Pump ship, dredging apparatus, and dredging method

Abstract

To provide a pump ship capable of pumping dredged mud over a long distance.SOLUTION: In the pump ship 21 provided with a relay pump 22 and a relay sand discharging pipe 14 for pressure-feeding dredged mud 9 by the relay pump 22, a suction branch pipe for sucking water around the pump ship 21 is provided in the relay sand discharging pipe 14, and a branch pipe on-off valve is provided in the suction branch pipe, so that the branch pipe on-off valve is opened, water around the pump ship 21 is sucked from a suction port 25S of the suction branch pipe, and the water is pressure-fed to the downstream side by the relay pump 22. The dredged mud 9 can be force-fed, and the dredged mud 9 can be force-fed over a long distance by jointly using the pump 8 of the dredger 1 and the relay pump 22 of the pump ship 21. Since a plurality of branch pipes for suction are provided between the inflow end 15 of the relay sand discharge pipe 14 and the relay pump 22, when a failure occurs in one branch pipe for suction, work can be continued by using the remaining normal branch pipes for suction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pump vessel, a dredging apparatus and a dredging method. [Background technology]

[0002] Conventional methods for pumping this type of dredged mud include a pump dredger equipped with a large suction pump on the hull, a suction pipe extending from the pump to the front of the hull equipped with a cutter for scraping sediment from the bottom of the water at the end, and a sand discharge pipe extending from the pump to a long distance behind the hull (for example, Patent Document 1), and a pump dredger equipped with a ladder inserted into the water with the tip facing the bottom of the water from the dredger body, a rotating means for rotating the ladder, an excavating means located at the tip of the ladder, a sand discharge pipeline with a suction port opening at the tip of the ladder, and a suction pump connected to the sand discharge pipeline (for example, Patent Document 2).

[0003] Other known prior art techniques include a dredger using a grab bucket and a soil transporter that transports dredged mud (see, for example, Patent Document 3).

[0004] For example, in the case of the pump dredger, the dredged mud is sucked up together with the water from the bottom of the water and transported to a distant discharge location through a sand discharge pipe, which can cause problems such as not being able to transport the mud or taking too long if the transport distance is long. Also, if a malfunction occurs in the pump of the pump dredger, the dredged mud cannot be transported and the sand discharge pipe may become clogged with the dredged mud.

[0005] Furthermore, when the pump boat finishes dredging work for the day and needs to retreat from the dredging site to a designated location, it cannot move until all the dredged mud inside the sand discharge pipe is discharged because it is connected to a long sand discharge pipe. This creates a waiting time, which results in a loss of working time. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 60-208525 [Patent Document 2] Japanese Patent Application Publication No. 2017-048623 [Patent Document 3] Japanese Patent Application Publication No. 4-187299 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above-mentioned problems, the present invention aims to provide a pump ship capable of pumping dredged mud over long distances, and also to provide a dredging device and dredging method that allows a dredging ship to secure dredging time when moving from a dredging site to an evacuation site after dredging work. [Means for solving the problem]

[0008] The invention of claim 1 is a pump vessel equipped with a pump and a sand discharge pipe equipped on the pump vessel that uses the pump to pressurize dredged mud, characterized in that the sand discharge pipe equipped on the pump vessel is provided with a suction branch pipe that sucks in water around the pump vessel, and the suction branch pipe is provided with a branch pipe opening / closing valve.

[0009] The invention of claim 2 is characterized in that the sand discharge pipe equipped on the pump vessel has an inlet end and an outlet end, and the sand discharge pipe equipped on the pump vessel is provided with an inlet end side opening / closing valve between the inlet end of the sand discharge pipe equipped on the pump vessel and the suction branch pipe.

[0010] The invention of claim 3 is characterized in that the sand discharge pipe equipped on the pump vessel is provided with a plurality of suction branch pipes between the inlet end of the sand discharge pipe equipped on the pump vessel and the pump, and each of the suction branch pipes is provided with a branch pipe opening / closing valve.

[0011] The invention of claim 4 is a dredging device comprising a dredger having a pump that sucks up dredged mud and pressurizes it into a sand discharge pipe, and which pressurizes the dredged mud through the sand discharge pipe to a discharge location, wherein a pump ship equipped with a relay pump that pressurizes the dredged mud is placed in the middle of the sand discharge pipe, the pump ship has a relay sand discharge pipe in the middle of the sand discharge pipe, and the relay pump is installed in this relay sand discharge pipe, and a suction branch pipe is installed in the relay sand discharge pipe to suck up water around the pump ship, and a branch pipe opening / closing valve is installed in the suction branch pipe.

[0012] The invention of claim 5 is a dredging method using the dredging equipment described in claim 4, characterized in that, with the branch pipe opening / closing valve closed, the dredged mud sucked by the dredger is pressurized to the discharge location by the pump and the relay pump, the suction of the dredged mud is switched to suction of the water around the dredger, and after the dredged mud in the relay sand discharge pipe upstream of the relay pump position has turned into water, the pump stops pressing down, the branch pipe opening / closing valve is opened, the surrounding water is sucked up by the suction branch pipe and sent to the relay sand discharge pipe, and the dredged mud in the sand discharge pipe is pressurized to the discharge location. [Effects of the Invention]

[0013] According to the configuration of claim 1, the suction branch pipe sucks water around the pump ship, and the water is pumped out by the pump, thereby enabling the dredged mud to be pumped out.

[0014] According to the configuration of claim 2, by closing the opening / closing valve on the inlet end side of the sand discharge pipe equipped on the pump ship, it is possible to suck in surrounding water from the suction branch pipe and pump it downstream without sucking in air or the like from the inlet end.

[0015] According to the configuration of claim 3, if a failure occurs in one branch suction pipe, the remaining normal branch suction pipe can be used to continue work.

[0016] According to the configuration of claim 4, by using the dredger's pump and the pump ship's relay pump together, it becomes possible to pump dredged mud over long distances using the sand discharge pipe. Also, even if a malfunction occurs in the dredger's pump, clogging of the sand discharge pipe can be prevented by using the pump ship's relay pump. Furthermore, by sucking water around the dredger through the suction branch pipe and pumping that water with the relay pump, it is possible to pump dredged mud from the pump ship to the discharge site even when the dredger's pump is stopped.

[0017] According to the configuration of claim 5, when dredging work is completed, the surrounding water is sucked in and pumped out, and when the dredged mud in the sand discharge pipe between the dredger and the pump vessel has changed from dredged mud to water, the dredger's pump can be stopped and the dredger can be moved.The dredged mud remaining in the sand discharge pipe from the pump vessel to the discharge site can be pumped to the discharge site using water sucked in from the suction branch pipe, thereby shortening the time the dredger is shut down and ensuring the overall time for dredging work. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an overall explanatory diagram showing a first embodiment of the present invention; [Figure 2] FIG. 1 is a cross-sectional view of a pump ship. [Figure 3] FIG. 1 is a perspective view of a part of the pump ship in cross section. [Figure 4] FIG. 1 is a perspective view of a main part of the pump ship, with a partial cross section. [Figure 5] FIG. 1 is a plan view of the main parts of the pump ship. [Figure 6] FIG. 1 is a perspective view of the dredging site. [Figure 7] 7A and 7B show the suction port and its surroundings of the suction branch pipe, with FIG. 7A being a longitudinal cross-sectional view and FIG. 7B being a bottom view. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present invention will be described with reference to the accompanying drawings. [Example]

[0020] An embodiment of the present invention will be described below with reference to the accompanying drawings. Figures 1 to 7 show a first embodiment of the present invention. As shown in these figures, a pump dredger 1 capable of navigating the water surface S of the sea, river, lake, swamp, or the like has a ladder 2 swingable up and down at its bow and a pair of spuds 3, 3 at its stern. A ladder shear 4 serving as a ladder support member is provided at the bow of the dredger 1, facing diagonally upward. The leading end of this ladder shear 4 and the ladder 2 are connected by a hanging member 5. The ladder 2 swings up and down around a rotation axis 6 of the ladder 2 depending on the amount of material taken up by the hanging member 5 using a take-up drum (not shown) attached to the ladder shear 4. A rotatable cutter 2A is provided at the leading end of the ladder 2, and this cutter 2A is used to cut up sediment and the like on the bottom 10 of the water.

[0021] In addition, winches (not shown) are provided on the left and right sides of the bow of the dredger 1, and one end of left and right swing wires (not shown) is connected to these left and right winches, respectively, and the other ends of the left and right swing wires are fixed in position.

[0022] Then, at the dredging site, one of the spuds 3 is driven into the water bottom 10, the ladder 2 is rotated to lower the cutter 2A to a predetermined depth position, the cutter 2A is rotated as necessary, dredging is performed by suction from the suction pipe 7 attached to the ladder 2, and the dredger 1 is swung using the left and right swing wires to dredge the construction area.

[0023] A pump 8, which is a pump equipped on the dredger, is connected to the downstream side of the suction pipe 7, and this pump 8 sucks up sediment and sand from the bottom of the water 10. A pump ship side sand flushing pipe 12, which forms part of the sand flushing pipe 11, is connected to the discharge port of the pump 8, and the upstream end of an upstream side sand flushing pipe 13, which forms part of the sand flushing pipe 11, is connected to the downstream end of this pump ship side sand flushing pipe 12.

[0024] A float 30 (Fig. 6) is provided in a part of the upstream sand flushing pipe 13, and as shown in Fig. 1, this float 30 makes the upstream and downstream ends of the upstream sand flushing pipe 13 surface piping sections 31, 32 located at the water surface S, and the remainder is a bottom piping section 33 that is located on the water bottom 10. The surface piping section 31 at the upstream end of the upstream sand flushing pipe 13, on which the float 30 is provided, is bent in a plan view (Fig. 6) and has a length that allows the dredger 1 to move between the dredging position and the docking position, which is the retreat position. Fig. 6 shows the dredger 1 in the dredging position, and the retreat position is in front of the dredger 1. The dredger 1 moves diagonally forward and to the right, pulling the surface piping section 31, and retreats to the docking position.

[0025] A pump vessel 21 is provided midway along the sand flushing pipe 11, and this pump vessel 21 is equipped with an intermediate sand flushing pipe 14 on its hull, which forms part of the sand flushing pipe 11 and is provided midway along the sand flushing pipe 11. A relay pump 22, such as an axial flow pump, is provided midway along the intermediate sand flushing pipe 14. The downstream end of the upstream sand flushing pipe 13 is connected to the inlet end 15, located on the bow side of the intermediate sand flushing pipe 14, and this connection can also be disconnected. In the sand flushing pipe 11, the upstream sand flushing pipe 13 is located upstream of the pump vessel 21. The intermediate sand flushing pipe 14 is the part of the sand flushing pipe 11 that is provided on the pump vessel 21 and is a pump vessel-equipped sand flushing pipe, and the relay pump 22 is a pump that is provided on the pump vessel 21 and is a pump vessel-equipped pump.

[0026] The upstream end of a downstream sand flushing pipe 17, which constitutes part of the sand flushing pipe 11, is connected to the outlet end 16 of the intermediate sand flushing pipe 14 located on the stern side, and this connection can also be disconnected. In the sand flushing pipe 11, the downstream sand flushing pipe 17 is located downstream of the pump vessel 21. As shown in FIG. 1 , the downstream sand flushing pipe 17 has, from the pump vessel 21 side to the downstream side, a surface piping section 35 equipped with the float 30, a bottom piping section 36, a surface piping section 37 equipped with the float 30, and a land piping section 38. The surface piping section 32 of the upstream sand flushing pipe 13 located on the bow side of the pump vessel 21 and the surface piping section 35 of the downstream sand flushing pipe 17 located on the stern side of the pump vessel 21 are bent and have a length that allows the pump vessel 21 to move between its working position and its docked position. Furthermore, the pump ship 21 does not need to retreat to a docked position even when not performing dredging work as long as it does not interfere with the navigation of other ships.

[0027] As shown in Figure 4, etc., suction branch pipes 23L and 23R are provided on the left and right sides of the relay pump 22 on the upstream side of the relay sand discharge pipe 14, at positions spaced apart in the front and rear, and the left suction branch pipe 23L is connected to the relay sand discharge pipe 14 forward (towards the bow / upstream) of the right suction branch pipe 23R.

[0028] The suction branch pipes 23L, 23R are each provided with a short branch pipe 24 connected to the relay sand discharge pipe 14 and a curved pipe 25 with a bending angle of approximately 90 degrees, and a branch pipe on-off valve 26 serving as an on-off means is provided between the short branch pipe 24 and the curved pipe 25. A dredge valve serving as a gate valve is used as the on-off valve 26. The on-off valve 26 and the short branch pipe 24 are connected by a flange, and the on-off valve 26 and one end of the curved pipe 25 are also connected by a flange.

[0029] The on-off valve 26 includes a valve body 27, a valve box 28 having a flow path (not shown) between the short branch pipe 24 and the curved pipe 25, and a valve element (not shown) that moves back and forth between the valve body 27 and the flow path by a cylinder 29 serving as an advancing / retracting means, and the valve element moves back and forth by the cylinder 29, and when the valve element blocks the flow path, the on-off valve 26 is closed, and when the valve element moves toward the inside of the valve body 27, the flow path is opened and the on-off valve 26 is opened. The on-off valve 26 is arranged horizontally so that the valve body 27 and the valve box 28 are side by side.

[0030] In addition, the branch short pipes 24, 24 face to one side in the left-right direction in a direction intersecting with the relay sand discharge pipe 14, one end of the curved pipe 25 faces to the same side in the left-right direction as the branch short pipe 24, and the other end of the curved pipe 25 is arranged facing downward.

[0031] The curved pipes 25 of these suction branch pipes 23L, 23R have an intake port 25S at the lower end on the other side that passes watertight through the bottom of the vessel and protrudes downward from the bottom of the pump vessel 21, and is configured so that water below the water surface S can be sucked in through the intake port 25S.

[0032] Therefore, when the on-off valve 26 of one of the suction branch pipes 23L, 23R is opened and the relay pump 22 is driven, water below the water surface is sucked in through the suction port 25S, sent to the downstream side of the relay sand discharge pipe 14, and discharged from the outlet end 16. Normally, the on-off valve 26 of one of the left and right suction branch pipes 23L, 23R is opened for use, and if one of them breaks down, the other on-off valve 26 can be used.

[0033] In addition, an inlet end opening / closing valve 26A, which serves as an opening / closing means, is provided in the horizontal portion 14S of the bow side in the fore-and-aft direction upstream of the connection position of the suction branch pipes 23L, 23R of the relay sand discharge pipe 14.This opening / closing valve 26A also uses a dredge valve, has the same configuration as the opening / closing valve 26, and is arranged horizontally in the same manner as the opening / closing valve 26.

[0034] As shown in Figure 3, the discharge pipe 22H of the relay pump 22 is arranged diagonally upward on one side in the left-right direction, and the portion of the relay sand discharge pipe 14 connected downstream of the discharge pipe 22H protrudes upward by a rising portion 14U and has a horizontal portion 14Z in the fore-and-aft direction from the rising portion 14U toward the stern, and has a falling portion 14D at the downstream end of this horizontal portion 14Z, and the rearward-facing outflow end 16 is provided at the lower end of this falling portion 14D.

[0035] As shown in Figure 3, the intermediate sand discharge pipe 14 has an upstream rising section 14A and a downstream falling section 14B on the upstream and downstream sides of the bow-side horizontal section 14S, and the forward-facing inlet end 15 is provided at the lower end of the upstream rising section 14A.

[0036] Figure 7 shows the area around the suction ports 25S of the suction branch pipes 23L, 23R, and a recess 42 higher than the bottom surface 41 of the pump vessel 21 is provided in the bottom surface 41 of the vessel, and the suction port 25S side of the curved pipe 25 is watertightly inserted into the upper surface 43 of this recess 42. The suction port 25S is stored within the recess 42, and is located at a position higher than the bottom surface 41 of the vessel.

[0037] In addition, a metal mesh body 45 is provided in the lower opening 44 of the recess 42, and as an example, this mesh body 45 is made up of a plurality of vertical bar members 46, 46... arranged at intervals in the horizontal direction, and a plurality of horizontal bar members 47, 47... that intersect with these and are arranged at intervals in the vertical direction, and has a plurality of mesh holes 48, which prevent impurities contained in the water below the surface that are larger than the mesh holes 48 from passing through, thereby preventing the impurities from entering the suction port 25S.

[0038] Next, we will explain the dredging method using the dredger 1 and the pump ship 21. The cutter 2A is lowered, and the tip of the suction pipe 7 is positioned, for example, about 1 to 2 m below the water surface S, away from the water bottom 10. The on-off valves 26, 26 are closed, and with the on-off valve 26A open, the pump 8 of the dredger 1 is started first to increase the rotation speed (output), and after the pump 8 is started, the relay pump 22 of the pump ship 21 is started to increase the rotation speed (output).

[0039] By doing this, the suction pressure by the pump ship 21 becomes higher than the discharge pressure of the water and dredged mud 9 (Fig. 1) from the dredger ship 1, and negative pressure is prevented from occurring in the upstream sand flushing pipe 13. This is because if negative pressure occurs, there is a risk of damage to the sand flushing pipe 11 between the pumps 8 and 22, the on-off valve 26 in the closed state, etc.

[0040] Then, when the air venting air valve 51 (Fig. 1) installed in the sand discharge pipe 11 closes due to the pressure of water, i.e., when the air inside the sand discharge pipe 11 is released, the dredged mud 9 is sucked in, that is, at the dredging site as described above, the ladder 2 is rotated to lower the cutter 2A to a predetermined depth position, the cutter 2A is rotated as necessary, and the dredger 1 is swung using the left and right swing wires to dredge the construction area (start of dredging of dredged mud). Note that multiple air valves 51 are installed in the sand discharge pipe 11.

[0041] In this case, after the pumps 8 and 22 are started, water is initially discharged from the downstream end 18 of the sand discharge pipe 11 located on land 39, and after a predetermined time has passed since dredging began, the dredged mud 9 is discharged, and this discharge is confirmed. This can be confirmed visually or using a remote camera, and by checking the discharge status, it can be confirmed that the device is operating correctly. The location where the downstream end 18 is located is the discharge location 40 for the dredged mud 9.

[0042] Next, we will explain the procedure when the dredging equipment is stopped. In the opposite way to when the operation started, the cutter 2A is raised, the tip of the suction pipe 7 is positioned away from the bottom 10, for example, about 1 to 2 m below the water surface S, and the sand discharge operation is started by switching to suction from the dredged mud 9 to water, and water is sent to the sand discharge pipe 11 and this water supply is continued.

[0043] After switching to suction of water from the dredged mud 9 and the predetermined time of 10 minutes has elapsed, the discharge pressure of the relay pump 22 is reduced, specifically the rotation speed is reduced, and then the discharge pressure of the pump 8 is reduced before the dredger 1 retreats. Note that even if the rotation speed is reduced, the inflow of water from the outlet end 16 located at the stern of the pump ship 21 continues, and the inflow of water from the suction pipe 7 of the dredger 1 also continues.

[0044] The reason why the discharge pressure of the relay pump 22 is lowered first and then the discharge pressure of the pump 8 is to prevent the generation of negative pressure in the upstream sand flushing pipe 13, as in the start of the operation.

[0045] After reducing the output of both pumps 8, 22, the operation of pump 8 of the dredger 1 is stopped. A clutch (not shown) is provided in the transmission mechanism that transmits rotational force to pump 8, and pump 8 is stopped by disengaging the clutch. In this case, even if pump 8 is stopped, water continues to flow in from inlet end 15 because relay pump 22 is still operating.

[0046] After stopping the pump 8, one of the on-off valves 26, 26 is opened. Then, water is sucked in from the suction port 25S of the open suction branch pipe 23, and the sucked water flows through the relay sand discharge pipe 14 to the relay pump 22 side. In this state, water also flows in from the inlet end 15, and this water and the water from the suction port 25S are sucked into the relay pump 22.

[0047] After opening the on-off valve 26 in this way, the on-off valve 26A at the bow of the pump vessel 21 is closed. After the predetermined time of 10 minutes has elapsed, it takes about 2 hours for the on-off valve 26A at the bow to close. Then, the dredged mud 9 is switched to suction into the water, and after 12 minutes have elapsed, the dredger vessel 1 can move.

[0048] After closing the on-off valve 26A at the bow of the pump vessel 21, increasing the rotation speed of the relay pump 22 increases the amount of suction from the suction port 25S. The relay pump 22 is then driven until all of the dredged mud 9 remaining in the downstream sand flushing pipe 17 is discharged from the downstream end 18. This can be confirmed by draining water from the downstream end 18 on land 39. This prevents any sediment from remaining in the sand flushing pipe 11 and prevents clogging of the sand flushing pipe 11.

[0049] Furthermore, after the sand discharge operation is started and the dredged mud 9 is switched to suction into the water around the dredger 1, the time until the on-off valve 26A is closed is the predetermined time until the dredged mud 9 is discharged from the upstream side of the sand discharge pipe 11 and turns into water, and after this predetermined time has elapsed, the dredger 1 can be moved from the dredging position to the evacuation position.In addition, in the shortest time, it is also possible to move after stopping the pump 8.

[0050] The predetermined time is the time required for the dredged mud 9 to be sent downstream from the discharge end 16 of the pump ship 21, and the sand discharge pipe 11 upstream of the discharge end 16 becomes water. That is, with the branch pipe on-off valve 26 closed, the dredged mud 9 sucked by the dredger 1 is pumped to the discharge site 40 by the pump 8 and the relay pump 22, and the suction of the dredged mud 9 is switched to the suction of the water around the dredger 1, and after the predetermined time required for the water inside the sand discharge pipe 11 upstream of the discharge end 16 to turn into water has elapsed, the pressure transfer by the pump 8 is stopped. Note that turning into water means that the water is no longer mixed with sand and is no longer turbid.

[0051] In the past, the dredged mud 9 in the sand discharge pipe 17 downstream of the sand discharge pipe 11 also had to be pressurized only by the pump 8 of the dredger 1, so it took time for the dredger 1 to retreat after the start of the sand discharge work, and the dredging work had to be completed earlier than in this embodiment.However, even if dredged mud 9 remains in the sand discharge pipe 11 downstream of the pump ship 21 after the start of the sand discharge work, it can be retreated, for example, about 12 minutes after closing the on-off valve 26A, which is 28 minutes earlier than in the past, and dredging can be carried out for that 28 minutes.

[0052] 1, these 12 minutes and 28 minutes are examples when the inner diameter of the sand flushing pipe 11 is 760 mm, the length of the upstream sand flushing pipe 13 is approximately 2.1 km, and the total length of the intermediate sand flushing pipe 14 and the downstream sand flushing pipe 17 is approximately 4.4 km, and these times will vary depending on the performance of the pumps 8 and 22 and the soil quality of the dredged mud 9. Thus, in this example, the downstream sand flushing pipe 17 is longer than the upstream sand flushing pipe 13.

[0053] In addition, to determine the 12 minutes and 28 minutes, an experiment was conducted on site, in which both pumps 8 and 22 were operated with the on-off valve 26 closed, and after dredging work, it took about 30 minutes for the water to be discharged from the downstream end 18 after switching to water suction. The total length of the upstream sand flushing pipe 13, approximately 2.1 km, plus the length of the intermediate sand flushing pipe 14, 0.06 km, is 2.16 km, and this total length is the length of the sand flushing pipe 11 from the stern of the dredger 1 to the outflow end 16. Furthermore, the length of the downstream sand flushing pipe 17, 4.34 km, is the length obtained by subtracting 0.06 km from the aforementioned length of 4.4 km. Therefore, the time it takes to discharge water from the downstream end 18 after switching to water suction, 30 minutes, is divided by the total length of 6.5 (2.16 + 4.34) km, and multiplied by the total length of 2.16 km to obtain approximately 10 minutes, which means that after 10 minutes have passed since switching to water suction, water will have filled up to the outflow end 16. Then, after the specified time of 10 minutes has passed and the 2 minutes of work has been completed, the dredger 1 can withdraw from the dredging site.

[0054] In the experiment, it was confirmed that the liquid had turned into water at the downstream end 18 in 30 minutes, but in actual construction, the time was extended by 10 minutes just to be sure, and after 12 minutes, the inlet end side on-off valve 26A was closed, and after 28 minutes, which is 18 minutes plus 10 minutes, the relay pump 22 was stopped. In this way, after dredging work, the relay pump 22 was stopped 40 minutes after switching to water suction.

[0055] In this way, in this embodiment, corresponding to claim 1, the pump ship 21 is equipped with a relay pump 22 as a pump and a relay sand discharge pipe 14 as a sand discharge pipe equipped on the pump ship that pressurizes dredged mud 9 using this relay pump 22, and the relay sand discharge pipe 14 is provided with suction branch pipes 23L, 23R that suck up water around the pump ship 21, and the suction branch pipes 23L, 23R are provided with branch pipe opening / closing valves 26, 26.Therefore, the dredged mud 9 can be pressurized by sucking up water around the pump ship 21 using the suction branch pipes 23L, 23R and pressurizing the water using the relay pump 22.

[0056] In this embodiment, corresponding to claim 2, the intermediate sand discharge pipe 14, which is a sand discharge pipe equipped on a pump ship, has an inlet end 15 and an outlet end 16, and the intermediate sand discharge pipe 14 is provided with an inlet end side opening / closing valve 26A between the inlet end 15 of the intermediate sand discharge pipe 14 and the suction branch pipes 23L, 23R.Therefore, by closing the inlet end side opening / closing valve 26A, it is possible to suck in surrounding water from the suction branch pipe 23L and pump it downstream without sucking in air or the like from the inlet end 15.

[0057] In this embodiment, corresponding to claim 3, the relay sand discharge pipe 14, which is a sand discharge pipe equipped on a pump ship, is provided with a plurality of suction branch pipes 23L, 23R between the inlet end 15 of the relay sand discharge pipe 14 and the relay pump 22, which is a pump, and each of the suction branch pipes 23L, 23R is provided with a branch pipe opening / closing valve 26, 26.Therefore, if a malfunction occurs in one suction branch pipe 23L, work can be continued using the remaining normal suction branch pipe 23R.

[0058] As described above, in this embodiment, in accordance with claim 4, the dredging equipment is provided with a dredger 1 having a pump 8 for sucking dredged mud 9 and for pressure-feeding it to a sand discharge pipe 11, and the dredged mud 9 is pressure-feeded to a discharge site 40 by the sand discharge pipe 11. A pump ship 21 having a relay pump 22 for pressure-feeding the dredged mud 9 is arranged in the middle of the sand discharge pipe 11, and the pump ship 21 has a relay sand discharge pipe 14 installed in the middle of the sand discharge pipe 11. In addition, a relay pump 22 is provided on the relay sand discharge pipe 14, and suction branch pipes 23L and 23R are provided on the relay sand discharge pipe 14 to suck in water around the pump vessel 21. Furthermore, the suction branch pipes 23L and 23R are provided with branch pipe on-off valves 26, 26. Therefore, by using the pump 8 of the dredger 1 in combination with the relay pump 22 of the pump vessel 21, it is possible to pump the dredged mud 9 over long distances using the sand discharge pipe 11. Even if a malfunction occurs in the pump 8 of the dredger 1, clogging of the sand discharge pipe 11 can be prevented by using the relay pump 22 of the pump vessel 21. By sucking in the surrounding water through the suction branch pipes 23L and 23R and pumping that water with the relay pump 22, the dredged mud 9 can be pumped from the pump vessel 21 to the discharge site 40, even when the pump 8 of the dredger 1 is stopped.

[0059] As described above, in this embodiment, in accordance with claim 5, in the dredging method using the dredging apparatus according to claim 4, with the branch pipe on-off valves 26, 26 closed, the dredged mud 9 sucked by the dredger 1 is pumped by the pump 8 and the relay pump 22 to the discharge site 40, the suction of the dredged mud 9 is switched to the suction of the water around the dredger 1, and after a predetermined time has elapsed, the pump 8 stops pumping, the branch pipe on-off valve 26 is opened, the surrounding water is sucked by the suction branch pipe 23L and sent to the relay sand discharge pipe 14, and the dredged mud in the sand discharge pipe 11 is discharged. Since the soil 9 is pumped to the discharge site 40, when dredging work is completed, the surrounding water is sucked in and pumped out, and when the dredged mud 9 between the dredger 1 and the pump ship 21 becomes the water, the pump 8 of the dredger 1 can be stopped and the dredger 1 can be moved.The dredged mud 9 remaining in the sand discharge pipe 11 from the pump ship 21 to the discharge site 40 can be pumped to the discharge site 40 using water sucked in from the suction branch pipe 23L, which shortens the operation downtime of the dredger 1 and ensures overall dredging work time.

[0060] The effects of the embodiment are as follows: the intermediate sand discharge pipe 14 has an inlet end 15 through which the dredged mud 9 flows in and an outlet end 16 through which the dredged mud 9 flows out; the inlet end 15 of the intermediate sand discharge pipe 14 is connected to the upstream sand discharge pipe 13, which is on the upstream side of the pump vessel 21 in the sand discharge pipe 11; the outlet end 16 of the intermediate sand discharge pipe 14 is connected to the downstream sand discharge pipe 17, which is on the downstream side of the pump vessel 21 in the sand discharge pipe 11; the intermediate sand discharge pipe 14 is provided with an inlet end opening / closing valve 26A between the inlet end 15 of the intermediate sand discharge pipe 14 and the suction branch pipes 23L, 23R; therefore, by closing the inlet end opening / closing valve 26A, the surrounding water can be sucked in from the suction branch pipe 23L and pumped downstream without sucking in air or the like from the inlet end 15.

[0061] In addition, one end of the curved pipe 25 faces one side in the left-right direction like the branch short pipe 24, and the other end of the curved pipe 25 faces downward in the up-down direction, so the suction port 25S at the lower end on the other end side can be placed on the bottom of the ship with facing downward.

[0062] Furthermore, since the on-off valves 26, 26A, 26B are arranged sideways, they do not take up space in the ship in the vertical direction.

[0063] In addition, since the suction port 25S is located higher than the vessel bottom surface 41, it is possible to reduce resistance during navigation of the pump vessel 21. Furthermore, since a mesh body 45 is provided in the recess 42 where the suction port 25S is located, it is possible to prevent foreign matter from entering the suction port 25S.

[0064] In addition, when starting the pumps 8, 22, the pump 8 of the dredger 1 is started first to increase the rotation speed, and after that pump 8 is started, the relay pump 22 of the pump ship 21 is started to increase the rotation speed, thereby preventing negative pressure from occurring in the sand discharge pipe 11 between the pumps 8, 22 and preventing damage due to negative pressure.

[0065] In addition, before the dredger 1 retreats, the suction pressure of the relay pump 22 is first reduced, and then the discharge pressure of the pump 8 is reduced, so that, as at the start, it is possible to prevent the generation of negative pressure in the upstream sand flushing pipe 13. Furthermore, even when the pump 8 and the relay pump 22 are driven simultaneously, the suction pressure of the relay pump 22 is made lower than the discharge pressure of the pump 8.

[0066] Furthermore, after reducing the output of both pumps 8, 22, the operation of pump 8 of the dredger 1 is stopped, and then the on-off valves 26, 26 of the suction branch pipes 23L, 23R are opened.Therefore, since there is no sediment in the sand discharge pipe 11 upstream of the relay pump 22 and the pressure is reduced, the on-off valves 26, 26 can be opened smoothly.

[0067] With the relay pump 22 still in operation, the dredger 1 stops pumping by the pump 8 and then moves to a sheltered location, thereby shortening the downtime of the dredger 1. After stopping the pump 8, one of the on-off valves 26, 26 is opened and the on-off valve 26A at the bow is closed, and then the rotation speed of the relay pump 22 is increased, so that the on-off valve 26A at the bow can be closed smoothly without applying excessive force to it. Furthermore, after stopping the pump 8, the dredged mud 9 is pumped using the sand discharge pipe 11 by driving the relay pump 22, so the dredger 1 can be sheltered.

[0068] In addition, experiments were conducted on site in accordance with the conditions under which the equipment would be used during actual dredging work, and both pumps 8 and 22 were driven with the on-off valve 26 closed.After dredging work, the pumps were switched to water suction and the time required for the water to be discharged from the downstream end 18 was measured.Based on this measured time, the time required for the dredged mud 9 in the intermediate sand discharge pipe 14 upstream of the position of the intermediate pump 22 to turn into water was calculated based on the total length of the sand discharge pipe 11.This makes it possible to estimate the time required for the dredged mud 9 in the intermediate sand discharge pipe 14 upstream of the position of the intermediate pump 22 to turn into water, and the time required to transport water can be obtained through the experiment.

[0069] The present invention is not limited to the present embodiment, and various modifications are possible within the scope of the present invention. For example, although a cutter-type dredger is illustrated in the embodiment, various types of dredgers can be used as long as they can continuously pump dredged mud through a sand discharge pipe. Also, various types of pumps and relay pumps can be used. Furthermore, the downstream sand discharge pipe may be shorter than the upstream sand discharge pipe, or the downstream and upstream sand discharge pipes may be the same length. [Explanation of symbols]

[0070] 1. Dredger 8 Pump (Dredger-equipped pump) 9 Dredged mud 10 underwater 11 Sand discharge pipe 12 Sand discharge pipe on pump ship side 13 Upstream sand flushing pipe (upstream side of pump ship in sand flushing pipe) 14. Intermediate sand discharge pipe (sand discharge pipe equipped on pump ship) 15 Inlet end 16 Outlet end 17 Downstream sand flushing pipe (downstream of the pump vessel in the sand flushing pipe) 21 Pump ship 22 Relay pumps (pumps and pump ships equipped pumps) 23L, 23R Suction branch pipe 25S suction port 26 Branch pipe on-off valve 26A Inlet end opening / closing valve 40 Disposal location S water surface

Claims

1. A pump ship equipped with a pump and a sand discharge pipe that pumps dredged mud using the pump, A pump vessel characterized in that the sand discharge pipe equipped on the pump vessel is provided with a suction branch pipe that sucks in water around the pump vessel, and the suction branch pipe is provided with a branch pipe opening / closing valve.

2. The sand discharge pipe equipped on the pump ship has an inlet end and an outlet end, 2. The pump vessel according to claim 1, wherein the sand discharge pipe equipped on the pump vessel is provided with an inlet end side opening / closing valve between the inlet end of the sand discharge pipe equipped on the pump vessel and the suction branch pipe.

3. A pump ship as described in claim 1 or 2, characterized in that the sand discharge pipe equipped on the pump ship has a plurality of suction branch pipes between the inlet end of the sand discharge pipe equipped on the pump ship and the pump, and each of the suction branch pipes has a branch pipe opening / closing valve.

4. A dredging device comprising a dredger having a pump that sucks dredged mud and pressure-feeds it to a sand discharge pipe, and pressure-feeds the dredged mud to a discharge location through the sand discharge pipe, A pump ship equipped with a relay pump for pumping the dredged mud is placed in the middle of the sand discharge pipe, The pump ship has a relay sand discharge pipe in the middle of the sand discharge pipe, and the relay pump is provided on this relay sand discharge pipe, A dredging device characterized in that the intermediate sand discharge pipe is provided with a suction branch pipe that sucks up water around the pump ship, and the suction branch pipe is provided with a branch pipe opening / closing valve.

5. A dredging method using the dredging device according to claim 4, With the branch pipe on-off valve closed, the dredged mud sucked by the dredger is pumped to the discharge location by the pump and the relay pump; The suction of the dredged mud is switched to the suction of the water around the dredger, and after the dredged mud in the relay sand discharge pipe upstream of the relay pump position has changed to the water, the pump is stopped from pumping. A dredging method characterized by opening the branch pipe on-off valve, sucking surrounding water through the suction branch pipe and sending it to the relay sand discharge pipe, and pressurizing the dredged mud in the sand discharge pipe to the discharge location.

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