When constructing in permafrost areas, how to effectively protect the frozen soil and improve the stability of the roadbed is the key to determining the fate of the project. In the design of the ***Yu Highway, we fully drew on and adopted the existing research results of highway construction, carefully carried out special geological surveys of permafrost along the route in detail, and designed in accordance with the principle of "protecting frozen soil and slowing down melting". Since the start of construction in May 2011, ***Yu Highway *** has made 15 technological advances and innovations, two of which have been awarded national patents, and has made major breakthroughs in key technologies for permafrost roadbeds, bridges, culverts, and tunnels.
Protecting permafrost is the basic principle of project construction in my country's permafrost areas. The "Qinghai-Tibet Plateau G214 Trunk Highway Upgrading and Renovation Science and Technology Demonstration Project" extensively integrates existing scientific research results in the transportation industry, combined with the ***-Yu Expressway According to the actual needs of road construction, existing technologies are systematically applied to "re-freeze" the frozen soil as much as possible, thereby improving the stability and durability of the project.
On some sections of the ***-Yu Expressway and shallow sections of tunnels, there are large areas of long iron rod-shaped facilities, which are called "hot rods." Thousands of "hot rods" are inserted into the frozen soil to dissipate the heat in the frozen soil and transfer the coldness in the air into the soil layer to keep the frozen soil frozen and stabilize the roadbed.
In the subgrade structure of some road sections, culvert-shaped ventilation pipes with different diameters are also buried, so that the heat can be taken away by air flow inside the roadbed to achieve the purpose of thermal insulation; the roadbed of some road sections is made of different sizes. This kind of stone roadbed or gravel roadbed is also designed to achieve effective insulation of frozen soil.
In fact, many technologies for treating frozen soil have been effectively used in the construction of the Qinghai-Tibet Highway and Qinghai-Tibet Railway, but this is the first time they have been applied on a large scale in the construction of high-grade highways on the Qinghai-Tibet Plateau. Therefore, the accumulation over the past many years has become the key to the success of the ***-Yu Expressway project in crossing the plateau permafrost area. Some areas need to be thawed. Construction workers in perennially frozen soil sections use thickened cotton tarps to cover them to keep warm at night when the temperature is low. When the temperature rises above 5°C during the day, the cotton tarpaulins are rolled up and opened to allow direct sunlight to shine on the frozen soil, ensuring that the frozen soil is protected. The area thawed quickly, greatly improving construction production efficiency and reducing construction costs.