Have you ever seen a four-story screw with a thick washbasin? A new high-speed railway in Ningxia is fixed on this kind of screw.
On January 7, the Science and Technology Daily came to the construction site of Ningxia Yinwu passenger dedicated line and found concrete discs the size of dinner tables on the rammed foundation. These discs are nuts; below are screws 20 meters long and 40 centimeters in diameter, buried in the soil. This kind of concrete screw is called "screw pile" by engineers.
"screws are stronger than nails." Gou Yilao, chief engineer of the China Railway first Bureau Municipal Environmental Protection Company, said, "by the same token, threaded piles are more secure than smooth piles. Its lower 2/3 is a screw pattern, which tightly bites the soil layer. "
The new technology has just been invented and has been tried out in a small amount in the past, and the Yinwu high-speed rail project is its first large-scale application. The consumption of the whole line is more than 120000. The first Bureau of China Railway has innovated a series of construction methods for this.
The high-speed railway is not bumpy because the track is so flat that the roadbed cannot be settled. The Yinwu high-speed railway is supported by a 15-20-meter-long cement pile that passes through the soft soil and is inserted into the harder stratum.
The big screw is made like this: the drilling rig rotates the screw into the ground and rotates out in a moment; the pipe at the top of the screw shoots out concrete at the same time and pours into the hole, and a cement screw is formed from the bottom up.
The threaded pile will squeeze the foundation soil and have more friction with the foundation. After the threaded pile replaces the smooth pile, the pile density can be reduced by half, and the material consumption can be greatly reduced.
"the key is to synchronize the entry and exit of boreholes. If you turn three times to decrease one pitch, you have to turn three times to increase one pitch, otherwise the newly drilled thread will be destroyed." "for this reason, the current of the rig must be very stable and the distribution box must be accurately controlled by a computer," Gou said. " The new screwdriver is more than twice as expensive as the traditional drilling rig.
At present, the only provinces and regions that do not have high-speed rail are Xizang and Ningxia. The Yinwu high-speed railway, which connects the two largest cities in Ningxia, Yinchuan and Wuzhong, will be opened in August. It is also China's first ballasted high-speed railway. Ballast means that the track is laid on the gravel. Previously, China's high-speed railways were laid on cement slabs. The Beijing-Zhangjiakou railway under construction will be the second ballasted high-speed railway. The ballasted track is easy to adjust settlement and the maintenance cost is lower.
In order to ensure the quality, the China Railway Municipal Environmental Protection Corporation has used a lot of new technologies and built the largest prefabricated beam yard in the world. At present, the project is in the final stage. The main project of high-speed rail was completed in 15 months, setting a record for the speed of high-speed rail construction.
