JPH10114956A - Method of boiling countermeasure by groundwater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provie a method of construction, by which boiling can be stopped quickly and easily even when boiling by groundwater is generated in the excavating plate of a shaft, etc. SOLUTION: In the method of boiling-countermeasure construction by groundwater, crushed stones 12 are put to an excavating plate 5, in which boiling 6 by groundwater 4 is generated, in the excavation process of a shaft and a cutting, etc., 10 for construction. Accordingly, a crushed-stone heap 13 in specified height is heaped up. The crushed-stone heap 13 inhibits the election energy of groundwater 4 by its own weight. Only groundwater 4 is drained through clearances 15 formed among each mutual crushed stone 12 constituting the crushed-stone heap 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for countermeasures against boiling due to groundwater, and more particularly, to a method suitable for countermeasures against boiling when performing excavation work such as pitting or excavation of a building on sandy ground.

[0002]

2. Description of the Related Art Shafts and root excavation of buildings on the ground
In order to perform the excavation work of the shaft, the excavation of the shaft 10, etc. is started after the pile 1 such as the sheet pile, the continuous wall, and the continuous column shaft wall is constructed on the ground G as shown in FIG. With the progress of such excavation, the ridge 1 is stopped in the lateral direction by the bulge 2 and the ridge 1 is inserted between the bulges 2 to stabilize the ridge 1 while excavating further downward. I will proceed. Then, when the excavation has been performed to a predetermined depth, processing of discarded concrete or the like is performed, and the process proceeds to the next operation such as construction of a structure or setup such as starting a tunnel.

[0003] When excavation work such as a shaft is performed on sandy ground, groundwater 4 flows along the lower part 1a of the ridge 1 and flows into the shaft 10, and then flows further upward to sediment. The particles were ejected to the excavator 5 together with the particles, and so-called boiling 6 occurred.

As shown in FIG. 4, the groundwater flow acts on the sediment particles 9, and the distance e between the center of gravity w and the floating center u rotates the sediment particles 9. As a result, the sediment particles 9 dance and are violently disturbed.
This further developed and caused a piping phenomenon to form the water supply 7, and finally, the spouting of the earth and sand particles 9 resulted in the boiling 6.

[0005] The earth and sand particles 9 erupted in this manner rise in a mountain shape, and as a result, the periphery of the water supply 7 is loosened.
Came off, causing the surface to sink.

Therefore, as a countermeasure against groundwater, depending on the geological conditions, peripheral conditions, construction method, etc., a deep well is excavated in advance around the shaft 10 or the like, and groundwater is pumped from the deep well. Was injected into the ground to reduce the permeability of the ground.

However, such boiling 6 does not always occur at the final stage of excavation, and may occur during excavation as an unexpected situation. In this case, as a countermeasure for boiling, 1) submerge the shaft, etc. to lower the groundwater level and then pump up water, and then excavate, or 2) submerge the shaft, etc., and perform underwater excavation. 3) Submerge the shaft and place a water point after placing the concrete. 3) Pour the water while preventing the inflow of sediment particles by the well point, and then place concrete. Boiling countermeasures were taken.

[0008]

However, the above-described conventional groundwater countermeasure works have the following problems. That is, in order to excavate a deep well around a shaft or the like in advance, a sufficient space is required around the excavation, and the cost of the deep well excavation is large, so that it is not economical. In addition, as a countermeasure against boiling that occurred during excavation, it takes time to immerse a shaft or the like in submerged concrete and place underwater concrete, or to place well points. There was a risk that the damage would increase.

In addition, the above countermeasures require the subsequent pumping, preparation of large-scale temporary objects such as underwater concrete and well points, or the necessity of cleaning up these items. There was also an economic problem, because the cost of goods increased.

[0010] Furthermore, the location of the occurrence of boiling is not limited to the vicinity of the ridge, and the location of occurrence of the boiling tends to move after the above-mentioned countermeasure for the above-mentioned boil is taken. .

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem. Even if boring due to groundwater occurs in a drilling machine such as a vertical shaft, it is possible to quickly and easily stop the boiling. It is an object of the present invention to provide a method for countermeasures against boiling caused by groundwater.

[0012]

Means for Solving the Problems The present invention relates to a method for countermeasures against boiling due to groundwater, and is constituted as follows in order to solve the above-mentioned technical problems. In other words, the method of the present invention for countermeasures against boiling by groundwater is that, in an excavation process such as a shaft, a crushed stone is poured into a drilling machine in which boiling by groundwater has occurred to excavate a crushed rock mountain having a predetermined height, and the groundwater is weighed by its own weight. It is characterized in that the blast energy is suppressed and that only groundwater can be drained through gaps formed between the crushed stones constituting the crushed stone mountain. Hereinafter, important components of the present invention will be described in more detail.

As the crushed stone, any suitable crushed stone can be used as long as only groundwater can be drained through a gap formed between the crushed stones.
S) Single-grain crushed stone specified in A5001-1995, 1
No. (60-100 ^{m / m} ) and / or No. 2 (40-8
0 ^{m / m 2} ).

[0014] The height of the crushed stone is only required to be able to suppress boiling by the weight of the crushed stone.
60 cm is preferred. However, if it is impossible to suppress the discharge energy of the groundwater in the above range, the crushed rock mass exceeding the upper limit of the height is raised. Alternatively, the energy may be equal to or less than the above range as long as the blast energy of groundwater is small.

Further, as a means for charging crushed stone, at least one dump truck loaded with crushed stone may be arranged around the shaft in advance, but it is preferable to provide a plurality of dump trucks and crumbs.

According to the method of countermeasures against groundwater-based boiling according to the present invention, when boiling occurs in a drilling machine, crushed stone prepared in advance is put into the location. Then, the movement of the earth and sand particles is suppressed by the weight of the crushed stone, and the gap between the particles of the crushed stone acts as a strainer to drain only groundwater.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a construction method of a countermeasure against boil- ing with groundwater according to the present invention. FIG. 1 is an explanatory diagram of a construction state of a method for countermeasures against boiling due to groundwater according to one embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a crushed stone pile state.

First, a ridge 1 such as a sheet pile, a continuous wall, a continuous column shaft wall, etc. is constructed on a sandy ground G, and then a shaft 1 is formed.
0 excavation is started. As the excavation progresses, the ridge 1 is stopped in the lateral direction by the gusset 2, and the cutting beam 3 is inserted between the gussets 2 to stabilize the ridge 1 as shown in FIG. Continue drilling.

Further, a dump truck 8 previously loaded with single-grained crushed stones 12 of No. 1 and / or No. 2 specified in JIS A5001-1995 is arranged around the shaft 10. Although only one dump truck 8 is shown in FIG. 1, the number is not limited to one, and a plurality of dump trucks may be installed. Although not shown, a crumb is also provided.

During the excavation of the shaft 10, the groundwater 4 flows through the lower part 1a of the embankment 1 and flows into the shaft 10, further flows upward, and as shown in FIG.
At the same time, when the boring 6 is generated by erupting from the excavator 5, the dump truck 8 is immediately driven to put the crushed stone 12 into the location where the boiling has occurred, and the crushed stone pile 13 is raised to a predetermined height h to control the boiling 6. FIG. 1 shows a case where the boiling 6 occurs near the ridge 1, but when the boiling 6 is suppressed in one place, it often shifts to another place. In that case, the crushed stone 12 is further charged with a crumb or the like (not shown) toward the location where the boiling 6 has moved.

The height h of the crushed rock pile 13 is usually 40 to 60 cm in the present embodiment. This is because the mountain-shaped ridge formed by the ejection of the sediment particles 9 is at most several tens of centimeters, the concrete thickness is about 10 to 20 cm in order to suppress the boiling caused by the underwater concrete, and The height of the crushed rock mountain 13 was set in view of the fact that the jet power multiplied by the water mouth cross-sectional area was dispersed at the bottom of the crushed rock mountain and smaller than the weight of the crushed rock mountain. Of course, the height h of the crushed rock mountain 13 is not limited to the above range.

The crushed stone pile 13 suppresses the energy of the groundwater 4 that causes the earth and sand particles 9 to be ejected from the ground G by its own weight, and a gap 15 formed between the crushed stones 12 constituting the crushed stone pile 13 forms a strainer of the strainer. It plays a role and only groundwater 4 is drained.

As described above, if the blasted stone 12 is put into the location where the boiling 6 is generated, the energy of the spouting of the groundwater can be suppressed, the shaft 10 and the like themselves become large wells. And the groundwater level can be lowered without drawing water, and the boiling 6 ends. Then, excavation is further started from this point.

[0024]

As described above, according to the method of the present invention for countermeasures against boiling by using groundwater, the crushed stone is put into the excavator in which the boring due to the groundwater has occurred, and is simply raised to a predetermined height. In addition to suppressing jetting energy and preventing sedimentation of sediment particles, it can drain only groundwater as a strainer.Even if a dump truck loaded with crushed stones is kept waiting around a shaft, etc., it is economical immediately. Therefore, it is possible to cope with boiling and to minimize the subsidence of the ground due to lowering of the groundwater level. In addition, even if the location where the boiling occurs is moved, it is possible to respond immediately and flexibly.

In the present invention, large-scale temporary construction such as underwater concrete or well points is not required by using crushed stones used for excavation as in the conventional construction method. It does not require any special treatment for cleaning up, it can be treated as soil dumping together with excavation, and it can flexibly cope with unexpected boiling during excavation of shafts, etc., and is economical and safe.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a construction state of a method for countermeasures against boiling due to groundwater according to an embodiment of the present invention.

FIG. 2 is a partial explanatory view showing details of a crushed stone erected state in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a state of occurrence of boiling when excavating a shaft or the like.

FIG. 4 is an explanatory diagram of a cause of sediment particles being disturbed by a groundwater flow.

[Explanation of symbols]

 4 Groundwater 5 Excavator 6 Boiling 10 Shaft 12 Crushed Stone 13 Crushed Stone Mountain 15 Clearance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mikihiko Tanaka 2-10-26 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. (72) Inventor Akira Gobo 3-1-1-18 Iidabashi, Chiyoda-ku, Tokyo (Kokuni Building) Inside Fujimi Koken Co., Ltd.

Claims (1)

[Claims] In an excavation process such as a shaft or a root excavation for a building, crushed stone is injected into an excavator in which boiling due to groundwater has occurred to excavate a crushed rock mountain having a predetermined height. A method for preventing groundwater boiling, characterized in that only groundwater can be drained through gaps formed between the crushed stones constituting the crushed stone mountain.