Method of transporting dredged earth and sand

Abstract

To provide a dredged earth and sand conveying method capable of efficiently conveying dredged earth and sand.SOLUTION: In the method for transporting dredged earth and sand, the temporary storage sites A and B are installed in advance on the dam lake bottom 3 that is exposed above the water when the water level of the dam lake is low and is submerged below the water surface when the water level is high, earth and sand dredged from the dam lake bottom 3 are put into and temporarily stored in the temporary storage sites A and B, and the earth and sand accumulated in the temporary storage sites A and B are carried out of the lake when the water level is low and the dam lake bottom 3 is exposed above the water.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for transporting dredged soil efficiently, which is generated when dredging soil deposited at the bottom of a dam lake. [Background technology]

[0002] Mud, sediment, and other materials (hereinafter referred to as sediment) flow into dams from upstream rivers, and since this sediment can accumulate at the bottom of the dam lake, especially near the bottom of the embankment, and this could impair the dam's function, dredging of the accumulated sediment is carried out regularly.

[0003] Dredging of this sediment is mainly carried out during the non-flood season from October to July of the following year. For example, the sediment excavated using a dredger's grab bucket is landed on the exposed lake bottom when the water level drops, and then transported from that location to an exit point before being removed from the dam lake.

[0004] A known method for transporting the unloaded dredged soil to the discharge port is to transfer the soil to a vehicle such as a dump truck at the unloading site, and then have the vehicle move over the bottom of the dam lake exposed by the drop in water level to transport it out the discharge port. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-106497 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the conventional technology described above, as shown in Figure 5, the water level of the dam lake fluctuates greatly throughout the year, and as the water level drops, the areas where the lake bottom is exposed also change. This means that it is difficult to land the dredged soil at the same location throughout the dredging work and transport it by dump truck.

[0007] Furthermore, if the unloading point can only be located at a distant location upstream due to reasons such as the steep slope of the dam lake bank, it takes time to transport the soil using vehicles such as dump trucks, and due to the changes in water level mentioned above, the unloaded soil cannot be temporarily stored, so dredging work has to be stopped while it is being transported.

[0008] Furthermore, while dredging of sediment has traditionally been carried out during the non-flood season from October to June of the following year, it is desirable to be able to carry out dredging work during the flood season (July to September) in order to improve operational efficiency.

[0009] Therefore, in consideration of these conventional problems, the present invention has been made with the aim of providing a method for transporting dredged soil that can efficiently transport dredged soil without limiting the period of dredging work. [Means for solving the problem]

[0010] The feature of the invention described in claim 1 for solving the above-mentioned conventional problems is that in a method for transporting dredged soil produced when dredging soil from the bottom of a dam lake, the method involves setting up a temporary storage area in advance at the bottom of the dam lake, which is exposed above water when the water level of the dam lake is low and submerged below water when the water level is high, and when the water level of the dam lake is high and the bottom of the dam lake is submerged, the dredged soil is dumped into the temporary storage area from above water, and the dredged soil produced by dredging the bottom of the dam lake is dumped into the temporary storage area and temporarily stored there, and when the water level is low and the bottom of the dam lake is exposed above water, the dredged soil deposited in the temporary storage area is transported out of the lake.

[0011] The invention described in claim 2 is characterized in that, in a method for transporting dredged soil produced when dredging soil from the bottom of a dam lake, the dredged soil is transported out of the dam lake by installing temporary storage areas in advance at the bottom of a plurality of dam lakes of different depths that are exposed above water when the water level of the dam lake is low and submerged below water when the water level is high, the dredged soil produced by dredging the bottom of the dam lake is dumped into the temporary storage areas and temporarily stored there, and when the water level is low and the bottom of the dam lake is exposed above water, the dredged soil accumulated in the temporary storage areas is transported out of the lake.

[0012] The invention as set forth in claim 3 is characterized in that, in addition to the configuration of claim 1 or 2, the temporary storage area is provided with an outflow prevention wall at least on the downstream side. [Effects of the Invention]

[0013] The method for transporting dredged soil according to the present invention, by incorporating the configuration described in claim 1, enables dredging work to be carried out even during flood seasons or other periods when the water level is high, eliminates the need to stop dredging work, and enables the soil deposited in the dam lake to be transported efficiently.

[0014] Furthermore, in the present invention, by providing the configuration described in claim 2, dredged soil can be transported in each season when the water level differs.

[0015] Furthermore, in the present invention, by providing the configuration described in claim 3, it is possible to reliably prevent the soil and sand accumulated in the temporary storage site from flowing out. [Brief explanation of the drawings]

[0016] [Figure 1] (a) is a plan view showing the state of preparatory work in the method of transporting dredged soil according to the present invention, (b) is a plan view showing the state of work when the water level is at its lowest, and (c) is a plan view showing the state of work when the water level has risen to the middle level. [Figure 2] FIG. 10 is a vertical cross-sectional view showing the dredging operation and the transportation of dredged soil when the water level is low. [Figure 3](d) is a plan view showing the working conditions when the water level is high, (e) is a plan view showing the working conditions when the water level has dropped to a medium level, and (f) is a plan view showing the working conditions when the water level has dropped to a low level. [Figure 4] FIG. 2 is a vertical cross-sectional view showing the state of dredging work when the water level is high. [Figure 5] 1 is a graph showing an example of fluctuations in the water level of a dam lake. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, an embodiment of a method for transporting dredged soil according to the present invention will be described based on the examples shown in Figures 1 to 5. In the figures, reference numeral 1 denotes a dam.

[0018] As shown in Figures 1 and 2, the downstream side of the dam lake is blocked by a dam body 2, and the water depth downstream near the dam body 2 is deep.As shown in Figure 5, the water depth changes depending on the season and the dam's release, and when the water level is low, the bottom 3 of the dam lake on the upstream side is exposed.

[0019] The symbol 3 indicates the exposed bottom of the dam lake, and symbol 4 indicates the outer edge of the dam lake. The area where the bottom of the dam lake 3 is submerged is indicated by diagonal lines for convenience, and symbol 5 indicates the water surface.

[0020] In this dam 1, sediment (hereinafter referred to as sediment) accumulated at the bottom 3 of the dam lake is dredged, and the sediment (hereinafter referred to as dredged sediment) produced during dredging is transported out of the dam lake through an outlet 4a set up upstream.

[0021] The method for transporting this dredged soil 6 out of the dam lake is to dump the dredged soil 6 produced by dredging the bottom 3 of the dam lake into temporary storage areas A and B that have been set up in advance at designated locations, and then, when the water level 5 is low and the bottom 3 of the dam lake is exposed above water, the dredged soil 6 accumulated in temporary storage areas A and B is transported to the discharge port 4a using a dump truck 7 or the like and removed from the lake.

[0022] The specific method for transporting dredged soil is described in detail below.

[0023] First, as shown in Figure 1(a), a pier 8 is assembled at a designated location during a period when the water level is low due to the release of water from the dam 1 (for example, from September to October), and this pier 8 is used to assemble transportation means such as a dredger 9 and a soil transporter 10, as well as a temporary storage area A downstream.

[0024] The specified location is a location where the bottom 3 of the dam lake is exposed when the water level of the dam lake is at its lowest and is submerged below the water surface 5 when the water level is at its highest, and is preferably near the boundary with the water surface when the water level of the dam lake is at its lowest.

[0025] As shown in Figure 1(a), the temporary storage area A is equipped with an outflow prevention body 11 that is U-shaped in plan view and has wall portions 11b, 11b on both sides of an outflow prevention wall 11a located downstream, allowing dredged soil 6 to be temporarily stored within the outflow prevention body 11.

[0026] The outflow prevention wall 11a and wall portions 11b, 11b are constructed, for example, by a continuous sheet pile wall formed by engaging the sides of multiple steel sheet piles driven into the bottom 3 of the dam lake, and are designed to block the dredged soil 6 and prevent it from outflowing downstream.

[0027] It is preferable that the outflow prevention body 11 is of a height that allows the upper end to be sufficiently submerged below the water surface 5 when the water level rises and does not hinder the operation of the dredger 9 or the soil transport boat 10.

[0028] The form of the outflow prevention body 11 is not limited to the above-described embodiment, and it is sufficient if it is provided with an outflow prevention wall 11a at least on the downstream side.

[0029] Furthermore, the form of the temporary storage areas A and B is not limited to those using the above-mentioned outflow prevention body 11, but may be, for example, those in which a recess for dumping soil is provided by excavating the bottom 3 of the dam lake, which is exposed when the water level of the dam lake is at its lowest and submerged below the water surface 5 when the water level is at its highest, or those that make use of the topography of the dam lake.

[0030] The dredger 9 may be one that excavates the bottom 3 of the dam lake with a grab bucket delivered from a crane installed on a barge, or a pump-type dredging device may be used.

[0031] The transport means is not limited to the soil transport barge 10, and may be, for example, a pump that pumps the soil from the dredger 9 to the temporary storage sites A and B through a pressure pipe.

[0032] Next, once the preparations for transportation means such as the dredger 9 and soil transporter 10, and the temporary storage area A downstream, are complete, the dredger 9 begins dredging the bottom 3 of the dam lake near the embankment 2, as shown in Figures 1(b) and 2, and the transportation of dredged soil 6 to the temporary storage area A begins.

[0033] In the figure, reference numeral 12 denotes a backhoe, which is used to load soil from the soil transport barge 10 into the temporary storage site A or transfer soil from the temporary storage sites A and B to the dump truck 7.

[0034] The dredged soil 6 transported to the temporary storage area A contains a lot of moisture and is difficult to transport by dump truck as it is. Therefore, the dredged soil 6 is improved as necessary by dehydration, aeration, addition of solidifying material, etc., and the improved dredged soil 6 is loaded onto a dump truck 7 or the like and transported to the discharge point 4a.

[0035] During the period when the water level at the location where Temporary Storage Site A is installed is low, the above-mentioned dredging work, transporting of soil and sand to Temporary Storage Site A, and transporting and conveying work to the discharge port 4a by dump trucks 7 or the like are repeated.

[0036] Next, during periods when the water level gradually rises (for example, from January to February), before the pier 8 is submerged, the transportation of dredged soil 6 using dump trucks 7 and the like is stopped, and heavy machinery such as backhoes 12 at temporary storage area A is evacuated to an area upstream where the bottom 3 of the dam lake is exposed.

[0037] Furthermore, in the area where the bottom 3 of the dam lake on the upstream side is exposed, an outflow prevention body 11 is installed, as shown in FIG. 1(c), and a temporary storage area B on the upstream side is constructed.

[0038] Meanwhile, dredging work by the dredger 9 continues even after transportation work by the dump trucks 7 etc. has stopped, and the dredged soil 6 is transported by the soil transporter 10 to the temporary storage area A downstream, and the dredged soil 6 is dumped from the soil transporter 10 into the temporary storage area A downstream using a backhoe 12 mounted on the soil transporter 10.

[0039] Then, when the water level rises further (for example, in March to April), approximately half of the dam lake bottom 3 is submerged, and the temporary storage area A on the downstream side is submerged.

[0040] After the downstream temporary storage area A is submerged, dredging work continues using the dredger 9, and as shown in Figure 4, the dredged soil 6 is transported to the downstream temporary storage area A by the soil transporter 10, and the dredged soil 6 is dumped from the soil transporter 10 onto the downstream temporary storage area A from the water using a backhoe 12 mounted on the soil transporter 10.

[0041] At this time, an outflow prevention body 11 is installed in the temporary storage area A, so that the dredged soil 6 poured into the underwater temporary storage area A is blocked from flowing downstream, and the dredged soil 6 is piled up in the temporary storage area A and temporarily stored in that state.

[0042] Furthermore, during periods when the water level rises further (for example, from May to June), most of the dam lake bottom 3 is submerged, but dredging work continues using the dredger 9 during this time, and as shown in Figures 3(d) and 4, the dredged soil 6 is transported by a soil transporter 10 to temporary storage areas A and B set up on the dam lake bottom 3 at different water depths on the downstream and upstream sides, and the dredged soil 6 is dumped from the soil transporter 10 onto the temporary storage areas A and B on the downstream and upstream sides from the water using a backhoe 12 mounted on the soil transporter 10.

[0043] At this time, since anti-flow bodies 11 are installed at the downstream and upstream temporary storage areas A and B, respectively, the dredged soil 6 dumped into the underwater temporary storage areas A and B is prevented from flowing downstream, and the dredged soil 6 is deposited in the temporary storage areas A and B and temporarily stored in that state.

[0044] Furthermore, the dredging work of the dam lake bottom 3 by the dredger 9 and the dumping of dredged soil 6 into temporary storage areas A and B can be continued as long as the capacity of each temporary storage area A and B is not exceeded.

[0045] Next, during the flood season (for example, July to September), the water level is rapidly lowered by releasing water from the dam as a flood prevention measure, so the water level of the dam lake gradually drops from the upstream side. As shown in Figure 3(e), first, temporary storage area B on the upstream side is exposed from the water, and as the water level drops further, it becomes possible to pass through exit 4a.

[0046] Therefore, the dredged soil 6 temporarily stored in the upstream temporary storage area B is improved as necessary by dehydration, aeration, addition of solidifying material, etc., and the improved dredged soil 6 is loaded onto a dump truck 7 or the like and transported toward the discharge point 4a.

[0047] Furthermore, when the water level drops and the top of the downstream temporary storage area A and the pier 8 are exposed from the water, as shown in Figure 3(f), heavy machinery such as a backhoe 12 is placed on the pier 8, and the dredged soil 6 temporarily stored in both temporary storage areas A and B is improved as necessary by dehydrating, aerating, adding solidifying materials, etc., and the improved dredged soil 6 is loaded onto a dump truck 7 or the like, and transportation work toward the discharge point 4a is resumed.

[0048] At this time, the transportation of dredged soil 6 from the upstream and downstream temporary storage areas A and B can begin without waiting for dredging work by the dredger 9, since the dredged soil 6 that has already been dredged is temporarily stored at the temporary storage areas A and B.

[0049] On the other hand, dredging work by dredger 9 is carried out even during flood season, and as the transportation of dredged soil 6 from temporary storage areas A and B is resumed, the storage capacity of temporary storage areas A and B decreases, and the newly dredged soil can be transported to temporary storage areas A and B, which now have excess capacity.

[0050] Furthermore, since floods are expected to occur during the flood season, it is desirable to provide mooring facilities so that dredgers 9 and soil transporters 10 can be moored in the event of a flood.

[0051] After the desired amount of sediment deposited at the bottom of the dam lake 3 has been dredged, the outflow prevention structures 11 and piers 8 that make up the temporary storage areas A and B are removed, and if dredging work is to be continued, the above-mentioned series of dredging work and sediment transportation work will be repeated throughout the year.

[0052] In this method of transporting dredged soil, temporary storage areas A and B are set up in advance at the bottom 3 of the dam lake, which is exposed above water when the water level of the dam lake is low and submerged below water when the water level is high. Dredged soil 6 produced by dredging the bottom 3 of the dam lake is dumped into temporary storage areas A and B for temporary storage. This allows dredging work, which was previously limited to periods when transportation work using dump trucks 7 etc. could be carried out at any time, making it possible to use the same construction machinery throughout the year and to create a construction plan with no interruptions to work, thereby improving work efficiency and increasing the amount of dredged soil per year.

[0053] In more detail, the amount of material transported by dump trucks 7, etc. usually depends on the number of dump trucks 7, etc. available per day and the number of days (number of operating days) that the lake bottom is exposed due to a drop in the water level, so dredging work by dredgers 9 is generally limited to the operating period of dump trucks 7, etc., and cannot exceed the amount of material transported by dump trucks 7, etc.

[0054] In contrast, in the method of transporting dredged soil according to the present invention, the dredged soil 6 is temporarily stored in temporary storage areas A and B. Therefore, even outside the operating periods of dump trucks 7, etc., dredging work on the bottom 3 of the dam lake by the dredger 9 and transporting the soil to temporary storage areas A and B can be continued as long as the capacity of temporary storage areas A and B is not exceeded, allowing for a seamless construction plan throughout the year.

[0055] On the other hand, the transportation work using dump trucks 7, etc., is carried out because the dredged soil 6 has already been stored in temporary storage areas A and B before the water level rises. Therefore, once temporary storage areas A and B are exposed from the water, the transportation work of the dredged soil 6 can begin without waiting for the completion of the current dredging work. This means that the number of operating days can be increased, a larger amount of dredged soil can be transported, and the efficiency of the transportation work can be improved.

[0056] In addition, in this method of transporting dredged soil, by setting up temporary storage areas A and B at the bottom 3 of multiple dam lakes with different water depths, the work of transporting soil can be resumed sequentially from the upstream temporary storage areas A and B, allowing the dredged soil to be transported more efficiently. [Explanation of symbols]

[0057] 1. Dam 2 Embankment body 3. Bottom of the dam lake 4 Outer edge of the dam lake 5 water surface 6 Dredged soil 7. Dump Truck 8. Pier 9 Dredger 10 Soil Carrier 11. Outflow prevention body 12 Backhoe

Claims

1. A method for transporting dredged soil produced when dredging soil from the bottom of a dam lake out of the dam lake, comprising: A temporary storage area is set up in advance at the bottom of the dam lake, which is exposed above the water when the water level of the dam lake is low and is submerged below the water surface when the water level is high; The dredged soil produced by dredging the bottom of the dam lake is poured into the temporary storage area and temporarily stored therein. A method for transporting dredged soil, characterized in that the dredged soil accumulated in the temporary storage area is transported out of the lake when the water level is low and the bottom of the dam lake is exposed above water.

2. 2. The method for transporting dredged soil according to claim 1, wherein the temporary storage site is provided with an outflow prevention wall at least on the downstream side.

3. 3. A method for transporting dredged soil as claimed in claim 1 or 2, wherein the dredged soil is dumped into the temporary storage area from above water when the water level of the dam lake is high and the bottom of the dam lake is submerged below the water surface.

4. 3. The method for transporting dredged soil according to claim 1, wherein the temporary storage areas are installed at the bottoms of a plurality of dam lakes having different water depths.

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