What Is a Ventilation Shaft?

In order to ensure safety, in the engineering design, ventilation and exhaust channels are set as required. Ventilation shafts are one type of exhaust facility.

Underground facilities such as mine tunnels, railway and highway tunnels, subway passages, basements, and air-raid shelters, due to water vapour and other harmful, explosive gases emitted from the ground, exhaust gases emitted by internal combustion engines during work, workers The water vapour and carbon dioxide emitted during breathing can accumulate in large quantities and cause unsafe factors. In order to ensure safety, in the engineering design, ventilation and exhaust channels are set as required. Ventilation shafts are one type of exhaust facility. Generally, the ventilation shaft is a vertically upward channel structure, just like a "well", so it is called a ventilation shaft. One end of the ventilation shaft is connected to the space of the underground building, and the other end is open to the ground space.

In the design of shaping the high-quality outdoor landscape environment of the building, the location and form of the ground ventilation shafts in the underground buildings are important factors restricting the design. Therefore, scientifically and reasonably arranging the ventilation shafts of underground buildings and coordinating the relationship between the ventilation shafts and the building landscape environment after the ground will help us improve the design quality of the project.

First, the approach to architectural design.

First, using traditional architectural design methods, combined with certain new technical means, the ventilation shafts intended to be out of the ground are integrated and arranged inside the main building, and appear in the form of a design element in the main building facade. Realize the "stealth" of the ventilation shaft. This method is applicable when all or most of the area of the local substructure is included in the range of the ground building projection line, and only a small amount of area is located below the ground of the outdoor plaza.

Secondly, using the architectural design method with ecological concept, by setting a sunken courtyard, the natural ventilation of underground buildings can be replaced, instead of the traditional method (ground ventilation shafts are set up in outdoor squares). This design method not only perfectly hides the ventilation shafts of underground buildings, but also benefits the building's environmental protection and energy saving.

Second, the approach to landscape design.

Use landscape design techniques to consider the location and form of ventilation shafts above the ground, and integrate ventilation shafts as part of landscape design into the square.

Choice of inclined and vertical shafts

I. Influence of topographical and geological conditions

Topographical conditions are often the primary basis for choosing a ventilation shaft plan. If you choose

Main diseases and causes

The bad direction of the curve and the wear of the curved rail are the main diseases of the curve. The direct cause of the bad direction of the curve is the effect of the horizontal horizontal force, and the magnitude of the horizontal horizontal force depends on the plane shape of the curve, and the two are mutually dependent. The direction of the curve is bad. When the locomotive passes, a severe lateral sway will occur, which exacerbates the impact and vibration of the locomotive wheels on the track and worsens various undesirable phenomena on the curve line. The deterioration will in turn increase the sway when the locomotive passes , Affecting the smooth operation of the locomotive, causing a vicious cycle, and aggravated the wear of the rails. The vertical wear of the rail is mainly due to the difference in length between the inner and outer rail wheel rolling distance and the length of the inner and outer rail line, which is caused by the wheel pair sliding on the rail. The cause of side wear of the rail is mainly the role of the guide wheel. In addition, if the height is too high or too small, the curve gauge will increase, and the incorrect slope of the curve will also cause or aggravate the wear of the rails.

Remediation method

(1) The positive and negative errors do not exceed the limit. Use the rope straight method to do a good job in the calculation of the curve correction and the lane assignment, maintain the correct position of the curve marking stakes, and perform irregular lane assignments on key diseased areas. Strengthen routine maintenance work and maintain The head and tail of the curve are round and smooth, and the diseases such as "goose head" and "branch mouth" of the curve are corrected in a timely manner. The curve is fully corrected, and special attention should be paid to the treatment of small directions and small broken bends.

(2) Maintain the correct gauge and level. Poor positive loss makes it difficult to maintain gauge and level, but exceeding gauge and level will also affect changes in positive loss. Therefore, it must be set according to regulations. Keep ultra-high and wide gauge, completely lock the line, prevent crawling, correct hard-bent steel rails, repair and replace bad track studs, tighten the gauge lever, and keep track bed tidy. Strengthen tamping, eliminate potholes in a timely manner, and eliminate the bracket of rail joints. When rerouting, take into account the normal loss and not exceed the limit, and achieve full, positive, tight, and reliable connection parts, and reroute without leaving rope".

(3) Keep the curve round and round. If the direction of the straight line at both ends of the curve is not the direction of the tangent of the curve, or the curve stakes are incorrectly drawn into a curve or a curve into a straight line; The curves are not rounded. Therefore, before measuring the positive and negative errors at the scene when the curve is adjusted, you must dial the straight direction at both ends to eliminate the "goose head", and then use the rope positive method to determine the correct position of each curve stake, correctly set the planned positive and negative and calculate the amount of lanes During the lane setting operation, you can drive from the two ends of the curve to the middle.

(4) Correctly adjust the superelevation of the outer track of the curve and mitigate the superelevation of the curve. The setting of the superelevation of the curve and the superelevation along the slope have a direct impact on the wear of the rails. If the curve outer track is set too high, it will make the locomotive wheels closer to the inner track, the bogie sliding of the locomotive will increase, the outer track will increase side wear, the vertical load of the inner track will increase passively, and the vertical wear of the inner track will increase; instead The outer height of the curved outer rail is too small, the guiding force increases, and the outer rail will increase the load, which will cause the lateral and vertical two-way wear of the outer rail to increase. Setting the correct superelevation according to the actual load running speed measurement is one of the main means to reduce rail wear. If the super high downslope is too large, the outer wheels of the front axle of the locomotive body will float, which may even cause a derailment accident. Therefore, the correct setting of the super-high sloping curve is another guarantee to prevent the curve from derailing. Therefore, it is important to reduce the rail wear and to properly set the ultra-high curve and to ease the ultra-high curve along the slope. ^[2]