JP2698768B2 - Method of forming underground continuous wall - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an underground continuous wall.

[0002]

2. Description of the Related Art Conventionally, slag grout has been introduced as a stabilizing liquid into a drill hole to prevent collapse of the hole wall of the drill hole, and thereafter, after a predetermined period of time, a calcium ion compounding agent has been added to the slag grout. No. 59-326 is a method of forming a continuous underground wall by hardening slag grout by administration.
No. 21 is known.

In this conventional example, slag, which is a main component of slag grout, does not harden simply by being mixed with water. Therefore, slag grout does not harden when slag grout is used as a stabilizing solution. There is no concern about hardening of slag grout when inserting drilled holes and reinforcing pillars, and when necessary, administer calcium ion compounding agent for the first time to induce latent hydraulicity of slag and harden slag I have. That is, in this conventional example,
The slag grout used as a stabilizing liquid is hardened by administering a calcium ion compounding agent only at the stage where the hardening is required, without curing during use as a stabilizing liquid.

[0004]

In the above conventional example, the slag grout used as the stabilizing liquid is cured as it is to form an underground continuous wall. Although it has the feature that the step of discharging the stabilizing liquid is not necessary, it is formed because the underground continuous wall is formed by administering the calcium ion compounding agent to the slag grout and curing the slag grout. The underground continuous wall is made of a hardened slag. For this reason, a large amount of slag to be used is required, and there is a case where sufficient strength cannot be ensured as an underground continuous wall because the aggregate is not mixed in the cured slag.

The present invention has been made in view of the above-mentioned problems of the prior art, and its main objects are as follows.
The slag grout placed in the preceding hole until the stage of formation of the trailing hole prevents collapse of the hole wall of the leading hole and facilitates formation of the trailing hole without hardening of the slag grout, and
When excavating while discharging cement milk in the following hole forming process, it is possible to easily excavate using a multi-axis excavator using the preceding hole as a guide, and stable in the following hole forming process. An object of the present invention is to form a strong underground continuous wall in which slag which is a main component of slag grout as a liquid, cement which is a main component of cement milk, and excavated earth and sand which are aggregates are mixed and integrated. Another purpose is to make the diameter of the leading hole smaller than that of the trailing hole, despite the fact that a wide thing can be formed as the underground continuous wall to be finally formed. To prevent as much as possible the collapse of the hole wall of the preceding hole, and furthermore, the slag, which is the main component of slag grout as a stabilizing liquid, the cement, which is the main component of cement milk, and the excavated earth and sand that become aggregate The purpose is to enable uniform mixing in the direction. Another purpose is to stir and mix the slag, which is the main component of slag grout as a stabilizing liquid, the cement, which is the main component of cement milk, and the excavated earth and sand that becomes the aggregate. The purpose of the present invention is to prevent the excavated soil from becoming uneven in the vertical direction. Another object is to increase the specific gravity of the stabilizing solution by mixing a part of the excavated earth and sand generated by the excavation of the preceding hole in the slag graph put in the preceding hole to increase the hole of the preceding hole. The purpose is to prevent the collapse of the wall.

[0006]

In order to solve the above-mentioned problems of the prior art and achieve the object of the present invention, the method of forming an underground continuous wall according to the present invention uses a preceding hole in which a slag grout 1 is inserted. 2 are formed with a gap therebetween, and then the outer ground of the preceding hole 2 is excavated to form a large-diameter trailing hole 3 and the unexcavated ground between the preceding holes 2 is excavated to form a large-diameter trailing hole. The hole 3 is formed to form a continuous hole 5 in which adjacent large diameter trailing holes 3 partially overlap each other in a plan view, and the cement milk 4 is discharged when the continuous hole 5 is formed. And excavated earth and sand,
The slag grout 1 of the preceding hole 2 is stirred and mixed.

Further, a plurality of leading holes 2 in which the slag grout 1 is inserted are formed with a gap therebetween, and thereafter, the unexcavated ground between the leading holes 2 is excavated to form trailing holes 3 to form adjacent holes. Forms a continuous hole 5 partially overlapping in plan view,
The method may be characterized in that the cement milk 4 is discharged at the time of forming, and the cement milk 4, the excavated earth and sand, and the slag grout 1 of the preceding hole 2 are stirred and mixed.

In forming the preceding hole 2 in which the slag grout 1 is inserted, almost all of the excavated earth and sand generated when the preceding hole 2 is formed is replaced with the slag grout 1 and the excavated earth and sand is discharged to the ground. In addition, it is preferable that the slag grout 1 is filled in the preceding hole 2. Conversely, when forming the preceding hole 2 in which the slag grout 1 is inserted, part of the excavated earth and sand generated during the formation of the preceding hole 2 is left in the preceding hole 2 and the other is placed on the ground. In the slag grout 1 which is discharged and put in the preceding hole 2, the leading hole 2
It is also preferable that a part of excavated earth and sand generated at the time of formation is mixed.

[0009]

According to the method of the present invention as described above, the slag grout 1 in the preceding hole 2 is formed by forming a plurality of preceding holes 2 containing the slag grout 1 with a gap therebetween. It acts as a stabilizing solution and prevents the collapse of the hole wall of the preceding hole 2. Since the stabilizing liquid is the slag grout 1, the slag grout 1 does not harden even after a long time (for example, one day or more from the formation of the leading hole 2 to the formation of the trailing hole 3), and the trailing hole 3 can be performed without any trouble. In forming the trailing hole 3, the outer peripheral ground of the preceding hole 2 is excavated to form a large diameter trailing hole 3, and the unexcavated ground between the preceding holes 2 is excavated to form a large diameter trailing hole. 3 to form a continuous hole 5 in which the adjacent large diameter trailing holes 3 partially overlap each other in a plan view, and discharge the cement milk 4 when the continuous hole 5 is formed. , Excavated earth and sand,
Since the slag grout 1 in the preceding hole 2 is stirred and mixed, the latent hydraulic property of the slag is induced by the cement component of the cement milk 4, and the slag is hardened together with the hardening of the cement, and the excavation becomes cement, slag, and aggregate. A strong underground continuous wall can be formed by an integrated product of slag, cement and soil in which earth and sand are integrated. In forming the trailing hole 3, a large diameter trailing hole 3 is formed by excavating around the leading hole 2, and the unexcavated ground between the leading holes 2 is drilled to form the trailing hole 3. In the formation of the large-diameter trailing hole 3, excavation can be performed using the multi-hole excavator with the leading hole 2 as a guide. In the trailing hole 3 formed around the leading hole 2, excavated earth and sand is generated when the trailing hole 3 is formed, and the trailing hole 3 formed in the undigged ground between the leading hole 2 is formed. Inside the trailing holes 3, excavated sediment is generated when the trailing holes 3 are formed. As a result, when the excavated sediment, cement milk, and slag grout are stirred and mixed, the excavated sediment is present in each trailing hole 3, The excavated earth and sand as the material can be uniformly dispersed in the lateral direction.

Further, a plurality of leading holes 2 in which the slag grout 1 is inserted are formed with a gap therebetween, and thereafter, the unexcavated ground between the leading holes 2 is excavated to form trailing holes 3 to form adjacent holes. Forms a continuous hole 5 partially overlapping in plan view,
In the case where the cement milk 4 is discharged at the time of forming and the cement milk 4, the excavated earth and sand and the slag grout 1 of the preceding hole 2 are stirred and mixed, the preceding hole 2 in which the slag grout 1 is put is filled with a gap. By forming multiple at a distance,
The slag grout 1 placed in the preceding hole 2 acts as a stabilizing liquid to prevent the collapse of the hole wall of the preceding hole 2. Here, the slag grout 1 is used as the stabilizing liquid, and therefore, the slag grout 1 has a long time (for example,
The slag grout 1 does not harden even after a lapse of one day from the formation of the trailing hole 3 to the formation of the trailing hole 3, so that the forming operation of the trailing hole 3 can be performed without any trouble. The unexcavated ground between the preceding holes 2 is excavated to form a continuous hole 5 in which adjacent holes partially overlap with each other in a plan view, and when the continuous hole 5 is formed, the cement milk 4 is discharged and the cement milk 4 is discharged. By stirring and mixing the milk 4, excavated earth and sand, and the slag grout 1 of the preceding hole 2, the latent hydraulic property of the slag is induced by the cement component of the cement milk 4, and the slag is hardened together with the hardening of the cement, A strong underground continuous wall can be formed by an integrated product of slag, cement, and soil in which cement, slag, and excavated earth and sand as aggregate are integrated. In forming the continuous hole 5, the preceding hole 2 formed with a gap in between.
While excavating the unexcavated ground between the preceding holes 2 while inserting the rotating shafts at both ends of the multi-screw excavator into the preceding holes 2 with the guide as a guide, cement milk 4, excavated earth and sand, and the slag grout 1 of the preceding holes 2 The agitation and mixing of the slag and the slag make it easy and easy and reliable to excavate the continuous hole 5 and a strong underground with a strong slag / cement / soil integrated with cement, slag, and excavated earth and sand as aggregate. A continuous wall can be formed.

In forming the preceding hole 2 in which the slag grout 1 is inserted, almost all of the excavated earth and sand generated during the formation of the preceding hole 2 is replaced with the slag grout 1 and the excavated earth and sand is discharged to the ground. In addition, in the case where the slag grout 1 is filled in the preceding hole 2, the excavated earth and sand generated when the preceding hole 2 is formed is almost completely replaced with the slag grout 1, and Means that almost only the slag grout 1 is filled. Here, if the excavated earth and sand are mixed in the preceding hole 2, when a long time elapses until the formation process of the following hole, the excavated earth and sand having a large specific gravity gradually increases because the hardening of the slag has not started. There is a possibility that the mixed state of the excavated earth and sand in the preceding hole 2 will be different between the upper and lower parts by sinking to the lower side of the preceding hole 2.
When the excavated sediment and the slag grout are almost completely replaced as described above and the excavated sediment is discharged to the ground, there is no such a possibility. As a result, the excavated sediment and the excavated sediment excavated in the formation process of the trailing hole 3 are eliminated. When mixing and hardening with cement milk, the excavated earth and sand starts to harden in a state in which those excavated in the formation process of the trailing hole 3 are mixed almost uniformly in the vertical direction, and slag and excavation are performed. Mixing of earth and sand and cement can form an underground continuous wall that is substantially uniform in the vertical direction.

In forming the preceding hole 2 in which the slag grout 1 is inserted, part of the excavated earth and sand generated during the formation of the preceding hole 2 is left in the preceding hole 2 and the other is discharged to the ground. In addition, when the slag grout 1 placed in the preceding hole 2 contains part of the excavated earth and sand generated during the formation of the preceding hole 2, the excavated earth and sand is filled in the slag grout 1 filled in the preceding hole 2. By being mixed, the specific gravity of the stabilizing liquid becomes larger than that of the slag grout 1 alone, and as a result, the collapse of the hole wall of the preceding hole 2 becomes more reliable.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments shown in the accompanying drawings. 1 to 7 show one embodiment of the present invention. First, the leading hole 2 is formed in the ground 30 by a drilling device such as the screw auger 6. The preceding hole 2 is formed by an anhydrous drilling, and excavated earth and sand is discharged and removed to the ground when the preceding hole 2 is excavated by an excavator such as a screw auger 6. Then, the slag grout 1 is put into the preceding hole 2 where the excavated earth and sand is discharged to the ground. Here, as an example, FIG.
The preceding hole 2 is formed in the ground 30 by the screw auger 6 in the order of (a) to (e), and the excavated earth and sand 20 generated at the time of forming the preceding hole 2 is discharged to the ground. Then, FIG.
As shown in (f), a method in which the slag grout 1 is filled in the preceding hole 2 can be adopted. Further, as another method, the construction is performed in the order of FIGS. 2A to 2E. In this embodiment, when the screw auger 6 shown in FIG. The slag grout 1 is discharged from the lower end to fill the slag grout 1 at the trace where the excavated earth and sand 20 is discharged.

Here, the excavated earth and sand 20 generated at the time of forming the preceding hole 2 discharged on the ground is not mixed with the liquid.
Even if it can be treated as it is, it can be treated as backfill at the site, or it can be transported outside the site, but it is treated as industrial waste such as soil cement mud because it is soil. In comparison, the processing cost is much lower.

Slag grout 1 used in the present invention
Is, for example, slag 1000 kg, bentonite 90 k
g and 25,000 kg of water, and the specific gravity is about 1.25. The leading holes 2 filled with the slag grout 1 as described above are spaced apart from each other at regular intervals in FIG.
A plurality is formed as shown in FIG. In this case, the hole diameter of the leading hole 2 is, for example, 450 mm, and the leading hole 2 has a pitch of 900 mm.
Is formed so that the 450 mm unexcavated ground exists between the preceding holes 2 to sequentially form the preceding holes 2 filled with the slag grout 1.

Here, in forming the preceding hole 2, the working efficiency is improved by continuously constructing only the preceding hole 2, so that the preceding hole 2 is continuously constructed to some extent and only the preceding hole 2 is continuously constructed. After the leading hole 2 is formed, the trailing hole 3
It takes a long time (for example, one day or several days) to form slag grout 1. During this time, slag grout 1 has latent hydraulic property, but hardening is not performed because calcium such as cement is not added. When the slag grout 1 is not formed, the slag grout 1 is hardened at the time of forming the trailing hole 3 so as not to hinder the formation of the trailing hole 3. During the period from the formation of the leading hole 2 to the formation of the trailing hole 3, a heavy machine equipped with the screw auger 6 moves on the ground to form the plurality of leading holes 2, or forms the leading hole 2. In order to prevent the hole wall of the leading hole 2 from collapsing due to, for example, a machine for disposing of the excavated earth and sand 20 discharged on the ground or a truck for transportation moving on the ground, etc. The slag grout 1 placed therein acts as a stabilizing liquid to prevent the wall of the preceding hole 2 from collapsing.

Next, a large diameter trailing hole 3 is formed by excavating around the preceding hole 2 and a large diameter trailing hole 3 is formed by excavating the unexcavated ground between the preceding holes 2. A continuous hole 5 is formed by partially overlapping the large-diameter trailing holes 3 in plan view, and the cement milk 4 is discharged by discharging the cement milk 4 when the continuous large-diameter trailing holes 3 are formed. And excavated earth and sand, preceding hole 2
And the slag grout 1 is stirred and mixed. Here, in forming the large-diameter trailing hole 3, the rotary kneading shaft 7 is used.
Uses a multi-axis excavator in which a plurality of drills are arranged. Here, in the multi-spindle excavator, the rotation trajectories of the adjacent rotary kneading shafts 7 partially overlap in plan view. Specifically, the rotation trajectory of the bit 8 and the stirring means 9 provided on the rotary kneading shaft 7 partially overlaps in plan view with the rotation trajectory of the bit 8 and the stirring means 9 provided on the adjacent rotary kneading shaft 7. Is used.

FIG. 3 shows the order of forming the large-diameter trailing hole 8 using the above-described multi-screw excavator. First, as described above, as shown in FIG. 3A, a plurality of preceding holes 2 in which the slag grout 1 is placed are formed with a gap therebetween, and thereafter, after an elapse of an arbitrary time, FIG. The first preceding hole 2a and the second preceding hole 2
b, the lower ends of the rotary kneading shafts 7 on both sides of the multi-screw excavator are positioned, and in this state, the rotary kneading shafts 7 on both sides are brought into the first leading position as shown in FIGS. 3 (c) and 3 (d). The first and second preceding holes 2 are excavated using the holes 2a and the second preceding holes 2b as guides.
a and 2b are excavated by the rotary kneading shafts 7 on both sides to form a large diameter trailing hole 3 and an intermediate rotary kneading shaft 7 is provided.
To excavate the unexcavated ground between the adjacent first and second preceding holes 2a and 2b to form a large-diameter trailing hole 3 in this portion, while the large-diameter trailing hole 3 partially overlaps A continuous hole is formed. Here, in the embodiment, for example, the diameter of the large diameter trailing hole 3 is 550 mm. In this excavation, excavation is performed while cement milk is injected from the rotary kneading shaft 7. At this time, the excavation and the stirring and mixing may be improved by simultaneously injecting air from an arbitrary rotary kneading shaft 7. Stirring means provided on each rotary kneading shaft 7 with slag grout put in the preceding hole 2 at the time of excavation, cement milk injected at the time of excavation, and excavated earth and sand generated at the time of forming the large diameter trailing hole 3 9 and mixed.
Next, the multi-screw excavator is pulled up as shown in FIGS.

Next, as shown in FIG. 5 (a), the multi-axis excavator is moved laterally by one pitch of the leading hole 2, and
(B), as shown in FIG. 5C, the rotary kneading shafts 7 on both sides are dug while inserting the leading hole 2 as a guide to form a large-diameter trailing hole 3 on the outer periphery of the leading hole 2 and are both intermediate. Rotary kneading shaft 7
Thereby, the large-diameter trailing hole 3 is formed in the unexcavated ground, and the large-diameter trailing hole 3 forms a continuous hole 5 that partially overlaps and continues. In this excavation, excavation is performed while the cement milk 4 is injected from the rotary kneading shaft 7. In this excavation, excavation is performed while cement milk is injected from the rotary kneading shaft 7.
At this time, the excavation and the stirring and mixing may be improved by simultaneously injecting air from an arbitrary rotary kneading shaft 7. Each rotary kneading shaft 7 is provided with the slag grout 1 that has been put in the preceding hole 2 at the time of the excavation, the cement milk 4 injected at the time of the excavation, and the excavated earth and sand generated at the time of forming the large-diameter trailing hole 3. The mixture is stirred and mixed by the stirring means 9. Next, as shown in FIGS. 6A and 6B, the multi-screw excavator is pulled up. Cement milk may or may not be injected when the multi-screw excavator is lifted during the above process. In addition, air may or may not be injected at the time of lifting.

Similarly, the large diameter trailing holes 3 are successively formed one after another. When the large diameter trailing hole 3 is continuously formed, the slag in the slag grout having latent hydraulicity is induced by stirring and mixing by the stirring means 9 to harden the slag and cement. This makes it possible to form a strong underground continuous wall formed by integrating slag, cement, and soil in which cement, slag, and excavated earth and sand as aggregate are integrated.

The construction order of the above embodiment is shown in a plan sectional view as shown in FIGS. 7 (a), (b), (c), (d)... By the way, the slag cement soil formed in this way has a long-term strength due to the hardening of the slag compared to the so-called soil cement, which is a solidified product of the conventional cement and the soil that is the excavated earth and sand of the original ground. In addition, the strength is increased due to the presence of excavated earth and sand as aggregate, compared to the case where the slag grout is only hardened by adding a calcium component to the slag grout. It is possible to form an underground continuous wall having a higher strength than an underground wall or an underground wall obtained by hardening slag grout. And since the slag grout used as the stabilizing liquid for the preceding hole 2 is used as it is as the constituent material of the underground continuous wall without discharging, the step of discharging the stabilizing liquid to the ground and treating it is not necessary. (Also, even if a part of the slag grout comes out on the ground, it is easy to dispose because it is a small amount.) Also, it is used as it is as a constituent material of the underground continuous wall without discharging the stable liquid to the ground. In addition, by using it as a hardening material, the amount of cement milk used as a hardening material can be reduced, and the amount of high-cost cement used can be reduced, making it possible to use slag that is easier to use than cement. The construction cost can be reduced.

FIGS. 8 to 12 show another embodiment of the present invention. In this embodiment, the steps up to FIG. 3 and FIG. 4 are performed in the same manner as in the above-described embodiment (that is, excavation of the outer periphery of the first and second leading holes 2a and 2b by the multi-axis excavator and the first step). , Excavation of the unexcavated ground between the second preceding holes 2a, 2b, and agitation and mixing of the cement milk, slag grout, and excavated earth and sand are finished, and the multi-screw excavator is lifted to the ground. 8 (a) and 8 (b)
(C), excavation of the ground around the third and fourth leading holes 2c and 2d by the multi-axis excavator in the order of FIGS.
Excavation of unexcavated ground between the fourth preceding holes 2c and 2d, and agitation and mixing of cement milk, slag grout, and excavated earth and sand, and then perform a process of lifting the multi-axial excavator to the ground, After that, the large diameter formed by excavating the outer peripheral ground of the second preceding hole 2b and the third preceding hole 2c in the order of FIGS. 10 (a), (b), (c) and FIGS. 11 (a), (b). The rotary kneading shaft on both sides of the multi-screw excavator is inserted into the trailing hole 3 to excavate the unexcavated ground between the trailing holes 3 with both large diameters, and the cement milk, slag grout, and the excavated earth and sand are stirred. Mixing is performed.

The construction order of the above embodiment is shown in a plan sectional view as shown in FIGS. 12 (a), (b), (c), (d), (e), (f). In each of the above-described embodiments, an example is shown in which the leading hole 2 has a smaller diameter than the trailing hole 3. This is because the smaller the diameter of the preceding hole 2 is, the more difficult it is for the hole wall to collapse, and the longer the distance between the preceding holes 2 is, the more difficult it is for this portion to collapse. The longer the distance between the holes 2, the better the prevention of collapse. In addition, since the leading hole 2 has a smaller diameter than the trailing hole 3, when forming the trailing hole 3 with a large diameter, the ground around the outer periphery of the small diameter hole 2 is excavated to form the trailing hole 3 with a large diameter. Excavation of the unexcavated ground between the small diameter holes 2 results in excavation of the large diameter trailing holes 3. As a result, excavated earth and sand is deposited in each large diameter hole 3 portion of the continuous large diameter trailing holes 3. As a result, the mixture of slag, excavated earth and sand, and cement can form a substantially uniform underground continuous wall in the lateral direction.

In the embodiment shown in FIG.
An example is shown in which the diameters of the trailing hole 3 and the trailing hole 3 are the same. In this embodiment, in the embodiment shown in FIGS. 1 to 7, the leading hole 2 and the trailing hole 3 have the same diameter, and when the trailing hole 3 is formed, the rotary kneading shafts 7 on both sides of the multi-screw excavator are used. 1 except that the outer peripheral ground of the preceding hole 2 is not excavated, and only the unexcavated ground between the preceding holes 2 is excavated by the intermediate rotary kneading shaft 7. This is performed in the same manner as in the example.

In the embodiment shown in FIG. 14, there is shown another example in which the leading hole 2 and the trailing hole 3 have the same diameter. In this embodiment, the leading hole 2 and the trailing hole 3 have the same diameter in the embodiment shown in FIGS.
When the trailing hole 3 is formed, the rotary kneading shafts 7 on both sides of the multi-screw excavator are provided.
8 except that the outer ground of the preceding hole 2 is not excavated and only the unexcavated ground between the preceding holes 2 is excavated by the intermediate rotary kneading shaft 7. This is performed in the same manner as in the example.

When the leading hole 2 has the same diameter as the trailing hole 3 as in the embodiment shown in FIGS. 13 and 14, when the trailing hole 3 is formed by the multi-screw excavator, the distance between the leading hole 2 is reduced. Since only the unexcavated ground needs to be excavated, the rotational power of the multi-axis excavator can be reduced. By the way, in the above embodiment, the leading hole 2 in which the slag grout 1 is
Is formed, almost all of the excavated earth and sand generated during the formation of the preceding hole 2 is discharged to the ground, and the slag grout 1 is filled in the discharge trace of the excavated earth and sand of the preceding hole 2. An example in which excavated earth and sand generated by the formation of the preceding hole 2 and the slag grout 1 are almost completely replaced is shown. When the slag grout 1 and the excavated soil generated by the formation of the preceding hole 2 are almost completely replaced in this way, the leading hole 2
The inside is almost completely filled with the slag grout 1. Here, if excavated earth and sand are mixed in the preceding hole 2, the slag grout, which is a stable liquid, is hardened when a long time elapses from the formation of the preceding hole 2 to the formation of the large-diameter trailing hole 3. Has not started, the excavated earth and sand having a large specific gravity gradually sinks to the lower side of the preceding hole 2, and the mixed state of the excavated earth and sand in the slag grout in the preceding hole 2 may be different between the upper part and the lower part. If the large diameter trailing hole 3 is formed in this state, there is a possibility that the mixing ratio of the excavated earth and sand will be higher at the lower part, but the leading hole 2 is formed until the trailing hole 3 is formed as in the present embodiment. By forming only the slag grout which is almost a stable liquid into the inside, when forming the large diameter trailing hole 3 in the final step, the excavated earth and sand, the slag grout, and the cement milk are vertically aligned. Almost evenly mixed Mixing stirrable, is cured in this state is started, in which slag, drilling soil, mixing of the cement to form a substantially uniform continuous underground wall in the vertical direction.

On the other hand, contrary to the above embodiment, when forming the preceding hole 2 in which the slag grout 1 is inserted, a part of the excavated earth and sand generated at the time of forming the preceding hole 2 is left in the preceding hole 2. Alternatively, some of the excavated earth and sand generated during the formation of the preceding hole 2 may be mixed in the slag grout 1 placed in the preceding hole 2 while discharging the others to the ground. In this case, the slag grout 1 is well mixed and stirred so that a part of the excavated earth and sand generated by the excavation of the preceding hole 2 and the slag grout 1 are not separated. In this embodiment, since the excavated earth and sand are mixed in the slag grout 1 filled in the preceding hole 2, the specific gravity as a stabilizing liquid is larger than that of the slag grout 1 alone. Thus, the collapse of the pore wall becomes more reliable. By the way, when only the slag grout 1 of the above embodiment is filled in the preceding hole 2, for example, slag 1000 kg, bentonite 90 kg, water 25000
kg, and the specific gravity is about 1.25.
When 280 kg and 520 g of water contained in the earth and sand are mixed, the specific gravity of the earth and sand is 2.65, so that the entire specific gravity is about 1.59, which is higher than that of the slag grout alone. Thus, the higher the specific gravity of the stabilizing liquid filled in the preceding hole 2, the better the effect of preventing the peripheral wall of the preceding hole 2 from collapsing.
It is effective in the ground where the surrounding wall is easily collapsed.

The above-mentioned construction method in which the excavated earth and sand generated during the excavation of the preceding hole 2 is not mixed in the slag grout filled in the preceding hole 2, and the method of excavating the preceding hole 2 in the slag grout filling the preceding hole 2. The method of mixing part of the excavated earth and sand is selected according to the conditions of the site, the strength of the underground continuous wall to be formed, and the like. After the preceding hole 2 is formed, the casing may be fitted into the upper end of the preceding hole 2 to more reliably prevent the ground from collapsing. This casing is removed when the trailing hole 3 is formed.

In each of the above embodiments, after the trailing hole 3 is formed, a structural column such as H steel may be inserted into the hole. Further, in the above embodiment, the example of the three-axis excavator is shown, but the number of the multi-axis excavator may be three or more.

[0030]

According to the first aspect of the present invention, as described above, a plurality of leading holes containing slag grout are formed with a gap therebetween, and thereafter, the outer peripheral ground of the leading holes is excavated. To form a large-diameter trailing hole and excavate the unexcavated ground between the preceding holes to form a large-diameter trailing hole, and adjacent large-diameter trailing holes partially overlap in plan view. Forming a continuous hole,
Since the cement milk is discharged at the time of forming the continuous hole and the cement milk, the excavated earth and sand, and the slag grout of the preceding hole are stirred and mixed, the trailing hole is formed after forming a plurality of leading holes with a gap therebetween. When the trailing hole is formed by excavation with a multi-axis excavator, it is possible to excavate using the preceding hole as a guide, and by forming the preceding hole, the power of the multi-axis excavator can be reduced. is there. In order to form slag grout in the preceding hole when forming a plurality of preceding holes with a gap therebetween, it is possible to prevent collapse of the hole wall of the preceding hole by slag grout. Is not cured by itself, so that even if a long time elapses between the formation of the leading hole and the formation of the trailing hole, there is no problem in forming the trailing hole. In addition, excavating around the preceding hole to form a large-diameter trailing hole, and excavating the unexcavated ground between the preceding holes to form a large-diameter trailing hole. By partially overlapping in plan view, discharging cement milk at the time of forming the continuous large-diameter trailing hole, by stirring and mixing the cement milk, excavated earth and sand, and slag grout of the preceding hole,
The hardening of the slag in the slag blout used as the stabilizing liquid is induced by cement, and the stabilizing liquid can be used as a hardening material without the need to discharge the stabilizing liquid to the outside and dispose it on the ground. As it is used as a material, the amount of cement milk used can be reduced accordingly,
The cost can be reduced, and the slag and cement become hardening materials and harden integrally with the aggregate soil (that is, excavated earth and sand). It can form an underground continuous wall. Also, in forming the trailing hole, a large diameter trailing hole is formed by excavating around the preceding hole to form a large diameter trailing hole, and a large diameter trailing hole is formed by excavating the unexcavated ground between the preceding holes. In a continuous large-diameter trailing hole, excavated earth and sand is generated at the time of forming the trailing hole even in a trailing hole formed around the leading hole, and formed in unexcavated ground between the leading holes. In the trailing holes, excavated sediment is also generated during the formation of the trailing holes, and as a result, upon stirring and mixing the excavated soil, cement milk and slag grout, excavated sediment exists in each trailing hole. In addition, the excavated earth and sand as the aggregate can be uniformly dispersed in the lateral direction.

Further, in the invention according to claim 2 of the present invention, a plurality of leading holes in which slag grout is inserted are formed with a gap therebetween, and then the unexcavated ground between the leading holes is excavated to form a hole. A row hole is formed to form a continuous hole in which adjacent holes partially overlap each other in a plan view, and cement milk is discharged when the continuous hole is formed, and the cement milk, excavated earth and sand, and a slag of the preceding hole are formed. Since the grout and stirring are mixed, after forming a plurality of leading holes with a gap therebetween, a trailing hole will be formed, and when the trailing hole is formed by excavation with a multi-axis excavator, the leading hole is used as a guide. Of course, it is possible to excavate, and by forming the leading hole, the power of the multi-axis excavator can be reduced,
In particular, in forming a trailing hole using a multi-axis excavator, it is only necessary to excavate the unexcavated ground between the preceding holes and form a trailing hole, so that the power of the multi-axis excavator can be further reduced. Yes. In order to form slag grout in the preceding hole when forming a plurality of preceding holes with a gap therebetween, it is possible to prevent collapse of the hole wall of the preceding hole by slag grout. Is not cured by itself, so that even if a long time elapses between the formation of the leading hole and the formation of the trailing hole, there is no problem in forming the trailing hole. In addition, cement induces the hardening of the slag in the slag blowout that was used as a stabilizing liquid when the trailing hole was formed, and the stabilizing liquid can be used as a hardening material as is, and it is necessary to discharge the stabilizing liquid to the outside and dispose it on the ground. In addition, since slag is used as a hardening material, the amount of cement milk used can be reduced accordingly, and costs can be reduced.In addition, slag and cement become hardening materials and bone It hardens integrally with the material soil (that is, excavated earth and sand), and can form a strong underground continuous wall with the integrated slag, cement, and soil.

According to the third aspect of the present invention, in addition to the effect of the first or second aspect, in forming the preceding hole into which the slag grout is formed, Substantially all of the excavated soil generated during the formation of the hole is replaced with slag grout and the excavated soil is discharged to the ground and the slag grout is filled in the preceding hole, so after a long time has elapsed since the formation of the preceding hole, Even if you form a row hole,
The excavated sediment mixed with slag grout and cement milk is excavated sediment generated during the formation of trailing holes,
The sedimentation of excavated earth and sand is small, and the mixture of slag, excavated earth and sand, and cement can form a substantially uniform underground continuous wall in the vertical direction.

According to the invention of claim 4 of the present invention, in addition to the effect of the invention of claim 1 or 2, in forming the preceding hole in which the slag grout is formed, Part of the excavated soil generated during the formation of the preceding hole in the slag grout placed in the preceding hole while leaving some of the excavated soil generated during the formation of the hole in the preceding hole and discharging the other to the ground Since the excavated earth and sand are mixed in the slag grout filled in the preceding hole, the specific gravity as a stabilizing liquid is larger than that of only the slag grout, and as a result, the collapse of the hole wall of the preceding hole It will be more certain.

[Brief description of the drawings]

FIGS. 1A to 1F are explanatory views showing an example of a forming order of preceding holes.

FIGS. 2A to 2E are explanatory views showing another example of the order of forming the leading holes.

3 (a) to 3 (d) are explanatory views showing a process of inserting a multi-axis excavator when forming a trailing hole.

4 (a) and 4 (b) are explanatory views showing a lifting step of the multi-axis excavator after the step of FIG.

5 (a) to 5 (c) are explanatory views of a step of re-inserting the multi-axis excavator after being shifted laterally after the step of FIG.

6 (a) and 6 (b) are explanatory views showing a step of lifting the multi-screw excavator after the step of FIG.

FIGS. 7 (a) to 7 (d) are plan sectional views showing a construction order of the above.

FIG. 8 shows a construction order of another embodiment of the present invention, and (a).
(C) is an explanatory view showing a step of inserting a multi-axis excavator when forming a trailing hole.

9 (a) and 9 (b) are explanatory views showing a lifting step of the multi-axis excavator after the step of FIG.

10 (a) to 10 (c) are explanatory diagrams of a step of re-inserting the multi-axis excavator after being shifted laterally after the step of FIG. 9;

11 (a) and (b) are explanatory views showing a lifting step of the multi-screw excavator after the step of FIG.

FIGS. 12 (a) to 12 (f) are plan sectional views showing a construction order according to the embodiment.

FIG. 13 shows still another embodiment of the present invention, and (a) to (d) are cross-sectional plan views showing the same working order.

FIG. 14 shows still another embodiment of the present invention, and (a) to (f) are plan sectional views showing the same working order as in the above.

[Explanation of symbols]

 Reference Signs List 1 slag grout 2 leading hole 3 trailing hole 4 cement milk 5 continuous hole

Claims (4)

(57) [Claims] 1. A plurality of preceding holes containing slag grout are formed with a gap therebetween, and thereafter, the outer peripheral ground of the preceding holes is excavated to form a large diameter trailing hole and unexcavated ground between the preceding holes. Excavating to form a large-diameter trailing hole to form a continuous hole in which adjacent large-diameter trailing holes partially overlap in plan view, and discharge cement milk when forming the continuous hole, A method of forming an underground continuous wall, comprising stirring and mixing said cement milk, excavated earth and sand, and slag grout of a preceding hole. 2. A plurality of preceding holes in which slag grout is inserted are formed with a gap therebetween, and thereafter, unexcavated ground between the preceding holes is excavated to form a trailing hole, and adjacent holes are formed in plan view. Underground continuity characterized by forming a continuous hole partially overlapping, discharging cement milk at the time of forming the continuous hole, and stirring and mixing the cement milk, excavated earth and sand, and slag grout of the preceding hole. How to form the wall. 3. When forming the preceding hole in which the slag grout is formed, almost all of the excavated earth and sand generated during the formation of the preceding hole is replaced with slag grout, and the excavated earth and sand is discharged to the ground and the slag grout is discharged. The method of forming an underground continuous wall according to claim 1 or 2, wherein the space is filled in the preceding hole. 4. When forming a preceding hole in which slag grout is formed, a part of the excavated earth and sand generated at the time of forming the preceding hole is left in the preceding hole, and the other is discharged to the ground, and the excavated soil is formed in the preceding hole. 3. The method of forming an underground continuous wall according to claim 1, wherein a part of excavated earth and sand generated at the time of forming the preceding hole is mixed in the slag grout put into the slag.