JP7410812B2 - Drilling system and ground excavation method - Google Patents

Description

The present invention relates to an excavation system for excavating the ground and a method for excavating the ground.

Conventionally, when drilling holes in the ground using an excavator, mud with a density of 1.10 or less, which is a mixture of clay such as bentonite and water, is used as a stabilizing liquid to form an impermeable mud on the hole wall. A wall is built to protect the hole from collapsing. The stabilizing liquid removes and cleans the drilling debris from the bottom of the hole and around the bit, circulates inside the hole, and transports the drilling debris to the surface, and also cools the core bit's heat generated by friction when breaking the strata. It plays the role of preventing contact between the casing pipe and the boring rod by using the lubricity of the clay content, thereby preventing wear on the pipe.

If the underground water pressure in the ground where the hole is to be drilled is high, it is necessary to increase the density of the stabilizing liquid to prevent oil, gas, water, or other fluids that exist underground from gushing out. As high-density stabilizing liquids, stabilizing liquids containing magnetic substances that can be attracted by magnetic force (for example, see Patent Document 1) and stabilizing liquids containing an increased amount of kaolin mineral (see, for example, Patent Document 2) have been proposed. There is.

Patent No. 5167190 Patent No. 3932377

However, in Patent Document 1, the viscosity of the stabilizing liquid was high, which placed a heavy burden on the excavator during drilling. In addition, large-scale equipment was required to recover the magnetic material. Further, in Patent Document 2, the density adjustment range was small, making it difficult to increase the density.

In addition, the stabilizing liquids described in Patent Documents 1 and 2 both have low dispersion stability because they cloud solid particles such as magnetic ferrite and kaolin minerals in water, and the solid and water are separated. The problem was that it was easy to do. If solids and water are likely to separate, when the circulation of the stabilizing liquid is temporarily stopped for purposes such as refilling a boring rod, the cuttings and added materials will separate, and the slime in the mud will settle, causing damage to the hole wall. There was a possibility that the boring rod would be buried at the same time as the collapse. Furthermore, if the mud wall built to protect the hole wall is too thick, the boring rod may stick to the mud wall, making drilling impossible.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide an excavation system and a ground excavation system that can efficiently excavate the ground using a stabilizing liquid that does not separate and whose density can be easily adjusted. The purpose is to provide a method.

In order to achieve the above-mentioned object, a first invention provides an excavation system for excavating the ground, comprising: an excavation section for excavating the ground; a pump for supplying a stabilizing liquid to the ground from the vicinity of the excavation section; a recovery unit for recovering the liquid, the stabilizing liquid contains sodium polytungstate , and the stabilizing liquid has a density of 2.7 g/cm ³ or more and 3.1 g/cm ³ or less. This is a unique excavation system.

In the first invention, the density of the stabilizing liquid can be easily adjusted by using sodium polytungstate (hereinafter referred to as SPT). SPT is a harmless, odorless, and nonflammable solid, and SPT solution, which is made by dissolving SPT in water, is also harmless, reducing environmental impact and providing high safety during construction. Moreover, solid SPT can be recovered from an SPT solution at a high recovery rate. Furthermore, since the SPT solution is an aqueous solution, SPT and water will not separate even if the circulation of the stabilizing liquid in the ground is temporarily stopped.

Further, since the density of the stabilizing liquid is 2.7 g/cm ³ or more and 3.1 g/cm ³ or less, the wall surface of the hole can be stably protected even in an environment with high groundwater pressure. Further, when a stabilizing liquid containing SPT is supplied to the ground, the drilling load on the excavation part is reduced as the density of the stabilizing liquid increases, so it is possible to improve the efficiency of excavation.

It is preferable that the stabilizing liquid collected by the collecting section be separated from the excavated soil and then circulated to the ground by the pump.
Although SPT is expensive, construction costs can be reduced by collecting and reusing the stabilizing liquid.

The recovery section includes a recovery pit into which the stabilizing liquid and excavated soil after excavation flow from a branch pipe provided at the top of a casing pipe installed at the excavation position of the ground, and the stabilizing liquid and excavated soil flow into the recovery pit. The excavated soil having a lower density may float upward, and the excavated soil having a higher density than the stabilizing liquid may sink to the bottom, thereby separating the stabilizing liquid from the excavated soil.

A second invention is a ground excavation method in which the ground is excavated in an excavation section while a stabilizing liquid is supplied to the ground by a pump, and the stabilizing liquid contains sodium polytungstate. , a ground excavation method characterized in that the density of the stabilizing liquid is 2.7 g/cm ³ or more and 3.1 g/cm ³ or less, and the stabilizing liquid after excavation is separated from excavated soil and recovered. .

In the second invention, by using a stable liquid containing SPT, it becomes easier to transport excavated soil to the surface due to the effect of heavy liquid separation, which reduces the drilling load during excavation and improves excavation efficiency. do. In addition, construction costs can be reduced by separating the stabilizing liquid from the excavated soil, collecting it, and repeatedly reusing it.
Further, since the density of the stabilizing liquid is 2.7 g/cm ³ or more and 3.1 g/cm ³ or less, the wall surface of the hole can be stably protected even in an environment with high groundwater pressure. Further, when a stabilizing liquid containing SPT is supplied to the ground, the drilling load on the excavation part is reduced as the density of the stabilizing liquid increases, so it is possible to improve the efficiency of excavation.

In the second aspect of the invention, for example, the excavation of the ground is boring, and the excavation part drills a hole in the ground in a substantially vertical direction. Further, a casing pipe having a branch pipe at the upper part is installed at the excavation position of the ground, and a recovery pit is provided into which the stabilizing liquid and excavated soil after excavation flow from the branch pipe, and in the recovery pit, the stabilizing liquid The excavated soil having a lower density may float upward, and the excavated soil having a higher density than the stabilizing liquid may sink to the bottom, thereby separating the stabilizing liquid from the excavated soil. Further, the ground may be an underwater bottom, and the stabilizing liquid and excavated soil after excavation may be recovered by a pipe disposed above the excavation part.
This makes it possible to efficiently drill holes substantially vertically in the ground above ground or at the bottom of the water.

Further, the excavation of the ground may be performed by drilling a hole using a shield machine, and the excavation unit may perform drilling in a substantially horizontal direction with respect to the ground.
This makes it possible to efficiently drill holes in the ground in a substantially horizontal direction.

According to the present invention, it is possible to provide an excavation system and a method for excavating the ground that can efficiently excavate the ground using a stable liquid whose density can be easily adjusted and does not separate.

FIG. 3 is a diagram showing a state in which a hole 23 is being excavated using the excavation system 2; Diagram showing the excavation procedure. The figure which shows the relationship between the density of a stabilizing liquid, and a torque value. The figure which shows the state where the hole 23 is being excavated using the excavation system 2a. The figure which shows the state where the hole 23a is being excavated using the excavation system 2b.

Hereinafter, a first embodiment of the present invention will be described in detail based on the drawings.
FIG. 1 is a diagram showing a state in which a hole 23 is being excavated using the excavation system 2. As shown in FIG. 1, the excavation system 2 includes an excavation part 3 provided at the tip of a rod 5 held by a boring machine 9 on the ground 1, a recovery pit 13 formed in the ground 1, and an adjustment part 14 built in. It consists of a supply pump 11b and the like. In the first embodiment, a hole 23 is excavated in the ground 1 in a substantially vertical direction using the excavation system 2.

FIG. 2 is a diagram showing the procedure for drilling the hole 23. To drill the hole 23, first, a stabilizing liquid 15 containing SPT is prepared (S101). In S101, the stabilizing liquid 15 is prepared by dissolving solid SPT in water in the adjustment unit 14. SPT is a harmless, odorless, nonflammable solid, and an SPT solution prepared by dissolving SPT in water is also harmless. The density of the stabilizing liquid 15 is determined according to the conditions of the ground 1 to be excavated, but it is preferably 1.8 g/cm ³ or more and 3.1 g/cm ³ or less, and preferably 2.7 g/cm ³ or more. Particularly desirable.

Next, it is confirmed whether the density of the stabilizing liquid 15 is equal to or higher than a predetermined density (S102). If the predetermined density is not reached, the process returns to S101 and the density of the stabilizing liquid 15 is adjusted.

If the SPT solution has a predetermined density or higher, the ground 1 is excavated while supplying the stabilizing liquid 15 (S103). In S103, the excavation part 3 at the tip of the rod 5 is rotated and lowered by the boring machine 9 from inside the casing pipe 7 installed at the excavation position of the ground 1, and a substantially vertical hole 23 is drilled in the ground 1. I will do it. During drilling of the hole 23, the supply pump 11b is operated to send the stabilizing liquid 15 from the adjustment unit 14 to the excavation part 3 via the supply pipe 21, and the stabilizing liquid 15 is supplied to the ground 1 from the vicinity of the excavation part 3. do. The stabilizing liquid 15 removes and cleans the excavated soil 17 from the bottom of the hole 23 and the vicinity of the excavated portion 3, and also transports the excavated soil 17 to the vicinity of the ground. In addition, the hole 23 is filled with the hole 23 to prevent the hole wall 25 from collapsing.

The stabilizing liquid 15 containing SPT is a heavy liquid having a higher density than muddy water such as a bentonite solution. Therefore, the excavated soil 17 tends to float in the stabilizing liquid 15 due to the effect of heavy liquid separation. The excavated soil 17 rises in the hole 23 filled with the stabilizing liquid 15 and flows into the recovery pit 13 from the branch pipe 71 of the casing pipe 7 together with the stabilizing liquid 15. In the recovery pit 13, excavated soil 17a, which has a lower density than the stabilizing liquid 15, separates from the stabilizing liquid 15 and floats upward. If excavated soil 17b, which has a higher density than the stabilizing liquid 15, is mixed, it sinks to the bottom of the recovery pit 13.

In the example shown in FIG. 1, the stabilizing liquid 15 and the excavated soil 17 are collected from the branch pipe 71 provided in the casing pipe 7 to the collection pit 13, but the collection method is not limited to this. The stabilizing liquid 15 and the excavated soil 17 may be recovered from the inside of the casing pipe 7 into the recovery pit 13 using a pump.

Here, the density of the stabilizing liquid 15 and the drilling load in the excavation section 3 will be described. FIG. 3 is a diagram showing the relationship between the density of the stabilizing liquid 15 and the torque value. The dotted line 27 in FIG. 3 shows the torque value when sand alone is directly excavated, and the dotted line 28 shows the torque value when sand is mixed with bentonite mud, which is commonly used. The black circles are calculated from the density of Stabilizing Solution 15 and the vane shear strength when performing an indoor vane shear test by changing the density of Stabilizing Solution 15 on a mixture of Stabilizing Solution 15 containing SPT and gravel soil. The relationship between the torque value and the torque value during drilling is shown.

From FIG. 3, it can be confirmed that when the stabilizing liquid 15 containing SPT is used, as the density of the stabilizing liquid 15 increases, the torque value becomes smaller and the drilling load is reduced. If the density of the stabilizing liquid 15 is set to the above-mentioned desirable value of 1.8 g/cm ³ or more, the torque value can be reduced more than when a general bentonite slurry is used. Moreover, if the torque value is set to 2.7 g/cm ³ or more, which is a particularly desirable value, the torque value can be significantly reduced. This is thought to be due to the fact that when the stabilizing liquid 15 with a high density is used, even sand with a density of about 2.7 g/cm ³ becomes easier to float upward.

After boring is performed in S103, the stabilizing liquid 15 is collected and the excavated soil 17 is separated by, for example, a filter or a separator (S104). In S104, the recovery pump 11a built in the adjustment unit 14 is operated to recover the stable liquid 15 from the recovery pit 13 via the recovery pipe 19. As a result, the stabilizing liquid 15 separated from the excavated soil 17a and 17b in the recovery pit 13 is stored in the adjustment section 14. In the adjusting section 14, the recovered stabilizing liquid 15 may be further filtered in order to more reliably separate the excavated soil 17 from the stabilizing liquid 15. Incidentally, the excavated soil 17a and the excavated soil 17b in the recovery pit 13 are appropriately scooped out and disposed of.

Next, it is confirmed whether the hole 23 has been drilled to a predetermined depth (S105). After confirming that the hole has been drilled to a predetermined depth, the drilling is finished.

If the hole has not been drilled to a predetermined depth, a stabilizing liquid 15 containing SPT is prepared (S101). Note that before S101, SPT may be extracted from the recovered stabilizing liquid 15 (S106). When performing S106, the stabilizing liquid 15 is distilled in the adjustment unit 14 to extract solid SPT.

In S101 for the second and subsequent times, the adjustment unit 14 evaporates and concentrates water from the collected stabilizer liquid 15 to prepare a new stabilizer liquid 15. Alternatively, the solid SPT extracted in S106 may be made into a solution again to prepare a new stable liquid 15. Further, from the second time onward, the stabilizing liquid 15 may be circulated as it is by simply adjusting the density of the stabilizing liquid from which the excavated soil has been separated.

When drilling the hole 23, the steps shown in FIG. 2 are performed in parallel. That is, the hole 23 is drilled in the excavation part 3 while supplying the stabilizing liquid 15 to the ground 1, and at the same time, the stabilizing liquid 15 supplied to the ground 1 is collected and separated from the excavated soil 17, and the density of the stabilizing liquid 15 is determined. Readjust.

In the first embodiment, the density of the stabilizing liquid 15 can be easily adjusted by using SPT. Although SPT is expensive, recovery efficiency from the solution is good, so by separating the stabilizing liquid 15 from the excavated soil 17, recovering and reusing it, the cost of excavation can be reduced. Further, since the stabilizing liquid 15 containing SPT has a high density, the hole wall 25 can be stably protected even in an environment with high groundwater pressure. Furthermore, when the stabilizing liquid 15 containing SPT is used, as the density of the stabilizing liquid 15 increases, the drilling load is reduced, making it possible to improve the efficiency of drilling.

Stabilizing liquid 15 easily suspends excavated soil 17 due to the heavy liquid effect, and water-soluble SPT is difficult to separate from water in stabilizing liquid 15. Therefore, compared to the conventional stabilizing liquid in which solids are turbid, even if the circulation of the stabilizing liquid 15 is temporarily stopped for adding rods 5, etc., the excavated soil 17 in the stabilizing liquid 15 and SPT will not settle and the hole wall 25 will not collapse or the excavated portion 3 will be buried. Furthermore, the rod 5 is not stuck to the hole wall 25 due to thick mud walls, and the excavated portion 3 is not worn out.

Note that the stabilizing liquid 15 may be prepared by dissolving SPT in muddy water such as a bentonite solution. This makes it possible to reduce the material cost when increasing the density of the stabilizing liquid 15.

Further, in S102 shown in FIG. 2, the density is used as a control standard for the stabilizing liquid 15, but the stabilizing liquid 15 may be managed using viscosity instead of density. In this case, for example, the relationship between density and viscosity may be obtained in advance.

Hereinafter, other examples of the present invention will be described as second and third embodiments. In each embodiment, points different from the embodiments described up to that point will be explained, and similar configurations will be denoted by the same reference numerals in the figures, etc., and the explanation will be omitted. Furthermore, the configurations described in each embodiment, including the first embodiment, can be combined as necessary.

First, a second embodiment will be described. FIG. 4 is a diagram showing a state in which a hole 23 is being excavated using the excavation system 2a. The second embodiment differs from the first embodiment mainly in that the hole 23 is excavated into the ground 1 at the bottom of the water. The second embodiment is applicable to, for example, drilling holes in support foundations for offshore wind power generation (monopile type, jacket type, tripod type, tripile type), etc.

In the excavation system 2a, the recovery pit 13 and the adjustment section 14 are not provided, but a recovery adjustment section 16 is provided. The recovery adjustment unit 16 incorporates a recovery pump 11a to which a recovery pipe 19 is connected, a supply pump 11b to which a supply pipe 21 is connected, and the like.

In the second embodiment as well, a hole 23 is excavated in the ground 1 according to the procedure shown in FIG. In the second embodiment, in S101, the stable liquid 15 is prepared by dissolving solid SPT in water in the recovery adjustment unit 16 installed on the workbench 37 above the water.

In S103, the excavating part 3 at the tip of the rod 5 is rotated and lowered by the boring machine 9 on the workbench 37 to drill a hole 23 in the ground 1 at the bottom of the water in a substantially vertical direction. During drilling of the hole 23, the supply pump 11b is operated to send the stabilizing liquid 15 from the recovery adjustment section 16 to the excavation section 3 via the supply pipe 21, and the stabilizing liquid 15 is supplied from the vicinity of the excavation section 3 to the ground 1. supply The excavated soil rises in the stabilizing liquid 15 filled in the hole 23. Since the stabilizing liquid 15 has a higher density than seawater or the like, the stabilizing liquid 15 in the hole 23 protects the hole wall 25 without being easily replaced with seawater or the like.

In S104, the recovery pump 11a is operated to recover the stabilizing liquid 15 to the recovery adjustment section 16 via the recovery pipe 19 whose end is disposed above the excavation section 3. Since the recovered stabilizing liquid 15 contains excavated soil, the excavated soil 17 is separated from the stabilizing liquid 15 by filtration or the like in the recovery adjustment section 16 .

In S101 from the second time onwards, the recovery adjustment unit 16 evaporates and concentrates water from the recovered stable liquid 15 to prepare a new stable liquid 15. Alternatively, the solid SPT extracted in S106 may be made into a solution again to prepare a new stable liquid 15. Alternatively, the excavated soil may be separated, only subjected to density adjustment, and then circulated as is.

In the second embodiment, the same effects as in the first embodiment can be obtained by preparing the stabilizing liquid 15 using SPT and drilling the hole 23 using the stabilizing liquid 15 containing SPT. .

In the second embodiment, the end of the recovery pipe 19 is placed deep in the hole 23 (close to the excavation part 3), but the end of the recovery pipe 19 is located above the excavation part 3 and in the ground 1. It suffices if it is placed at a position somewhat deeper than near the surface layer. By arranging the end of the recovery pipe 19 in such a position, it is possible to prevent seawater or the like from entering the recovered stabilizing liquid 15.

Next, a third embodiment will be described. FIG. 5 is a diagram showing a state in which a hole 23a is being excavated using the excavation system 2b. The third embodiment differs from the first embodiment mainly in that the hole 23a is excavated in the ground 1 in a substantially horizontal direction.

In the excavation system 2b, the recovery pit 13 and the adjustment section 14 are not provided, but the recovery adjustment section 16 is provided. A sludge pipe 19a is connected to the recovery pump 11a of the recovery adjustment section 16, and a supply pipe 21a is connected to the supply pump 11b. Further, in the excavation system 2b, the excavation part 3 provided at the tip of the rod 5 held by the boring machine 9 is not provided, but the excavation part 3a is provided at the tip of the shield machine 29.

In the third embodiment as well, a hole 23a is excavated in the ground 1 according to the procedure shown in FIG. In the third embodiment, in S101, solid SPT is dissolved in water to prepare a stabilizing liquid 15 in the recovery adjustment unit 16 installed on the ground 1.

In S103, the shield machine 29 is started from within the shaft 30 built in the ground 1, and the hole 23a is drilled in the ground 1 in a substantially horizontal direction with the excavation part 3a at the tip of the shield machine 29. The shield machine 29 constructs the shield tunnel 35 by assembling the lining segments of the hole 23a within the main body 33. While drilling the hole 23a, the supply pump 11b is operated to send the stabilizing liquid 15 from the recovery adjustment section 16 to the chamber 31 of the shielding machine 29 via the supply pipe 21a. The stabilizing liquid 15 in the chamber 31 functions similarly to conventionally used muddy water.

In S104, the recovery pump 11a is operated to recover the stabilizing liquid 15 and the excavated soil to the recovery adjustment section 16 via the mud removal pipe 19a whose end is disposed within the chamber 31. Then, the excavated soil is separated from the stabilizing liquid 15 by filtration or the like in the recovery adjustment section 16 .

In S101 from the second time onwards, the recovery adjustment unit 16 evaporates and concentrates water from the recovered stable liquid 15 to prepare a new stable liquid 15. Alternatively, the solid SPT extracted in S106 may be made into a solution again to prepare a new stable liquid 15. Alternatively, the excavated soil may be separated and only the density adjusted, and the soil may be circulated as it is.

In the third embodiment as well, the same effects as in the first embodiment can be obtained by producing the stabilizing liquid 15 using SPT. Since water-soluble SPT is difficult to separate from water in the stabilizing liquid 15, the stabilizing liquid 15 does not separate in the chamber 31 even if the shielding machine 29 temporarily stops digging.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that those skilled in the art can come up with various changes or modifications within the scope of the technical idea disclosed in this application, and these naturally fall within the technical scope of the present invention. Understood.

1... Ground 3, 3a... Excavation part 5... Rod 7... Casing pipe 9... Boring machine 11a... Recovery pump 11b... Supply pump 13... Recovery pit 14... ...Adjustment part 15...Stabilizing liquid 16...Recovery adjustment part 17, 17a, 17b...Excavated soil 19...Recovery pipe 19a...Sludge removal pipe 21, 21a...Supply pipe 23, 23a……hole 25……hole wall 27, 28……dotted line 29……shield machine 30……shaft 31……chamber 33……main body 35……shield tunnel 37……work Stand 71……Branch pipe

Claims (8)

An excavation system for excavating the ground,
an excavation section that excavates the ground;
a pump that supplies a stabilizing liquid from the vicinity of the excavation part to the ground;
a recovery unit that recovers the stabilizing liquid;
Equipped with
An excavation system characterized in that the stabilizing liquid contains sodium polytungstate , and the density of the stabilizing liquid is 2.7 g/cm ³ or more and 3.1 g/cm ³ or less . 2. The excavation system according to claim 1 , wherein the stabilizing liquid recovered by the recovery section can be circulated to the ground by the pump after being separated from the excavated soil. The recovery unit includes a recovery pit into which the stabilizing liquid and excavated soil after excavation flow from a branch pipe provided at the top of a casing pipe installed at the excavation position of the ground,
In the recovery pit, excavated soil having a lower density than the stabilizing liquid floats upward, and excavated soil having a higher density than the stabilizing liquid sinks to the bottom, so that the stabilizing liquid is separated from the excavated soil. The excavation system according to claim 1 or claim 2. A ground excavation method in which the ground is excavated in an excavation section while supplying a stabilizing liquid to the ground with a pump,
The stabilizing liquid contains sodium polytungstate, and the stabilizing liquid has a density of 2.7 g/cm ³ or more and 3.1 g/cm ^{3 or} less,
A method for excavating ground, characterized in that the stable liquid after excavation is separated from excavated soil and recovered. The excavation of the ground is boring,
5. The ground excavation method according to claim 4 , wherein the hole is drilled in a substantially vertical direction with respect to the ground by the excavation part. A casing pipe having a branch pipe at the top is installed at the excavation position of the ground,
A recovery pit is provided into which stabilizing liquid and excavated soil after excavation flow from the branch pipe,
In the recovery pit, excavated soil having a lower density than the stabilizing liquid floats upward, and excavated soil having a higher density than the stabilizing liquid sinks to the bottom, so that the stabilizing liquid is separated from the excavated soil. The ground excavation method according to claim 5. the ground is an underwater bottom;
6. The ground excavation method according to claim 5 , wherein the stabilizing liquid and excavated soil are recovered after excavation by a pipe arranged above the excavation part. The excavation of the ground is drilling with a shield machine,
5. The ground excavation method according to claim 4 , wherein the hole is drilled in a substantially horizontal direction with respect to the ground by the excavation part.

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