Method for correcting inclination of concrete slab caused by ground settlement

Abstract

The object of the present invention is to provide a method for correcting the inclination of a concrete slab by returning the sunken side to a predetermined height when one side of the concrete slab has sunk due to subsidence of the ground. (1) The process of creating a gutter along the edge of the sunken concrete slab to accommodate jacks for lifting the concrete slab from the side. (2) The process of placing a jack in the gutter and lifting the concrete slab from the side (3) A process in which expansive resin is injected into the void created under the concrete slab by lifting the concrete slab with a jack through an injection hole drilled in the concrete slab, allowing the resin to expand. (4) The process of removing the jacks installed in the gutters At least

Description

[Technical field]

[0001] The present invention relates to a method for correcting the inclination of a concrete slab caused by subsidence of the ground. [Background technology]

[0002] In recent years, the tilt of concrete slabs due to land subsidence in harbor areas has become a problem. As a method for dealing with this problem, the research group of the present inventors has proposed a method in Patent Document 1 in which expansive resin is injected into the interior of the subsided ground or into gaps that have occurred between the ground and the concrete slab through injection holes drilled into the concrete slab, and then expanded, so that the concrete slab is returned to a specified height by being pushed up by the expansion of the expansive resin.

[0003] An RTG (Rubber Tired Gantry) crane (tired transfer crane), which is a loading and unloading machine in a container terminal in a port area, is a gantry crane used to transport containers in a yard, and plays a role in unloading containers from trucks to the yard and loading them from the yard to trucks. An RTG crane does not require rails, which are required for a rail-type transfer crane to travel, and its travel lane is composed of a long and narrow concrete slab, for example, 10 to 300 m long, 1 to 3 m wide, and 0.1 to 0.5 m thick (some are composed by pouring ready mixed concrete on the spot, and some are composed by connecting multiple PC concrete slabs that have been brought in). Even when the long and narrow concrete slabs that compose the travel lane of such an RTG crane tilt due to subsidence of the ground, the method of using an expansive resin proposed by the research group of the present inventors in Patent Document 1 is effective. However, if one of the longitudinal sides of the concrete slab sinks (if the concrete slab tilts parallel to the longitudinal direction), when an attempt is made to return the concrete slab on one side to a specified height by injecting and expanding expandable resin into the ground on that side or into the void between the ground and the concrete slab, the concrete slab on the other side, which does not need to be pushed up by the expansion of the expandable resin, may end up being pushed up at the same time because the width of the concrete slab is short. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-144269 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a method for correcting the inclination of a concrete slab by returning one side of the concrete slab to a predetermined height when the one side of the concrete slab sinks due to subsidence of the ground. [Means for solving the problem]

[0006] In view of the above, the present invention provides a method for preventing ground subsidence caused by ground subsidence. , elongated, with a length at least three times its width Concrete slab Subsidence on one side of the length Tilt , using expandable resin The method for correcting the above-mentioned problem is as described in claim 1. (1) The process of creating a gutter along the edge of the sunken concrete slab to accommodate jacks for lifting the concrete slab from the side. (2) The process of placing a jack in the gutter and lifting the concrete slab from the side (3) A process in which expansive resin is injected into the gap below the concrete slab, which is formed by lifting the concrete slab with a jack, through an injection hole drilled in the concrete slab, and the resin is allowed to expand. (4) The process of removing the jacks installed in the gutters Contains at least By returning the sunken side to the specified height, . Effect of the Invention

[0007] According to the present invention, when one side of a concrete slab sinks due to subsidence of the ground, a method can be provided for correcting the inclination of the concrete slab by returning the sunken side to a predetermined height. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view (schematic cross-sectional view in the width direction of the concrete slab) showing the state in which a gutter for installing a jack to lift the concrete slab from the right side has been provided along the right edge of the sunken concrete slab in step (1). [Diagram 2] FIG. 11 is a schematic cross-sectional view showing the state in which the right side of the concrete slab has been lifted to its original height from the right side by a jack installed in the gutter in step (2). [Diagram 3] This is a schematic cross-sectional view showing the state in which expandable resin is injected into a void below the concrete slab formed by lifting the right side of the concrete slab with a jack in step (3) through an injection hole drilled into the concrete slab. [Figure 4] FIG. 11 is a schematic cross-sectional view showing the state after the jack installed in the gutter has been removed in step (4). BEST MODE FOR CARRYING OUT THEINVENTION

[0009] The method for correcting the inclination of a concrete slab caused by subsidence of the ground of the present invention comprises the steps of: (1) The process of creating a gutter along the edge of the sunken concrete slab to accommodate jacks for lifting the concrete slab from the side. (2) The process of placing a jack in the gutter and lifting the concrete slab from the side (3) A process in which expansive resin is injected into the gap below the concrete slab, which is formed by lifting the concrete slab with a jack, through an injection hole drilled in the concrete slab, and the resin is allowed to expand. (4) The process of removing the jacks installed in the gutters At least

[0010] The method of the present invention will be described below with reference to the drawings, but the method of the present invention should not be construed as being limited to the following description.

[0011] FIG. 1 is a schematic cross-sectional view (schematic cross-sectional view in the width direction of the concrete slab) showing a state in which a gutter for installing a jack to lift the concrete slab from the right side is provided along the right side of the sunken concrete slab in step (1) when the right side of the length of a long and narrow concrete slab (for example, a slab with a length of 250 m, a width of 1.25 m, and a thickness of 0.3 m, which is constructed by pouring ready mixed concrete on the spot) constituting the travel lane of an RTG crane in a container terminal in a port area sinks (when the concrete slab tilts parallel to the length direction). The scale and size of the gutter provided for installing the jack may be appropriately determined according to the state of sinking of the concrete slab (for example, the center part in the length direction is more likely to sink than the ends, so the sunken concrete slab tends to have a twisted shape (the degree of sinking is not uniform)), the size, performance, and number of jacks to be used, etc.

[0012] 2 is a schematic cross-sectional view showing the state in which the right side of the concrete slab is lifted from the right side to the original height as a predetermined height (target height) by a jack installed in the gutter in step (2). Lifting the concrete slab from the side with a jack can be performed by, for example, using an L-shaped angle member made of metal (e.g., steel) as a member for lifting the concrete slab from the side with a jack, fixing one outer surface of the member to the side of the concrete slab, and lifting the other outer surface from below by applying pressure to a hydraulic jack installed on a reaction plate (the hydraulic jack may be manual or electric, and a steel pipe pile pressed into the ground may be used instead of the reaction plate). As a method for fixing one outer surface of the L-shaped angle member to the side surface of the concrete slab, for example, a hole for inserting a bolt used for fixing one outer surface of the L-shaped angle member is drilled in the side surface of the concrete slab, a chemical anchor (registered trademark) is injected into the bolt insertion hole, the bolt is inserted, and the L-shaped angle member is fastened with a nut through the bolt through hole. The bolt should be, for example, 150 to 300 mm in total length and 10 to 30 mm in diameter, and 50 mm or more should be inserted into the insertion hole. The number of bolts used may be, for example, 2 to 4 per jack. The L-shaped angle member may be prevented from deforming into the L-shape by attaching a steel plate or the like as a corner reinforcement to the inner surface so that the L-shape does not deform when lifted from below with a jack, preventing the concrete slab from being lifted. The degree of lifting of the concrete slab may be confirmed, for example, by using a laser level.

[0013] FIG. 3 is a schematic cross-sectional view showing the state in which expansive resin is injected from an injection hole drilled in the concrete slab into a gap below the concrete slab formed by lifting the right side of the concrete slab with a jack in step (3). The injection hole for the expansive resin is preferably provided, for example, 200 to 500 mm away from the edge of the concrete slab and in a range of 10 to 50 mm in diameter. If the injection hole is provided too close to the edge of the concrete slab, the expansive resin injected into the gap below the concrete slab is likely to flow out from the side (resulting in poor construction efficiency). The injection of the expansive resin from the injection hole may be performed using a known injection gun. The expansive resin injected into the gap below the concrete slab first flows toward the side with the lower slope (the right side of the concrete slab) and expands within a short time (for example, 2 to 10 seconds. An appropriate time can be selected according to the size of the gap by adjusting the composition and components of the expansive resin), and then expands in the remaining gap by continuous or intermittent injection of a specified amount, filling the gap. Therefore, it is possible to prevent the concrete slab on the left side, which does not need to be pushed up by the expansion of the expansive resin, from being pushed up. It is desirable to inject the expansive resin from the injection hole to the extent that the side of the expanded resin filling the gap overflows into the gutter, in order to ensure that the expanded resin fills the gap below the concrete slab sufficiently and firmly.

[0014] FIG. 4 is a schematic cross-sectional view showing the state in which the jack installed in the gutter is removed in step (4) after completing step (3) (the reaction plate is also removed together with the hydraulic jack, and the L-shaped angle member with one outer surface fixed to the side of the concrete plate is also removed by releasing the nut tightening. The bolt inserted from the side of the concrete plate into the inside is cut off at the side of the concrete plate and left behind). It is confirmed, for example, by using a laser level that the concrete plate is maintained at its original height even after loosening the jack to remove it, and if it is confirmed that the original height is maintained, the injection hole drilled in the concrete plate is blocked with, for example, non-shrink mortar. If the concrete plate falls from its original height by loosening the jack, the concrete plate is raised to its original height by applying pressure to the jack again, and an expansive resin is injected from the injection hole into the void below the concrete plate formed by lifting the concrete plate, and the void is filled with the expanded resin. The gutter can be returned to its original state by backfilling and compacting it using the prescribed method, and then pouring ready mixed concrete or installing a precast concrete slab. If the overflow of the sides of the expanded resin that filled the gap below the concrete slab in step (3) into the gutter is so excessive that it could hinder backfilling and compaction of the gutter, backfilling and compaction of the gutter shall be carried out after cutting or cutting off the excessive overflowing part of the expanded resin (overflow of more than 10 mm should be cut or cut off).

[0015] When the concrete slab subsidence extends over a wide area, the lifting of the concrete slab using the jacks in step (2) can be performed, for example, by lining up the jacks in the gutter, for example, at intervals of 1 to 3 m, and first applying pressure to the jack installed at the very edge of the area where the concrete slab needs to be lifted, then to the jack next to it, then to the jack next to it, and so on, or by first applying pressure to the jack installed at the area where the degree of subsidence is greatest, then to the jacks on both sides of it, then to the jack next to it, and so on, in succession. The condition of all the installed jacks should be constantly checked, and if any jack has not been able to lift the concrete slab to its original height, additional pressure should be applied to further lift the concrete slab. Even if a jack has been able to lift the concrete slab to its original height, if it does not function as a support for the lifted concrete slab, the concrete slab may fall from its original height again, so sufficient pressure should be applied to enable it to function as a support. By limiting the spacing between jacks to 3m, it is possible to prevent the load of the concrete slab from being placed on each individual jack too heavily, making it easier for multiple jacks to work together to lift the concrete slab.

[0016] Furthermore, the injection of the expandable resin in step (3) may be performed by providing injection holes for the expandable resin in a row in the concrete slab, for example, at intervals of 0.5 to 1.5 m, in order from the points where the concrete slab has been raised to its original height, or after the concrete slab has been raised to its original height at all points. By setting the upper limit of the intervals for providing the injection holes for the expandable resin to 1.5 m, it becomes easy to prevent voids from remaining below the concrete slab after the expandable resin injected through the injection holes expands.

[0017] It is not necessary to have enough jacks to install in all areas where the concrete slab needs to be lifted; for example, 5 to 30 jacks can be installed in some of the areas where the concrete slab needs to be lifted, and the jacks that were installed can be removed in order from the areas where the inclination of the concrete slab has been corrected by using the jacks to lift the concrete slab and injecting the expansive resin, and the removed jacks can be installed in areas where no jacks have been installed yet and where lifting is required, and the concrete slab can then be lifted using the jacks and the expansive resin can be injected.

[0018] The expandable resin may be an expandable resin that has been known to be usable for ground improvement. Among them, non-fluorocarbon expandable resins that are environmentally friendly and do not cause global warming are preferable. Examples of non-fluorocarbon expandable resins include commercially available resins made of polyol and isocyanate that react to form urethane foam without generating fluorocarbon gas (specifically, a combination of non-fluorocarbon polyol FF5020-UC and isocyanate NP-90 from Nippon Paftem Co., Ltd. is exemplified). The non-fluorocarbon expandable resin may be one made of polyol and isocyanate, one that foams with carbon dioxide gas by reacting with water and isocyanate, one that foams using liquefied carbon dioxide gas, or a hydrocarbon-based resin with foaming properties.

[0019] The expandable resin may contain a third component that can improve the strength of the expanded resin when added to the expandable resin, such as granular or powdery solid substances (not reactive with the expandable resin) that are stronger than the expanded resin, such as steel slag, metal powder such as iron powder, soil, sand, gravel, etc. Adding such a third component to the expandable resin has the advantage of suppressing the occurrence of scorch (burning) caused by the reaction heat during the expansion of the expandable resin. The third component is added in a weight ratio of 0.1 to 50.0 to 1 part of the expandable resin to provide the expanded resin with the desired strength (for example, 130 to 1400 kN / m 2 ) to the expanding resin.

[0020] In the above explanation, the right side of the concrete slab is lifted from the right side to its original height with a jack installed in the gutter in step (2), but the height to which the concrete slab is lifted by the jack may be set lower than its original height (for example, 1 to 10 mm lower than its original height), and the concrete slab may be returned to its original height by being pushed up by the expansion of the expansive resin injected into the gap below the concrete slab. This makes it easier to remove the jack in step (4) (a gap is created between the jack and the L-shaped angle member after the concrete slab is returned to its original height, allowing the jack to be easily removed).

[0021] In the above explanation, in step (2), the right side of the concrete slab is lifted from the right side to its original height with a jack installed in the gutter, and then in step (3), expandable resin is injected into the gap below the concrete slab to expand it. However, if pressure is applied to the jack to lift the concrete slab in step (2) and at the same time expandable resin is injected into the gap below the concrete slab and expanded in step (3), so that the expanded resin not only fills the gap but also pushes up the concrete slab, the concrete slab can be returned to its original height even if the load on the concrete slab exceeds the allowable load of the jack.

[0022] The above explanation has been given as an example of correcting the inclination of a long, narrow concrete slab that constitutes the travel lane of an RTG crane in a container terminal in a port area, but the present invention can also be applied to correcting the inclination of a long, narrow concrete slab that constitutes the travel lane of an AGV (Automated Guided Vehicle) or a travel lane for trucks in a container terminal in a port area.

[0023] Furthermore, the concrete slabs whose inclination can be corrected by applying the present invention are not limited to long and narrow concrete slabs (for example, a concrete slab whose length is three or more times its width), and the present invention can be applied to correcting the inclination of concrete slabs of various lengths and widths (for example, a concrete slab whose length is 10 to 500 m and whose width is 1 to 10 m, and whose thickness may be, for example, 0.1 to 0.5 m). [Industrial Applicability]

[0024] The present invention has industrial applicability in that it provides a method for correcting the inclination of a concrete slab by returning one side of the concrete slab that has sunk due to ground subsidence to a predetermined height.

Claims

[Claim 1] A method for correcting an inclination caused by subsidence of one side of a long and narrow concrete slab, the length of which is three times or more than the width of the slab, by using an expansive resin, the method comprising the steps of: (1) A process of creating a gutter along the edge of the sunken concrete slab to install a jack to lift the concrete slab from the side. (2) The process of placing a jack in the gutter and lifting the concrete slab from the side (3) A process of injecting expansive resin into the gap below the concrete slab formed by lifting the concrete slab with a jack through an injection hole drilled in the concrete slab, and allowing the resin to expand. (4) The process of removing the jacks installed in the gutters The method includes at least returning the sunken side to a predetermined height.

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