Key Technologies for High-speed Railway and Highway Construction in Plateau, Alpine and Frozen Soil Areas
- Chinese keyword
- Alpine plateau; High-speed railway; Permafrost; Foundation treatment; Hydrothermal protection
- English keyword
I. Overview of Issues
High-speed railway has become "China's business card". At present, China is implementing the "the belt and road initiative" initiative and pushing our high-speed railway to go global strategy, which involves the Sino-Russian high-speed corridor and the Eurasian continental bridge. In addition to crossing a wide range of seasonal frozen regions, China will inevitably encounter permafrost regions. About 1/4 of the territory in China alone is distributed with permafrost. China has successfully built more than 10 high-speed railways in seasonal frozen soil areas such as northeast and northwest, with a total mileage of more than 7,000 kilometers. From structural design to construction control, a complete set of technologies has been basically formed for high-speed railway subgrade in seasonal frozen soil areas, which has controlled frost heaving of high-speed railway subgrade as a whole and ensured the smooth opening and safe operation of high-speed railway in seasonal frozen soil. Aiming at the railway construction technology in permafrost region, As one of that "100 great project" of the century, During the construction of Qinghai-Tibet Railway, China has overcome a series of world problems in plateau and alpine permafrost engineering, mastered a series of technologies to keep high temperature permafrost "not melting", and adopted active measures such as rubble ventilation embankment, ventilation pipe embankment, rubble (broken) stone insulation and protection road, thus realizing the design concept of "principle of protecting permafrost".
The complete set of technical system for seasonal frozen soil is established on the principle of "no frost heaving" of foundation bed, and its design concept is inconsistent with the principle of permafrost treatment. Although the relevant technologies of Qinghai-Tibet Railway mainly solve the permafrost problem, due to the low control standard, the formed technology and standard system cannot fully apply to the high-speed railway with millimeter deformation control requirements. Therefore, the construction technologies of the existing high-speed railway in seasonal frozen regions and the general-speed railway in permafrost regions cannot meet the needs of high-standard control construction and operation of high-speed railway in permafrost regions, and there is no mature experience to learn from.
The main problems faced by the construction of high-speed railway in permafrost regions include permafrost degradation, long-term thawing settlement of foundation, deformation and cracking of subgrade, local thermal thawing collapse, ice cone damage and frost heaving diseases. This is related to many factors such as permafrost type, permafrost ground temperature zoning, subgrade structure, atmospheric rainfall intrusion into foundation, It is necessary to break through a series of major issues including permafrost reclassification, geothermal rezoning, permafrost foundation treatment, anti-thawing subgrade structure, subgrade waterproof and drainage measures, etc. of high-speed railway subgrade, so as to establish a brand-new technology and standard system and provide technical support for the construction of high-speed railway in plateau and alpine regions. The key technical problems faced by the construction of high-speed railway in plateau and alpine regions mainly include:
1. Climate evolution law in plateau region and its influence on permafrost foundation of high-speed railway. Global warming is an indisputable fact. Permafrost degradation caused by climate change will be the root cause of long-term thawing and settlement of high-speed railway foundation. Grasping the climate evolution law in plateau and alpine regions, obtaining its influence law on permafrost foundation of high-speed railway, and then formulating scientific, reasonable and targeted technical measures are the fundamental problems that high-speed railway construction in permafrost regions has to face.
2. Reconstruct the permafrost index system suitable for millimeter control requirements of high-speed railway. A set of systematic technical index system has been established in the field of ordinary speed railway and highway in plateau area. Such as permafrost classification, geothermal zoning, etc., but these index systems cannot be applied to the millimeter control requirements of high-speed railway. It is necessary to propose a permafrost index system more suitable for high-speed railway, so as to provide more scientific and reasonable basis for design and construction.
3. Establish the principle of permafrost treatment and explore the design theory and engineering technology of permafrost foundation treatment for high-speed railway. Reasonable permafrost foundation treatment is the foundation for high-speed railway to maintain long-term safety and stability. According to the complex existing state and long-term evolution law of permafrost performance, it is a key technical problem for high-speed railway construction in plateau and alpine regions to establish the design theory of high-speed railway foundation treatment and explore relevant foundation treatment engineering technologies.
4. Anti-thaw settlement control technology for high-speed railway subgrade in permafrost region in. Different from the subgrade structure of high-speed railway in seasonal frozen soil, In addition to preventing frost heaving and thawing settlement of the moving bed for one year, it also has the functional requirement of preventing thawing settlement in permafrost areas, which requires the high-speed railway subgrade to have the capability of "heat resistance and cold transfer". Therefore, scientific and reasonable design of the subgrade structure of high-speed railway subgrade and permafrost maintenance technology are one of the technical problems.
5. Hydrothermal protection technology for permafrost foundation of high-speed railway. The lack of rigorous hydrothermal protection technology leads to surface water intrusion into the foundation, which is one of the main reasons for permafrost thawing and settlement. It is a very important technical problem to put forward stricter hydrothermal protection technology to ensure that atmospheric precipitation and surface water flow are kept outside the permafrost boundary of high-speed railway.
6. Operation and maintenance technology of high-speed railway in permafrost areas in. The climate conditions in plateau and alpine regions are worse and the duration of low temperature conditions is longer, which poses unprecedented challenges to the operation and maintenance of high-speed railways. It involves a series of adaptive transformation and upgrading of high-speed rail operation and maintenance equipment, and proposes corresponding high-speed maintenance and renovation technologies.
The overcoming of the above-mentioned series of major technical problems, It will improve the technical level of China's high-speed railway construction in plateau and alpine regions. Breaking the concept that permafrost regions are "forbidden zones" for high-speed rail construction, To train and bring up a large number of scientific and technological talents, To form a complete set of standard technology system with independent intellectual property rights, It provides important support for the construction and maintenance of high-speed railway in plateau and alpine regions. We will help China's "going global" strategy for high-speed railways, contribute the "China Plan" to the construction of high-speed railways in plateau and alpine regions in the world, enhance and drive the transportation capacity and social and economic development of countries and regions along the high-speed railways, and fully integrate them into the grand construction of "the belt and road initiative" initiated by China.