log chute
Horizontal joint crossing wooden dam facilities. Most of them are located in non-navigable rivers and low-head small and medium-sized water conservancy projects. According to the structure type, it can be divided into platform type, falling sill type and stepped raft path; According to the form of bottom slope, it can be divided into single slope and variable slope raft (see figure); According to the groove surface structure, it can be divided into rough raft and rough raft. The plane layout of the raft passage should be based on the principle that the raft can pass smoothly, and determined according to the general plane layout and topographic and geological characteristics of the water control project. Liferafts should be as far away from the intake and spillway as possible. At the entrance of the raft near the overflow dam, induction facilities not less than the maximum platoon leader should be set up. If a sensing wall is used, the top of the wall should be higher than the maximum discharge level. The entrance of the raft generally needs to be arranged in a trumpet shape, with gates and navigation facilities; The life raft exit should be close to the mainstream direction, and the induced protection facilities should be set up.
lock
Navigation structure of ships and timber. Suitable for wooden rafts crossing dams in navigable rivers. According to the structural form, it can be divided into single-stage lock and multi-stage lock. The plane layout of the ship lock should be determined according to the general plane layout and topographic and geological conditions of water conservancy and hydropower projects, and generally arranged on one side of the dam. There should be enough water areas suitable for berthing and drainage in the upstream and downstream of the lock. It is best to increase a certain spare width on the width of the gate row. The critical water depth should be greater than the draft of the raft. The length and width of lock chamber should meet the length and width of passing through lock and standby raft. The size of the filling and discharging culvert should be reasonably determined according to the water level and flow rate of the ship lock. The upstream and downstream approach channels and navigation walls should be flat and as straight as possible with the gate, so that the raft foundation can enter and exit smoothly.
Elevator (ship) machine
There are three types: vertical-inclined mixed type, inclined type and vertical type, which are divided into dry transportation and wet transportation. Generally speaking, the hoist is dry and is specially used for crossing the raft. Ship lifts are mostly wet transportation, which is a common navigation structure for ships and rafts. ① Vertical and oblique mixed lifting unloader: it is suitable for bamboo and wood to be discharged horizontally across the dam. The water level in the upstream reservoir area should meet the requirement that the trolley depth is greater than the draft of the dam-crossing section, and the downstream outlet velocity and depth should ensure the smooth outflow of the dam-crossing section. The lifting unloader consists of a cart (vertical lifting platform cart), a trolley (load-bearing row of trolley running on inclined plane), a winch room, a vertical lifting track and an inclined plane running track. During operation, the trolley is locked on the track supported by the trolley, the two trolleys descend along the vertical lifting track at the same time, and the trolley motor is in a feedback braking state. Drop to the necessary water depth below the water surface of the reservoir area, introduce the platoon and install the trolley, then lift the trolley, and the trolley and trolley will rise at the same time. Stop the car automatically when it reaches the upper limit, release the locking device of the car, and the car will derail from the cart and go downhill along the hinge. The car is braked by a reverse motor. In order to prevent steep slope and out of control, a manual ratchet is set on the adjusting screw of the automobile brake to obtain sufficient braking torque. When the car goes down to the downstream water surface and enters the water to a certain depth, the fully loaded raft leaves the small traffic flow due to buoyancy, inertia and water flow. At this point, the raft has been completed. (2) Inclined lifting unloader: used for raft and bamboo raft crossing the dam. It is generally composed of track drift, flat car and winch. Flat lanes are divided into horizontal sections and upstream and downstream slope sections. In the slope section, traction cable idlers are set at appropriate intervals, and guide pulley blocks are adopted to ensure that the traction cable can normally pull the flat car in the upstream and downstream slope sections. The forward and reverse rotation of the motor is realized by the travel switch on one side of the guide pulley block. (3) Ship lift: it is a mechanical method to lift the bearing box for loading and discharging. Its main body consists of the ship-bearing box and its supporting and guiding structure, and at the same time, it is attached with a driving device to drive the ship-bearing box to lift; Accident prevention device; Balance equipment for reducing driving power; Fastening, sealing, water filling and drainage equipment to realize the connection between the ship-bearing box and the gate head; Supporting and guiding equipment to ensure the stable operation of the ship-borne box; Corresponding electrical equipment, such as transmission, distribution and control system. There are two main types of wet ship lifts: inclined and vertical. Inclined ship lifts can be divided into longitudinal inclined ship lifts and transverse inclined ship lifts; Vertical ship lifts include counterweight type, buoy type and hydraulic type.
Future development trend of timber crossing the dam: ① With the development of water conservancy and hydropower, how to solve the contradiction between timber water transport and hydropower, farmland water conservancy and shipping, especially timber crossing the dam as an integral part of hub construction and operation, its problems will become more and more prominent. (2) Hydraulic dam crossing and mechanical dam crossing will be tailored to local conditions. In the low-head water conservancy project carrying rivers, water rafts will be developed to cross the dam. In view of high and medium water head projects, economic and reasonable dam-crossing machinery such as hoist has been developed. The construction of single-stage and multi-stage shiplocks or ship lifts will be the main projects of middle and low-head waterways, and ship lifts will be developed in high-head hydropower and water conservancy projects. It is not uncommon to build 100 meter or even more than 200 meters high head high dam hydropower station. More and more people pay attention to how to solve the problem of timber crossing the dam and navigation of this high dam more scientifically. With the cascade development of hydropower projects and channelization construction of navigable rivers, in order to avoid the change of water transport technology as much as possible, it is necessary to study the unification of types and specifications of navigation structure or dam-crossing wooden facilities in the same basin and the standardization and serialization of different types of dam-crossing wooden facilities through rafts and fleets with the same specifications.