Abstract
The Lhasa–Linzhi Railway is located in the sandy area of the South Tibet valley, with high elevation and cold temperature. The Xierong section is a bridge section where blown sand hazards are severe. However, the disaster-causing mechanism of blown sand hazards in this section is currently unclear, thereby hindering targeted sand prevention and control. To address this problem, the wind dynamic environment of and causes of sand damage in this section are investigated through the field observation of the locale and a wind tunnel simulation experiment. Results show that the dominant sand-moving wind direction in the Xierong section is SSE. The wind speed, frequency of sand-moving wind, sand drift potential (DP), and maximum possible sand transport quantity (Q) in this section are relatively high during spring (March to May) and low during other seasons. The yearly resultant sand transport direction (RDD, RA) is SW. The angle between the route trend of this section and the sand transportation direction is 30°–45°, and the sand source is located in the east side of the railway. During spring, sand materials are blown up by the wind, forming blown sand flow and movement from the NE to SW direction. Increased wind speed area is formed between the top of the slope shoulder of the windward side of the bridge and the downwind direction of 3H, causing blown sand erosion. Meanwhile, weakened wind speed areas are formed within the distance of -3H at the upwind direction and from the downwind direction of the 3H to 20H of the bridge. These areas accumulate sand materials at the upwind and downwind directions of the bridge, thereby resulting in blown sand hazards. This research provides a scientific basis for the prevention and control of sand damage in the locale.
Highlights
The Lhasa–Linzhi Railway passes southeast of the Qinghai–Tibet Plateau, the middle reaches of the Yalu Tsangpo River and its two tributary valleys of the Lhasa River and the Nyang River, and the railway west from Lhasa City, which is the terminus of the Qinghai–Tibet Railway
The maximum possible sand transport quantity (Q), resultant quantity (RQ), and resultant angle (RA) of the maximum possible sand transport were calculated according to a method proposed in the literature [16,17]
The wind tunnel simulation experiment has many similarity requirements, and meeting all the similar conditions in the simulation process is difficult [24]. In this wind tunnel experiment, the bridge model was placed within the boundary layer of the wind tunnel test section, and the pitot tube was set at the bottom center of the wind tunnel test section
Summary
The Lhasa–Linzhi Railway passes southeast of the Qinghai–Tibet Plateau, the middle reaches of the Yalu Tsangpo River and its two tributary valleys of the Lhasa River and the Nyang River, and the railway west from Lhasa City, which is the terminus of the Qinghai–Tibet Railway. The ttotal leength of tthhe Lhasa–Linzhi Railway is 436 kkmm The construction of this railway started in December 2014 and iiss expected to be completteedd anndd oppeenneedd ttoo trraaffifficc bbyy tthhee eenndd ooff 22002200. Surveys and statistics indicate that the LLhhaasa–Linzhi Railway currently has 12 bblloowwn ssaanndd sseeccttiioonns wwiitthh aa ttoottaall lleennggtthh ooff 1122..3355 kkmm [[55]]. These sections are mainly distributed in the river broad valley sections, such as XXiieerroonngg, SShhaannnnaan, aanndd MMaaiinnlliinngg ((FFiigguurree 11)). Thereforree,, thhrroouugghh tthhee fifieelldd oobbsseerrvvaattiioonn ooff tthhee looccaallee and a wind tunnel simmuullaattiioonneexxppeerriimmeenntt,,tthheeaauutthhoorrssaatttteemmppttttoo asceerrttaaiinntthhee charaacctteerriissttiiccssooff thhee blown sand dynamic eennvviirroonnmmeennttaannddrerveevaelatlhethfoermfoarmtioantimonecmhaencihsamniosfmsaonfd sdaanmdagdeaminatgheisisnectthioisn tsoecptrionvidtoe apsrcoiveindteifica bscaiseins tfiofirctbhaespisrefovrenthtieonpraenvdenctoinontroalnodfcsoantdrodlaomf asagnedindtahmealogceailne.the locale
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