Paper Keywords: flood gate entrance flood gate

Abstract: Sluices are very common in water conservancy projects. When the gate is closed, it can block flood, tide and water, so as to raise the upstream water level and meet the needs of upstream water intake or navigation. Take water by opening floodgates for flood discharge, drainage and sand washing, or adjust the flow according to the downstream water demand. Sluices are mostly built in rivers, canals, reservoirs, lakes and coastal areas. This paper analyzes the function and composition of sluice in detail to provide reference for water conservancy work.

1 Function of sluice

Low-head hydraulic structures that control water level and regulate flow are the leading projects in farmland water conservancy, and often form water conservancy hubs with dams, shiplocks, fishways, water stations and pumping stations to meet the needs of flood control, flood discharge, shipping, irrigation and power generation.

2 Classification of sluices

2. 1 Control the sluice according to the tasks undertaken by the sluice. Adjust the water level and control the flow. Raise the water level in dry season to facilitate water intake and upstream shipping, and control the flow in flood season. The gate in canal system buildings is generally built downstream of the outlet of the branch canal to raise the water level and meet the needs of water diversion of the branch canal.

Water intake sluice: it is built on the banks or channels of rivers and lakes to transfer water for irrigation, power generation or other water demand. In the irrigation canal system, a water intake sluice is built at the head of the canal below the main canal to guide the water from the upstream channel to the downstream channel, and a water diversion sluice, a bucket gate and a gate drainage sluice are built along the river at the outlet of the drainage channel. The outer river is flooded, the sluice is closed, and flood control and flooding prevention are carried out. The water level of the outer river recedes, and the floodgates are opened for drainage to prevent flooding. It has the function of retaining water on both sides. Tidal sluice is built at the mouth of the river to prevent seawater from flowing backwards. Improve the water level of inland rivers to meet the needs of fresh water storage and irrigation. Low tide and waterlogging. There are navigation holes, which can also be used to ventilate the tide in flat tide. Flood diversion sluice with two-way water retaining function-tidal sluice and drainage sluice: It is often built on one side of the river to discharge the flood exceeding the safe flood volume of the downstream river into the predetermined lakes and depressions, and even if the flood peak is lowered, the safety of the downstream river can be ensured.

2.2 according to the lock chamber structure type

Open gate and culvert gate.

The sluice consists of upstream connecting section, sluice chamber section and downstream connecting section.

3. 1 The upstream connecting section leads the upstream inflow water into the lock chamber horizontally and smoothly, and at the same time plays the role of scour prevention, seepage prevention and soil retaining.

3.2 The upstream connecting section forms an upstream wing wall to guide the water flow smoothly into the sluice.

Cushion: it plays the role of seepage prevention and erosion resistance.

Slope protection and bottom protection: protect river banks and riverbeds from erosion.

Upstream scour trough: protect the head of revetment and prevent the riverbed from scouring and developing in the direction of bottom protection.

3.3 The downstream connection section includes stilling basin, floodplain, downstream scouring trough, downstream wing wall and slope protection (to make the water flow out of the lock chamber smoothly after effective energy dissipation and connect with the downstream riverbed section).

Stilling basin: it is arranged beside the lock chamber, which has the functions of forming hydraulic jump and protecting the river bed from scouring within the hydraulic jump range, and is the main measure of energy dissipation.

Submergence: arranged behind stilling basin to eliminate residual energy and adjust velocity distribution. It is made of stone.

Scouring trough: a scour prevention measure to prevent the riverbed from developing upstream after the flood at the end of the flood.

Downstream wing wall: the water flow is even, protecting the river bank from scouring.

Slope protection: within the scope of marine invasion and gully prevention, stones are generally used.

3.4 The lock chamber section is the main body of the lock, including bottom plate, pier, gate, breast wall, shore wall, working bridge and traffic bridge.

Bottom plate: the foundation of the lock chamber, which bears all the load of the lock chamber, transfers the load evenly to the foundation, uses the friction between the bottom plate and the foundation drawing to maintain the stability of the lock chamber, and also has the functions of anti-scouring and anti-seepage.

Pier: divide the gate hole, support the gate and bridge.

Work bridge: used to install cranes and workers to operate machines.

Shore wall: the connecting structure between the lock chamber and the river bank, which is mainly used for retaining soil and has lateral seepage control effect.

4 sluice selection requirements

The sluice site of the control sluice or flood discharge sluice should be selected in the reach where the river is straight and the river regime is relatively stable. After technical and economic comparison, it can be selected in the newly-opened curved reach. The sluice site of intake sluice, diversion sluice or flood diversion sluice should be selected in the straight river section where the riverbank is basically stable or slightly downstream of the apex of the concave bank of the bend, but the sluice site of flood diversion sluice should not be selected in the dangerous embankment section and the downstream embankment section of the protected important town. The gate site of the drainage gate or the flood discharge gate should be selected in a low-lying place with smooth water flow, and the gate site of the drainage gate should be selected on the old embankment line near the important waterlogging area and the flood discharge area. The dam site of tidal sluice should be selected near the tidal estuary with stable coastline and slope. The sediment in the floodplain at the sluice site has little change, and the upstream channel has sufficient water storage.

5 characteristics of energy dissipation and scour prevention flow of sluice

The outlet speed is high and the turbulence is strong. The upstream water level difference is small. The flow pattern changes with the opening procedure of the gate.

6 Sluice scour

Generation of wave-like hydraulic jump: submerged hydraulic jump did not occur or flooded too much. Under diffusion, the flow is uniform, resulting in water flow breaking. The water level difference between upstream and downstream is small, resulting in wave-like hydraulic jump and low energy dissipation efficiency.

Basic energy dissipation mode: underflow energy dissipation is the main mode, which is composed of stilling basin, flood discharge and gully prevention. Its form can be selected according to water flow, terrain conditions, building capacity and energy dissipation effect.

Precautionary measures for wave hydraulic jump: in the general layout, try to use the upstream channel with a straight section to ensure the horizontal stability and uniformity; Control the diffusion angle of the downstream wing wall, which should be 7 ~ 12 to make the water flow diffuse evenly; Formulate reasonable sluice opening procedures, pay attention to the principles of uniform start and symmetrical opening, and avoid ups and downs in opening and closing and water leakage in some sluice holes of porous sluice.

7 Common seepage control and drainage facilities

Horizontal seepage control equipment: drainage bodies and filter layers such as tooth wall, plate wall and cutoff wall. The main purpose is to improve drainage, continue to decompress and guide seepage to the downstream safely.

The function of sheet pile is to reduce the pressure when covering the front or upstream end of the chamber floor. The rectangular plate arranged on the downstream side of the bottom plate of the lock chamber is mainly to reduce the seepage pressure at the outlet.

Structural layout of lock chamber: including bottom plate, pier, breast wall, gate, working bridge and traffic bridge.

The function of pier: separating the gate hole, supporting the gate and the breast wall of the superstructure, reducing the height of the gate, reducing the weight of the vertical door and reducing the requirements for the weight of the hoist. Function of the working bridge: set the elevator and operate it by the management personnel.

When the sluice is connected with the river bank, dam, dam, etc. , it is necessary to set up connecting buildings, including upper and lower wing walls, piers, and sometimes anti-seepage stab walls. Their functions are:

(1) Retain the fill on both sides to keep the earth dam and its two sides stable.

(2) When the sluice discharges water or pumps water, the upstream buttress wall will be used to guide the water flow smoothly into the sluice, and the downstream buttress wall will make the outlet water flow evenly dispersed to reduce scouring.

(3) Prevent the river bank or earth dam slope from being washed by flood discharge water.

(4) Control the seepage on both sides of the sluice body to prevent the seepage deformation of the bank slope or earth dam connected with it.

(5) Setting independent bank wall on soft foundation can reduce the influence of foundation settlement on the stress of sluice body. ? Previous page [1]? [2]?

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