JP7015749B2 - Dredging device and method - Google Patents

Description

The present invention relates to a dredging device and a method for dredging sediment deposited on the bottom of the water.

Pump dredging and grab dredging are known for dredging sediment accumulated on the bottom of rivers, dams, and the sea. In particular, in the case of thin-layer dredging in which the dredging layer thickness at the time of dredging is thin, it is required to dred the bottom surface thinly and uniformly. As a dredging device for performing such thin-layer dredging, in Patent Document 1, a mud collecting device provided at the tip of a hydraulic excavator is lowered to the bottom of the water, and the lower end of the mud collecting device is tilted by a predetermined angle with respect to the water bottom. It is disclosed that the mud is scraped into the mud collecting chamber by penetrating the excavation claws of the excavator into the bottom of the water and operating the rudder so that the mud collecting device moves horizontally.

Japanese Patent No. 3900532

However, in the dredging device described in Patent Document 1, it is necessary to lower the lower end of the mud collecting device to the bottom of the water using a hydraulic excavator, and there is a problem that the dredging device tends to be heavy and large.

Therefore, a technical problem to be solved for dredging the earth and sand accumulated on the bottom of the water without using a large heavy machine arises, and an object of the present invention is to solve this problem.

The present invention has been proposed to achieve the above object, and the dredging device according to the present invention is a dredging device for dredging sediment accumulated on the bottom of the water, and is landed on the bottom of the water to form a closed region. Dredging rod, drainage means for draining water in the dredging rod to the outside, water supply means for supplying water in the dredging rod, and pushing force according to the penetration resistance when the dredging rod is penetrated into the water bottom. The dredging rod is provided with a control means for controlling the amount of drainage of the drainage means and the amount of water supply of the water supply means so as to generate a differential pressure inside and outside the dredging rod.

According to this configuration, a negative pressure is generated in the closed region of the dredging rod to generate a pushing force larger than the penetration resistance of the water bottom, so that the lower end of the dredging rod can penetrate into the water bottom without using heavy machinery or the like. can. Further, by supplying water to the dredging rod and boosting the pressure in the closed region, the dredging rod can be easily pulled out from the bottom of the water without using a heavy machine or the like.

Further, in the dredging device according to the present invention, it is preferable that the drainage means is a pump for dredging the earth and sand accumulated on the water bottom.

According to this configuration, by using a pump for dredging the sediment accumulated on the bottom of the water as a drainage means, the water in the dredging rod can be drained without adding a new device, which simplifies the configuration of the dredging device. be able to.

Further, in the dredging device according to the present invention, it is preferable that the water supply means is a jet nozzle for discharging jet water.

According to this configuration, by using the jet water that diffuses the bottom sediment as a water supply means, water can be supplied into the dredging rod without adding a new device, so that the configuration of the dredging device can be simplified. can.

Further, in the dredging device according to the present invention, the drainage means is arranged substantially in the center of the dredging rod when viewed from a plane, and a plurality of the water supply means are provided on the peripheral edge of the dredging rod at substantially equal intervals when viewed from a plane. It is preferable that the dredging is done.

According to this configuration, the water supply means supplies water from the peripheral edge of the dredging rod, and the drainage means drains water at the substantially center of the dredging rod, so that the water flows from the outside to the inside of the dredging rod in a well-balanced manner. The dredging rod can be penetrated into the bottom of the water while maintaining the horizontal state.

Further, it is preferable that the dredging device according to the present invention further includes a differential pressure measuring means for measuring the differential pressure inside and outside the dredging rod.

According to this configuration, the differential pressure measuring means can accurately grasp the negative pressure inside the dredging rod by measuring the differential pressure inside and outside the dredging rod, so that the pushing force of the dredging rod can be appropriately managed.

Further, in the dredging device according to the present invention, it is preferable that the dredging rod is suspended from a float floating on the water surface.

According to this configuration, the dredging rod can be moved smoothly, so that the dredging range can be arbitrarily set.

Further, in the dredging device according to the present invention, it is preferable that the opening of the dredging rod is formed in a substantially rectangular shape when viewed from a plane.

According to this configuration, by setting the construction range to a substantially rectangular shape according to the opening of the dredging rod, the adjacent construction ranges can be set without overlapping and without gaps, so that the water bottom can be dredged continuously and efficiently. can do.

Further, the dredging method according to the present invention is a dredging method for dredging sediment accumulated on the water bottom, in which a dredging rod is landed on the water bottom to form a closed region, and water in the dredging rod. The amount of drainage to be drained to the outside by the draining means is set to be equal to or greater than the supply amount of water supplied into the dredging rod, and the pushing force corresponding to the penetration resistance when the dredging rod is penetrated into the water bottom is inside and outside the dredging rod. The penetration step of generating a differential pressure and penetrating the dredging rod into the water bottom, the dredging step of dredging the inside of the dredging rod, and the supply amount being set to be equal to or higher than the drainage amount with the dredging rod penetrating into the water bottom. , The drawing step of pulling out the dredging rod from the bottom of the water.

According to this configuration, a negative pressure is generated in the closed region of the dredging rod to generate a pushing force larger than the penetration resistance of the water bottom, so that the lower end of the dredging rod can penetrate into the water bottom without using a heavy machine or the like. can. Further, by supplying water to the dredging rod and boosting the pressure in the closed region, the dredging rod can be easily pulled out from the bottom of the water without using a heavy machine or the like.

Further, in the dredging method according to the present invention, it is preferable that the drainage means starts pumping before the dredging rod has landed.

According to this configuration, by starting drainage in the dredging rod before the dredging rod reaches the bottom of the water, it is possible to prevent the sediment accumulated on the bottom of the water from scattering to the surroundings due to the impact of the dredging rod landing on the bottom. be able to.

According to the present invention, by generating a negative pressure in the closed region of the dredging rod and generating a pushing force larger than the penetration resistance of the water bottom, the lower end of the dredging rod can be penetrated into the water bottom without using a heavy machine or the like. can. Further, by supplying water to the dredging rod and boosting the pressure in the closed region, the dredging rod can be easily pulled out from the bottom of the water without using a heavy machine or the like.

The front view which shows the dredging apparatus which concerns on one Embodiment of this invention. A side view of the dredging device shown in FIG. 1. The plan view of the dredging apparatus shown in FIG. The schematic diagram which shows the procedure of the dredging method using the dredging apparatus which concerns on this invention. The schematic diagram which shows various numerical values when calculating a pushing force and a penetration resistance.

An embodiment of the present invention will be described with reference to the drawings. In the following, when the number, numerical value, quantity, range, etc. of the components are referred to, the number is limited to the specific number unless it is explicitly stated or the principle is clearly limited to the specific number. It is not a thing, and it may be more than or less than a specific number.

In addition, when referring to the shape and positional relationship of components, etc., unless otherwise specified or when it is considered that it is not clearly the case in principle, those that are substantially similar to or similar to the shape, etc. are used. include.

In addition, the drawings may be exaggerated by enlarging the characteristic parts in order to make the features easy to understand, and the dimensional ratios and the like of the components are not always the same as the actual ones. Further, in the cross-sectional view, hatching of some components may be omitted in order to make the cross-sectional structure of the components easy to understand.

FIG. 1 is a front view of the dredging device 1. FIG. 2 is a side view of the dredging device 1. FIG. 3 is a plan view of the dredging device 1. The dredging device 1 is a device for dredging sediment accumulated on the bottom of a reservoir, a river area, a lake, an estuary, a dam, the sea, or the like. Depending on the purpose of dredging, the depth of dredging by the dredging device 1 and the particle size of the sediment to be dredged differ.

The dredging device 1 is arranged at the center of the pontoon float 2 floating on the water surface. The pontoon float 2 is formed in a substantially rectangular shape in a plan view, and an opening 21 is provided in the center thereof.

The dredging device 1 includes a dredging rod 3, a drainage pump 4 as a drainage means, and a jet nozzle 5 as a water supply means.

The dredging rod 3 is arranged at a position corresponding to the opening 21 when viewed from a plane, and is suspended on a gantry 22 installed on the pontoon float 2. A winch 23 is interposed between the dredging rod 3 and the gantry 22. The dredging rod 3 includes a cylindrical upper casing 31 whose upper end is closed, and a bottom skirt 32 which is continuous with the lower portion of the upper casing 31. The bottom skirt 32 has an opening 33 formed at the lower end. The opening 33 is formed in a substantially rectangular shape.

The drainage pump 4 is provided in the center of the lower part of the dredging rod 3. The muddy water containing the earth and sand pumped by the drainage pump 4 is drained to the outside through the drainage pipe 41. The amount of drainage of the drainage pump 4 can be arbitrarily changed.

A plurality of jet nozzles 5 are provided in the dredging rod 3. The jet nozzle 5 discharges jet water supplied from a water supply source (not shown) via a water supply pipe 51. The jet nozzle 5 discharges jet water horizontally or diagonally downward. It is preferable that the jet nozzles 5 are arranged at substantially equal intervals on the peripheral edge of the dredging rod 3 when viewed from a plane. As a result, the jet water is evenly distributed inward from the peripheral edge of the dredging rod 3. The water pressure and discharge amount of the jet water can be arbitrarily changed.

Further, a mixer 6 is provided inside the dredging rod 3. The two mixers 6 are arranged on opposite sides of the drainage pump 4. The mixer 6 stirs the muddy water in the dredging rod 3.

Further, the dredging rod 3 is provided with a pressure sensor 7. The pressure sensor 7 measures the differential pressure inside and outside the dredging rod 3.

The operation of the dredging device 1 is controlled by the control device 8. The control device 8 is, for example, a personal computer mounted on the pontoon float 2. The control device 8 includes an input unit and an output unit (not shown), and an operator on board the pontoon float 2 can operate the control device 8 and confirm the underwater position of the dredging rod 3.

Next, the procedure for dredging the earth and sand deposited on the water floor with the dredging device 1 will be described with reference to FIGS. 4 and 5. The order of the steps described later is only an example, and the order of each step can be changed as appropriate.

[Bottoming process]
As shown in FIG. 4A, first, the pontoon float 2 is navigated, and the dredging rod 3 is moved above the bottom of the water to be dredged. At this time, the dredging rod 3 may be wound above the water surface, or the lower end of the dredging rod 3 may be submerged in water.

Next, the winch 23 is wound down, the dredging rod 3 is lowered to the bottom of the water, and the lower end of the bottom skirt 32 is landed. When the dredging rod 3 lands on the bottom of the water, the inside of the dredging rod 3 becomes a closed area isolated from the outside. It is preferable to start the drainage pump 4 to start drainage in the dredging rod 3 before the dredging rod 3 reaches the bottom of the water. As a result, the earth and sand scattered by the impact of the dredging rod 3 landing on the bottom can be recovered.

[Penetration process]
Next, as shown in FIG. 4B, the control device 8 adjusts the drainage amount of the drainage pump 4 and the discharge amount of the jet nozzle 5 to generate a water pressure difference inside and outside the dredging rod 3, and the water pressure difference is changed to this water pressure difference. The resulting negative pressure causes the dredging rod 3 to penetrate the bottom of the water.

Specifically, when the dredging rod 3 is penetrated, the drainage amount of the drainage pump 4 is increased by the jet nozzle 5 so that the pushing force Fp due to the negative pressure described above exceeds the penetration resistance FR when the dredging rod 3 is penetrated. Set more than the discharge amount. The calculation formulas for the general pushing force Fp and penetration resistance FR are described in, for example, the "Suction Foundation Structure Technology Manual" (written by the Coastal Development Technology Research Center). In the following, a case of penetrating a uniform cohesive soil layer by about 1 m will be described as an example. The pushing force Fp is calculated by the formula 1.

Further, the suction pressure p when the atmospheric pressure is 0 is calculated by the mathematical formula 2.

The unit accumulation weight γw of water is 9.8 kN / m3, and assuming that the water level difference hs inside and outside the dredging rod 3 is 1 m, the suction pressure p is calculated to be 9.8 kN / m2 from Equation 2. The water level difference hs may be set based on, for example, the measured value of the pressure sensor 7, or may be calculated from the drainage amount of the pump 4 and the discharge amount of the jet nozzle 5.

The inner area A of the dredging device 1 is a numerical value (2.99 m2) obtained by subtracting the horizontal cross-sectional area (0.5 m square) of the upper casing 31 from the horizontal cross-sectional area (1.8 m square) of the bottom skirt 32. be. The effective weight W is the weight (6.0 kN) of the dredging device 1. Further, since the dredging device 1 does not use a heavy machine for penetrating the dredging rod 3, the load Q is set to zero. Therefore, from Equation 1, the pushing force Fp is calculated to be 35.3 kN.

Next, the intrusive resistance FR is calculated by the mathematical formula 3.

Further, the peripheral resistance Pf (peripheral resistance Pfi, Pfo) in the mathematical formula 2 is calculated by the mathematical formula 4.

The adhesive force coefficient αc is a numerical value determined according to the adhesive force Cu of the soil layer. For example, when the adhesive force Cu is 2 kN / m2, the peripheral surface resistance Pf is 1.2 kN / m2 according to the mathematical formula 4.

Further, the tip resistance qt in the mathematical formula 2 is calculated by the mathematical formula 5.

Assuming that the adhesive force C0 is 2 kN / m2 as in the case of the adhesive force Cu of the soil layer, the tip resistance qt is 10.3 kN / m2 according to the mathematical formula 5.

In this way, the peripheral resistances Pfi and Pfo of Equation 3 are calculated to be 1.2 kN / m2, and the tip resistance qt is calculated to be 10.3 kN / m3. Assuming that the peripheral areas Afi and Afo of the bottom skirt 32 are 7.2 m2 and the tip area of the bottom skirt 32 is 0.07 m2, the penetration resistance FR is calculated to be 18.0 kN from Equation 3.

That is, it is possible to allow the dredging rod 3 to penetrate 1 m from the water bottom without using a heavy machine or the like only by generating a head difference of about 1 m in the dredging rod 3 from the state of landing on the water bottom of a uniform cohesive soil layer. can. By controlling the drainage amount of the drainage pump 4 and the discharge amount of the jet nozzle 5 to appropriately adjust the penetration amount of the dredging rod 3, excessive penetration and over-digging can be suppressed.

[Dredging process]
After the dredging rod 3 has penetrated into the soil layer, the bottom of the water is dredged. Specifically, the jet water discharged from the jet nozzle 5 causes the earth and sand on the bottom of the water to fly up into the dredging rod 3. Further, by stirring the muddy water in the dredging rod 3 with the mixer 6, the earth and sand on the bottom of the water can be diffused in the dredging rod 3. Then, the dredging of the bottom of the water is performed by draining the muddy water in the dredging rod 3 to the outside by the drainage pump 4.

[Pulling process]
After the dredging of the water bottom is completed, the dredging rod 3 is pulled out from the soil layer by controlling the drainage amount of the drainage pump 4 and the discharge amount of the jet nozzle 5 so as to eliminate the difference in water pressure inside and outside the dredging rod 3. Can be done. The resistance at the time of pulling out is relatively easy to pull out the dredging rod 3 as compared with the time of penetrating because the tip resistance is reduced and the viscous force due to the dredging inside the device is reduced to about half of the resistance at the time of penetrating. be able to.

Then, as shown in FIG. 4 (c), the winch 23 is wound up, the dredging rod 3 is pulled up, and the pontoon float 2 is moved to the next dredging place.

Since the bottom skirt 32 has a substantially rectangular shape in a plan view, the dredging range corresponding to the opening 33 is also set to have a substantially rectangular shape, so that the bottom of the water can be dredged efficiently without any gaps.

In this way, the dredging device 1 according to the present embodiment adjusts the drainage amount of the drainage pump 4 and the discharge amount of the jet nozzle 5 to the water in the dredging rod 3 and negative pressure in the closed region of the dredging rod 3. By generating a pushing force larger than the penetration resistance of the water bottom, the dredging rod 3 can be penetrated into the water bottom without using a heavy machine or the like. Further, by supplying water to the closed region of the dredging rod 3 and boosting the pressure, the dredging rod 3 can be easily pulled out without using a heavy machine or the like.

It should be noted that the present invention can be modified in various ways as long as it does not deviate from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

For example, the present invention can also be applied to the removal of contaminated soil and the recovery of seabed resources such as rare earth mud and methane hydrate.

1 ・ ・ ・ Dredging device 2 ・ ・ ・ Pump float 21 ・ ・ ・ Opening 22 ・ ・ ・ Stand 23 ・ ・ ・ Winch 3 ・ ・ ・ Dredging rod 31 ・ ・ ・ Top casing 32 ・ ・ ・ Bottom skirt 33 ・ ・・ Opening 4 ・ ・ ・ Drainage pump (drainage means)
41 ・ ・ ・ Drainage pipe 5 ・ ・ ・ Jet nozzle (water supply means)
51 ・ ・ ・ Water supply pipe 6 ・ ・ ・ Mixer 7 ・ ・ ・ Pressure sensor (differential pressure measuring means)
8 ・ ・ ・ Control device

Claims (9)

It is a dredging device that dredges the sediment accumulated on the seabed.
A dredging rod that is landed on the bottom of the water to form a closed area,
A drainage means for draining the water in the dredging rod to the outside,
A water supply means for supplying water into the dredging rod,
The drainage amount of the drainage means and the water supply amount of the water supply means are controlled so as to generate a differential pressure inside and outside the dredging rod, which is a pushing force according to the penetration resistance when the dredging rod is penetrated into the water bottom, and the dredging is performed. A control means for controlling the drainage amount of the drainage means and the water supply amount of the water supply means so as to increase the pressure inside the dredging rod according to the pull-out resistance when the rod is pulled out from the bottom of the water .
A dredging device characterized by being equipped with. The dredging device according to claim 1, wherein the drainage means is a pump for dredging the earth and sand accumulated on the water bottom. The dredging device according to claim 1 or 2, wherein the water supply means is a jet nozzle for discharging jet water. The drainage means is arranged substantially in the center of the dredging rod when viewed from a plane.
The dredging device according to any one of claims 1 to 3, wherein a plurality of the water supply means are provided on the peripheral edge of the dredging rod at substantially equal intervals when viewed from a plane. The dredging device according to any one of claims 1 to 4, further comprising a differential pressure measuring means for measuring the differential pressure inside and outside the dredging rod. The dredging device according to any one of claims 1 to 5, wherein the dredging rod is suspended from a float floating on a water surface. The dredging device according to any one of claims 1 to 6, wherein the opening of the dredging rod is formed in a substantially rectangular shape when viewed from a plane. It is a dredging method for dredging the earth and sand accumulated on the bottom of the water.
A bottoming step of landing a dredging rod on the bottom of the water to form a closed region,
The amount of drainage to drain the water in the dredging rod to the outside by the drainage means is set to be equal to or larger than the supply amount to supply water into the dredging rod, and the pushing force corresponding to the penetration resistance when the dredging rod is penetrated into the water bottom is used. A penetration step of creating a differential pressure inside and outside the dredging rod to penetrate the dredging rod into the bottom of the water.
The dredging process of dredging the inside of the dredging rod and
The supply amount is set to be equal to or higher than the drainage amount with the dredging rod penetrated into the water bottom so as to increase the pressure inside the dredging rod according to the withdrawal resistance when the dredging rod is pulled out from the water bottom. The drawing process of pulling out from the bottom of the water and
A dredging method characterized by including. The dredging method according to claim 8, wherein the drainage means starts pumping before the dredging rod has landed.

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