As one of the most important transportation roads in China, many friends have seen it.In addition to the iconic two rails, which are always parallel, some of them are covered with dense gravel.
Many friends may have such doubts, what is the use of piling stones on the railway?Isn't it smoother and more comfortable to walk directly on the concrete floor?What's more, why do some railway lines have and some don't?
I believe that there are not a few friends who have such doubts. Therefore, China Railway has also brought us the answer.
According to his introduction, in the railway line, above the subgrade level, The part under the sleeper is called the track bed, and the stone in the track bed is called the professional name
The role of stone paving on the railway has a variety of functions, the most important isAs hundreds of thousands of tons of train passing through the railway line quickly, it will have a huge impact on the railway line.
The ballast (stone) can reduce the pressure on the upper part of the sleeper,Evenly distributed to the subgrade to prevent the rail from sinking into the subgrade due to too much pressure.
In addition, the track bed can fix the position of the sleeper, prevent the sleeper from moving vertically or horizontally, and increase the elasticity of the track. on the whole,Ballast plays a buffer role between sleeper and subgrade, which helps to protect rail, sleeper and subgrade.
So why are there no stones on some railway lines? This is because the track bed is divided into ballasted track bed and ballastless track bed.The ballast bed is paved with stones; the ballastless track bed without stones is ballastless track bed.
The material of ballast bed should be hard, not easy to be weathered, elastic and conducive to drainage.The commonly used materials are gravel, pebble, coarse sand, etc., among which the gravel is the best, and the gravel bed is generally used in China's railways.
Ballastless track bed is solidified by pouring cement slurry or asphalt and other materials to make it become a whole to support the rail. For example, the main line of Beijing Shanghai high-speed railway is laid with ballastless track bed.
In addition, compared with ballastless track bed, ballasted track bed has the following advantages,It has the advantages of low construction cost, small noise transmission range, short construction period and easy repair.
There are certain standards for the selection of ballast stones. Not every stone has a chance to be used as ballast.
The crushed stone can only be put into use after crushing, screening and processing, and meeting the specific requirements. At present, the most commonly used are basalt and granite.
See here, is not found a small ballast stone, incredibly has such a big role, and the selection standard is also very strict.
But, also formally these insignificant small stones, agglomerate together, guaranteed our domestic railroad transportation safety.