Grab dredging attachments, dredging grab buckets and dredging methods

Abstract

To provide an attachment for grab dredge, a grab bucket for dredge, and a dredge method allowing surplus water loaded under dredge work to be effectively reduced in a simple configuration.SOLUTION: A dredge method includes a descent process descending a grab bucket 10 for dredge toward a water bottom ground B after attaching on an inner wall 12 of a bucket shell 11 of the grab bucket 10 for dredge a deformable bag portion 2 in which gas G is included, to make the bag portion 2 in a contracted state. An ascent process ascending the grab bucket 10 for dredge thereafter discharges surplus water W in the bucket shell 11 out of the bucket shell 11 by relaxing the contracted state of the bag portion.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a grab dredging attachment, a dredging grab bucket, and a dredging method, and more particularly to a grab dredging attachment, a dredging grab bucket, and a dredging method that are simple in configuration but can effectively reduce excess water lifted during dredging work. [Background technology]

[0002] In dredging work using a grab bucket, the final finish excavation involves shallowly digging the bottom of the water, so the depth of the finish excavation is shallower than the grab bucket's maximum excavation depth. As a result, the amount of sediment scooped up by the bucket shell during finish excavation is less than when digging deeply, and a lot of excess water (surplus water) is taken into the closed bucket shell. As a result, the ratio of sediment volume to bucket capacity (mud content) is low during finish excavation. Since excess water is also lifted up along with the dredged sediment, transported, and treated, if a large amount of excess water is lifted up, it can reduce transportation efficiency and treatment efficiency at the sediment treatment plant.

[0003] Therefore, as a means of improving the mud content during finish excavation, a dredging grab bucket that can change the volume of the sealed space inside the bucket has been proposed (see, for example, Patent Document 1). In the dredging grab bucket of Patent Document 1, a volume reduction space relative to the bucket capacity is defined by attaching a partition body made of plate-shaped first and second partition plates to a compartment divided inside the bucket shell. A filler member made of foamed resin is then placed inside the volume reduction space to prevent water from entering.

[0004] However, with this dredging grab bucket, it is necessary to prepare a filler element that is pre-processed to fit the shape of the volume reduction space, and the filler element must be installed inside the volume reduction space at the dredging site. When the bucket capacity is large, the filler element becomes huge and difficult to handle. Even if the filler element is divided into multiple pieces, it requires a lot of labor to transport and install them. Furthermore, because the bucket shell's capacity is reduced by the volume reduction space (filler element), excavation of soil and sand is performed with the bucket shell's capacity reduced, making it difficult to smoothly load the soil and sand into the bucket shell, which may reduce the workability of excavation work. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-83734 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a grab dredging attachment, a dredging grab bucket, and a dredging method that have a simple configuration yet can effectively reduce excess water lifted during dredging operations. [Means for solving the problem]

[0007] In order to achieve the above object, the grab dredging attachment of the present invention is a grab dredging attachment that is attached to the inside of the bucket shell of a dredging grab bucket, and is characterized in that it has a bag portion attached to the inner wall of the bucket shell, the bag portion is filled with gas and is deformable, and the bag portion deforms in response to water pressure to change the storage volume of the bucket shell. 。

[0008] The dredging grab bucket of the present invention is characterized by being equipped with the above-mentioned grab dredging attachment.

[0009] The dredging method of the present invention is a dredging method using a dredging grab bucket. 、 A deformable bag portion filled with gas is attached to the inner wall of the bucket shell of the dredging grab bucket, and in the lowering step of lowering the dredging grab bucket toward the bottom ground, the bag portion is Depending on the water pressure In the subsequent raising process of raising the dredging grab bucket toward the water surface, the bag portion is kept in a deflated state. Depending on the water pressure By reducing the pressure, excess water in the bucket shell is discharged to the outside of the bucket shell. [Effects of the Invention]

[0010] According to the grab dredging attachment, dredging grab bucket, and dredging method of the present invention, a deformable bag filled with gas is attached to the inner wall of the bucket shell of the dredging grab bucket. During the descent process, in which the grab bucket is lowered toward the bottom of the water, the bag is contracted, ensuring a large capacity within the bucket shell and enabling smooth scooping of sediment from the bottom of the water. During the subsequent ascent process, in which the grab bucket is raised toward the water surface, the contracted state of the bag is relaxed inside the bucket shell, reducing the capacity within the bucket shell and allowing excess water within the bucket shell to be discharged outside the bucket shell. Therefore, despite its simple configuration, the excess water lifted during dredging can be effectively reduced, increasing the ratio of sediment volume to bucket capacity (mud content). The reduction in excess water improves transportation efficiency and treatment efficiency at sediment treatment plants. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram illustrating a vertical cross-sectional view of a dredging grab bucket equipped with a grab dredging attachment of the present invention in a fully open state near the water surface. [Figure 2] FIG. 2 is a view taken along the arrow A in FIG. [Figure 3] 2 is an explanatory diagram illustrating a state in which the dredging grab bucket of FIG. 1 is lowered to near the bottom of the water in a vertical cross section. FIG. [Figure 4] 4 is an explanatory diagram illustrating a state in which the dredging grab bucket of FIG. 3 scoops up earth and sand from the water bottom ground and the bucket shell is closed, as viewed in vertical section. FIG. [Figure 5] 5 is an explanatory diagram illustrating a state in which the dredging grab bucket of FIG. 4 is raised to near the water surface in a vertical cross section. FIG. [Figure 6] FIG. 2 is an explanatory diagram illustrating, in a longitudinal cross section, the state in which an air supply and exhaust device is connected via a connecting pipe to a valve provided in the bag portion of FIG. 1, and the dredging grab bucket scoops up soil from the bottom of the water and the bucket shell is closed. [Figure 7] 7 is an explanatory diagram illustrating a state in which the dredging grab bucket of FIG. 6 is raised to near the water surface in a vertical cross section. FIG. [Figure 8] FIG. 1 is an explanatory diagram illustrating a vertical cross-sectional view of a dredging grab bucket equipped with another grab dredging attachment of the present invention. [Figure 9] FIG. 9 is an explanatory diagram illustrating the grab dredging attachment of FIG. 8 in cross section. [Figure 10] FIG. 10 is an explanatory diagram illustrating a dredging grab bucket equipped with yet another grab dredging attachment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the grab dredging attachment, the dredging grab bucket, and the dredging method of the present invention will be described based on the embodiments shown in the drawings.

[0013] A grab dredging attachment 1 (hereinafter referred to as attachment 1) of the present invention shown in Figs. 1 and 2 is attached to the inside of a bucket shell 11 of a dredging grab bucket 10 (hereinafter referred to as grab bucket 10).

[0014] The attachment 1 is mainly used when performing finish excavation, which involves dredging a depth shallower than the maximum excavation depth of the grab bucket 10. When finish excavation is performed with the grab bucket 10 without the attachment 1 attached, the bucket capacity is large compared to the finish depth, so a lot of excess water W (hereinafter referred to as surplus water W) is taken into the bucket shell 11, and a lot of surplus water W is lifted up as is. Therefore, in the present invention, by attaching the attachment 1 to the inside of the bucket shell 11, the storage volume of the bucket shell 11 can be changed, thereby reducing the amount of surplus water W lifted up during dredging work.

[0015] The attachment 1 is attached to a so-called sealed grab bucket 10. When the sealed grab bucket 10 scoops up sediment S from the water bottom ground B and closes the pair of bucket shells 11, the sediment S taken into the bucket shells 11 is unlikely to flow out, but there are relatively small gaps between the open ends 14 of the bucket shells 11 through which water W can pass. The open ends 14 of the bucket shells 11 are end portions located below the inner walls 12 of the bucket shells 11 when the grab bucket 10 is fully open. The inner walls 12 of the bucket shells 11 are wall surfaces located at the top and inside of the bucket shells 11 when the pair of bucket shells 11 are closed. Some bucket shells 11 have water holes in the wall surfaces through which water can pass.

[0016] The attachment 1 has a bag portion 2 attached to the inner wall 12 of the bucket shell 11. The bag portion 2 is deformable and has a gas G sealed therein. An example of the gas G sealed in the bag portion 2 is air, but a gas G other than air can also be sealed in the bag portion 2. The bag portion 2 is made of, for example, rubber or resin. The bag portion 2 can be formed, for example, by bonding the peripheral edges of two sheet members together. It is preferable that the bag portion 2 is stretchable. It is advisable that at least a portion of the bag portion 2 is made of an elastic material. For example, the bag portion 2 can be made of multiple types of materials so that the bag portion 2 has stretchable and non-stretchable portions.

[0017] In this embodiment, a plate-shaped protrusion is provided on the periphery of the bag portion 2, and the protrusion is fixed to the inner wall 12 of the bucket shell 11 by an attachment mechanism 4. The shape, size, capacity (external volume), etc. of the bag portion 2 can be determined appropriately according to the shape and size of the bucket shell 11. In this embodiment, one bag portion 2 is attached to each of the left and right bucket shells 11, but multiple bag portions 2 can also be arranged in the bucket shell 11.

[0018] In this embodiment, a protective part 3 is provided that covers the outer surface of the bag part 2. The protective part 3 prevents damage to the bag part 2 due to soil S, stones, etc. The protective part 3 is made of, for example, a sheet-like or plate-like member, and is formed of synthetic fibers such as aramid fibers, resin, etc. The protective part 3 is bonded to the outer surface of the bag part 2 and is integrated with the bag part 2. It is preferable that the protective part 3 is configured to be deformable to follow the bag part 2. In this embodiment, the protective part 3 is bonded to a part of the outer surface of the bag part 2 that is located on the lower side when the bucket shell 11 is fully opened, and the base part of the bag part 2 that is not covered by the protective part 3 is configured to be expandable and contractable. When a protective part 3 that is difficult to deform is used, multiple protective parts 3 can be arranged at intervals from each other, for example, to allow the bag part 2 to easily deform (expand and contract).

[0019] In this embodiment, the attachment mechanism 4 enables the bag portion 2 to be attached to and detached from the bucket shell 11. The attachment mechanism 4 includes a fixing member 4a that is fixed to the inner wall 12 of the bucket shell 11, and a fixture 4b that detachably fixes the bag portion 2 to the fixing member 4a. The fixing member 4a is made of, for example, a metal tubular member, a metal plate member, or a steel section, and is fixed to the inner wall 12 of the bucket shell 11 by welding, bolting, or the like. The shape and arrangement of the fixing member 4a can be determined appropriately depending on the shape of the inner wall 12 of the bucket shell 11, the size of the bag portion 2, and the like. The fixture 4b is made of a plate-like member and a bolt, and a protrusion provided on the periphery of the bag portion 2 is sandwiched between the fixing member 4a and the plate-like member and fixed by the bolt. The attachment mechanism 4 is not limited to the configuration in this embodiment, and various other configurations are also possible.

[0020] In this embodiment, a valve 5 for injecting and discharging gas G is provided in the bag portion 2. In this embodiment, the valve 5 is inserted into a through-hole formed in the inner wall 12 of the bucket shell 11, and the tip of the valve 5 is detachably connected to a connecting portion 2a (through-hole) provided in the bag portion 2. In this embodiment, the intake and exhaust port of the valve 5 is disposed outside the bucket shell 11, but, for example, the intake and exhaust port of the valve 5 can also be disposed inside the bucket shell 11. For example, the valve 5 can be configured with a lid (cap) that prevents the outflow of gas G from the bag portion 2, but convenience is enhanced if the valve 5 has a check valve structure that suppresses the outflow of gas G from the bag portion 2.

[0021] Next, a dredging method using the grab bucket 10 equipped with the attachment 1 will be described.

[0022] The grab bucket 10 is used to dredge the water bottom ground B, leaving a predetermined finishing depth. The finishing depth is shallower than the maximum digging depth of the grab bucket 10. Then, the attachment 1 is attached to the inside of the bucket shell 11 and finishing digging is performed. The attachment 1 is attached to the bucket shell 11 on a ship or on land, for example.

[0023] In this embodiment, the fixing member 4a and the valve 5 are fixed to the bucket shell 11 in advance before dredging work begins. The fixing member 4a and the valve 5 can also be fixed to the bucket shell 11 immediately before finish excavation. When finish excavation is performed, the bag portion 2 is attached to the inner wall 12 of the bucket shell 11. Specifically, the tip of the valve 5 fixed to the bucket shell 11 is connected to the connecting portion 2a provided on the bag portion 2. Then, the protrusions provided on the periphery of the bag portion 2 are fixed to the fixing member 4a by the mounting fixtures 4b.

[0024] Then, gas G is injected into the bag portion 2 through the valve 5 using an air supply / exhaust device such as a compressor, thereby sealing the gas G inside the bag portion 2. The amount of gas G to be sealed in the bag portion 2 and the internal pressure of the bag portion 2 are set based on the capacity of the bucket shell 11 and the estimated amount of sediment (past actual value) to be taken into the bucket shell 11 during dredging. As shown in FIG. 1, the amount of gas G to be sealed in the bag portion 2 is set so that when the grab bucket 10 is located at a shallow depth near the water surface and the bag portion 2 is in an inflated state, the volume occupied by the bag portion 2 inside the bucket shell 11 is within a range of 20% to 80%, more preferably 50% to 80%, of the remaining volume obtained by subtracting the volume of the estimated amount of sediment to be taken into the bucket shell 11 during dredging from the capacity of the bucket shell 11 when the attachment 1 is not attached. The operation of injecting the gas G into the bag portion 2 can also be performed before the bag portion 2 is fixed to the bucket shell 11.

[0025] Next, the grab bucket 10 with the attachment 1 attached is lowered in an open state toward the water bottom ground B. During this lowering process, the water depth at which the grab bucket 10 is located becomes deeper, and the water pressure gradually increases. As the water pressure increases, the bag portion 2 in which the gas G is sealed gradually contracts.

[0026] As shown in Fig. 3, when the grab bucket 10 is located near the water bottom ground B, the bag portion 2 is crushed and deformed by water pressure, and enters a contracted state. Then, as the volume of the bag portion 2 decreases, the capacity of the bucket shell 11 becomes larger than when the grab bucket 10 is located at a shallow depth near the water surface. Then, as shown in Fig. 4, with the bag portions 2 contracted, the pair of bucket shells 11 are closed to scoop up earth and sand S from the water bottom ground B.

[0027] Next, the pair of bucket shells 11 are raised above the water in a closed state. During this raising process, the water depth where the grab bucket 10 is located becomes shallower, and the water pressure gradually decreases. As the water pressure decreases, the contracted state of the bag portion 2 in which the gas G is sealed is relaxed, and the bag portion 2 gradually expands. Then, during the raising process, the volume of the bag portion 2 becomes larger than when the bucket shell 11 was used to excavate the earth and sand S of the waterbed ground B, and accordingly the capacity of the bucket shell 11 becomes smaller, and part of the excess water W that had been taken in the bucket shell 11 flows out of the bucket shell 11 through gaps between the open ends 14 of the bucket shells 11, etc.

[0028] As shown in Figure 5, when the grab bucket 10 is located at a shallow depth near the water surface, the bag portion 2 is in a relatively large expanded state, and the amount of excess water W taken up inside the grab bucket 10 is reduced compared to when the grab bucket 10 was located near the water bottom ground B. Next, the grab bucket 10 is lifted onto the water and moved onto a soil transport barge or the like, and the pair of bucket shells 11 are opened to discharge the dredged sediment S and the remaining excess water W.

[0029] After dredging work is completed, the attachment 1 is removed from the bucket shell 11. In this embodiment, the bag portion 2 is released from the restraint by the fixing members 4a and the mounting fixtures 4b, and the connection between the valve 5 and the connecting portion 2a of the bag portion 2 is released, and the bag portion 2 is removed from the bucket shell 11. The attachment 1 can be used repeatedly at different work sites or with different grab buckets 10.

[0030] As described above, according to the present invention, by keeping the bag portion 2 in a contracted state during the descent process in which the grab bucket 10 is lowered toward the waterbed B, a large storage volume within the bucket shell 11 can be secured, enabling smooth scooping of sediment S from the waterbed B. Ensuring a large storage volume within the bucket shell 11 reduces the possibility of problems such as leaving unexcavated material or making it difficult for sediment S to be taken into the bucket shell 11 during excavation. During the subsequent ascent process in which the grab bucket 10 is raised toward the water surface, the contracted state of the bag portion 2 is relaxed inside the bucket shell 11, reducing the storage volume within the bucket shell 11, allowing excess water W within the bucket shell 11 to be discharged to the outside of the bucket shell 11. Therefore, despite the simple configuration, the excess water W lifted during dredging work can be effectively reduced, and the ratio of the amount of sediment to the bucket capacity (mud content) can be increased. The reduction in excess water W improves transportation efficiency and treatment efficiency at the sediment treatment plant.

[0031] Furthermore, the excess water W within the bucket shell 11 can be discharged outside the bucket shell 11 while underwater before the grab bucket 10 is raised above the water. Therefore, the sediment S can be quickly discharged onto a soil transport barge or the like after the grab bucket 10 is raised above the water, allowing for extremely efficient dredging work. The bag portion 2 deforms to match the inner shape of the bucket shell 11 and the shape (undulations) of the sediment S captured within the bucket shell 11, so the excess water W within the bucket shell 11 can be effectively discharged outside the bucket shell 11. Furthermore, complex control is not required, and the attachment 1 can be easily applied to existing grab buckets 10. The amount of sediment to be dredged and the amount of excess water W to be discharged can be adjusted by changing the amount of gas G sealed in the bag portion 2 and the size of the bag portion 2, making it possible to flexibly respond to on-site conditions. Therefore, this is extremely useful for those skilled in the art.

[0032] If at least a part of the bag portion 2 is made of an elastic member, the part of the bag portion 2 made of the elastic member will be in a contracted state during the descending stroke, making the bag portion 2 more compact and facilitating the smooth operation of scooping up the sediment S from the water bottom ground B. Also, during the ascending stroke, the bag portion 2 will be more likely to deform to fit the shape of the inside of the bucket shell 11 and the shape of the sediment S inside the bucket shell 11, which is advantageous for more effectively discharging the excess water W inside the bucket shell 11.

[0033] If the protective part 3 covers at least a part of the outer surface of the bag part 2, the protective part 3 can prevent the excavated earth and sand S and stones from coming into contact with the bag part 2, which is advantageous in reducing the risk of damage to the bag part 2. Furthermore, by attaching the protective part 3 to a part of the bag part 2 made of a stretchable material, it is possible to easily increase the durability of the bag part 2 while maintaining the stretchability of the bag part 2. If the protective part 3 is configured to be deformable in accordance with the bag part 2, the bag part 2 and the protective part 3 will deform to match the shape of the earth and sand S taken into the bucket shell 11, which is advantageous in effectively discharging excess water W from the bucket shell 11.

[0034] If the attachment 1 is configured to have a valve 5, it becomes possible to appropriately adjust the amount of gas G injected into the bag portion 2 and the internal pressure of the bag portion 2 according to the expected amount of sediment to be dredged, which is more advantageous for effectively reducing excess water while ensuring the workability of the dredging work. For example, the valve 5 can also be configured to have an internal pressure adjustment mechanism that, when the internal pressure of the bag portion 2 exceeds a predetermined threshold, discharges the gas G inside the bag portion 2 until the internal pressure of the bag portion 2 falls below the threshold. The internal pressure adjustment mechanism prevents the internal pressure of the bag portion 2 from becoming excessive, and more reliably prevents the bag portion 2 from bursting, even when a pressure greater than expected is applied to the bag portion 2.

[0035] If the bag portion 2 is configured to be detachable from the bucket shell 11, the bag portion 2 can be removed from the bucket shell 11 when deep digging the waterbed ground B, eliminating the need to prepare separate grab buckets 10 for deep digging and finish digging. This also eliminates the need to change the grab bucket 10 between deep digging and finish digging, which is advantageous for improving the efficiency of dredging work.

[0036] 6 and 7, in the present invention, for example, dredging work can be performed with an air supply and exhaust device 8 connected to a valve 5 provided in the bag portion 2 via a connecting pipe 6. In this embodiment, an internal pressure detector 7 that detects water pressure is installed inside the bucket shell 11, and the air supply and exhaust device 8 is controlled based on the detection data of the internal pressure detector 7.

[0037] As shown in Fig. 6, in this embodiment, in the lowering process of lowering the grab bucket 10 toward the water bottom ground B, the gas G sealed in the bag portion 2 is exhausted by the air intake and exhaust device 8, thereby contracting the bag portion 2. More specifically, the higher the water pressure detected by the internal pressure detector 7, the more the air intake and exhaust device 8 controls to reduce the gas G sealed in the bag portion 2. Then, with the bag portion 2 contracted, the pair of bucket shells 11 are closed to scoop up soil S from the water bottom ground B.

[0038] Next, in the ascending process in which the grab bucket 10 is raised toward the water surface, the air supply and exhaust device 8 injects gas G into the bag portion 2 to alleviate the contracted state of the bag portion 2. Then, by the time the grab bucket 10 is raised near the water surface, the bag portion 2 is expanded and excess water W in the bucket shell 11 is discharged to the outside of the bucket shell 11. More specifically, the lower the water pressure detected by the internal pressure detector 7, the more control is exercised so that the air supply and exhaust device 8 increases the amount of gas G sealed in the bag portion 2. Next, the grab bucket 10 is raised above the water and moved onto a soil transport barge or the like, and the pair of bucket shells 11 are opened to discharge the sediment S and excess water W.

[0039] In this way, when dredging work is performed with the air supply and exhaust device 8 connected to the valve 5 via the connecting pipe 6, for example, even when dredging work is performed in a water area where the water bottom B is relatively shallow, the bag portion 2 can be deflated by exhausting the gas G from the bag portion 2. This makes it possible to ensure a larger storage volume within the bucket shell 11 during excavation, thereby reducing the possibility of a problem in which residual excavation material or earth and sand S is difficult to take into the bucket shell 11. During the ascent process, the air supply and exhaust device 8 injects the gas G into the bag portion 2, thereby making it possible to expand the bag portion 2 more greatly. This makes it possible to increase the amount of change in the storage volume within the bucket shell 11 caused by the bag portion 2, which is more advantageous for reducing excess water W while ensuring workability in dredging work.

[0040] Furthermore, if the air intake and exhaust device 8 is configured to be controlled based on detection data from the internal pressure detector 7 installed in the bucket shell 11, it is possible to reduce the risk of excessive gas G being injected into the bag portion 2 at a water depth where the water pressure is high, placing an excessive load on the air intake and exhaust device 8 and the bag portion 2, or the risk of the bag portion 2 being damaged due to excessive expansion at a water depth where the water pressure is low. Note that while this embodiment illustrates a case where the air intake and exhaust device 8 is automatically controlled based on detection data from the internal pressure detector 7, an administrator can also manually operate the air intake and exhaust device 8 based on detection data from the internal pressure detector 7. Also, instead of the internal pressure detector 7, for example, a depth detector that measures the water depth at which the grab bucket 10 is located can be provided, and the amount of gas G injected into the bag portion 2 can be adjusted based on the measurement value of the depth detector.

[0041] 8 and 9 show an attachment 1 and a grab bucket 10 according to another embodiment of the present invention.

[0042] The attachment 1 of this embodiment has partition walls 2b that divide the internal space of the bag part 2 into a plurality of compartments (spaces). A valve 5 is provided in each compartment divided by the partition walls 2b, and the amount of gas G injected into each compartment can be adjusted.

[0043] In this way, by providing the partition wall 2b in the bag part 2, even if a hole is made in part of the bag part 2, the range from which the gas G escapes can be limited to the compartment with the hole, and the function of the other compartments without holes can be maintained. Therefore, the risk of interrupting the dredging work can be reduced, which is more advantageous for carrying out the dredging work efficiently.

[0044] Furthermore, for example, by changing the amount of gas G injected or the internal pressure of each compartment separated by the partition walls 2b to change the degree of expansion of each compartment, it becomes possible to guide the excess water W taken into the grab bucket 10 to a drainage location and more effectively discharge the excess water W. Specifically, for example, the amount of gas G injected into compartments far from the open end 14 of the bucket shell 11 is set to be relatively large, and the amount of gas G injected into compartments close to the open end 14 is set to be relatively small, so that the bag portion 2 expands in order from the compartments farthest from the open end 14 to the compartments closest to the open end 14. In this way, the bag portion 2 can guide the excess water W toward the open end 14 during the ascending process, and the excess water W can be more efficiently discharged to the outside.

[0045] FIG. 10 illustrates an attachment 1 and a grab bucket 10 according to still another embodiment of the present invention.

[0046] As shown in Fig. 10, reinforcing ribs 13 that reinforce the bucket shell 11 may be provided on the inner wall 12 of the bucket shell 11. Typical reinforcing ribs 13 are arranged in a grid pattern and protrude inward from the inner wall 12. In this embodiment, a bag portion 2 is provided in each of a plurality of compartments divided by the reinforcing ribs 13. The configurations of each bag portion 2, attachment mechanism 4, and valve 5 are generally the same as those in the embodiment illustrated in Figs. 1 to 5.

[0047] In this way, by configuring the bucket shell 11 so that multiple bag sections 2 are arranged on the inner wall 12 thereof, even if a hole is made in one bag section 2, the functionality of the other unopened bag sections 2 can be maintained. This reduces the risk of interrupting dredging work, which is more advantageous for efficient dredging work. Furthermore, by changing the number of bag sections 2 attached to the bucket shell 11, the amount of sediment to be dredged and the amount of excess water W to be discharged can be adjusted, making it possible to respond more flexibly to on-site conditions.

[0048] Furthermore, for example, by changing the degree of expansion of each bag portion 2 by changing the degree of stretchability of the bag portion 2 or the amount of gas G injected into each bag portion 2, it becomes possible to guide the excess water W taken into the bucket shell 11 to a drainage location and more effectively discharge the excess water W. Specifically, for example, the bag portions 2 are made to expand in order from the bag portion 2 farthest from the opening end 14 to the bag portions 2 closest to the opening end 14. In this way, the excess water W can be guided toward the opening end 14 by the multiple bag portions 2 during the ascending process, and the excess water W can be more efficiently discharged to the outside.

[0049] Even when the reinforcing ribs 13 are provided on the inner wall 12 of the bucket shell 11, for example, by fixing the fixing members 4a that protrude inward beyond the reinforcing ribs 13 to the inner wall 12 of the bucket shell 11 by welding, bolting, or the like, it is possible to eliminate the effect of the reinforcing ribs 13 and attach the bag portion 2 so as to straddle the reinforcing ribs 13.

[0050] The size, number, and arrangement of the bag portions 2 attached to the grab bucket 10 are not limited to those in the above embodiment, and can be determined appropriately depending on the shape and size of the bucket shell 11. For example, bag portions 2 of different sizes can be attached to the left and right bucket shells 11, or a bag portion 2 can be attached to only one of the bucket shells 11. The grab bucket 10 equipped with the attachment 1 can also be used for other dredging operations, not limited to finish excavation. Also, for example, the bag portions 2 can be attached to the bucket shell 11 in advance during deep excavation work before finish excavation, and the amount of gas G to be stored in the bag portions 2 during deep excavation work can be set to a small amount. Then, gas G can be injected into the bag portions 2 during finish excavation. [Explanation of symbols]

[0051] 1 Grab Dredging Attachment 2 bag part 2a Connecting part 2b Bulkhead 3 Protective part 4 Mounting mechanism 4a Fixing member 4b Mounting fixture 5 valves 6 Connecting pipe 7 Internal pressure detector 8. Air intake and exhaust system 10 Dredging Grab Bucket 11 Bucket Shell 12 Inner wall 13 Reinforcing rib 14 Open end G gas S. Soil W water B Underwater ground

Claims

1. A grab dredging attachment that is attached to the inside of the bucket shell of a dredging grab bucket, A grab dredging attachment characterized in that it has a bag portion attached to the inner wall of the bucket shell, the bag portion is filled with gas and is deformable, and the bag portion deforms in response to water pressure to change the storage volume of the bucket shell.

2. 2. The grab dredging attachment according to claim 1, wherein at least a portion of the bag portion is formed from an elastic material.

3. 3. A grab dredging attachment as described in claim 1 or 2, which has a protective portion covering at least a portion of the outer surface of the bag portion.

4. A grab dredging attachment as described in any one of claims 1 to 3, wherein the bag portion has a valve for injecting and discharging the gas.

5. 5. A grab dredging attachment as described in claim 4, wherein the valve has an internal pressure adjustment mechanism that, when the internal pressure of the bag portion exceeds a predetermined threshold, discharges the gas inside the bag portion until the internal pressure of the bag portion becomes equal to or lower than the threshold.

6. A grab dredging attachment as described in any one of claims 1 to 5, having partitions that divide the internal space of the bag portion into multiple compartments.

7. A dredging grab bucket equipped with the grab dredging attachment according to any one of claims 1 to 6.

8. The dredging grab bucket according to claim 7, wherein the bag portion is configured to be detachable from the bucket shell.

9. 9. The dredging grab bucket according to claim 7, wherein a plurality of the bag portions are arranged on the inner wall of the bucket shell.

10. In the dredging method using a dredging grab bucket, A dredging method characterized by attaching a deformable bag portion filled with gas to the inner wall of the bucket shell of the dredging grab bucket, and in a lowering step of lowering the dredging grab bucket toward the bottom of the water, the bag portion is contracted in response to water pressure, and in a subsequent ascent step of raising the dredging grab bucket toward the water surface, the contracted state of the bag portion is relaxed in response to water pressure, thereby discharging excess water from within the bucket shell to the outside of the bucket shell.

Images