JP3715259B2 - Lightweight earth and sand dredging device and dredging method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dredging device for lightweight earth and sand which dredges lightweight earth and sand deposited on the bottom of the water and pumps it to a dredged sand receiving part on water.
[0002]
In the present invention, the “lightweight earth and sand” refers to sedimentary earth and sand such as sludge and sludge that have a relatively small specific gravity and are easily diffused in water in the conventional dredging work and easily cause water pollution.
[0003]
[Prior art]
When dredging sludge and sludge deposited on the bottom of the water, conventionally, open / close buckets have been used as in the case of dripping relatively heavy sediment.
[0004]
[Problems to be solved by the invention]
However, when dripping light sludge such as sludge and sludge using an openable bucket, the specific gravity of the light sand itself is small and it is easy to diffuse even with a slight fluid pressure. In addition, there are problems that the lightweight bucket cannot be grasped efficiently and the work efficiency is lowered depending on the openable bucket.
[0005]
The present invention has been proposed in view of the above circumstances, and provides a lightweight earth and sand dredge device that can solve the conventional problems at once, and a lightweight earth and sand dredge method using the same apparatus. The purpose is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a lightweight earth and sand dredger device that dredges light earth and sand accumulated on the bottom of the water and pumps it to the dredged sand receiving part on the water. A cylindrical moving cylinder that is suspended and has a substantially horizontal axis, a transport pipe that connects between the base end of the moving cylinder and the dredged sand receiving portion, and a cage that is accommodated in the moving cylinder and introduced therein A helical screw for forcibly sending earth and sand to the transport pipe side, screw drive means mounted on the moving cylinder so that the screw can be forcibly rotated, and an earth and sand intake opening on the lower peripheral wall of the moving cylinder A main door supported by the movable cylinder so as to be opened and closed, main door driving means for forcibly opening and closing the main door, and the movable cylinder so as to be able to open and close a drain opening opened in an upper peripheral wall of the movable cylinder Auxiliary door supported by and forcing this auxiliary door It is characterized in that an auxiliary door driving means for closed.
[0007]
According to a second aspect of the present invention, in addition to the above feature, the movable cylinder is suspended from the work ship via a wire and a support frame, and the main door opens and closes the left half of the earth and sand intake. Each main door body is divided into at least one left main door body pivotally supported by the movable cylinder and at least one right main door body pivotally supported by the movable cylinder so as to open and close the right half. Is opened and closed by main door driving means provided between the support frame and each main door body, and the invention of claim 3 is characterized in that, in addition to the above features, the screw is The pitch is reduced so as to approach the transport pipe.
[0008]
Furthermore, the invention of claim 4 is the lightweight earth and sand dredging method using the light weight earth and sand dredging device according to claim 1, 2, or 3, wherein the movable cylinder is submerged with the main door and the auxiliary door fully opened. The lightweight sediment layer is lowered and the sediment and water of the layer are allowed to flow into the moving cylinder from the sediment intake, and the excess water is allowed to escape from the drain, and the main door and the auxiliary door are closed, By rotating the screw, the step of pumping dredged sand in the moving cylinder to the transport pipe side, the moving cylinder is lifted from the lightweight sediment layer, and the water is laterally moved over the adjacent lightweight sediment layer. By repeating the operation step of one cycle from the step of lowering again, the lightweight sediment is intermittently dredged from the lightweight sediment accumulation layer and pumped to the dredged sand receiving portion on the water.
[0009]
According to the features of each of the first to fourth aspects of the present invention, the movable cylinder is lowered to the lightweight sediment layer on the bottom of the water with the main door and the auxiliary door fully opened, and the sediment and water in the layer are removed. Inflow from the entrance into the moving cylinder, escape excess water from the drain, then close the main door and auxiliary door, and rotate the screw to pump the sand in the moving cylinder to the transport pipe side. Can do. After that, the moving cylinder is lifted from the lightweight sediment layer, moved horizontally over the adjacent lightweight sediment layer, and then lowered again. By repeating such work steps, the water area around the dredging site is contaminated. It is possible to intermittently dredge the lightweight earth and sand from the lightweight earth and sand accumulation layer and pump it to the dredged sand receiving part on the water.
[0010]
In particular, according to the feature of the invention of claim 2, the main door that swings open and close can be used as dredged sand guiding means (that is, a bucket) into the movable cylinder, thereby improving dredging work efficiency.
[0011]
In particular, according to the feature of the invention of claim 3, by adopting the variable pitch screw, the pumping efficiency of dredged sand from the inside of the movable cylinder to the transport pipe side is increased, and the dredging work efficiency is improved.
[0012]
According to a fifth aspect of the present invention, there is provided a lightweight soil and sand dredging method in which the lightweight earth and sand accumulated on the bottom of the water is dredged and pumped to a dredged sand and sand receiving portion on the water. A cylindrical moving cylinder, a transport pipe connecting the base end of the moving cylinder and the dredged sand receiving portion, and an outer diameter slightly smaller than the inner diameter of the moving cylinder . The dredged sand that has been accommodated and introduced there is forcibly pumped to the transport pipe side , and the spiral screw with a smaller pitch as it approaches the transport pipe, and the earth and sand intake opening opened on the peripheral wall on the left and right sides of the moving cylinder are fully closed. A main door body whose upper end is pivotally supported by the movable cylinder so that the movable cylinder can swing between a fully closed position and a fully opened position that projects outwardly from the fully closed position and opens the earth and sand intake. using the dredging apparatus provided with a holding the main door body in the fully open position A step of lowering said movable barrel to the bottom of the water weight sedimentation layer in the state, while rotating the screw while holding the main door body in the fully open position, the movable cylinder along the sea bed weight sedimentation layer By horizontally moving the left and right sides to the sedimentary sediment of the layer from the open soil intake port into the moving cylinder and continuously pumping it to the transport pipe side with a screw; It is characterized by including.
[0013]
According to the above feature of the invention of claim 5, in the state where the main door body whose upper end is pivotally supported by the movable cylinder is held at the fully open position where it projects outward from the movable cylinder, the movable cylinder is a lightweight sediment deposit layer on the bottom of the water. after lowered to, while rotating the screw in the state holding the main door body in the fully open position, by horizontally moving the right and left one side of the movable cylinder along the sea bed weight sedimentation layer, the layer Sediment can be continuously flowed into the moving cylinder from the open sediment inlet, and it can be continuously pumped to the transport pipe side with a screw, so it is lightweight without polluting the water area around the dredge site. It is possible to continuously dredge light sediment from the sediment accumulation layer and pump it to the dredged sand receiving part on the water , and in particular, by adopting a variable pitch screw, the pumping efficiency of dredged sand from the moving cylinder to the transport pipe side Is raised 高 めWork efficiency improve.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.
[0015]
In the accompanying drawings, FIGS. 1 to 10 show an embodiment of the present invention, FIG. 1 is an overall schematic view showing an outline of dredging work by a dredger, and FIG. 2 is an arrow 2 in FIG. FIG. 3 is a perspective view showing the main part of the scissors apparatus, FIG. 4 is a view taken in the direction of the arrow 4 in FIG. 3, FIG. 5 is a view taken in the direction of the arrow 5 in FIG. 7 is a cross-sectional view taken along the line 7-7 in FIG. 5, FIG. 8 is a cross-sectional view of the main part of the dredger device showing the first dredging work form, and FIG. 9 is an overall plan view showing the first dredging work form. 10 is a sectional view (corresponding to FIG. 8) of the main part of the dredge apparatus showing the second dredging operation mode, and FIG. 11 is an overall plan view (corresponding to FIG. 9) showing the second dredging operation mode.
[0016]
First, in FIGS. 1 and 2, the submarine sediment transport system according to the present embodiment uses the dredging device A attached to the dredger ship B to drown the sediment from the light sediment layer L such as sludge on the bottom of the water. Is transported forcibly through the transport pipe 1, and the transported sediment is accommodated in a self-propelled earth transport ship B ′ near the dredger work ship B, and is transported to a disposal site far from the site water by the soil transport ship B ′. I am doing so.
[0017]
In the hull 2 of the dredger vessel B, a hopper-shaped storage tank P for temporarily storing dredged sand that has been forcibly conveyed to the water through the transport pipe 1 and a downstream end of the transport pipe 1 are stored. The selective communication means S for selectively communicating with the inside of the tank P and the hopper-like sediment storage part 3 of the soil carrier B ', and the selective communication means S are configured separately and stored in the storage tank P. Forced transfer means D for forcibly transferring the earth and sand to the earth and sand storage part 3 of the earth transport ship B ′ is provided.
[0018]
The selective communication means S is a first branch pipe C1 having a tip extending into the storage tank P and a tip that can be arbitrarily inserted into and removed from the sediment storage portion 3 of the soil transport ship B ′ that is placed next to the dredger work boat B. The bifurcated pipe C2 and the first or second branch in the transport pipe P interposed between the base ends of the first and second branch pipes C1 and C2 and the downstream end of the transport pipe P And a three-way valve V for selectively communicating with the pipes C1 and C2.
[0019]
The second branch pipe C2 has a base end portion fixed to the hull 2 of the dredger vessel B, and a tip portion that is connected to and supported by the base end portion so as to be pivotable about the vertical axis and extends substantially horizontally. The front part is a standby position (solid line position in FIG. 2) stored on the hull 2 side of the dredger B by the turning, and the earth and sand storage part 3 side of the earth transport ship B ′ laid next to the ship B. It is configured such that it can be moved manually or by an actuator (not shown) between the use position (a chain line position in FIG. 2) projecting to the position.
[0020]
The forced transfer means D includes a transfer pipe 4 capable of connecting the inside of the storage tank P and the earth and sand storage part 3 of the earth transport ship B ′, and the stored earth and sand in the storage tank P through the suction pipe 4 ′. And a pump 5 for sucking and pumping through the transfer pipe 4 into the sediment storage section 3 of the earth transport ship B ′.
[0021]
The transfer pipe 4 has a base end portion fixed to the hull 2 of the dredger B, and a tip portion that is connected and supported by the base end portion so as to be pivotable about a vertical axis and extends substantially horizontally. , And its tip part is extended to the standby position (solid line position in FIG. 2) stored on the hull 2 side of the dredger B by the turning, and to the sediment storage part 3 side of the earth transport ship B ′ lying next to the ship B. It is configured so that it can be moved manually or by an actuator (not shown) between the use positions (chain line positions in FIG. 2).
[0022]
Thus, when the earth transport ship B 'is placed on the dredger work ship B, the transport pipe 1 is connected to the earth transport ship B' via the second branch pipe C2 at the use position by the three-way valve V of the selective communication means S. In this way, the dredged soil is directly conveyed into the earth transport ship B ′.
[0023]
Further, when the earth transport ship B ′ is not placed on the dredger work ship B, the transport pipe 1 is communicated with the inside of the storage tank P through the first branch pipe C1 by the three-way valve V of the selective communication means S, The earth and sand are transported and stored temporarily in the storage tank P. Then, after waiting for the empty earth carrier B 'to be laid on the dredger B, the three-way valve V of the selective communication means S again causes the transportation pipe 1 to pass through the second branch pipe C2 and the earth and sand of the earth carrier B'. The dredged soil is communicated directly into the storage unit 3 to directly transport the dredged soil into the earth transport ship B ′. At the same time, the stored sand in the storage tank P is sucked by the pump 5 of the forced transfer means D. It is forcibly transferred into the sediment storage part 3 of the earth transport ship B ′ via the pipe 4 ′ and the transfer pipe 4.
[0024]
Thus, dredged sand can be stored in the storage tank P of dredger B, even if dredger B 'is not near dredger B, so dredging by dredger A must be temporarily interrupted. Therefore, the dredging work can be continuously performed regardless of whether or not the earth transport ship B ′ is near the dredging work ship B, and the work efficiency is improved.
[0025]
Next, the structure of the dredger device A attached to the dredger work boat B will be described mainly with reference to FIGS. This dredging device A dredges light sediment such as sludge accumulated on the bottom of the water, and receives the dredged sand receiving part on the water through the transport pipe 1 (in the illustrated example, the sediment P of the dredging tank B or the soil transport ship B ′). Used to pump to the reservoir 3).
[0026]
Thus, dredging device A includes a cylindrical moving cylinder T suspended from dredging work boat B via wire W and having an axial line extending substantially horizontally, and a base end of the moving cylinder T and the dredged sand receiving portion. The transport pipe 1 connecting the two and the outer diameter slightly smaller than the inner diameter of the moving cylinder T are accommodated in the moving cylinder T, and the introduced earth and sand into the cylinder T is forcibly pumped to the transport pipe 1 side. A spiral screw 6, a motor M1 as a screw driving means mounted at the tip of the movable cylinder T for rotationally driving the screw 6, and an earth and sand intake Ti opened at least on the peripheral wall of the lower half of the movable cylinder T A main door 7 that can open and close the main door 7, a main door driving means M 2 that forcibly opens and closes the main door 7, and an auxiliary that can open and close a drain outlet To that is opened in the upper peripheral wall of the movable cylinder T and is smaller than the earth and sand intake Ti. A door 8 and auxiliary door driving means M3 for forcibly opening and closing the auxiliary door 8; Provided.
[0027]
The transport pipe 1 is made of a material having at least a part (intermediate part) of the transport pipe 1 so that the moving tube T connected to the lower end of the transport pipe 1 can be moved up and down without difficulty. It has become acceptable.
[0028]
The wire W extends from a winch (not shown) installed in the hull 2 of the dredger B, so that the wire W can be fed out. A lattice frame in which a movable cylinder T is fixedly supported at a lower end as a free end. A shaped support frame F is suspended. The intermediate portion of the wire W is guided and supported by a crane 10 that is mounted on the hull 2 so as to be able to turn around a vertical axis. Therefore, by the cooperation of the crane 10 and the winch, the support frame F, and thus the movable cylinder T can be arbitrarily moved up and down through the wire W and swiveled around the swing axis of the crane 10.
[0029]
The main door 7 is a movable cylinder that opens and closes each left half of a plurality of (two in the illustrated example) earth and sand intakes Ti and Ti that are opened in parallel in the axial direction on the peripheral wall of the lower half of the movable cylinder T. A plurality of (two in the illustrated example) left main door bodies 7L and 7L pivotally supported by T at their upper ends so as to swing and the right half of the earth and sand intakes Ti and Ti are also opened and closed. A plurality of (two in the illustrated example) right main door bodies 7R and 7R that are pivotally supported at their upper ends are divided.
[0030]
The main door bodies 7L and 7R are individually opened and closed by main door driving means M2 and M2 such as hydraulic cylinders provided between the support frame F and the main door bodies 7L and 7R. In addition, a plurality of claw portions 7La and 7Ra that are alternately meshed with each other at the front edge portions of the left and right main door bodies 7L and 7R that are in contact with each other in the closed state are arranged in an integrated manner. Established.
[0031]
The auxiliary door 8 has a movable cylinder that opens and closes the left halves of a plurality (three in the illustrated example) of drain holes To and To that are opened in parallel in the axial direction on the peripheral wall of the upper half of the movable cylinder T. A plurality of (three in the illustrated example) left auxiliary door bodies 8L and 8L pivotally supported by T at their lower ends and the right half of the drain outlets To and To are respectively opened and closed. A plurality of (three in the illustrated example) right auxiliary door bodies 8R and 8R whose lower ends are pivotally supported are configured to be divided. The auxiliary door bodies 8L and 8R are individually opened and closed by auxiliary door driving means M3 and M3 such as hydraulic cylinders provided between the support frame F and the auxiliary door bodies 8L and 8R.
[0032]
The screw 6 is formed in a variable pitch type in which the pitch gradually decreases toward the downstream side thereof (that is, as the transport pipe 1 is approached), whereby the screw 6 is moved from the inside of the movable cylinder T to the transport pipe 1 side. The pumping efficiency of earth and sand is increased, and dredging work efficiency is improved.
[0033]
Further, the base end portion of the movable cylinder T is formed in a tapered shape that tapers toward the transport pipe 1, and a connection portion between the end portion and the transport pipe 1 is a part from the inside of the movable cylinder T to the transport pipe 1 side. A check valve 11 is provided that allows only directional flow. By this check valve 11, there is no possibility that the earth and sand in the transport pipe 1 will flow backward to the movable cylinder T side.
[0034]
Next, the 1st dredging operation | work form using the dredge apparatus A of a present Example is demonstrated with reference to FIG.
[0035]
In this first dredging work mode, the main cylinders 7L and 7R and the auxiliary doors 8L and 8R are fully opened (see FIG. 8), and the movable cylinder T is lowered to the lightweight sediment layer L on the bottom of the water. It is allowed to sink into the layer L by its own weight up to a specified depth. At that time, the sediment and water of the light sediment layer L are caused to flow into the movable cylinder T from the sediment intakes Ti and Ti, and excess water is drained. The first step that escapes from the mouths To, To, To, and then the main door bodies 7L, 7R and the auxiliary door bodies 8L, 8R are closed, and then the screw 6 is rotated, so The second step in which the water pipe is pumped to the transport pipe 1 side, and the movable cylinder T is lifted from the lightweight sediment layer L, moved laterally above the adjacent lightweight sediment layer L, and then lowered again. Work that makes the 3rd process done one cycle Degree of also repeated several times, so that slide into escalated dredging zone as indicated by the chain line in FIG. As a result, the lightweight earth and sand can be intermittently drowned from the lightweight earth and sand accumulation layer L without causing water contamination due to the diffusion of the lightweight earth and sand around the dredging site and pumped to the dredged sand receiving part on the water.
[0036]
In this case, in the first step, excess water that has entered the moving cylinder T from the earth and sand intakes Ti and Ti with the dredged sand escapes from the drain ports To, To and To. It can be left efficiently. In the second step, the main door bodies 7L and 7R and the auxiliary door bodies 8L and 8R are closed at the same time as the screw 6 is rotated at a low speed, and the rotation speed of the screw 6 is adjusted according to the completion of the closing of the door bodies. The conveyance pressure may be generated by raising it sufficiently.
[0037]
In order to move the movable cylinder T lifted from the lightweight sediment layer L in the third step in the water to the adjacent lightweight sediment layer L, the crane 10 is swung by a predetermined angle, and / or The dredger B is moved forward or backward by a predetermined stroke (see the chain line in FIG. 9).
[0038]
Next, the 2nd dredging operation | work form using the dredging apparatus A of a present Example is demonstrated with reference to FIG.
[0039]
This second dredging operation form is only a specific main door body, that is, all the main door bodies 7R and 7R on the left and right sides, or the main door body 7R on the upstream side of the screw 6 (that is, the side far from the transport pipe 1). In a fully open state and the other doors in a fully closed state (see FIG. 10), the moving cylinder T is lowered to the lightweight sediment layer L on the bottom of the water so as to sink into the layer L by its own weight to a specified depth. The screw 6 is rotated while the fully opened state of the specific main door body 7R is maintained, and the movable cylinder T is horizontally moved to the left or right side along the lightweight sediment layer L on the bottom of the water. As a result, the sedimentary sediment of the layer L is continuously introduced into the movable cylinder T from the open sediment intake Ti (the right half corresponding to the specific main door body 7R), and the inflow sediment is rotated. The screw 6 was continuously pumped to the transport pipe 1 side. And a two-step. As a result, the lightweight soil can be continuously dredged from the lightweight sediment deposit layer L and sent to the dredged sediment receiving part on the water without causing contamination of the water area due to the diffusion of the lightweight soil around the dredging site.
[0040]
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various design change can be performed.
[0041]
For example, in the said Example, the 1st dredging work form corresponding to Claim 4 (FIGS. 8 and 9) and the 2nd dredging work form corresponding to Claim 5 (FIGS. 10 and 11) are common. Although the apparatus A has been shown to be able to be implemented in any way, in the implementation of claim 5, a dedicated dredge apparatus may be used for the second dredging work mode, in which case the movable cylinder Auxiliary door bodies 8R, 8L that open and close the outlets To on the upper peripheral wall of T are omitted (that is, closed), and the left and right half of the earth and sand intake Ti on the lower peripheral wall is omitted (that is, closed). The main door body 7L may be omitted.
[0042]
【The invention's effect】
As described above, according to each of the first to fourth aspects of the present invention, the lightweight sediment is intermittently dredged from the lightweight sediment deposit layer without causing water pollution due to the diffusion of the lightweight sediment around the dredging site, Since it can be pumped to the earth and sand receiving part, it is intended for dredging such as sludge that spreads easily, but the dredging work can be performed accurately while avoiding contamination of the water area due to the diffusion of light earth and sand during dredging. It can be done efficiently.
[0043]
In particular, according to the feature of the invention of claim 2, since the main door that swings open / close can be used as dredged sand guiding means (that is, a bucket) into the movable cylinder, dredging work efficiency is improved.
[0044]
In particular, according to the feature of the invention of claim 3, the variable pitch screw increases the efficiency of dredging the dredged sand from the moving cylinder to the transport pipe side, so that the dredging work efficiency is improved.
[0045]
According to the invention of claim 5, with the main door body whose upper end is pivotally supported by the movable cylinder being held in the fully open position where it projects outwardly from the movable cylinder, the movable cylinder is lowered to the lightweight sediment layer on the bottom of the water. and then, while rotating the screw in the state holding the main door body in the fully open position, by horizontally moving the right and left one side of the movable cylinder along the sea bed weight sedimentation layer, the layer of sediment Since it can be continuously flowed into the moving cylinder from the open earth and sand intake, it can be continuously pumped to the transport pipe side with a screw. It is possible to continuously dredge light sediment from the light sediment deposit layer without inviting it and pump it to the dredged sand receiving part on the water . Pumping dredged soil Rate can be increased, thus, also the dredged lightweight sand subject such as diffuse easily sludge is performed accurately and efficiently dredging while avoiding water contamination due to diffusion of light sediment during the dredging be able to.
[Brief description of the drawings]
FIG. 1 is an overall schematic view showing an outline of dredging work by a dredger working ship according to an embodiment of the present invention. FIG. 2 is a plan view taken along the arrow 2 in FIG. 1. FIG. 4 is a view taken along arrow 4 in FIG. 3. FIG. 5 is a view taken along arrow 5. FIG. 6 is a view taken along arrow 6. FIG. 7 is a sectional view taken along line 7-7 in FIG. FIG. 9 is a cross-sectional view of the main part of the dredging apparatus showing the first dredging work mode. FIG. 9 is an overall plan view showing the first dredging work form. (Figure corresponding to FIG. 8)
FIG. 11 is an overall plan view showing the second dredging operation mode (corresponding to FIG. 9).
[Explanation of symbols]
B Dredging ship F Support frame L Light earth sediment layer M1 Motor M2 as screw driving means Main door driving means M3 Auxiliary door driving means P Storage tank T of dredging work ship as a dredged sand receiving part on the water T Moving cylinder Ti Earth and sand Inlet To Drain W W Wire 1 Transport pipe 3 Sediment storage part 6 of the earth transport ship as dredged sand receiving part on the water Screw 7 Main door 7L Left main door body 7R Right main door body 8 Auxiliary door

Claims (5)

In the dredging device for lightweight earth and sand, which dredged the lightweight earth and sand accumulated on the bottom of the water and pumped it to the dredged sand receiving part on the water,
A cylindrical moving cylinder (T) suspended from a work boat (B) on the water and having an axis substantially horizontal, and a transport pipe (a pipe connecting the base end of the moving cylinder (T) and the dredged sand receiving portion ( 1), a spiral screw (6) forcibly pumping the dredged sand contained in and introduced into the movable cylinder (T) to the transport pipe (1) side, and the screw (6) can be forcibly rotated. The screw driving means (M1) attached to the moving cylinder (T) and the moving cylinder (T1) opened in the peripheral wall on the lower side of the moving cylinder (T) can be opened and closed. A main door (7) supported by T), main door driving means (M2) for forcibly opening and closing the main door (7), and a drain opening (To) opened in the peripheral wall on the upper side of the movable cylinder (T) And an auxiliary door (8) supported by the movable cylinder (T) so that the auxiliary door (8) can be opened and closed. Characterized in that a drive means (M3), light sediment for dredging device.   The movable cylinder (T) is suspended from the work ship (B) via a wire (W) and a support frame (F), and the main door (7) is a left half of the earth and sand intake (Ti). And at least one left main door (7L) pivotally supported by the movable cylinder (T) so as to open and close, and at least one right main pivotally supported by the movable cylinder (T) so as to open and close the right half. The main door drive means provided between the support frame (F) and the main door bodies (7L, 7R). The dredging device for lightweight earth and sand according to claim 1, wherein the dredging device is opened and closed by (M2, M2).   The dredging device for lightweight earth and sand according to claim 1, wherein the screw (6) is formed so that a pitch becomes smaller as it approaches the transport pipe (1). In the dredging method for lightweight earth and sand using the dredging apparatus for lightweight earth and sand according to claim 1, 2, or 3,
With the main door (7) and the auxiliary door (8) fully opened, the moving cylinder (T) is lowered to the light sediment layer (L) on the bottom of the water, and the sediment and water in the layer are taken in the sediment inlet ( Ti) flows into the movable cylinder (T) and escapes excess water from the drain (To);
Closing the main door (7) and the auxiliary door (8) and rotating the screw (6) to pump the dredged sand in the movable cylinder (T) toward the transport pipe (1);
A step of lifting the moving cylinder (T) from the lightweight sediment layer (L), laterally moving the water over the adjacent lightweight sediment layer (L), and then lowering again, as one cycle. By repeating, the dredging method for lightweight earth and sand characterized by intermittently dripping the lightweight earth and sand from the lightweight earth and sand accumulation layer (L) and pumping it to the dredged sand receiving part on the water. In the dredging method for lightweight earth and sand, the lightweight earth and sand accumulated on the bottom of the water is dredged and pumped to the dredged sand receiving part on the water.
A cylindrical moving cylinder (T) suspended from a work boat (B) on the water and having an axis substantially horizontal, and a transport pipe (a pipe connecting the base end of the moving cylinder (T) and the dredged sand receiving portion ( 1) and the dredged sand that has an outer diameter slightly smaller than the inner diameter of the moving cylinder (T) and is accommodated in the moving cylinder (T) and introduced therein is forcibly pumped to the transport pipe (1) side. A spiral screw (6) having a smaller pitch as it approaches the transport pipe (1), and a fully closed position for fully closing the earth and sand intake (Ti) opened in the peripheral wall on the left and right sides of the movable cylinder (T) ; The upper end of the movable cylinder (T) is pivotally supported so that it can swing between the fully closed position and the fully open position where the earth and sand intake (Ti) is fully opened by projecting outward from the movable cylinder (T) . Using the dredge device (A) with the main door (7R),
Lowering the movable cylinder (T) to the lightweight sediment layer (L) at the bottom of the water with the main door (7R) held in the fully open position ;
While rotating the screw (6) the main door body (7R) while held in the fully open position, horizontal in the right and left one side the moving cylinder (T) is along the bottom of the water weight sedimentation layer (L) By moving it, the sediment of the layer is continuously flowed into the moving cylinder (T) from the open sand intake (Ti) and continuously to the transport pipe (1) side with the screw (6). And a method for dredging earth and sand.

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