JP4831615B2 - Manufacturing method of expansion type steel pipe for subsidence foundation repair - Google Patents

Description

  The present invention relates to a method of manufacturing an expandable steel pipe for subsidence foundation repair for lifting up a foundation of a building or the like when the foundation on which the building or the like is built sinks.

  For example, if the ground that constitutes the back marsh, coastal landfill, Mitsushima lowland, drowned valley, coastal sand bar, etc. is formed by peaty ground or slow-consolidated ground, etc., it becomes a soft ground There are many. Such soft ground has a low ground holding force and is likely to continue to be consolidated. Therefore, when a structure such as a building is built above the soft ground, the subsidence (non- Subsidence).

As a restoration means when subsidence occurs in a structure such as a building, for example, as seen in Patent Document 1, the part where subsidence is lifted up with a foundation using a jack, and is generated by lifting up A method of filling and solidifying mortar, grout, etc. in the gap between the foundation and the foundation is adopted.
However, this method not only has the risk of destroying the foundation in order to impose an excessive load that was not assumed at the time of design on a foundation with a small installation area, but also requires labor other than the work itself. Yes.
Further, Patent Document 2 discloses a technique for restoring a subsidence foundation by using a displacement when a steel tube that has been pressed flat in advance is expanded and returned to the original round shape.
JP 2000-8398 A Japanese Patent Application No. 2005-351906

In the method of Patent Document 2, an expansion-type steel pipe that has been pressed flat in advance is disposed in a portion where the settlement of the building is expected between the pressure receiving plate provided on the surface layer portion of the foundation ground and the foundation of the building. An expansion fluid is press-fitted into the expansion type steel pipe and the foundation is lifted by expanding and deforming the expansion type steel pipe so as to return from the flattened cross-sectional shape to the original cross-sectional shape, thereby attempting to repair the settlement of the building. Is.
Moreover, in the said patent document 2, it replaces with the expansion-type steel pipe pressed flatly, and the present applicant has proposed by Unexamined-Japanese-Patent No. 2003-206698 of the concave type which folded some outer peripheral surfaces into the hollow inside. It has also been introduced that an expandable steel pipe consisting of an expandable deformed pipe having a cross-sectional shape can be used.

However, when an expandable steel pipe having a concave cross-sectional shape with a part of the outer peripheral surface folded into the hollow interior is used, there is a limit to the amount of expansion, that is, the amount of recovery of the subsidence foundation accompanying the expansion of the steel pipe. Further, even when the flat-type expanded steel pipe of Patent Document 2 is used, since the circular pipe whose end is sealed with a closing plate is flattened, the flat part when expanded with high-pressure water. Not only can the steel pipe near the obstruction plate be deformed but there is a risk that the vicinity of the obstruction plate may rupture, so a large flatness ratio (width / height of the flat portion) cannot be taken. The lift-up amount obtained is also limited. In order to secure a high recovery height, it is necessary to dispose the expansion type steel pipe as described above in two or more stages, which makes the construction difficult and results in an increase in cost. .
The present invention has been devised to solve such a problem, and by devising the shape, an expansion type steel pipe for subsidence foundation repair that can increase the expansion amount, that is, the recovery amount of the subsidence foundation can be increased. Is intended to be manufactured at low cost.

  In order to achieve the object, the method for manufacturing an expansion type steel pipe for subsidence foundation repair of the present invention uses a deformed pipe having a predetermined cross-sectional shape with a part of the outer peripheral surface folded into a hollow interior as a raw pipe, and at both ends thereof. High-pressure water is injected from a high-pressure water injection hole provided in one sleeve of a tubular body having a watertight structure to which a cylindrical sleeve having a strength that is not deformed by application of high water pressure is attached, and the concave cross-section portion is formed. After inflating, the middle part of the inflated tube is inserted into a press die having a flat surface or a curved surface and press-molded, and the circumferential length is substantially the same in any cross section in the longitudinal direction of the tubular body, In addition, a tubular body having a cross-sectional shape in which a tubular body portion excluding a portion adjacent to the sleeve is flattened is obtained.

  As a raw pipe, the process which roll-forms to the raw material steel pipe in the cross section which consists of two types of large and small convex curved surfaces, and applies a disk-shaped roll to the center of the convex curved surface with a large curvature radius of the two types of convex curved surfaces, and Roll forming process so that a convex curved surface with a large radius of curvature is recessed inside the tube, and then the roll is applied to both sides of the cross-section that is recessed in the center and curved in a bowl shape to narrow the flange opening and reduce the tube outer diameter. It is preferable to use a deformed tube cut into a predetermined dimension after being formed into a concave cross-sectional shape through a small roll forming step.

  According to the method of the present invention, sleeves for making a watertight structure are attached to both ends thereof, and an irregularly shaped subsidence foundation repair expansion type steel pipe having a flattened cross section for expansion between the sleeves is obtained. For this reason, when inflating and deforming the flattened cross section into a circular cross section by injecting high-pressure water from a water injection hole provided in one of the sleeves, deformation of the tube end sealing portion is suppressed by the sleeve. Therefore, there is no risk of rupture of the tube at the unsteady parts at both ends, and it is possible to increase the flatness of the tube (width / height of the flat tube), and the lift-up height is higher than the conventional one. That is, an expandable steel pipe capable of remarkably increasing the repair height of the settlement foundation can be manufactured at low cost.

As described above, an expansion type steel pipe having a flat-shaped cross-sectional shape or an expansion type steel pipe having a concave cross-sectional shape obtained by folding a part of the outer peripheral surface into a hollow interior is used to form the expansion type steel pipe. Even when the technique for expanding and repairing the settlement foundation is used, the amount of expansion, that is, the recovery amount of the settlement foundation accompanying the expansion of the steel pipe is limited.
Accordingly, the present inventors have made various studies on the shape that can increase the expansion amount of the expansion-type steel pipe for subsidence foundation repair, that is, the recovery amount of the subsidence foundation.

  As a result, as an expansion type steel pipe for subsidence foundation repair, if a deformed pipe having an expansion recess is pre-expanded and made into a cross-sectional shape flattened by press molding, the expansion amount, that is, accompanying the expansion of the steel pipe It has been found that the amount of subsidence recovery can be greatly increased. Below, the expansion-type steel pipe shape which can increase the recovery amount of a settlement foundation significantly is demonstrated in detail.

  The applicant has a hollow body having one or more expansion recesses extending in the axial direction, with a watertight sleeve attached at one end and a sleeve having a water injection hole connected to a high pressure water supply source at the other end. Proposes rock bolts. The expansion recess extending in the axial direction has a concave cross-sectional shape with a part of the outer peripheral surface folded into the hollow interior, and high pressure water is injected into the hollow interior so that the recess returns to the original cross-sectional shape. The steel pipe is inflated and deformed, and the outer peripheral surface of the steel pipe is pressed against the inner wall surface of the hole drilled in the rock by the expansion force at this time, and a restraint force is applied to the natural ground.

Although the present invention basically uses an expansion-type deformed tube of this shape, the amount of recovery of the settlement foundation cannot be increased as described above.
Therefore, the present invention is to expand the diameter of the above-described expansion-type deformed tube once, and then apply a press pressure from above and below to flatten the cross-sectional shape (see FIG. 1). For this reason, as for the shape between the sleeves, the circumferential length is almost the same in any cross section in the longitudinal direction of the tube, and the portion where the tube cross-sectional shape is adjacent to the sleeve is a concave cross-section, and the portion adjacent to the sleeve The part except for is a flattened cross section (see FIG. 2).

Here, the reason why “the circumference is substantially the same” is described as follows. The deformed tube having the expansion recess has the same peripheral length in any cross section. And even when expanded completely to a circular cross section of the original diameter, the circumference is the same in any cross section. In the present invention, a deformed pipe having a concave cross section is once expanded to a circular cross section and then press molded to obtain a flat cross section, but since the plastic deformation is involved in the expansion process, there is a slight change in the pipe circumference during the expansion deformation. It can be expected to happen. In this case, the circumferential length is not the same in any cross section, and the portion with a large expansion amount is slightly longer than the sleeve adjacent portion. The present invention includes such an embodiment.
In this way, once the deformed tube having the recess for expansion is inflated to a circular cross section and then formed into a flat cross section by pressing, the height of expansion, i.e., recovery of the subsidence foundation, is compared with the case of simply having the recess. The amount can be increased significantly.

The steel pipe according to the present invention is required to have a deformability capable of being deformed without breaking to a substantially circular cross section after flattening. As a material that satisfies these conditions, it is necessary that the elongation (result of a tensile test using a No. 11 tensile test piece specified by JIS) once expanded from a concave tube to a substantially circular cross section is approximately 40%. A steel pipe having a tensile strength of 400 N / mm ² can be applied.
In a high-strength steel material having a tensile strength exceeding 400 N / mm ² , the elongation is much less than 40%, and therefore, there is a risk of rupture during expansion from a flat shape. Assuming that the allowable stress of a steel pipe with a tensile strength of 400 N / mm ² is 400 N / mm ² , the ratio t / D of the wall thickness t to the outer diameter D of the steel pipe is about 3% or more in order to withstand a water pressure of 25 MPa during expansion. It is necessary to be. In addition, if the height is extremely lowered during flattening, the bending strain at both ends of the cross section of the flat tube becomes excessive, and there is a risk that the deformability of that portion will be impaired and rupture may occur. The thickness should be about 7 times the wall thickness of the tube.

Next, the manufacturing method of the expansion type steel pipe for foundation subsidence restoration of the present invention is explained. Basically, a deformed pipe for expansion is first manufactured by the same method as that for the lock bolt described above.
A hollow tube with a predetermined length of a deformed tube with a part of the outer peripheral surface folded into a hollow tube is used as a raw tube, and cylindrical sleeves with strength that will not be deformed by the application of high water pressure are attached to both ends. An expansion tube having a structure is produced. A flat surface or curved surface facing a portion excluding the vicinity of the sleeve at both ends of the expanded tube after the high-pressure water injection hole is drilled in one sleeve and high-pressure water is injected from the water injection hole to expand the concave cross section. A tubular body that is inserted into a press mold having press and is press-molded, and the circumferential length is substantially the same in any cross section in the longitudinal direction of the tubular body, and the tubular body has a cross-sectional shape excluding a portion adjacent to the sleeve A tubular body having a flattened section is obtained.

In addition, it is preferable to use the plated steel pipe by which metal plating was given to both inner and outer surfaces in order to improve corrosion resistance as a base pipe of the expansion type deformed pipe of the present invention.
As the metal plating, Zn plating, Zn-Al alloy plating (Zn-5% Al plating, Zn-55% Al plating, etc.) and Zn-Al-Mg alloy plating are preferable. : 0.05 to 10% by mass, Al: 4 to 22% by mass, Zn-Al-Mg based alloy plating composed of the balance Zn and inevitable impurities is preferable.

A deformed tubular element tube having a concave cross-sectional shape with a part of the outer peripheral surface folded into the hollow interior is formed by a roll forming method, a method combining a press forming method and a drawing method, or the like.
When the roll forming method is adopted, for example, it is manufactured through the following steps.
As shown in FIG. 3, first, (a) a steel pipe welded by, for example, a high frequency welding method is prepared, and (b) the circumferential length of the concave portion of the concave deformed pipe and the circumferential length other than the concave portion are approximately Roll forming is performed on a cross-section composed of two kinds of large and small convex curved surfaces in which the radius and angle of the arc are set so as to fit (first step). Thereafter, (c) a disk-shaped roll is applied from the central surface of the two types of convex curved surfaces with a large radius of curvature, and roll forming is performed so that the surface with the large radius of curvature is recessed inside the tube (second step). ). Thereafter, (d) and (e) rolls are formed on both sides of the cross-section that is concave and curved in the center, narrowing the hook-shaped opening to reduce the outer diameter of the tube (third step), and in the radial direction An irregularly shaped tube for expansion in which a hollow is formed long in the axial direction is manufactured.

More specifically, it is as follows.
In the first forming step, the raw tube M is passed through a forming stand comprising a roll 11 having a recess having a large radius of curvature as shown in FIG. 4A and a roll 12 having a smaller radius of curvature. In this step, it is possible to pass through a molding stand having two or more stages in which the radius of curvature is sequentially increased.
Next, in the second forming step, the raw tube M is formed by a roll so that the cross section is formed of two kinds of large and small convex curved surfaces, so that the first tube as shown in FIG. Between a forming stand consisting of a roll 22 having a concave portion with a radius of curvature that is the same as or smaller than a roll having a concave portion with a small radius of curvature used in the molding step, and a disc-like convex roll 21 with a small radius of curvature at the end, The disc-shaped roll 21 is passed through the center of the convex curved surface having the larger curvature radius. Also in this process, it is possible to pass through two or more molding stands having successively reduced curvature radii. The cross section of the raw tube in this step has a shape in which the center is indented and curved in a bowl shape, and its outer shape is a semicircular shape close to the initial diameter of the raw tube.

  Therefore, it is necessary to reduce the outer diameter in the third molding step. As shown in FIG. 4 (c), it passes through a forming stand composed of a pair of rolls 31 and 32 having a concave portion having a radius of curvature smaller than the initial diameter of the raw tube M, and narrows the bowl-shaped opening portion outside the tube. Reduce the diameter. Even in this process, it is possible to pass between two or more rolls in which the radius of curvature is sequentially reduced. At this time, if the radius of curvature of the roll is reduced, the convex portion of the tube may protrude from the roll gap, and the overall shape may become distorted. Therefore, as shown in FIG. It is preferable to arrange the roll 33.

  The deformed tube obtained by such a method is manufactured by being cut into a predetermined length. A sleeve for sealing the end opening is attached to both ends of the deformed pipe, and a high-pressure water injection hole for injecting high-pressure water is formed in one of the sleeves. As the sleeve, a cylindrical one having a strength that does not deform due to a high water pressure load is used. In consideration of corrosion resistance during use, Zn-based plating, Zn-Al-based alloy plating (Zn-5% Al plating, Zn-55% Al-based plating, etc.), Zn-Al, etc., which have good corrosion resistance, like the base tube -It is preferable to use a plated steel pipe to which Mg-based alloy plating is applied. Alternatively, an unplated steel pipe may be used as the sleeve, and the welded portion between the deformed pipe and the sleeve, which will be described later, and the sleeve may be coated for rust prevention.

In order to seal by attaching sleeves to both ends of the deformed tube, it is preferable to adopt the following mode. That is, as shown in FIG. 5, a cylindrical sleeve S is press-fitted and attached to both ends of a hollow deformed tube M having an expansion recess.
After press-fitting the cylindrical sleeve S, in order to deform the inner surface of the end portion of the deformed pipe M constituting the expansion steel pipe, a pressing metal D having a shape in which the columnar portion 2 and the conical portion 1 are integrally combined is provided. Press fit from the end opening of the deformed tube. As the pressing metal D, when the one having the cylindrical portion 2 having an outer diameter obtained by subtracting four times the plate thickness from the inner diameter of the sleeve is used, the tube end portion is caused by the action of the columnar portion 2. The steel pipe wall can be deformed into a close contact state along the sleeve inner wall (see FIG. 6).

Even after the pressing metal D is pulled out, the inner surfaces of the deformed tubes M are in close contact with each other while forming a flat portion, and the outer surface of the deformed tube M is in close contact with the inner surface of the sleeve S. In this state, the deformed tubes M, the tube ends of the deformed tubes M, and the inner surface of the sleeve S are joined by, for example, CO ₂ arc welding W or the like. Thereafter, a high-pressure water injection hole H is drilled with a drill or the like through one sleeve S and the deformed pipe M (see FIG. 7).
In addition, when the high-pressure water injection hole H is provided after welding the end of the deformed pipe and the sleeve, distortion due to the influence of the dimensional accuracy of the deformed pipe or the sleeve or the effect of processing or welding when sealed. In some cases, the inner surface of the sleeve and the outer surface of the deformed tube are not in close contact with each other, and a gap is generated between them. For this reason, a hollow cylindrical pin (not shown) may be inserted so as to cover the inner wall of the fluid injection hole H penetrating both the sleeve S and the deformed tube M.

Injected high-pressure water from the water injection side sleeve of the expansion type deformed pipe, which consists of a deformed pipe with a concave cross section obtained in the above-described manner, with a distal end sleeve and a water injection side sleeve mounted and sealed at both ends. The concave deformed tube is expanded to return to the original circular cross-sectional shape. The pressure of the high-pressure water used at this time may be a pressure that can return the concave deformed pipe to a substantially circular cross section, and it is not always necessary to apply a high pressure close to the allowable internal pressure limit of the steel pipe.
After that, the part of the deformed pipe that has been expanded once is used to repair the settlement foundation of the building, placed in a pressing mold having an opposing flat surface or curved surface, press-molded from both sides, and the part used for the restoration is flattened. Thus, an expanded deformed tube having a flattened cross-sectional shape is obtained.

  For the press molding, for example, as shown in FIG. 8, a press die including a fixed die 42 and a moving die 43 is arranged on a base 41 via a fixed support base (not shown), and the press An apparatus is used in which a pipe support base 44 is movably attached to the press mold via a spring 45 or the like on the base 41 in the mold. The pipe support 44 is pressed against a predetermined position by a spring 45 by a stopper (not shown) provided in the upper direction of FIG. 8 so that the pipe can be positioned near the center in the vertical direction of the mold. When the pipe P is placed on the pipe support 44 in the press mold (FIG. 8A) and the moving mold 43 is forcibly moved to the fixed mold side by the hydraulic cylinder, the pipe P is pressed and flattened. It becomes. When the moving mold 43 is moved, the pipe support 44 supported by the spring 45 is retracted as the height of the pipe increases due to the flattening of the pipe, and the pipe P is easily flattened without being restricted in the vertical direction. (FIG. 8B).

The difference in the subsidence basic recovery ability between the expandable steel pipe obtained by the method of the present invention and the conventional expandable deformed pipe is introduced.
Using a steel plate with a thickness of 2 mm as a raw material, after forming into a pipe with an outer diameter of 54 mm (plate thickness / outer diameter = 3.7%) by high frequency induction welding, a deformed steel pipe having a concave cross section with an outer diameter of about 36 mm was immediately formed. .
This deformed steel pipe is cut to a length of 2 m, and about 100 mm of both pipe ends are reduced to a diameter of 33 mm with a reduction die, and then an outer diameter of 38.1 mm and a wall thickness of 2.55 mm as a sealing sleeve at one end. A pipe having a length of 70 mm was covered, and a punch was press-fitted into the punch press-fitting portion, thereby forming the tube end portion into a flat contact state along the sealing-side sleeve and sealing by welding. A pipe having an outer diameter of 41 mm, a wall thickness of 4 mm, and a length of 70 mm is covered with the other end of the deformed steel pipe similarly to form a water injection side sleeve, and a punch is press-fitted into the opening of the pipe end. After being formed in a tight flat state along the inner wall and sealed by welding, a high-pressure water injection hole having a diameter of about 3 mm is formed at a position about 25 mm from the tip of the water injection side sleeve, avoiding the concave portion of the deformed pipe, A steel pipe for expansion was produced by drilling so as to penetrate the wall thickness of 2 mm.

As a conventional example, the above-described expanded deformed pipe was used as it was.
In the present invention example, pressurized water for expansion is added from the water injection side sleeve of the expansion type deformed pipe manufactured as above, and finally the pressure is increased to 20 MPa so that the middle part of the deformed pipe has an original diameter of 54 mm. Then, the portions excluding the vicinity of the sleeves at both ends of the expanded tube were sandwiched between press mold apparatuses having opposing flat surfaces, and the portions were pressed to a thickness of 15 mm and flattened.
Comparing the two, in the expansion type steel pipe flattened after being expanded into a circular cross section obtained by the method of the present invention, it is possible to ensure an expansion height of 54 mm−15 mm = 39 mm by expansion, In the expansion type deformed tube having a concave cross section which is a conventional example, only an expansion height of 54 mm−36 mm = 18 mm can be secured by expansion.
It can be understood that the expansion-type steel pipe obtained by the method of the present invention has remarkably superior settlement recovery ability compared to the conventional example.

The perspective view explaining the shape of the expansion type steel pipe for subsidence foundation repair manufactured by the method of the present invention Sectional drawing explaining the shape of the expansion-type steel pipe for foundation subsidence restoration manufactured by this invention method Diagram explaining changes in cross-sectional shape in the process of deformation The figure explaining the roll shape used in each process of deformed pipe manufacture The figure explaining the shape of the end of a deformed pipe fitted with a sleeve The figure explaining the aspect which pushes a press metal fitting into a pipe end and deforms a deformed pipe end part The figure explaining the end part structure of the steel pipe for expansion The figure explaining roughly the process of flattening the steel pipe once expanded.

Claims (2)

  A watertight structure in which a hollow tube with a predetermined length of a deformed tube with a part of the outer peripheral surface folded into a hollow is used as a raw tube, and cylindrical sleeves having strength that does not deform due to the application of high water pressure are attached to both ends. After injecting high-pressure water from a high-pressure water injection hole provided in one sleeve of the tubular body having a structure to expand the concave cross-section, the tubular body portions excluding the sleeves at both ends of the expanded pipe and the vicinity thereof Inserted into a press die having an opposing flat surface or curved surface and press-molded, the circumference is almost the same in any cross section in the longitudinal direction of the tubular body, and the portion adjacent to the sleeve of the tubular body is excluded. A method for producing an expandable steel pipe for subsidence foundation repair, characterized in that a tubular body having a cross-section with a flattened cross-sectional shape is obtained.   A step of forming a steel pipe into a cross-section composed of two types of large and small convex curved surfaces, and applying a disk-shaped roll to the center of the convex curved surface having a large radius of curvature among the two types of convex curved surfaces, the convex having a large curvature radius. A roll forming process in which the curved surface is recessed inside the pipe, and a roll forming process in which the roll is applied to both sides of the cross section that is recessed in the center and curved in a bowl shape to narrow the bowl-shaped opening and reduce the outer diameter of the pipe. The manufacturing method of the expansion type steel pipe for subsidence foundation repair of Claim 1 which uses the deformed pipe cut | judged to the predetermined dimension after shape | molding through a concave shape through a raw material.

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