JP6502231B2 - Ground restoration method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method of restoring the ground which removes the columnar reformer constructed by the soil cement column method to realize the original state.

  When various structures and buildings are constructed on the ground, piles may be driven and ground improvement may be performed to prevent the settlement. There are various types of piles, such as iron, wood and concrete, and there are various embedding methods. Also for ground improvement, there are various methods as well, one of which is the soil cement column method. In this method, a cement-based solidifying material and water are pressed into the ground, and these are mixed with existing earth and sand to form a columnar reformer (soil cement column) with a substantially circular cross section. It can be constructed without any noise, and there is little noise and vibration at that time, and it is widely used mainly for residential applications.

  As an example of technical development on the soil cement column method, Patent Document 1 listed below can be mentioned. This document discloses a method of constructing and removing a soil cement column, and is characterized in that besides the construction, the removal can be easily implemented. Specifically, in the middle of construction of a soil cement column (hereinafter referred to as a column), a steel pipe (support and guide pipe) is inserted into the center, and it is gradually pulled up while rotating the stirring rod with this as a central axis. As described above, by using the steel pipe, the lateral movement of the stirring rod can be regulated, stable rotation is realized, mixing of the solidifying material and the earth and sand is promoted, and a uniform, high quality column can be constructed. Further, when removing the column, by embedding the hollow auger with the above-mentioned steel pipe as a guide, the cutting bit at the tip can contact with the column without escape and the whole column can be crushed smoothly.

  Next, with regard to the removal of the pile, various techniques have been developed according to the size and the like, and examples thereof include patent documents 2 and 3 listed below. Patent Document 2 discloses a removal apparatus for an existing pile with low noise and excellent workability as to a large diameter cast-in-place pile. This device is composed of a drilling casing equipped with two kinds of drilling blades, an intermediate casing connected to the rear of the drilling casing, etc., and the drilling casing is used to excavate the circumference of the existing pile annularly and the intermediate casing is sequentially Connect and push down the drilling casing. When the drilling casing reaches a deeper position than the existing pile, the periphery of the existing pile is cut off from the ground, and the existing pile can be lifted and removed without difficulty.

  Patent Document 3 discloses a method of removing an existing pile which is excellent in safety and which can obtain a stable ground by backfilling. In this method, the casing to be embedded so as to surround the existing pile is made a double structure, and the existing pile is drawn out with the inner pipe thereof, and then the filling material is supplied to the space where the existing pile has been removed and backfilling is performed. is there. However, the existing piles will not be pulled out at once, but will be pulled out in stages, and then filling materials will be supplied between the pulling operations to fill the space in the ground each time. Therefore, when the existing pile is completely withdrawn, backfilling is almost complete, and a stable ground can be obtained immediately. Moreover, by making a casing into a double structure, the existing pile can be pulled out on the ground as it is, and since the existing pile is crushed after that, it is excellent in safety.

Unexamined-Japanese-Patent No. 2012-21310 JP 2000-144735 A Japanese Patent Application Laid-Open No. 2003-64680

  Housing is also likely to be dismantled after about fifty years, as social factors such as generational changes are intertwined, and if the site is subsequently transferred, restoration of the situation may be required. At that time, if a columnar reformer is formed by the soil cement column method, it is necessary to remove it. Since this removal work is often performed in a narrow residential area, it is desirable that it can be performed without using a large-scale device. In addition, the surrounding environment such as vibration and noise should be fully considered. Although Patent Document 1 discloses a method for removing a soil cement column, the soil cement column here is premised on embedding a steel pipe in the center, and can not be used under any circumstances.

  The space created by the removal of the soil cement column is filled with earth and sand to be filled, but since the flowability of the original ground may be high, the earth and sand shall be injected with the casing embedded in the ground. There are many. Furthermore, in order to prevent the hollow from remaining in the ground, as in the case of Patent Document 3, the supply of earth and sand (filling material) may be performed stepwise. As described above, although various measures have been taken at the time of backfilling, due to the nature of soft ground, dents may occur in the ground surface after backfilling, making it impossible to realize the original restoration.

  The present invention has been developed based on the above situation, and aims to provide a method of restoring the ground which can remove the columnar reformer by soil cement column method while considering the surrounding environment, and also can realize the restoration of the original condition reliably. And

  The invention according to claim 1 for solving the above-mentioned problems is a method of restoring the ground on which a columnar reformer is formed, which cuts a portion surrounding a position away from the pillar reformer and excavating the ground. A cylindrical leading casing provided with a blade at its tip, a cylindrical intermediate casing connected to the rear of the leading casing, and a claw for entering the inside of both connected casings and breaking the columnar reforming portion The leading casing is rotated to excavate the periphery of the columnar reforming section, and the intermediate casing is sequentially connected to the rear portion of the leading casing, and the leading casing is subjected to the columnar modification. Next, the grab bucket is inserted into the two connected casings, and the columnar reformer is crushed by the claws and crushed. After the columnar reforming section is removed, the two connected casings are pulled up in stages several times, and inside the two casings. The backfill material is charged, and the backfill material is compacted at the front of the grab bucket, wherein the backfill material is charged, the two casings are pulled up, and the backfill material is compacted. The above three steps are repeated a plurality of times, and while raising all of the two casings to the ground, the method of restoring the ground is characterized in that the backfill material is uniformly pressed into the space from which the columnar reformer has been removed. .

  The present invention realizes the original restoration of the ground on which the columnar reformed portion is formed, and does not assume removal of a pile made of metal or concrete. The columnar reformer is generally called a soil cement column, which press-fits a cement-based solidifying material into the ground to solidify the existing earth and sand into a cylindrical shape and exerts a function equivalent to that of a pile. There is no limitation on the type of solidifying material and the method of construction. However, in order to strengthen soil cement columns, there may be restrictions when incorporating metal bars or reinforcing bars.

  The leading casing is used to excavate the outside of the columnar reformer annularly and is cylindrical. And "enclose a position away from the columnar reformer" in claim 1 means that the inner diameter of the leading casing is made larger than the outer diameter of the columnar reformer, and the existing casing is between the columnar reformer and the leading casing. It means that earth and sand of the sea enter. This is because the outer edge of the columnar reformed part is not clear, and the precipitate that has permeated from the columnar reformed part is removed by aging. In addition, the leading casing is embedded in the ground while being rotated using a construction machine such as an auger. Therefore, the lower end face of the leading casing is provided with a cutting blade for excavating the ground.

  The intermediate casing is connected to the upper end surface of the leading casing, is used to press the leading casing deep into the ground, and has a cylindrical outer diameter corresponding to the leading casing. Furthermore, it is also assumed that a plurality of intermediate casings are stacked vertically. However, since the connected casings are driven at the top projecting to the ground, adjacent casings are firmly connected by some means so that the propulsive force and rotational force can be transmitted reliably. Although this connecting means can be freely selected, a projection such as a flange is kept to a minimum because it hinders vertical movement.

  By sequentially connecting the leading casing and the intermediate casing, the overall length of the individual casings can be reduced, which makes it easy to carry in and out the site, and does not use a large crane at the time of construction. In addition to being able to lift individual casings with a small crane without difficulty, manual position adjustment is also possible, and connection and disconnection can be carried out smoothly. Besides, in the present invention, the leading casing is provided with a cutting blade, and the connected casing is rotated and pushed into the ground only by propelling downward. Therefore, noise and vibration are suppressed.

  At the time of construction, the intermediate casing is sequentially connected to the rear of the leading casing, but its reaching depth is in the vicinity of the lower portion of the columnar reformer. The depth of the columnar reformer will be determined based on materials at the time of construction and prior boring surveys. Then, after the casing reaches a predetermined depth, removal work of the columnar reformer is performed, but it is difficult to pull out to the ground while maintaining the shape due to its nature, and after being crushed internally, surrounding soil and sands It also discharges to the ground.

  The grab bucket is used for removing the columnar reforming section, and a pair of left and right buckets are hydraulically opened and closed. The grab bucket used in the present invention is circular as viewed from directly above, in consideration of insertion into the inside of the casing, and the gap with the inner circumferential surface of the casing is made as small as possible. Furthermore, the individual buckets that open and close are hemispherical, and the outer diameter is constant regardless of the degree of opening. In addition, the tips of the individual buckets are provided with a plurality of claws for breaking the columnar reforming portion. Therefore, when the bucket is fully opened, the claws are located near the inner circumferential surface of the casing, and when the bucket is subsequently closed, the columnar reforming section is pinched and broken from the outside.

  The grab bucket is attached to the tip of an arm of various construction machines, inserted into the inside of the casing, and its claws are hydraulically moved to break the columnar reformer. Further, the crushed columnar reformer etc. is scooped up from the casing and discharged to the ground by the inherent function of the grab bucket. Thus, by repeating crushing and discharging, excavation to the vicinity of the tip of the casing is completed. Since the crushing and discharge mentioned here are all performed inside the casing, it is possible to suppress the diffusion of noise. In addition, since the columnar reforming portion is crushed by being pinched by the claws, no impact noise is generated.

  After removing almost all the columnar reformer and sediments, and the inside of the casing becomes a mere hollow, a backfill material is put into it to recover the original condition. As for backfill materials, select the most suitable one according to the purpose, such as gravel and crushed stone. Further, in order to compact the backfilling material, the grab bucket is inserted into the inside of the casing and the surface is pressed. At the time of this pressing, the left and right buckets are closed, and the front surfaces thereof are brought into contact with the surface of the backfill material. As described above, the grab bucket is made as small as possible with respect to the inner circumferential surface of the casing, so that the entire surface of the backfill material is uniformly compressed.

  Loading of backfilling materials is done in conjunction with pulling up of the casing. Specifically, after a certain amount of backfilling material has been introduced, the casing is pulled up by a certain distance and then compacted. By adopting this procedure, the backfilling material is quickly pushed into the annular space from which the casing has been removed to prevent the hollow from remaining in the ground. Then, the backfill material is again introduced into the casing, and then the casing is pulled up to compact the backfill material. By repeating these three steps, all of the casing is pulled up to the ground, and the backfilling material is compacted almost equally regardless of the depth.

  The amount of backfilling material to be introduced at one time is determined in balance with the subsequent consolidation. Specifically, the input amount is adjusted so that the effect of the compaction can reach the lowermost portion of the back-filling material introduced immediately before that. Therefore, the density of the backfilling material is uniform regardless of its depth. In addition, the pulling distance of the casing at one time is determined in consideration of the amount of backfilling material input. Specifically, the pull-up distance is adjusted so that the backfilling material can be introduced without any gap into the annular space generated by the removal of the casing, thereby preventing the hollow from remaining in the ground.

  As the casing is pulled up, the entire intermediate casing appears on the ground. The intermediate casing is separated from the underlying casing and has a reduced height above the ground. Then, the entire leading casing appears on the ground, and when tamping of the backfill material is finished, restoration of the original state of the place is realized. In addition, although it is premised that the column-like reformed part and earth and sand which were discharged do not contain harmful | toxic substances, such as hexavalent chromium, they can also be used as a backfill material in another location.

  Thus, noise and vibration are suppressed by embedding the casing by the rotation main body. Further, by using a grab bucket corresponding to the casing and sandwiching the columnar reforming section inside the casing, the entire cross section can be crushed at once without generating an impact noise. Furthermore, the density of the backfilling material becomes uniform over the entire area by repeating the filling of the backfilling material and the consolidation thereof, and it is difficult to cause the later loosening. The pulling up of the casing is synchronized with the insertion and backfilling of the backfilling material to prevent the backfilling material from entering the space without gaps even in the annular space from which the casing has slipped out, thereby preventing the hollow from remaining in the ground.

  As in the invention according to claim 1, by using the lead casing provided with the cutting blade at the tip and pressing it against the ground while rotating it, the ground is excavated little by little continuously, so that impact noise and vibration are generated. The leading casing can be made to reach near the lower part of the columnar reforming section without being accompanied by In addition, by sequentially connecting the leading casing and the intermediate casing, the overall length of the individual casings is reduced, which facilitates loading / unloading and work on site, and various construction machines used are small. In time, it can be installed without difficulty in a narrow residential area. Furthermore, since the columnar reforming section is pinched and crushed by the grab bucket inside the casing, it does not generate an impact sound and can also suppress the diffusion of noise.

  After almost completely removing the columnar reformer and soil in the casing, the loading of the backfilling material and its compaction are repeated stepwise, but the amount of the backfilling material loaded at one time is Suppress the effect to the extent to which it extends. As a result, the density of the backfilling material becomes uniform over the entire area, making it less likely to cause later loosening. The pulling up of the casing is synchronized with the insertion and backfilling of the backfilling material to prevent the backfilling material from entering the gap without gaps in the annular space from which the casing has come off, thereby preventing the hollow from remaining in the ground. By these effects, the ground after backfilling is stabilized, and the restoration of the original condition can be realized reliably.

It is a figure showing the flow of the restoration method of the ground by the present invention, and a pillar-shaped reformed part is formed in the ground. It is a figure which shows the detail of the process of throwing in a backfill material.

  FIG. 1 shows the flow of the method of restoring the ground G according to the present invention, in which a columnar reformed portion C is formed. The columnar reformer C is a soil cement column formed by a technique generally called a soil cement column method, and is a solidified cement-based material and existing earth and sand mixed and solidified into a cylindrical shape, and rebar and steel frame Etc. are not included. In addition, existing earth and sand remains as it is on the outer side of the columnar reforming section C.

  In order to remove the columnar reformed portion C, first, the outside of the columnar reformed portion C is excavated with the leading casing 11 as depicted on the upper left and the center of FIG. 1. The leading casing 11 has a cylindrical shape made of metal, and the lower end face thereof is provided with a cutting edge 12 for excavating the ground G. By rotating the leading casing 11 and pushing it into the ground G, the cutting blade 12 is little by little The ground G is torn and the whole gradually gets into the ground G. The inner diameter of the leading casing 11 is larger than the outer diameter of the columnar reformed portion C. This is to avoid the hard area at the time of excavation and also to remove the area in which the cement-based solidifying material and the precipitates penetrated, and to realize the original recovery more reliably.

  When most of the leading casing 11 enters the ground G by excavation, the intermediate casing 21 is connected to the rear portion of the leading casing 11 as shown in the center of FIG. 1 and the leading casing 11 is subsequently pushed. The intermediate casing 21 has the same cross section as the leading casing 11, and there is no step or the like on the connecting surface. A plurality of intermediate casings 21 are stacked, and the leading casing 11 is pushed deeper. As a matter of course, the leading casing 11 and the intermediate casing 21 connected to each other apply a rotational force and a propulsive force to the uppermost intermediate casing 21. Therefore, adjacent casings 11 and 21 need to be connected firmly and to transmit various forces reliably.

  The connection method between the casings 11 and 21 can be freely selected, but a protrusion such as a flange causes resistance with the ground G. Therefore, asperities are provided on the connecting surfaces of the casings 11 and 21 and a method such as engaging them is introduced. However, care should be taken to minimize the time and effort required for connection and disconnection. Although a construction machine such as an auger is actually installed on the ground for rotation and propulsion of the casings 11 and 21, these are omitted in FIG.

  When excavation is continued while sequentially connecting the intermediate casings 21, the leading casing 11 reaches near the lower part of the columnar reforming section C as depicted in the upper right of FIG. 1. Drilling is finished here, and then the columnar reforming section C is removed using the grab bucket 31. The grab bucket 31 is circular as viewed from above assuming that it is inserted into the casings 11 and 21. Furthermore, the left and right buckets 33 opened and closed by oil pressure are both hemispherical, and the outer diameter is constant regardless of the opened / closed state. Therefore, the clearance with the inner peripheral surface of the casings 11 and 21 is small. Further, the tips of the individual buckets 33 are provided with claws 32 for crushing the columnar reforming portion C.

  With the left and right buckets 33 opened, the grab bucket 31 is inserted into the casings 11 and 21, the claws 32 are pressed against the upper end surface of the columnar reforming section C, and the buckets 33 are closed by hydraulic pressure. 11. From the vicinity of the inner peripheral surface of 11 and 21 toward the center, the columnar reformed portion C is sandwiched and crushed. Then, when the bucket 33 is pulled up to the ground with the bucket 33 closed, the columnar reforming section C is discharged to the ground. By repeating this work, as shown in the lower left of FIG. 1, almost all of the columnar reforming section C and the soil around it are removed.

  Next, as shown in the lower center of FIG. 1, the backfill material B is introduced into the casings 11 and 21. The back-filling material B is appropriately selected from gravel, crushed stone, etc. that is suitable for restoration of the original condition. The back-filling material B is not necessarily fed in all at once, but is repeatedly fed in several times. Then, after completion of each charging, the connected casings 11 and 21 are pulled up by a fixed distance, and then the backfill material B is compacted from above by the grab bucket 31. By this compaction, the back-filling material B enters the annular space generated by pulling up the casings 11 and 21 and prevents the generation of a cavity. At the time of compaction, the bucket 33 is in a closed state, and the refilling material B is pressed by the entire spherical front surface.

  By repeating the process constituted by the injection of the backfilling material B, the pulling up of the casings 11 and 21, and the tamping of the backfilling material B, the excavated part is backfilled stepwise. In addition, the intermediate casing 21 connected to the top appears in the whole on the ground soon after being pulled up. Therefore, only the intermediate casing 21 is separated to suppress the upward projection. Finally, as illustrated in the lower right of FIG. 1, all the casings 11 and 21 are pulled up, and the columnar reforming portion C and the earth and sand around it are replaced by the pressed-in backfill material B. , The restoration work of ground G is completed.

  FIG. 2 shows the details of the process of charging the backfill material B. As shown in FIG. 1, after removing the soil and soils in the columnar reforming section C and its periphery, the backfill material B is introduced into the casings 11 and 21. In order to pack uniformly, it is necessary to interlock the back-filling material B and the charging, its compaction, and the pulling up of the casings 11, 21 instead of separately.

  At the time of backfilling, first, while drawing the connected casings 11 and 21 as they are as shown in the upper left of FIG. Next, as drawn on the center of FIG. 2, the casings 11 and 21 are pulled up by a certain distance, but this causes an annular gap at the place where the leading casing 11 was present. However, as illustrated in the upper right of FIG. 2, when the grab bucket 31 is inserted into the casings 11 and 21 and the backfill material B is compacted from above, the backfill material B is washed away and the front casing 11 is removed. The gap is also filled up. In addition, since the front surface of the grab bucket 31 is spherical, the back-filling material B is inevitably pushed outward and smoothly enters the gap through which the leading casing 11 has been removed.

  Thereafter, as shown in the lower left of FIG. 2, the back-filling material B is again injected by a fixed amount. The casings 11, 21 are then pulled up, as depicted in the lower center of FIG. 2, with the top intermediate casing 21 appearing entirely on the ground. Therefore, the intermediate casing 21 is separated from the other casings 11 and 21 so as not to interfere with the operation. While this separation operation is advanced, the backfilling material B inside the casings 11 and 21 is compacted as shown in the lower right of FIG. 2 to fill up the annular gap from which the leading casing 11 is removed.

  By repeating the process of FIG. 2, all the casings 11 and 21 are pulled up to the ground, the ground G is completely backfilled, and restoration of the original state is realized. Thus, at the time of backfilling, by linking the three steps, it is possible to uniformly stuff the backfilling material B without gaps and prevent subsequent ground subsidence. In addition, although the input amount of the back-filling material B at once and the pulling distance of the casings 11 and 21 are determined on the premise that the back-up material B is uniformly press-fitted without gaps, in that case, the back-filling material B And various conditions such as the propulsive force of the grab bucket 31.

11 Leading casing 12 Cutting blade 21 Intermediate casing 31 Grab bucket 32 Claw 33 Bucket B Backing material C Column reformer (Soil cement column)
G ground

Claims (1)

It is a restoration method of the ground (G) in which the columnar reformer (C) is formed,
A cylindrical leading casing (11) having a cutting edge (12) at a tip end surrounding a position distant from the columnar reforming section (C) and digging the ground (G);
A cylindrical intermediate casing (21) connected to the rear of the leading casing (11);
A grab bucket (31) provided with claws (32) which enter the interiors of the two connected casings (11, 21) and crush the columnar reforming section (C);
Using
The leading casing (11) is rotated to excavate the periphery of the columnar reforming section (C), and the intermediate casing (21) is sequentially connected to the rear of the leading casing (11) to form the leading casing (11). ) To the vicinity of the lower part of the columnar reformer (C),
Next, the grab bucket (31) is inserted into the inside of the two connected casings (11, 21), and the columnar reformer (C) is crushed with the claws (32), and the crushed pillar Discharge the soil from the reforming section (C) and the surrounding area to the ground,
After removing the columnar reformer (C), the two connected casings (11, 21) are pulled up in stages and divided in a plurality of times, and are backfilled inside the both casings (11, 21) Insert the material (B), tamp the backfill material (B) with the front of the grab bucket (31),
At that time, three steps consisting of charging of the backfilling material (B), pulling up of both the casings (11, 21) and tamping of the backfilling material (B) are repeated several times, A ground restoration method characterized by pulling up all the two casings (11, 21) to the ground and uniformly pressing the backfill material (B) into the space from which the columnar reformed portion (C) has been removed.

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