step involves observing the discharge rate when the ground improvement material is discharged from the hopper as the discharge status, The method for evaluating the workability of a ground improvement material according to claim 1 or 2, wherein the discharge status determination step determines that the discharge status is acceptable when the discharge rate when the ground improvement material is discharged from the hopper is equal to or greater than a threshold.
The method for evaluating the workability of a ground improvement material according to claim 3, wherein the threshold for the discharge rate is 0.4 m/sec or more and 0.5 m/sec or less.
A method for evaluating the workability of a ground improvement material according to claim 1 or 2, wherein if the discharge condition is determined to be unacceptable in the discharge condition determination step, the repetition of the water addition step, the mixing step, and the discharge condition observation step is terminated.
The method for evaluating the workability of a ground improvement material according to claim 3, wherein if the discharge condition is determined to be unacceptable in the discharge condition determination step, the repetition of the water addition step, the mixing step, and the discharge condition observation step is terminated.
The system further includes a moisture content confirmation step for determining whether the moisture content of the ground improvement material is the saturation moisture content, The method for evaluating the workability of a ground improvement material according to claim 1 or 2, wherein, in the water content confirmation step, the water addition step is stopped if it is determined that the water content of the ground improvement material is the saturation water content.
The system further includes a moisture content confirmation step for determining whether the moisture content of the ground improvement material is the saturation moisture content, The method for evaluating the workability of a ground improvement material according to claim 3, wherein, in the water content confirmation step, the water addition step is stopped if it is determined that the water content of the ground improvement material is the saturation water content.
A method for constructing sand piles, comprising the workability determination step of the workability evaluation method for ground improvement materials according to claim 1 or 2, wherein the sand piles are constructed using ground improvement materials that have been determined to have good workability.
A method for constructing sand piles, comprising the constructability determination step of the method for evaluating the constructability of a ground improvement material according to claim 3, wherein the sand piles are constructed using a ground improvement material that has been determined to have good constructability.
A method for manufacturing a ground improvement material, comprising the step of obtaining a ground improvement material whose workability has been determined to be satisfactory, in the workability determination step of the workability evaluation method for a ground improvement material according to claim 1 or 2.
A method for manufacturing a ground improvement material, comprising the step of obtaining a ground improvement material whose workability has been determined to be satisfactory in the workability determination step of the workability evaluation method for the ground improvement material described in claim 3.

Description

This invention relates to a method for evaluating the constructability of ground improvement materials, a method for constructing sand piles, and a method for manufacturing ground improvement materials. The sand compaction pile method is a well-known method for constructing sand piles to improve the strength of soft ground. In this method, a casing pipe is driven into the soft ground, and ground improvement materials such as sand, gravel, or slag are placed inside the casing pipe. The casing pipe is then vibrated, and the process of pulling it out and driving it back in is repeated, thereby introducing the ground improvement material into the soft ground and forcibly constructing piles of ground improvement material within the soft ground. By constructing multiple such piles in the soft ground, the relative density of the entire soft ground is increased, compacting it and improving its strength. In the sand compaction pile method, ground improvement material is introduced into the soft ground via a casing pipe. Therefore, depending on the physical properties of the ground improvement material, the casing pipe may become clogged with the material, potentially worsening the constructability of the sand piles. Examples of such physical properties include particle size distribution. If the ground improvement material contains many small particles, clogging of the casing pipe is more likely. "Constructability" refers to the ease of constructing the sand piles. Poor constructability means that the casing pipe becomes clogged with the ground improvement material, making it difficult to construct the sand piles. The physical properties of the sand and gravel used in the sand compaction pile method vary depending on the source of the sand and gravel. Furthermore, the physical properties of the slag vary depending on the manufacturing method of the slag. Methods to suppress clogging of ground improvement materials in casing pipes have been conventionally studied. For example, Patent Document 1 describes a method in which a sliding material is attached to the inner wall of a casing pipe used in the sand compaction pile method. This improves the sliding of sand and gravel inside the casing pipe, thereby suppressing clogging of the ground improvement material within the casing pipe. Patent Document 2 describes a material for slag compaction pile construction, which is a mixture of blast furnace granulated slag and steelmaking slag. It states that this method suppresses clogging of the ground improvement material in the casing pipe, making it possible to improve the seismic resistance of the ground after construction while maintaining the constructability of the sand piles. Japanese Patent Publication No. 2000-1845Japanese Patent Publication No. 2019-167784 This figure illustrates a ground improvement material constructability evaluation device to which the constructability evaluation method for ground improvement materials according to this embodiment can be applied.This is a flowchart illustrating the method for evaluating the constructability of the ground improvement material according to this embodiment.This is another flowchart illustrating the method for evaluating the constructability of the ground improvement material according to this embodiment.This figure shows the evaluation results of the material according to the workability evaluation method for ground improvement materials according to this embodiment. The following describes embodiments of the present invention (hereinafter referred to as "this embodiment"). This embodiment is a preferred example of the present invention and is not limiting in any way. The method for evaluating the workability of ground improvement materials according to this embodiment is a method for evaluating the workability of ground improvement materials used to improve soft ground before actual construction. Examples of soft ground improvement methods using ground improvement materials include the construction method of sand piles, which involves creating multiple piles made of firmly compacted ground improvement materials in the soft ground to increase its strength. Specifically, a sand compaction pile method using mainly mountain sand, gravel, or steel slag as the ground improvement material can be cited. Examples of steel slag include blast furnace granulated slag, blast furnace slow-cooled slag, steelmaking slag, or electric furnace slag. (Evaluation device for the constructability of ground improvement materials) Figure 1 is a diagram illustrating a ground improvement material workability evaluation device to which the workability evaluation method for ground improvement materials according to this embodiment can be applied. The workability evaluation device 1 shown in Figure 1 has a mixer 2 and a hopper 3. The mixer 2 mixes the ground improvement material to ensure that the moisture content is uniform throughout the entire ground improvement material. In the example shown i