JP4316405B2 - Discharge method of sediment in the reservoir - Google Patents

Description

  The present invention relates to a method for discharging sediment sediment in a reservoir dammed up by a dam.

  In a reservoir formed by damming a river with a dam, if a large amount of sediment including mud generated by construction upstream of the river flows into the reservoir, they will sink into the reservoir, causing a sedimentation phenomenon and reducing the amount of stored water Cause.

  As a means of suppressing this sedimentation phenomenon, there is a method of removing sediment through a reservoir.

  As another means, there is a method of opening a spillway gate provided in a dam, winding up sediment by the pressure, and discharging it to the downstream side together with the discharged water.

  In the former dredging method, the dredging machine removes the sediment deposited on the riverbed evenly. However, if the amount of inflowing sediment is large, the amount of construction and the number of constructions increase, so the construction cost is extremely high.

  Moreover, in the latter method of opening the spillway gate, a method of sequentially opening a plurality of spillway gates, for example, from the right bank side to the left bank side is employed. However, there is a problem that a sufficient sedimentation effect cannot be obtained because the sediment component of sediment has not yet been discharged. Moreover, the problem of muddy water on the downstream side also occurred along with the discharge and discharge.

  The present invention solves the above-mentioned problems, and its purpose is to devise the distribution of pressure due to water flow, so that sediment sediment can be discharged and discharged efficiently by releasing the spillway gate. A method is provided.

  In order to achieve the above object, the method according to claim 1 is a method for discharging sediment accumulated at the bottom of a reservoir dammed up by a dam, and gradually decreases from the dam to the upstream side by dredging. By forming a water channel with a substantially inverted trapezoidal cross section with a sloped surface and opening a spillway gate provided in the dam, a high-pressure water flow is generated in the water channel, causing the surrounding sediment to collapse. The water channel is widened and discharged to the downstream side along with the water flow.

  In the first aspect of the present invention, a portion having a deep water depth and a strong flow momentum is formed by forming the water channel, and the portion of the sand and surrounding soil is scoured and collapsed by opening the gate to expand the water channel and remove the entrained sediment. At the same time, the water depth in the reservoir can be restored.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 show an embodiment of the present invention.

  In the figure, a dam 1 is constructed on the rock in the valley where the river flows, and a reservoir 2 is located upstream of the dam. In addition, although what is less than 15m in height is called a weir, here, it is called a dam collectively. There are various types of dams 1 such as gravity dams, arch dams, buttress dams, etc., any of which can be used, each of which has a spillway gate 3 and, if necessary, opens this gate 3 to create a reservoir. The water stored in 2 can be discharged.

  In the method of the present invention, first, as shown in FIG. 1 (b), the dredger 6 and the earth transport ship 7 are introduced into the reservoir 2, and the excavation soil is loaded into the earth transport ship 7 while performing the dredging work.

  Although the illustrated dredger 6 is a grab type, a conveyor bucket type or a pump type can also be used. Further, in a place where the reservoir area is small and the dredger 6 cannot be introduced, it is possible to use a civil engineering machine such as a backhoe, or If the water depth is shallow, you may go directly into the reservoir and perform excavation work.

  In the initial stage, the surface layer of the earth and sand 5 is uniformly crushed. This is because small particles such as mud and fine sand suspended by the dam 1's damming action settle mainly on the surface layer and cause turbid water at the time of subsequent discharge.

  Thereafter, as shown in FIG. 1 (b), an artificial waterway 8 having an inverted trapezoidal cross section is formed in one place as an inclined surface having a gentle gradient that gradually becomes shallower from directly below the dam 1 to the upstream side. FIG. 1C and FIG. 2B show the construction completion state of the water channel 8.

  After the dredging operation is completed and the dredger 6 and the excavation ship 7 are withdrawn, when the gate 3 is opened, the water pressure in the water channel 8 is higher than that in other places as shown by the arrow in FIG. 2 (d) and (e), the soil around the water channel 8 is carried by the water stream to the downstream side of the dam 1 while expanding the water channel 8 due to scouring and collapse due to water pressure. leak.

  Eventually, as shown in FIG. 2 (f), the original depth of water can be almost recovered while leaving a large amount of gravels that cannot be carried by the water flow in the river bed 4. After the gate 3 is closed, a predetermined value is obtained. Water can be stored in the reservoir 2 in a state in which the water depth is secured.

  During discharge, mud, fine sand, etc. are roughly removed in advance during the dredging process, and there are many components that are relatively easy to settle. The influence on the side can be minimized.

3 to 5 show reference examples of the present invention. First, as shown in FIG. 3, in a meandering river, the meandering side having a large curvature is likely to be eroded 10, and earth and sand 11 is likely to be deposited on the small side.

  In the case where the dam 12 is constructed downstream, for example, as shown in a cross-sectional view in FIG. 4, at the position directly above the dam 12, the sediment earth and sand 11 is unevenly distributed on the right bank side where the meandering curvature is small, and toward the left bank side. And accumulated in an inclined state. As a result, the deepest waterway is formed on the left bank.

  In order to open the spillway gate and discharge the sediment from this state, for example, when four spillway gates 14 are provided in a horizontal row as shown in FIG. By opening 14, water pressure concentrates on the opened discharge port 14 a, and the sediment deposited in the vicinity of the discharge port 14 a is scoured by the water flow and discharged downstream by the water flow. 11 is discharged downstream while collapsing.

  After that, the gate 14 is closed, and as shown in FIGS. 5B to 5D, the release of the gate 14 is sequentially moved to the right bank side, thereby concentrating the water flow on each discharge port 4a. The earth and sand near the discharge port 14a is discharged, and in the final state, as shown in FIG. 5 (e), the earth and sand 11 deposited in an unevenly distributed state upstream of the dam 14 is almost wiped out.

(A) ~ (c) is a side view showing the dredging and sedimentation conditions in Kazumi facilities embodiment of the present invention method. (A)-(f) is explanatory drawing which shows transition of the deposition state in the embodiment. It is plane explanatory drawing which shows the earth and sand accumulation condition by the reference example of this invention. It is AA sectional view explanatory drawing of FIG. (A)-(d) is sectional drawing for description which shows transition of the sediment accumulation state in the embodiment.

Explanation of symbols

1,12 Dam 2 Reservoir 3,14 Spillway gate 5,11 Sediment sediment 8 Waterway

Claims (1)

A method for discharging sediment deposited at the bottom of a reservoir blocked by a dam,
Formed a single channel with a roughly inverted trapezoidal cross-section with a gently sloping inclined surface that gradually becomes shallower from directly below the dam to the upstream side by dredging work,
By opening the spillway gate provided in the dam, a high-pressure water flow is generated in the water channel, so that the surrounding sediment is collapsed to widen the water channel, and the water channel is discharged to the downstream side. Discharge method of sediment.

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