JP3532464B2 - Construction method of horizontal drain - Google Patents

Description

Detailed Description of the Invention

[0001] The present invention relates to a method for constructing a horizontal drain for civil engineering / construction developed as an alternative to a sand mat for drainage, and particularly in cohesive soil for improvement work on soft ground, land reclamation work, and embankment work. It aims to stabilize the ground by effectively draining the pore water that springs and the rainwater that permeates the embankment to promote the consolidation and settlement of the cohesive ground.

[0002]

2. Description of the Related Art Generally, when road construction, embankment construction, or the like is carried out or a structure is constructed on soft ground such as cohesive ground that contains a lot of pore water, the load of the embankment or structure Since the interstitial water in the cohesive soil is gradually drained, the consolidation settlement of the cohesive soil will proceed for a long time, which may cause serious problems such as uneven settlement of the structure.

Therefore, in order to perform the above-mentioned construction on such soft ground, pore water in the cohesive soil is forcibly drained to promote consolidation settlement of the cohesive soil. , It is necessary to stabilize the ground.

Up to now, as a method of promoting the consolidation settlement of this type of cohesive land, for example, as shown in FIG. 7, a vertical drain 21 such as a sand drain or a paper drain as a water channel leading to the ground in the ground 20. While inserting the sand mat 22 at a predetermined interval, a sand mat 22 is spread over the ground 20 as a drainage channel for efficiently draining sideways the groundwater that rises above the ground through the vertical drain 21. There is known a method of forming the embankment 23 on the sand mat 22 as a weighting material for promoting compaction and loading the embankment 23 up to the planned height.

In this construction method, the pore water in the ground 20 is guided to the vertical drain 21 by the pressure from above by the embankment 23, and is taken into the vertical drain 21. And
Pore water in the vertical drain 21 is guided to the ground through the vertical drain 21 and drained to the side through the ground sand mat 22.

[0006]

In this construction method, various alternatives to the sand drain, such as a paper drain, have been developed for the vertical drain 21 and are widely used. However, an excellent alternative to the sand mat 22 is particularly preferable. Therefore, a large amount of natural sand such as mountain sand, river sand, and sea sand is used for the construction of the sand mat 22, and the sand consumption further increases when the sand drain is constructed as the vertical drain 21. Is.

[0007] Normally, for sand mats, sand is spread over the entire area of the ground improvement area to a thickness of about 50 to 100 cm, so that the amount of use reaches a huge amount. For this reason, in recent years, it has become difficult to obtain high-quality sand, resulting in a decrease in quality, an increase in material costs, and problems such as depletion of resources due to sand extraction and environmental destruction.

Further, since it is difficult to obtain good quality sand year by year, there is a problem in that the use of sand having a large amount of fine grains and low water permeability greatly impairs its role. Under such circumstances, there is a strong demand from the industrial world to develop an alternative product having a drainage function equivalent to that of the sand mat instead of the sand mat.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for constructing a horizontal drain having an extremely large drainage capacity.

[0010]

A method for constructing a horizontal drain according to a first aspect of the present invention is to install a plurality of horizontal drains on a soft ground in a grid pattern or a diamond pattern in plan view, and the horizontal drains are While installing a vertical drain in the ground at the position of intersecting each other, the upper end portion is overlaid on the horizontal drain, and in the method of constructing a horizontal drain to embed on the horizontal drain, in the soft ground is a depression shape Water collecting basins are provided at predetermined intervals, and the horizontal drains are installed on the bottom of the water collecting basin and its surroundings at intervals narrower than the installation intervals of the vertical drains.

The method for constructing a horizontal drain according to claim 2 is the method for constructing a horizontal drain according to claim 1, wherein
The horizontal drain has a plurality of water-absorbing ropes having water absorption between the upper and lower water-permeable outer jacket materials arranged in parallel in a radial direction thereof, and the water-might ropes between the water jacket ropes of the outer jacket material. It is characterized in that it is formed into a band shape by continuously sewing in the axial direction of. A method for constructing a horizontal drain according to a third aspect is the method for constructing a horizontal drain according to the second aspect, characterized in that a filling material having water absorbency is filled between the upper and lower casing materials.

The method for constructing a horizontal drain according to claim 4 is the method for constructing a horizontal drain according to claim 2 or 3, characterized in that the upper and lower jacket materials are installed in double or more layers. And A method for constructing a horizontal drain according to claim 5 is the method for constructing a horizontal drain according to any one of claims 2 to 4, wherein a water channel rope having a large diameter and a water channel rope having a small diameter are provided between the upper and lower jacket materials. It is characterized by alternately installing.

The method for constructing a horizontal drain according to claim 6 is the method for constructing a horizontal drain according to any one of claims 2 to 5, wherein the water channel rope is formed by bundling a plurality of thin water channel ropes. Is characterized by. A method for constructing a horizontal drain according to claim 7 is the method for constructing a horizontal drain according to any one of claims 2 to 6, wherein the water channel rope is formed by bundling a plurality of thin water channel ropes. To do.

The method for constructing a horizontal drain according to claim 8 is the method for constructing a horizontal drain according to any one of claims 2 to 7, wherein the horizontal drain is the horizontal drain according to any one of claims 2 to 7. It is characterized by forming a plurality of layers.

[0015]

1 and 2 show an example of a horizontal drain according to the present invention, in which a plurality of water line ropes 2 are arranged at predetermined intervals between upper and lower jacket materials 1a and 1b made of natural fibers. It is located in.

The upper and lower jacket materials 1a and 1b are formed by sewing threads 3 between the water ropes 2 and 2 respectively.
Are continuously sewn vertically in the axial direction to be connected.
In this way, the horizontal drain 4 is formed in a strip shape (width 7 to 11 cm, thickness 0.7 to 1.1 cm).

A thick horizontal drain is formed by stacking several horizontal drains 4, and by connecting several horizontal drains laterally, a wide one ((width 16 to 20 cm, thickness 0 .7 to 1.1 cm), or a wide and thick strip, and also FIG.
A large mat-shaped horizontal drain 5 is formed as shown in (a) and (b).

At this time, the horizontal drains are connected to each other by the same kind of sewing thread as the sewing thread 3 or by a stapler with a distance of about 1 m. In any of the horizontal drains, the upper and lower jacket materials 1a and 1b, the water rope 2, and the sewing thread 3 are all natural fibers having high water absorption and water permeability, such as natural fibers such as coconut fiber, jute, cannabis, and palm. It is made of fibers.

Particularly, after finishing the function as a horizontal drain by forming all of these with natural fibers, all the parts gradually corrode with time and are taken into the ground. It is possible to prevent a situation in which it is left as it is without being decomposed into industrial waste and becomes industrial waste.

Further, there is no possibility that the soil will be contaminated to cause pollution such as groundwater contamination when it is left in the ground, and the trouble of collecting can be saved. The upper and lower jacket materials 1a and 1b are, for example, a single jacket material folded in half at its substantially middle portion, and its free end side end portion is sewn with a sewing thread 3
The same sewing thread is used to sew longitudinally continuously in the axial direction of the water rope 2. Also, the upper and lower jacket materials 1a
And 1b are double or triple depending on the material and strength, and are further stacked.

Further, as shown in FIGS. 1 (a) to 1 (f), for example, the water line rope 2 is composed of upper and lower jacket materials 1.
They are arranged at equal intervals in the radial direction between a and 1b. Further, in principle, the water rope 2 has a substantially circular cross section, and in some cases, a substantially elliptical cross section or a flat rectangular cross section (see FIG. 1B).

The water channel ropes 2 having a large diameter and those having a small diameter are alternately installed (see FIG. 1 (c)), or the water channel ropes 2 and 2 having a large diameter are narrow. 2a may be installed in large numbers (Fig. 1
(See (d)).

Further, each of the water ropes 2 may be formed by bundling several thin ropes 2a (see FIG. 1 (e)). Furthermore, the fibrous filler 6 may be filled between the upper and lower jacket materials 1a and 1b and the plurality of water channel ropes 2 (see FIG. 1 (f)). As the filling material 6, it is desirable to use a fibrous material having both high water permeability and high water absorption, which are the same as the materials of the outer covering materials 1a, 1b and the water rope 2.

3 to 6 show an example of a construction method using the horizontal drain thus formed, in which a plurality of horizontal drains 4 are axially arranged on a soft ground 7 for which consolidation is to be promoted. They are laid while being connected to each other and crossing each other in a grid pattern (or a diamond pattern) in a plan view.

At that time, one horizontal drain 4 is formed depending on the geology of the ground, particularly two or several layers are piled up for the ground containing a large amount of pore water, and further horizontal. A wide number of drains 4 are connected to each other in the width direction, and the drains 4 are properly used and laid.

It is desirable that the water channels 2 between the horizontal drains 4 and 4 are connected in the longitudinal direction to each other so that the channels are not blocked by the joint between the horizontal drains 4 and 4.

As a method of connecting the water channel ropes 2 to each other, it is most preferable to directly connect the water channel ropes 2 to each other, but this is not always necessary. For example, the water channel ropes 2 may be overlapped between the horizontal drains 4 and 4. Alternatively, a method of filling a fiber material of the same material may be used.

In this way, the vertical drains 8 are respectively inserted into the ground at the positions where the laid horizontal drains 4 intersect with each other, and the upper end portions 8a thereof are overlapped on the intersecting portions of the horizontal drains 4.

The embankment 9 is laid up to the planned height on the laid horizontal drain 4. Further, in particular, when the target range is extremely wide, the soft ground 7 is dug down a little and the recessed water collecting basins 10 are provided at predetermined intervals, and the water collecting basin 10 passes through the embankment 9 to reach the ground. The spring pipes 11 that communicate with each other are inserted.

Further, horizontal drains 4 are arranged at the bottom of the catchment basin 10 and its surroundings at an interval narrower than the installation interval of the vertical drains 8, for example, at an installation interval of about 1/2 of the installation interval of the vertical drains 8. There is.

Further, a mat-shaped one formed by connecting several horizontal drains 4 and a thick one formed by stacking two or several horizontal drains 4 are laid. In such a structure, as shown in FIG. 6A, for example, pore water in the ground is guided to the vertical drain 8 by the pressure from above by the embankment 9 and is taken into the vertical drain 8. Then, the pore water in the vertical drain 8 is guided to the ground through the vertical drain 8 and drained to the side through the horizontal drain 4 on the ground.

Further, in particular, in the place where the collecting basin 10 and the spring pipe 11 are installed, a large amount of pore water taken into the collecting basin 10 is led to the ground at once through the spring pipe 11, and Drains laterally through the horizontal drain 4.

Further, as shown in FIG. 6B, for example, even when the sand mat 12 is used as before, by using the horizontal drain 4 together, the sand for the sand mat can be greatly reduced. it can.

[0034]

The present invention is as described above, and in particular, a plurality of water absorbent ropes having water absorbability are installed between the upper and lower water-permeable outer jacket materials in parallel in the radial direction to form a horizontal drain. Therefore, it has an extremely large water-passing capacity and a drainage function equivalent to that of a sand mat.

Therefore, when the consolidation of soft ground is promoted by using the vertical drain, by laying the horizontal drain instead of the sand mat on the soft ground, the groundwater flowing up to the ground through the vertical drain. The water can be quickly drained to the side, so that the enormous amount of sand required for the sand mat can be significantly reduced.

Further, since the outer covering material and the water rope are all made of natural fibers such as palm fiber and jute, they are flexible and have a high strength and are not cut even when loaded by construction heavy equipment. Absent.

Particularly, by installing a large number of thin water channels between water channels having a large diameter, or by bundling several thin water channels to form one water channel,
It is possible to reliably prevent breakage of the water rope.

Further, the horizontal drain, after having fulfilled its role, is decomposed by bacteria in the ground with the passage of time, and eventually corrodes and is assimilated with soil.
There are no problems such as being left in the ground and causing environmental pollution.

Further, by stacking several horizontal drains as necessary to make them thicker, it is possible to prevent the drainage function from being deteriorated by the pressure of the loading embankment as much as possible.

[Brief description of drawings]

1A to 1F are perspective views showing an example of a horizontal drain.

2A and 2B are perspective views showing another example of a horizontal drain.

3A and 3B show a laid state of a horizontal drain, in which FIG. 3A is a plan view thereof and FIG. 3B is a vertical sectional view thereof.

FIG. 4 is a partially enlarged plan view showing a laid state of a horizontal drain.

5A to 5C are cross-sectional views taken along the line aa in FIG.

6 (a) and 6 (b) are vertical cross-sectional views showing a construction method.

FIG. 7 is a vertical sectional view showing a conventional construction method.

[Explanation of symbols]

1a Jacket material 1b Jacket material 2 water road rope 3 sewing threads 4 horizontal drain 5 Horizontal drain 6 Filling material 7 Soft ground 8 vertical drain 8a Upper part of vertical drain 9 embankments 10 Water collecting basin 11 spring pipe 12 Sand mat

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 10-140550 (JP, A) JP 9-111803 (JP, A) Jikken 6-34113 (JP, Y2) (58) Field (Int.Cl. ⁷ , DB name) E02B 11/00 E02D 3/10

Claims (8)

(57) [Claims] 1. A plurality of horizontal drains are installed in a grid pattern or a rhomboid pattern on a soft ground in a plan view, and vertical drains are installed in the ground at positions where the horizontal drains intersect each other. In the method of constructing a horizontal drain in which the upper end portion is overlapped on the horizontal drain and the soil is filled on the horizontal drain, recessed water collecting cells are provided at predetermined intervals in the soft ground, and the bottom of the water collecting cell is provided. A horizontal drain construction method, characterized in that the horizontal drain is installed at a space narrower than the installation space of the vertical drain around the vertical drain. 2. The horizontal drain has a plurality of water-absorbing ropes having water-absorbing property arranged between the upper and lower water-permeable outer jacket materials in parallel in the radial direction, and between the water-might ropes of the outer jacket material. 2. A belt-like shape is formed by continuously sewn in the axial direction of the water channel rope.
How to install the horizontal drain described. 3. The method for constructing a horizontal drain according to claim 2, wherein a filling material having water absorbency is filled between the upper and lower jacket materials. 4. The method for constructing a horizontal drain according to claim 2, wherein the upper and lower jacket materials are installed in a double or more layered manner. 5. The method for constructing a horizontal drain according to any one of claims 2 to 4, wherein a water channel rope having a large diameter and a water channel rope having a small diameter are alternately installed between the upper and lower jacket materials. 6. The method of constructing a horizontal drain according to claim 2, wherein the water channel rope is formed by bundling a plurality of thin water channel ropes. 7. The method for constructing a horizontal drain according to claim 2, wherein the upper and lower jacket materials and the water rope are made of natural fibers. 8. A method for constructing a horizontal drain, wherein the horizontal drain is formed by stacking a plurality of the horizontal drains according to any one of claims 2 to 7.