JPH02308007A - Soil compaction of sandy ground - Google Patents

Abstract

PURPOSE:To decrease impulses, vibrations, and noises and also compact soil with a safe and low cost work, by arranging hydraulic pipes in the middle of a plurarity of drain columns with large water permeability and injecting the pulsating water into the ground. CONSTITUTION:A plurality of pits B are bored in the ground A and drain materials 2 with a large permeability than the ground A are charged to form a plurarity of drain columns 1. Next, a plurarity of hydraulic pipes 3 are positioned with a specified depth in the ground A at the almost equal distance from adjacent drain columns 1. Next, a water feeder 5 and pulsater 4 are con nected to the hydraulic pipe 3 to inject the pulsating water into the ground A. And by liquidification of the sandy ground A, the free water is discharged from the drain column 1 to compact the ground A by the downward osmotic pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of compacting sandy ground for the purpose of preventing liquefaction.

``Conventional technology'' Conventionally, as a compaction method for sandy ground, a large current is passed through a discharge electrode inserted into the ground to generate a high voltage discharge, and the impact force generated at that time is used to compact the ground. Impact method: An explosive method in which explosives are exploded in the ground and the resulting impact force is used to compact the ground.
The vibroflotation method uses a vibroflot (rod-shaped vibrator) for compaction, the cross-vibro method uses a cross-shaped vibro (rod-shaped vibrator) for compaction, vibration 1li (for vibro type), or They proposed the sand compaction method, which uses a pile driver (in the case of percassillin type) for compaction, and the left power compaction method, which uses a vibrator for compaction.

"Problems to be Solved by the Invention" However, each of these conventional construction methods has the following problems.

The electric shock method compacts the ground using the impact force generated when a high-pressure discharge occurs. Compaction using this method generates shock, vibration, and noise, and requires high construction costs. It takes.

In addition, the blasting method becomes more economical than other construction methods as the construction progresses on a larger scale, but it uses the impact force generated when explosives explode in the ground to compact the ground. When compaction is performed using this method, shock, vibration, and noise are generated, and it is also dangerous.

On the other hand, the vibroflotation method, cross-hybroflotation method, sand compaction method, and direct power compaction method do not use explosives or other dangerous materials. However, the vibrator, exciter or pile driver
Since they generate vibration and noise when used, compaction using the vibroflotation method or the like is accompanied by vibration and noise.

The present invention was made in view of these problems with conventional construction methods, and its purpose is to create sand that can be compacted safely and with less shock, vibration, and noise. The aim is to provide a compaction method for rough ground.

"Means for Solving the Problems" The gist of the present invention is to form a plurality of drain columns in the original ground using a drain material having a higher permeability coefficient than the soil of the original ground, and to connect a water injection pipe to the water pressure. A step of providing the water injection pipe in the ground at a predetermined depth at a position equidistant from the drain pillar adjacent to the water injection pipe, a pulsating means connected to the water injection pipe, and a water supply means connected to the pulsating means. , exists in a compaction method for sandy ground, which comprises a step of injecting water in a pulsating flow from the water injection pipe into the original ground.

"Operation" When water is injected into the ground from the water injection pipe by the pulsating means connected to the water injection pipe and the water supply means connected to the pulsating means, the pore water pressure (rises) in each soil. The effective stress acting between particles is reduced, making it easier for soil particles to move toward each other.Furthermore, the pulsations of water flow further vibrate the easily moved soil particles.As a result, the sandy ground becomes liquid. The sandy ground can be compacted by causing pore water to drain through the drain column and utilizing downward osmotic pressure.

"Example" Hereinafter, an example of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the component parts described in this example are not intended to limit the scope of this invention to only those, unless otherwise specified. , is merely an illustrative example.

In this embodiment, first, as shown in FIG. 1(A), a plurality of drain columns 1 are formed in the original ground A using a drain material 2 having a higher permeability coefficient than the soil to the original ground. The drain pillar 1 is formed by drilling a vertical hole B in the original ground A with an auger, and charging the drain material 2 into the vertical hole B from a hopper provided directly above the auger (in the case of a set of augers). A set of augers was used because it produces less vibration and noise than other construction methods. However, depending on the construction conditions, it is also possible to form the drain column 1 using a mandrel method or a water jet method. The reason why the drain material 2 is made of a material having a higher permeability coefficient than the soil of the original ground A is that this method utilizes the difference in permeability between the soil of the original ground A and the drain material 2. This is because the pore water existing therein is drained from the drain column 1. That is, since pore water flows from the soil with low permeability to the soil with high permeability, the pore water in the original ground A is made to flow to the drain column l and drained to the outside of the original soil. This is to make it possible. In order to improve drainage efficiency, it is desirable that the drain pillars 1 be arranged in a grid pattern as shown in FIG. 1(B). The number, diameter, length, relative position, etc. of the drain pillars 1 are determined based on the conditions of the original ground A, etc.

Next, as shown in FIG. 2, a water injection pipe 3 is installed in the original ground A at a predetermined depth at a position equidistant from the drain column l adjacent to the water injection pipe 3. The water press fitting pipe 3 has a substantially cylindrical shape, one end of which is an insertion portion 3a, and one end of which is a hose connection portion 3.
b. The insertion portion 3a has a conical shape so that it can be easily driven into the original ground A. The insertion part 3a
A slit portion 3C is provided near the slit 1. Part 3
C is provided with slits 3d of required length and number.

The pipe structure from the hose connection part 3b to the slit part 3C has a double structure, and the double structure consists of an outer pipe 3e and a water conduit 3f. The reason why the water injection pipe 3 is provided at positions equidistant from the drain pillar l adjacent to the water injection pipe 3 is to distribute the pore water existing in the original ground A evenly from each drain pillar l. Moreover, the purpose is to drain water in a short time. Here, "equal spacing" does not mean physically equal spacing (it refers to spacing that the constructor can think is approximately the same).Furthermore, the water injection pipe 3 is etc., it cannot be provided near the center of each adjacent drain pillar 1,
When close to one or two of the drain columns 1, the intervals between each of the drain columns 1 and the water injection pipe 3 are equal intervals as defined in the present invention. A vibro or the like is used to provide the water injection pipe 3 in the original ground A. Note that the predetermined depth of each of the water injection pipes 3 from the local surface of the original ground A is determined by taking into consideration the length of the drain column 1 and the like.

Next, the water whose flow is pulsating is forced into the original ground A from the water injection pipe 3 by the pulsating means 4 connected to the water injection pipe 3 and the water supply means connected to the pulsating means 4. As shown in FIG. 3, the pulsating means 4 includes a cylinder 4a having a water inlet 4g communicating with the water supply means 5 and a water outlet 4h communicating with the hose 6, and is fitted into the cylinder 4a and reciprocates. A moving piston 4b and a crank rod 4cs that transmits power to the piston 4b.
It consists of a flywheel 4d that uniformizes the power transmitted to the crank rod 4C, a belt 4e that transmits power to the flywheel 4d, and a drive motor 4f that provides power to the belt 4e, and communicates with each of the above. The portion is configured to have check valves 41, 4j.

Finally, one end of the hose 6 is connected to the water discharge part 4h of the pulsating means 4, and one end of the hose 6 is connected to the water pressure fitting pipe 3.
The pulsating means 4 and the water press-fitting pipe 3 are connected by connecting to the water conduit 3f that opens to the hose connecting portion 3b. Thereby, the pulsating flow of water generated by the pulsating means 4 and the water supplying means 5 can be sent to the water injection pipe 3. Note that it is desirable to use a high-pressure hose for the hose 6, taking into consideration the water pressure within the hose 6.

Next, the operation of this embodiment will be explained.

The pulsating means 4 sends a pulsating flow of water to the water injection pipe 3 through the high pressure pipe by the reciprocating movement of the piston 4b and the operation of the two check valves 4i and 4j. More specifically, when the piston 4b moves from the top dead center 4k to the bottom dead center 41, the check valve 41
is opened and water flows into the cylinder 4a from the water inflow portion 4g. At this time, since the check valve 4j of the function is closed, the water already discharged in the high pressure pipe does not flow back into the cylinder 4a from the water discharge part 4h. When the piston 4b moves from the bottom dead center 41 to the top dead center 4, the check valve 4j opens and the water existing in the cylinder 4a is discharged from the water discharge portion 4h. that time,
Since the check valve 41 of this function is closed, the water existing in the cylinder 4a will not flow back to the water supply means 5. Therefore, water whose flow is pulsating by the pulsating means 4 and the water supplying means 5 can be sent to the water injection pipe 3 via the hose 6. The pulsating water that has entered the water injection pipe 3 enters the slit portion 3C via the water guide pipe 3f. When water with a pulsating flow is injected into the original ground A through the slit 1) 3d provided in the slit portion 3C, the pore water pressure increases and the effective stress acting between each soil particle decreases. mutual movement becomes easier. Furthermore, the pulsation of the water flow further vibrates the easily moved soil particles. As a result, the sandy original ground A is liquefied, pore water is drained from the drain column 1, and the original ground A can be compacted by utilizing downward osmotic pressure.

Next, the effects of this embodiment will be explained.

Since this embodiment is configured as described above, it is possible to reduce shock, vibration, and noise compared to the conventional technology, and to perform compaction safely. As a result, it is possible to reduce the negative impact of compaction on structures built on the ground adjacent to or in the vicinity of the original ground A to be compacted, or on their residents. Therefore, the contractor can perform compaction safely.

In addition, the amount of electricity consumed during compaction is relatively small, so construction costs are not high. Furthermore, since the construction method according to the present invention is comprised of relatively simple steps, compaction can be easily performed. Furthermore, since the water injection pipe 3 and the pulsating means 4 are constructed as described above, they can be easily and inexpensively manufactured.

In this embodiment, the water injection pipe 3 and the pulsating means 4 are configured as described above, but this is merely an example, and other configurations may be used depending on the conditions of the original ground A, construction conditions, etc. It is also possible to have the following configuration.

"Effects of the Invention" Since the present invention is configured as described above, it is possible to reduce shock, vibration, and noise compared to the prior art, and to perform compaction safely. As a result, it is possible to reduce the negative impact of compaction on a structure built on the ground adjacent to or in the vicinity of the original ground to be compacted, or on its occupants.

Furthermore, since no explosives or the like are used, the constructor can safely perform compaction. Furthermore, the amount of electricity consumed during compaction is relatively small, so construction costs are not high. Furthermore, since the construction method according to the present invention is comprised of relatively simple steps, compaction can be easily performed.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the present invention, in which FIG. 1(A) is a vertical cross-sectional view of a drain pillar formed in the ground, and FIG. 1(B) is an arrangement of drain pillars. A plan view showing
FIG. 2 is a plan view showing the arrangement of water injection pipes, and FIG. 3 is a process explanatory diagram. A: Original ground, B: Pit, ■: Drain pillar, 2: Drain material 3: Water injection pipe, 3a...Insertion part, 3b...Hose connection IjLJ, 3c...Slit part 3d...Slit, 3e...Outer tube, 3f ... Water pipe, 4 ... Pulsation means, 4a ... Cylinder, 4b ... Piston, 4C ... Crank rod, 4d ... ...Flywheel 4e...Belt, 4f...Drive motor, 4g...Water inlet, 4h...Water outlet, 4i, 4j. ...Check valve 4k...Top dead center, 41...Bottom dead center 5...Water supply means 6...Hose

Claims (1)

[Claims] A step of forming a plurality of drain columns in the original ground using a drain material having a higher permeability coefficient than the soil of the original ground, and a step of placing a water injection pipe adjacent to the water injection pipe. A flow from the water injection pipe is caused by a step of installing it in the ground at a predetermined depth at positions equidistant from the water injection pipe, a pulsating means connected to the water injection pipe, and a water supply means connected to the pulsating means. A compaction method for sandy ground that involves the process of injecting pulsating water into the original ground.