JP3989267B2 - Ground improvement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground improvement method that is performed to drain water contained in the ground such as soft ground and dredged soil from the ground to improve it into a hard ground.
[0002]
[Prior art]
As a conventional ground improvement method, for example, there is one described in Japanese Patent No. 3138909. The improvement method for soft ground in this publication is that the surface of the soft ground is covered with an airtight sheet, and the horizontal drainage member between the airtight sheet and the surface of the soft ground is the upper end of the vertical drainage member protruding above the ground. And draining the water in the ground through the vertical drainage member and the horizontal drainage member to the outside of the soft ground by a vacuum pump connected to the horizontal drainage member.
[0003]
That is, as shown in FIG. 5, the upper end portion of the vertical drain material 11 placed on the ground A so as to extend in the vertical direction protrudes from the upper surface of the ground A and is bent, and the bent portion lies on the upper surface of the ground A. The horizontal drain material 12 arranged in this manner is brought into contact. As shown in FIG. 6, a plurality of the horizontal drain members 12 are arranged side by side within the ground improvement range M, and a single water pipe 13 is provided at the center of each of the plurality of horizontal drain members 12. The water received from 12 is passed through the vacuum pump 15.
[0004]
[Problems to be solved by the invention]
However, in such a conventional ground improvement method, in the improvement range Ma in the width direction of the ground improvement range M, as shown in FIG. In the central part through which the water pipe 13 passes, subsidence progresses remarkably due to drainage, while subsidence delays from the central part as it goes to both ends of the improved range Ma.
[0005]
This is because subsidence corresponding to the amount of drainage from the ground A progresses in the center of the improved area Ma, but continues to the outside of the improved area Ma of the ground even if drained as it goes to both ends of the improved area Ma. This is because the water from the ground is also drawn together, so subsidence can not be realized to match the amount of drainage.
[0006]
For this reason, when the road is constructed by building up the earth and sand on the ground with the central part of the improvement area Ma in the width direction of the ground improvement area M submerged more than the both ends, Both ends of the improved area Ma will sink later than the center as time passes. For this reason, both sides of the road will also sink, and the flatness of the road will be lost. There was a problem that had to be fixed.
[0007]
Therefore, in view of the above problems, the present invention is a ground improvement method capable of preventing the disadvantage that only the center portion in the width direction of the ground improvement range sinks significantly more than both ends during ground improvement work. It is a problem to provide.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the ground improvement method according to the present invention is:
Dividing the ground improvement range into an outer peripheral part and a central part, providing multiple drainage systems,
Start drainage from the ground of the outer periphery through the drainage system provided in the ground of the outer periphery, and precede the consolidation of this ground,
After a predetermined time has elapsed, the drainage from the center ground is started and consolidated through a drainage system provided on the center ground, so that the outer periphery and center of the improved area of the ground sink substantially uniformly. The height of the ground on the outer periphery and the center is the same ,
Each of the drainage systems is provided with an opening variable valve that can adjust the amount of drainage per hour and a flow meter that detects the amount of drainage per hour,
The opening of the variable opening valve is controlled such that the flow rate detected by the flow meter is equivalent to the flow rate detected by a flow meter of another drainage system .
[0009]
According to the ground improvement method of the present invention as described above, drainage from the ground at the outer peripheral portion is started via the drainage system provided at the outer peripheral portion of the ground improvement range, and the consolidation of this ground is preceded, for a predetermined time. After the passage of time, by starting drainage from the ground at the center through the drainage system provided at the center of the ground improvement area, the entire ground improvement area was improved uniformly. When draining from the ground, the amount of drainage from the ground at the outer periphery can be adjusted to prevent drawing more water than necessary from the ground that continues outside the improved range. It is possible to prevent the inconvenience that only the central part in the width direction of the improved range sinks significantly more than the both end parts.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIGS. 1 to 4 are views referred to for explaining an embodiment of the ground improvement method according to the present invention. The same reference numerals are used for the same members as in the prior art.
[0011]
First, as shown in FIG. 1, the ground improvement range M is divided into an outer peripheral portion Mo and a central portion Mc. It is assumed that the vertical drain material 11 (see FIG. 5) and the horizontal drain material 12 (see FIG. 2) described in the description of the conventional example are already provided in the ground improvement range M.
[0012]
Next, as shown in FIG. 2, a large number of holes were formed in the peripheral portion on the left and right sides of the ground corresponding to the outer peripheral portion Mo of the ground improvement range M, and the overall shape was a U-shape. The porous water pipes 23 </ b> A and 23 </ b> B are arranged so as to contact both end portions of each horizontal drain material 12. Then, on the left and right sides of the ground corresponding to the center portion Mc of the ground improvement range M, each of the straight perforated water pipes 23C and 23D, in which a large number of holes are formed in the peripheral portion, is provided in each horizontal direction. It arrange | positions so that the center part of the drain material 12 may be contacted.
[0013]
The perforated water pipes 23A and 23B have a large number of holes in the periphery connected to the vacuum pump 25 on the outer side of the center in the vertical direction in the figure on the left and right ends in the figure of the improved range M. The distal end portions of the longer first tube portions 30A and 30B of the non-porous water-permeable tube 30 are connected.
[0014]
At the center of the length of the porous water pipes 23C and 23D, there is a third pipe part connected to the second pipe parts 30C and 30D which are shorter and narrower than the first pipe parts 30A and 30B of the non-porous water pipe 30. 30E and 30F are connected so that the water from the perforated water pipes 23C and 23D can be sucked from the openings at both ends thereof.
[0015]
In the middle of the first pipe parts 30A, 30B and the second pipe parts 30C, 30D constituting the plurality of drainage systems of the non-porous water pipe 30, an opening variable valve 32 that can adjust the amount of drainage per hour, A flow meter 34 for detecting the amount of drainage is provided. After each of these members is provided, an airtight sheet (not shown) is placed over the improved range M and the peripheral portion of the airtight sheet is subjected to an airtight process.
[0016]
The ground improvement method implemented using such facilities will be described below.
First, as a first stage, the opening variable valve 32 provided in the second pipe portions 30C and 30D of the non-porous water pipe 30 is closed, and the opening variable valve 32 provided in the first pipe portions 30A and 30B is opened. By operating the vacuum pump 25 in the grounded state, the ground Ao (see FIG. 3) of the outer peripheral portion Mo of the ground improvement range M through the porous water pipes 23A and 23B, the horizontal drain material 12 and the vertical drain material 11 Start draining water.
[0017]
Thus, when a predetermined time has elapsed since the drainage of the ground Ao of the outer peripheral portion Mo of the ground improvement range M is started, the ground surface of the ground Ao sinks as shown in FIG. 3 and the ground Ao is hardened. It becomes difficult to permeate and acts to block moisture W from the ground A outside the ground improvement range M from entering the ground Ac in the central portion Mc of the ground improvement range M.
[0018]
Then, as a second stage, the opening degree variable valve 32 provided in the second pipe portions 30C and 30D of the non-porous water pipe 30 is opened, and the porous water pipes 23C and 23D, the horizontal drain material 12 and the vertical drain material 11 are opened. Then, drainage of moisture in the ground Ac in the central portion Mc of the improved range M is started. At this time, when a predetermined time elapses by adjusting the amount of drainage from the ground Ao, as shown in FIG. 4, the ground Ac in the central portion Mc sinks evenly, and the ground surface is as high as the ground surface of the outer peripheral portion Mo. It will be.
[0019]
That is, when the ground Ac of the central portion Mc is drained by the porous water pipes 23C and 23D, it becomes difficult for the water W from the ground A outside the ground Ao to enter the ground Ac through the ground Ao and the ground Ao. Therefore, it is possible to prevent only the central part of the ground Ac in the improved range Ma from sinking more significantly than the both end parts as shown in FIG.
[0020]
For this reason, drainage can be performed evenly from the outer periphery Mo of the improved area M of the ground and the ground Ao, Ac of the central part Mc, and when a road is built by stacking earth and sand on the ground of the improved area M In addition, it is possible to prevent the ground from being partially drained later and the flatness of the road from being lost or having to rebuild the road.
[0021]
In addition, when the water distribution in the original ground is uneven, the water is drained only from a place with a lot of water, and drainage from other places may not proceed. For this reason, by comparing the detection values of the flow meters 34 of the first pipe portions 30A and 30B and the second pipe portions 30C and 30D of the non-porous water passage tube 30, the opening degree variable valve 32 of the pipe portion having an extremely large detection value. By controlling so as to squeeze and close, the water in the ground in the improved range M can be drained evenly, and the ground surfaces of the grounds Ao and Ac can be evenly sunk as shown in FIG.
[0022]
Further, by increasing the pipe cross-sectional area of the first pipe portions 30A, 30B relative to the second pipe portions 30C, 30D of the non-hole water-permeable pipe 30, the outer periphery continuous with the ground A outside the improved range M The drainage from the ground Ao of the part Mo can be effectively promoted.
[0023]
In the above embodiment, the case where the ground improvement method for draining water by putting an airtight sheet on the equipment composed of each member and making the inside of the airtight sheet negative pressure has been explained. However, other airtight treatment may be performed to drain water, and in that case, the airtight sheet is not necessarily required in the practice of the present invention.
[0024]
In addition, the opening degree variable valve 32 in the above embodiment can be remotely operated, and the detection value of the flow meter 34 can be transmitted to a remote location via a communication line, so that the detection value of the flow meter 34 can be obtained from a remote location. It is also possible to monitor so that the opening degree variable valve 32 can be operated by changing the opening degree from a remote place according to the detected value.
[0025]
【The invention's effect】
As described above, according to the ground improvement method of the present invention, drainage from the ground at the outer peripheral portion is started via the drainage system provided at the outer peripheral portion of the ground improvement range, and the consolidation of this ground is preceded. Since the drainage from the ground in the central part is started through the drainage system provided in the central part of the ground improvement range after a predetermined time, the whole ground improvement range is improved uniformly. When draining from the ground in the central part, the water in the outer peripheral part is made difficult to permeate, and by adjusting the amount of drainage from the outer peripheral part, water from the ground that is continuous outside the improved range is drawn together Therefore, it is possible to prevent the inconvenience that only the center portion in the width direction of the ground improvement range sinks more than the both ends at the time of ground improvement work.
[Brief description of the drawings]
FIG. 1 is a plan view showing an outer peripheral portion Mo and a central portion Mc which are divided in a ground improvement range M;
FIG. 2 is a plan view showing each member for carrying out the improvement method of the ground in the improvement range M;
3 is a cross-sectional view taken along the line BB of the improved range M in FIG. 1 showing the ground Ao, Ac according to the first stage of the ground improvement method.
4 is a cross-sectional view taken along the line B-B of the improved range M in FIG. 1 showing the ground Ao, Ac according to the second stage of the ground improvement method.
FIG. 5 is a sectional view of ground A in a conventional ground improvement method.
FIG. 6 is a plan view showing each member for carrying out a conventional ground improvement method.
FIG. 7 is a cross-sectional view taken along the line CC of the improvement range M in FIG. 6 of the ground A by performing the conventional ground improvement method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Vertical drain material 12 Horizontal drain material 13 Water pipe 15 Vacuum pump 23A, 23B, 23C, 23D Porous water pipe 25 Vacuum pump 30 Non-hole water pipe 30A, 30B 1st pipe part 30C, 30D 2nd pipe part 30E, 30F 1st Three pipe sections 32 Variable opening valve 34 Flowmeters A, Ao, Ac Ground M, Ma Ground improvement range Mo Improvement range outer circumference Mc Improvement range center W

Claims (2)

Dividing the ground improvement range into an outer peripheral part and a central part, providing multiple drainage systems,
Start drainage from the ground of the outer periphery through the drainage system provided in the ground of the outer periphery, and precede the consolidation of this ground,
After a predetermined time has elapsed, the drainage from the center ground is started and consolidated through a drainage system provided on the center ground, so that the outer periphery and center of the improved area of the ground sink substantially uniformly. The height of the ground on the outer periphery and the center is the same ,
Each of the drainage systems is provided with an opening variable valve that can adjust the amount of drainage per hour and a flow meter that detects the amount of drainage per hour,
A ground improvement method characterized in that the opening of the opening variable valve is controlled so that the flow rate detected by the flow meter is equal to the flow rate detected by a flow meter of another drainage system .   The ground improvement construction method according to claim 1, wherein a pipe cross-sectional area of a drainage system provided on the ground of the outer peripheral part is made larger than a pipe cross-sectional area of a drainage system provided on the ground of the central part.

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