**4. Sand prevention and control technology along the Qinghai-Tibet Railway**

The frequent occurrence of sand disasters along the Qinghai-Tibet Railway has seriously threatened the safe operation of the railway. For a long time, the prevention and control of sand disasters along the Qinghai-Tibet Railway have mostly adopted the management model of "distant resistance and adjacent fixation". That is, high vertical sand barriers such as sand retaining walls are built in sections far away from the railway to block wind and sand flow, and low vertical sand barriers such as stone grids are built to fix sand surfaces in sections near the railway [13]. But in fact, this governance model does not scientifically determine the source of wind and sand and the path of wind and sand movement. The function of the sand retaining wall to block the wind and sand flow is not fully utilized. The stone grid sand barrier is often buried by the wind and sand and loses its effectiveness. A large amount of accumulated sand has posed a huge threat to railway tracks and roadbeds [14]. Therefore, the Qinghai-Tibet Railway Company needs to spend a lot of manpower, material resources, and financial resources for manual and mechanical sand removal in the road area every year. In addition, due to the lack of sand barrier construction materials such as stone grids in some areas, has objectively pushed up the cost of prevention and control of sandstorms on the Qinghai-Tibet Railway.

#### *Desertification and Its Control along the Qinghai-Tibet Railway DOI: http://dx.doi.org/10.5772/intechopen.101701*

In view of this, on the basis of scientifically determining the characteristics and mechanism of sand damage along the Qinghai-Tibet Railway, and fully combining the natural conditions and the degree of land desertification along the Qinghai-Tibet Railway, the wind-sand disaster prevention system along the Qinghai-Tibet Railway has been explored and developed. It broke the traditional governance model of "distant resistance and adjacent fixation". The system mainly includes: (1) proposed the "source control, comprehensive prevention and control" governance technology model. By clarifying the source and path of sand materials, the protection and restoration of the source can be carried out to achieve source control. (2) Developed a governance technology system that combines "fixation, resistance, and transmission". Based on the site conditions of sand-damaged sections and the suitability of sand-fixing materials, a series of "sand-fixing" technologies suitable for use along the Qinghai-Tibet Railway has been developed, including the use of soil modification and mulching technology, planting bag technology, and multi-grass mixed planting technology for rapid vegetation reconstruction and rapid sand fixation technology using environmentally friendly chemical sand fixation agents. The "blocking" sand technology mainly refers to the use of new Highdensity polyethylene (HDPE) sand barrier materials. By comparing the single-width sand transport under the conditions of natural sand transport and HDPE sand fixation barriers, the sand control efficiency of HDPE below 1 m from the ground surface can reach 67.82%, of which the sand control efficiency can reach 86.34% below 20 cm from the ground surface. The sand transport technology is mainly to invent the sand transport railway subgrade. It is mainly suitable for the severe sandstorm section of railway embankment where the main wind direction is single and the angle is large or perpendicular to the railway line, in order to reduce the threat of sandstorm. (3) Invented the technology of combining biological sand fixation with engineering sand control. It combined high vertical sand barriers, cement board grid sand barriers and vegetation restoration measures. The cold-resistant, drought-resistant, and sand-tolerant native plants selected by the project were used as vegetation restoration materials, including Elymus, Poa, and Fescue spices [15, 16].

#### **Figure 2.**

*Sand prevention and control technology along the Qinghai-Tibet Railway. (a) The promotion and application of the concept of "sand fixing in the distance". (b) Biological measures + engineering measures realize the control of sand materials from the source. (c) Low vertical net sand barriers are combined with biological measures to control sand sources. (d) High vertical net sand barriers are combined with biological measures to control sand sources.*

The above-mentioned sand disaster control technology has been demonstrated and promoted in the severely sand-hazard sections of the Qinghai-Tibet Railway such as Hongliang River, Xiushui River, Beilu River, Tuotuo River, Tongtian River, Za'gya Zangbo, Cuona Lake, etc (**Figure 2**). The Qinghai-Tibet Railway Company adopted it in the prevention and control of the 78.8 km railway section of severe sand damage. It overcomes the shortcomings of using long-distance resistance and adjacent fixation in the past to intercept sand near the railway subgrade. This has effectively curbed the occurrence of railway sand disasters. Thus, the safe operation of the Qinghai-Tibet Railway is ensured.
