Jack-up device, jack-up method, and repair method of existing foundation

Abstract

To provide a jack-up device, a jack-up method, and a repair method of an existing foundation that can prevent an object to be jacked up, such as a floor post, from sliding down or being damaged.SOLUTION: A jack-up device comprises: a pair of gripping members 26 arranged horizontally facing each other across an object to be jacked-up 14; a screw-type fastening member 28 tightening the pair of gripping members 26 in a direction in which they are brought closer to each other; and a jack 30 raising the pair of gripping members 26. The screw-type fastening member 28 is tightened with a predetermined tightening force. The tightening force is set to a tightening force that prevents the object to be jacked-up 14 from sliding down from the gripping members 26 and prevents damage caused by the gripping members 26 sinking into the object to be jacked-up 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a jacking-up device, a jacking-up method, and a method for repairing an existing foundation, which are suitable for jacking up columns on a foundation when repairing the foundation of an existing wooden building, for example.

Background Art

[0002] Conventionally, in wooden buildings such as shrines and temples, when the foundation stones supporting the bundled columns are unevenly settled, a method for repairing the settled foundation stones is known (see, for example, Patent Document 1).

[0003] The method shown in this Patent Document 1 is to attach a horizontal support frame to the bundled column via a column gripping fitting, push up the horizontal support frame by a required amount with a jack to lift the bundled column from the foundation stone, and then repair the foundation stone. The column gripping fitting includes a pair of clamping members made of C-shaped steel or H-shaped steel that sandwich the bundled column from both sides, and a tightening bolt and nut that are interposed between both ends of the clamping members while sandwiching the bundled column at a position orthogonal to the clamping members to tighten the clamping members and fix them at a predetermined position of the bundled column. This column gripping fitting is attached in two upper and lower stages, and the horizontal support frame is horizontally fixed while being sandwiched therebetween.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method of the conventional Patent Document 1 described above, in short, the bundled columns are jacked up via column gripping fittings frictionally joined to the bundled columns. The frictional force of the frictional joint is greatly affected by the rigidity of the column gripping fittings and the tightening force of the bolts that clamp the column gripping fittings to the bundled columns. For example, if the bolt tightening force is too small or if an unexpected event occurs after jacking up, slippage may occur at the frictional joint and the bundled columns may slip down. Conversely, if the bolt tightening force is too large, the column gripping fittings may sink in and damage the bundled columns.

[0006] Also, the load input to the bundled columns when jacking up is determined by factors such as the scale of the building. However, in the method of the conventional Patent Document 1 described above, there is a possibility that the load cannot be supported in some cases. Also, if a sudden slip occurs at the frictional joint due to a load exceeding the bearing capacity, etc., the work safety may be impaired.

[0007] Also, when jacking up an existing column for a certain period of time, creep may occur at the frictional joint of the column gripping fittings. Therefore, it is desirable to confirm the creep behavior when a load acts for a long time.

[0008] The present invention has been made in view of the above, and an object thereof is to provide a jacking-up device, a jacking-up method, and a method for repairing an existing foundation that can prevent slippage and damage of a jacking-up object such as a bundled column.

Means for Solving the Problems

[0009] In order to solve the above-mentioned problems and achieve the object, the jacking-up device of the present invention is a device for jacking up a columnar object to be jacked up, and comprises a pair of gripping members arranged horizontally opposite each other on either side of the object to be jacked up, screw-type fastening members arranged horizontally on both sides of the gripping members and tightening the pair of gripping members in a direction bringing them closer to each other, and a jack that jacks up the object to be jacked up by raising the pair of gripping members, wherein the screw-type fastening members are tightened with a tightening force set based on the contact area between the object to be jacked up and the gripping members and the embedment strength of the object to be jacked up, and the tightening force is set to a tightening force that prevents the object to be jacked up from slipping off the gripping members during jacking up and prevents damage caused by the gripping members embedding into the object to be jacked up.

[0010] Further, another jack-up device according to the present invention is characterized in that, in the above-mentioned invention, a buffer member is provided between the object to be jacked up and the gripping member.

[0011] In addition, the jacking method of the present invention is a method for jacking up a columnar object to be jacked up, and includes the steps of: arranging a pair of gripping members horizontally opposite each other across the object to be jacked up; inserting and arranging screw-type fastening members horizontally on both horizontal sides of the gripping members, and then tightening the screw-type fastening members in a direction that brings the pair of gripping members closer to each other; and jacking up the object to be jacked up by raising the pair of gripping members with a jack, wherein the screw-type fastening members are tightened with a tightening force that is set based on the contact area between the object to be jacked up and the gripping members and the embedding resistance strength of the object to be jacked up, and the tightening force is set to prevent the object to be jacked up from slipping off the gripping members during jacking up, and to prevent damage caused by the gripping members embedding into the object to be jacked up.

[0012] Further, another jacking-up method according to the present invention is characterized in that, in the above-described invention, after providing a buffer member between the object to be jacked up and the gripping member, the screw fastening member is tightened.

[0013] Further, a method for repairing an existing foundation according to the present invention is a method for repairing an existing foundation, characterized in that, after using the above-described jacking-up method to jack up an existing column as the object to be jacked up, the existing foundation below the existing column is repaired.

[0014] Further, another method for repairing an existing foundation according to the present invention is characterized in that, in the above-described invention, after jacking up the existing column, a protection member is inserted directly below the existing column, and the protection member and the gripping member are fixed.

Effect of the Invention

[0015] According to the jacking-up device of the present invention, there is provided a device for jacking up a columnar object to be jacked up, including a pair of gripping members arranged horizontally opposite to each other with the object to be jacked up sandwiched therebetween, a screw fastening member inserted horizontally on both horizontal sides of the gripping members and configured to tighten the pair of gripping members in a direction approaching each other, and a jack configured to jack up the object to be jacked up by raising the pair of gripping members. The screw fastening member is tightened with a tightening force set based on the contact area between the object to be jacked up and the gripping member and the indentation endurance of the object to be jacked up. The tightening force is set to prevent the object to be jacked up from slipping off the gripping member during jacking up and to prevent damage caused by the gripping member indenting into the object to be jacked up. Therefore, it is possible to prevent the object to be jacked up, such as a bundled column, from slipping off or being damaged.

[0016] In addition, according to another jack-up device of the present invention, a buffer member is provided between the object to be jacked up and the gripping member, which has the effect of effectively preventing damage to the object to be jacked up.

[0017] Further, according to a jacking-up method of the present invention, there is provided a method for jacking up a columnar object to be jacked up, comprising the steps of: arranging a pair of gripping members facing each other in the horizontal direction with the object to be jacked between them; inserting threaded fastening members horizontally on both sides of the gripping members, and then tightening the threaded fastening members in a direction that brings the pair of gripping members closer to each other; and lifting the pair of gripping members with a jack to jack up the object to be jacked up. The screw-type fastening member is tightened with a tightening force set based on the contact area between the object to be jacked up and the gripping member and the embedding resistance strength of the object to be jacked up. The tightening force is set to prevent the object to be jacked up from slipping off the gripping member during jacking up and to prevent damage caused by the gripping member embedding into the object to be jacked up, thereby achieving the effect of preventing the object to be jacked up, such as a post, from slipping down or being damaged.

[0018] In addition, according to another jacking-up method of the present invention, a buffer member is provided between the object to be jacked up and the gripping member, and then the screw-type fastening member is tightened, thereby achieving the effect of effectively preventing damage to the object to be jacked up.

[0019] Furthermore, according to the method for renovating an existing foundation of the present invention, the method for renovating an existing foundation uses the above-mentioned jacking-up method to jack up the existing column, which is the object to be jacked up, and then renovates the existing foundation below the existing column, thereby achieving the effect of being able to renovate the existing foundation while preventing the existing column from sliding down or being damaged.

[0020] Also, according to another method for repairing an existing foundation according to the present invention, after jacking up the existing column, a protection member is inserted directly under the existing column, and the protection member and the gripping member are fixed. Therefore, it is possible to prevent the existing column from slipping down due to unexpected slipping and improve the work safety.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of a jacking-up device, a jacking-up method, and a method for repairing an existing foundation according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by this embodiment.

[0023] (Jacking-up Device) As shown in Fig. 1, taking the case where three existing columns 14 on the existing foundation 12 are simultaneously jacked up to repair the existing foundation 12 under the existing wooden building 10 as an example for explanation. The existing columns 14 are columnar objects to be jacked up, and in this embodiment, they are arranged at intervals in the left - right direction. Each of the existing columns 14 is composed of four wooden corner columns 16 arranged in close proximity. A part between the corner columns 16 is filled with grout material 18, and the integration between the corner columns 16 is achieved at that part. At the lower end and the middle position of the existing column 14, a lower member 20 and an intermediate member 22 extending in the left - right direction are respectively provided. Also, a diagonal member 24 is provided from the lower end of the left - hand existing column 14 diagonally upward to the right.

[0024] The jack - up device 100 according to this embodiment includes a pair of gripping brackets 26 arranged to face each other horizontally on the left and right sides with the existing column 14 in between, a bolt 28 for tightening the pair of gripping brackets 26 in a direction to bring them closer to each other, and a jack 30 for jacking up the existing column 14 by raising the pair of gripping brackets 26.

[0025] The gripping bracket 26 is a gripping member that sandwiches the existing column 14 from both the left and right sides and extends horizontally in the front - rear direction, and is composed of, for example, C - shaped steel (channel material). In this embodiment, a configuration with only one - stage arrangement of the gripping brackets 26 is assumed. However, as shown by the dashed line for the existing column 14 in the center of Fig. 1, a configuration with two - stage vertical arrangement of the gripping brackets 26 or a configuration with three - stage or more arrangement may also be used. The lower surface of the gripping bracket 26 is fixed to the upper surface of the jack - up base 32 with a fixture 34 such as a chuck vice. The base 32 is composed of H - shaped steel extending horizontally on both the front and rear sides of the existing column 14. Both ends of the base 32 are fixed to the upper surface of a base frame 36 made of H - shaped steel with a fixture 34. The base frame 36 is arranged on the jack 30.

[0026] The bolt 28 is a screw fastening member that is inserted and arranged in the horizontal left - right direction on both the front and rear sides in the horizontal direction of the gripping fitting 26. Nuts 38 are screwed onto both ends of the bolt 28. By tightening the nut 38 to the gripping fitting 26 with a predetermined tightening force, the pair of gripping fittings 26 can be fastened and fixed in a direction approaching each other. The tightening force of the bolt 28 and nut 38 is set to a tightening force that prevents the existing column 14 from slipping off the gripping fitting 26 during jack - up and also prevents damage caused by the gripping fitting 26 digging into the existing column 14. For example, it may be set within a set range based on the contact area between the existing column 14 and the gripping fitting 26 and the pre - calculated allowable indentation bearing capacity of the existing column 14. By doing so, slippage and damage of the existing column 14 can be prevented.

[0027] The jack 30 is a hydraulic jack arranged on the new foundation 40. By pushing up the gantry 32 by a required amount via the pedestal frame 36, the existing column 14 can be jacked up by a required amount via the gripping fitting 26, putting the existing column 14 and the lower member 20 in a state of floating from the existing foundation 12. Thereby, the existing foundation 12 directly below the existing column 14 and the lower member 20 can be repaired.

[0028] In the above - described embodiment, for suppressing damage to the existing column 14 and eliminating unevenness between the existing column 14 and the gripping fitting 26, a cushioning member such as a rubber sheet may be sandwiched between the existing column 14 and the gripping member 26. In this way, damage to the existing column 14 can be effectively prevented.

[0029] (Jack - up method) Next, an embodiment of a jack - up method using the above - described jack - up device will be described. As shown in FIG. 1, first, the jack 30, the pedestal frame 36, the gantry 32, and the gripping fitting 26 are arranged at predetermined positions around the existing column 14. The bolt 28 is inserted and arranged in the gripping fitting 26. Then, the bolt 28 and nut 38 are tightened with the above - described tightening force to fasten and fix the existing column 14 and the gripping fitting 26. Then, the jack 30 is operated to jack up the existing column 14.

[0030] When tightening the bolts 28 and nuts 38, torque management is performed. At this time, consideration is given to ensuring that the tightening of the bolts 28 and nuts 38 is uniform with each gripping fitting 26. For example, when the gripping fittings 26 are arranged in a single row, the two left and right bolts 28 (for example, A and B) are tightened alternately left and right, such as A→B, B→A, A→B, ···. Also, when the gripping fittings 26 are arranged in three upper and lower rows, a total of six bolts 28 in three upper and lower rows, two on the left and right (for example, bolt 1A and 1B in the first row, bolt 2A and 2B in the second row, bolt 3A and 3B in the third row) are tightened in order, such as 1A→1B, 2A→2B, 3A→3B, 1B→1A, 2B→2A, 3B→3A, 1A→1B, 2A→2B, 3A→3B, ···. At this time, each bolt is tightened in order, for example, by 20 N·m increments from 80 N·m. The same can be done when the gripping fittings 26 are arranged in two upper and lower rows. When tightening the bolts 28 and nuts 38, since the torque coefficient varies greatly depending on the storage method of the bolts 28 and nuts 38, it is desirable to apply a lubricant to the bolts 28 and nuts 38 before construction.

[0031] When a rubber sheet is arranged as a buffer member, since the rubber sheet has a property of creeping when a load is applied, the tightening force decreases after the gripping fitting 26 is tightened and a certain period of time has passed. However, as will be described later, it has been found that by tightening the bolts 28 and nuts 38 again after creeping (re-tightening) and performing torque management, the decrease in the tightening force is suppressed after re-tightening. Therefore, during actual construction, after tightening the gripping fitting 26 with the bolts 28 and nuts 38, it is desirable to perform re-tightening immediately before jacking up to suppress the decrease in the tightening force.

[0032] By tightening the gripping fitting 26 and the existing column 14 with the bolts 28 and nuts 38, the space between the existing column 14 and the gripping fitting 26 is frictionally joined, and the existing column 14 is jacked up through the gripping fitting 26. By doing so, the entire building 10 can be jacked up without causing the existing column 14 to sink or be damaged.

[0033] According to this embodiment, damage to the existing column 14 is prevented by calculating the design allowable compressive strength of the existing column 14 and applying a tightening force within that design range. For example, if the design allowable compressive strength of the existing column 14 is 100 kN, the gripping hardware 26 is a C-150 x 45 x 6.5 x 10 channel material (SS400) and the bolts 28 are 2-M20 (strength classification 4.8), the required tightening force can be achieved by controlling the bolt torque to 200 N·m or less, as shown in Figure 2(1). Furthermore, if a rubber sheet (black rubber sheet cloth (PET) manufactured by Tigers Polymer Co., Ltd.) is sandwiched between the existing column 14 and the channel material as a buffer material to prevent damage to the existing column 14, the required tightening force can be achieved by controlling the bolt torque to 200 to 220 N·m, as shown in Figure 2(2).

[0034] Generally, the torque coefficient is around 0.15 to 0.2, but if the bolts and nuts are not stored properly, the torque coefficient will be high, and even if the specified torque management is performed, the necessary bolt axial force may not be input. However, as shown in Figure 3, the inventors have confirmed that applying a lubricant (e.g., anti-rust lubricant KURE5-56 (registered trademark)) to the bolts and nuts improves the torque coefficient even for bolts and nuts in relatively poor condition.

[0035] When a rubber sheet is sandwiched between the existing column 14 and the clamping fixture 26 as a buffer material, the clamping force decreases immediately after tightening. However, retightening several hours after tightening suppresses this decrease in clamping force. For example, when the clamping fixture 26 is made of C-150 x 45 x 6.5 x 10 channel material (SS400) and the bolts 28 are 2-M20 (strength classification 4.8), and the existing column 14 is clamped via the rubber sheet, as shown in Figure 4, and a clamping force of 93.9 kN is applied, the clamping force decreases by approximately 4% (4.2 kN) in one hour (89.7 kN) immediately after tightening, and then decreases by another approximately 4% (3.5 kN) over approximately 20 hours (86.9 kN). However, the inventors have confirmed that after retightening to 94.9 kN immediately after that, the clamping force decreases by approximately 1% (1.2 kN) in eight hours (93.7 kN), and the clamping force is relatively maintained.

[0036] For example, if the gripping fittings 26 are made of C-150 x 45 x 6.5 x 10 channel material (SS400), the bolts 28 are 2-M20 (strength classification 4.8), and the existing column 14 is clamped with a rubber sheet in between, and the bolt torque is controlled at 2000 to 220 N·m, the inventors have confirmed that when there is one row of gripping fittings 26, as shown in Figure 5(1), the maximum friction resistance is 97.3 kN (average of six pieces, standard deviation 10.1), and when there are three rows of gripping fittings, as shown in Figure 5(2), the maximum friction resistance is 217.7 kN (average of six pieces, standard deviation 9.2).

[0037] Furthermore, for example, when the gripping fittings 26 are made of C-150 x 45 x 6.5 x 10 channel material (SS400), the bolts 28 are 2-M20 (strength classification 4.8), and the existing column 14 is clamped with a rubber sheet in between, and the bolt torque is controlled at 2000 to 220 N m, the inventors have confirmed that when a force of 70 kN is applied to the existing column for a long period of time when the gripping fittings 26 are in one stage, as shown in Figure 6 (1), or 145 kN is applied to the existing column for a long period of time when the gripping fittings are in three stages, as shown in Figure 6 (2), the existing column is able to continue to support the load for a long period of time, although it deforms by about 2 mm in 6 to 7 hours.

[0038] (Method of repairing existing foundations) As shown in Figure 1, the method for repairing an existing foundation according to an embodiment of the present invention involves jacking up an existing column 14 using the jacking-up method described above, and then repairing the existing foundation 12 below the existing column 14. According to this embodiment, since jacking up is performed using the jacking-up method described above, it is possible to repair the existing foundation 12 while preventing the existing column 14 from sliding down or being damaged.

[0039] By the above jacking-up method, after jacking up the existing column 14, a horizontal steel plate 42 (protective member) may be inserted directly below the existing column 14 as a fail-safe mechanism. In this case, a bolt 46 is suspended from an angle member 44 provided on the jacking-up base 32, and the bolt 46 and the steel plate 42 are tightly fixed with a nut 48. By supporting the existing column 14 via the bolt 46 and the steel plate 42, it is possible to prevent the existing column 14 from slipping down and subsiding due to unexpected slippage at the friction joint portion, and improve the work safety. Further, by this fail-safe mechanism, it is possible to make zero the subsidence of the existing column 14 caused by the decrease in the tightening force due to the creep of the rubber sheet (buffer member) described above. Also, it is possible to suppress the subsidence of the existing column 14 from the deterioration of the rubber sheet expected during construction and external forces such as earthquakes.

[0040] As described above, according to the jacking-up device according to the present invention, it is a device for jacking up a columnar object to be jacked up, and includes a pair of gripping members arranged to face each other in the horizontal direction with the object to be jacked up therebetween, a screw fastening member inserted horizontally on both horizontal sides of the gripping members and tightening the pair of gripping members in a direction approaching each other, and a jack for jacking up the object to be jacked up by raising the pair of gripping members. The screw fastening member is tightened with a tightening force set based on the contact area between the object to be jacked up and the gripping member and the indentation endurance of the object to be jacked up. The tightening force is set to prevent the object to be jacked up from slipping down from the gripping member during jacking up and to prevent damage caused by the gripping member indenting into the object to be jacked up. Therefore, it is possible to prevent the slipping down and damage of the object to be jacked up such as a bundled column.

[0041] Also, according to another jacking-up device according to the present invention, since a buffer member is provided between the object to be jacked up and the gripping member, it is possible to effectively prevent damage to the object to be jacked up.

[0042] Moreover, according to the jacking-up method of the present invention, it is a method for jacking up a columnar object to be jacked up, comprising the steps of: arranging a pair of gripping members horizontally opposite to each other with the object to be jacked up therebetween; inserting threaded fastening members horizontally on both horizontal sides of the gripping members respectively, and then tightening the threaded fastening members in a direction to bring the pair of gripping members closer to each other; and jacking up the object to be jacked up by raising the pair of gripping members with a jack. The threaded fastening member is tightened with a tightening force set based on the contact area between the object to be jacked up and the gripping member and the indentation resistance of the object to be jacked up. The tightening force is set to prevent the object to be jacked up from slipping off the gripping member during jacking up and to prevent damage caused by the gripping member indenting into the object to be jacked up. Therefore, it is possible to prevent the object to be jacked up, such as a bundled column, from slipping off or being damaged.

[0043] Moreover, according to another jacking-up method of the present invention, after providing a buffer member between the object to be jacked up and the gripping member, the threaded fastening member is tightened, so that damage to the object to be jacked up can be effectively prevented.

[0044] Moreover, according to the method for renovating an existing foundation of the present invention, it is a method for renovating an existing foundation. After jacking up an existing column, which is the object to be jacked up, by using the above-described jacking-up method, the existing foundation below the existing column is renovated. Therefore, it is possible to renovate the existing foundation while preventing the existing column from slipping off or being damaged.

[0045] Moreover, according to another method for renovating an existing foundation of the present invention, after jacking up the existing column, a protection member is inserted directly below the existing column, and the protection member and the gripping member are fixed, so that it is possible to prevent the existing column from slipping off due to unexpected slipping and improve the work safety.

[0046] The Sustainable Development Goals (SDGs) are 17 international goals adopted at the United Nations Summit in September 2015. The jacking-up device, jacking method, and existing foundation repair method according to this embodiment can contribute to achieving one of the 17 SDGs, for example, goal 11, "Make cities and towns inclusive and sustainable." [Industrial Applicability]

[0047] As described above, the jacking-up device, jacking-up method, and existing foundation repair method of the present invention are useful for jacking up columns and the like in repair work on existing foundations, and are particularly suitable for preventing the object being jacked up from sliding down or being damaged. [Explanation of symbols]

[0048] 10 Existing wooden buildings 12 Existing foundation 14 Existing pillar (object to be jacked up) 26 Grip fittings (gripping members) 28 Bolts (threaded fasteners) 30 Jack 32 Mounting stand 38 Nut 40 New foundation 42 Steel plate (protective material) 100 Jack-up device

Claims

1. An apparatus for jacking up a columnar object to be jacked up, comprising: a pair of gripping members arranged horizontally opposite to each other with the object to be jacked up therebetween; a screw fastening member inserted horizontally on both horizontal sides of the gripping members and configured to fasten the pair of gripping members in a direction approaching each other; and a jack configured to jack up the object to be jacked up by raising the pair of gripping members; wherein the screw fastening member is fastened with a fastening force set based on the contact area between the object to be jacked up and the gripping members and the indentation resistance of the object to be jacked up; the fastening force is set to prevent the object to be jacked up from slipping off the gripping members during jacking up and to prevent damage caused by the gripping members indenting into the object to be jacked up. A jacking-up apparatus characterized by this.

2. The jacking-up apparatus according to claim 1, characterized in that a buffer member is provided between the object to be jacked up and the gripping members.

3. A method for jacking up a columnar object to be jacked up, comprising: arranging a pair of gripping members horizontally opposite to each other with the object to be jacked up therebetween; inserting screw fastening members horizontally on both horizontal sides of the gripping members and then fastening the screw fastening members in a direction approaching each other; and jacking up the object to be jacked up by raising the pair of gripping members with a jack; wherein the screw fastening member is fastened with a fastening force set based on the contact area between the object to be jacked up and the gripping members and the indentation resistance of the object to be jacked up; the fastening force is set to prevent the object to be jacked up from slipping off the gripping members during jacking up and to prevent damage caused by the gripping members indenting into the object to be jacked up. A jacking-up method characterized by this.

4. The jacking-up method according to claim 3, characterized in that a buffer member is provided between the object to be jacked up and the gripping members and then the screw fastening member is fastened.

5. A method for renovating an existing foundation, After jacking up an existing column, which is an object to be jacked up, using the jacking-up method according to claim 3 or 4, an existing foundation repair method characterized by repairing an existing foundation below the existing column.

6. The existing foundation repair method according to claim 5, characterized in that after jacking up the existing column, a protection member is inserted directly below the existing column, and the protection member and the gripping member are fixed.

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