Difficulties in Building Beijing-Zhangjiakou Railway in Zhan Tianyou (Specific)

One. Limitations on preparation funds and project duration. Zhan Tianyou took pains to investigate three routes (the second route is today's national highway 1 10, and the third route is a "sand-rich line" with nearly 100 tunnels, which was built after liberation), and finally decided to take the Guan 'gou route, which shortened the Badaling tunnel by half.

Two. Dig the Guangou tunnel. In addition to experienced engineers and accurate measurement, there are new machines such as mountain cutters and water pumps to dig tunnels, but these machines were not available in China at that time. The four tunnels from Juyongguan to Badaling were all dug by workers with hammers, steel and explosives.

Juyongguan Mountain is high and the rock stratum is thick, so Zhan Tianyou decided to adopt the method of digging from both ends to the midpoint. The difficulty of this method lies in how to align the lines dug at both ends without deviation. Zhan Tianyou led engineers and technicians to investigate from the narrowest part of the valley, and then went up to the mountain to see the direction of the tunnel line. First, put the theodolite in the "position", straighten the "celestial point" and measure the "human point" in turn, so that the three points of heaven, earth and human are connected into a straight line. Then move the theodolite to the "human point", measure the sky and the earth, and verify whether the three points are in a straight line. After the measurement is accurate, stake is erected at each point, and the middle branch in the tunnel is determined according to this standard. Then, the difference of each branch is measured through transverse discussion, and the longitudinal section blueprint of the tunnel is drawn accordingly. When digging the tunnel, there were 60 workers at each end, including 40 chisels and 20 earth-rock transport vehicles. The chisel is lined up by two people, one holding a steel drill and the other waving a hammer. They took turns digging holes in the rocks, then filling them with explosives and blowing them to pieces. The size, depth, orientation and charge of each blasthole are all decided by Zhan Zaiyou himself. When the tunnel was dug to two or three hundred meters, the spring water at the top of the mountain seeped into the hole. At that time, there was no water pump, and Zhan Tianyou took the lead in draining water with buckets and washbasins.

Badaling tunnel is 109 1 m long, which is the longest of the four tunnels. Zhan Tianyou has designed a new excavation scheme-shaft construction method. Two shafts were dug on the hillside where the tunnel passed, and six working faces were constructed together with both ends of the tunnel, which greatly accelerated the project progress.

Three. The terrain near Badaling is steep. How can the train get into the ditch?

Zhan Tianyou comprehensively analyzed the geological conditions around Badaling, and designed a tortuous route scheme by using hard rock slopes. Starting from Qinglong Bridge, a multi-storey railway was built on the hillside, which was turned back once from the mountainside, one floor higher, and the train slowly climbed up Badaling. The train runs on a zigzag line. For safety and stability, two locomotives are used, one pulling in front and the other pushing behind.