Wind erosion has notable impacts on ecology, water supply and regional climate, but its distributions and longterm changes are still poorly quantified for the Tibetan Plateau (TP). This study develops a coupled land-surface wind-erosion model (HRLDAS-WEPS) in two dimensions horizontally to analyze wind-erosion distributions and its temporal variations under the climate change in 1979?2015 over the entire TP. Two model enhancements are also used, including the application of MODIS vegetation datasets and the optimization of snow-cover parameterizations. Evaluation results indicate that the enhanced coupled model can generally represent the winderosion distributions over the TP, being mainly located in the arid and semi-arid areas and occurring in winter and spring, as compared with station observations and satellite datasets. In 1979?2015, wind erosion has a significant (P < 0.01) decreasing trend of -0.54 kg m- 2 yr- 1 for annual total soil loss averaged over the arid and semi-arid areas of the TP, which is mainly due to the significant (P < 0.01) declining wind speed and increasing soil moisture. The severest wind-erosion reduction is located to the northwest of the 200 mm precipitation line and the Qaidam Basin. Furthermore, a significant turning point of wind-erosion variation is found in 1992. Specifically, wind erosion over the TP decreases from 1979 to 1991 (-1.26 kg m- 2 yr- 1), and then stays at a low level with a slight increase (0.08 kg m- 2 yr- 1) since 1993. This is probably due to the abrupt change of wind speed over the TP in 1991.

在地震荷载作用下,桩基在土层界面处易出现变形和应力集中,该现象在冻土与其他土层的界面处尤为明显,是导致冻土覆盖场地桩基失效重要原因。EPS材料(发泡聚苯乙烯)具有改善应力集中和减压的作用,在工程中被广泛用作路基填料。为评价EPS材料的减振性能,本文将EPS材料用作桩身和冻土层间的保护层,进行了振动台模型试验及数值计算。并进一步地在数值计算中探讨塑性材料的减振效果。结果表明,EPS材料能降低冻土覆盖场地中桩的应变、剪力、压力的峰值,具有良好的减振性能。塑性材料降低剪力、压力的性能更强,且效果随材料横截面积增大而变得更好。

Wind erosion along the Qinghai-Tibet Railway causes sand hazard and poses threats to the safety of trains and passengers. A coupled land-surface erosion model (Noah-MPWE) was developed to simulate the wind erosion along the railway. Comparison with the data from the Cs-137 isotope analysis shows that this coupled model could simulate the mean erosion amount reasonably. The coupled model was then applied to eight sites along the railway to investigate the wind-erosion distribution and variations from 1979 to 2012. Factors affecting wind erosion spatially and temporally were assessed as well. Majority wind erosion occurs in the non-monsoon season from December to April of the next year except for the site located in desert. The region between Wudaoliang and Tanggula has higher wind erosion occurrences and soil lose amount because of higher frequency of strong wind and relatively lower soil moisture than other sites. Inter-annually, all sites present a significant decreasing trend of annual soil loss with an average rate of - 0.18 kg m(-2) a(-1) in 1979-2012. Decreased frequency of strong wind, increased precipitation and soil moisture contribute to the reduction of wind erosion in 1979-2012. Snow cover duration and vegetation coverage also have great impact on the occurrence of wind erosion.

针对寒冷地区渠道冻胀问题,提出不同型式的防冻胀结构。通过不同垫层结构型式下的预制混凝土矩型渠道冻土力学模型试验,研究在冻融循环作用下预制混凝土矩型渠防冻胀效果。选取两种不同结构型式的矩型渠垫层,EPS颗粒轻质土垫层及砂垫层与常规试验土垫层做比较。对矩型渠的冻胀特性、温度场、冻胀量的变化趋势进行研究,结果表明:(1)冻融循环后,模型温度场变化均匀,没有温度夹层,热量传递均匀,最大冻深发生在升温阶段。(2)随着EPS颗粒轻质土掺量的增加,对冻胀量和冻深有很好的削减效果。(3)换填砂垫层可以起到抑制冻胀破坏的作用。

为了确保铁路路基稳定性,采用EPS保温材料的保温层对路基进行处理,研究了铺设EPS保温材料的路堤在上覆土层厚度不同时的路堤和路基的地温特性。

为了研究随外界环境条件改变聚苯乙烯(EPS)冻土路基温度场变化特征,运用ABAQUS有限元分析方法,对多年冻土区EPS隔热路基的温度场进行了数值模拟.计算时采用改变EPS铺设位置,模拟路面下多年冻土季节最大融深在路基修筑完工后8 a内随时间的变化.通过对计算结果分析得出,在多年冻土区路基中铺设保温材料对路面下多年冻土具有明显的保护作用.当EPS铺设在路堤底部时,路堤温度场分布比较均匀,路堤内部都为正温,在EPS板下,路基温度都为负温,说明EPS有效阻止了边坡和路面传入的热量.因此,如果要修筑EPS隔热路基,应将EPS板铺设于路堤底部.

通过 30 1国道实体工程针对冻土与湿地地区道路常常出现的融沉破坏 ,进行了“加筋土 +EPS板”等 7种试验路段的处理方案 ,并设置了相应的对比路段。实测了各段落的沉降、地温等。经分析对比“加筋土 +EPS板”的处理方案相对处理效果最好。其原因是 EPS板有效地阻碍了热量向下传播 ,减缓了冻土的融化程度。而加筋土增加了路基的整体强度和侧向约束 ,有效地扼制了沉降。本项目的研究为该地区今后修筑道路提供了科学依据

通过调查 30 1国道博～牙段的湿地冻土环境 ,对湿地多年冻土路段 ,提出了 6种加强和改良地基路基的处理方案 ,测试了地温、地表沉降、孔隙水压力和土层分层沉降及EPS材料的特性 ,研究了铺设EPS板对地温的影响。结果表明EPS板可以减少地表向深层的热流量、减少地下多年冻土层上限的下移、减缓多年冻土层的消融 ,保持道路的稳定

试验测试了EPS材料的材料特性,调查了301国道博克图-牙克石段的湿地多年冻土环境,勘察了湿地多年冻土路段,设计了3种铺设EPS板的加强和改良地基路基的设计方法并且实施,设计了地温、孔隙水压力、地表沉降和土层分层沉降的测试布置,测试了铺设EPS板对地温的影响。EPS板可以起到减少地表向深层的热流量、减少地下多年冻土层上限的下移、减缓多年冻土层的消融,保持道路的稳定。