秦巴山区铁路增建二线的水土流失影响分析

以秦巴山区的3条铁路增建二线工程为例,通过水土流失影响指数评价模型来定量分析、评判山区铁路增建工程的水土流失影响程度.结果表明:襄安线、西康线和安渝线增建二线工程的水土流失影响指数分别为0.240,0.184,0.202,均低于全国铁路建设项目水土流失影响指数的平均值,这说明与新建铁路工程相比,增建二线工程造成的水土流失影响程度相对较小.其主要原因是工程平均占地面积较小(2.54hm²/km)、工程总土石方量(6.99万m³/km)较轻、工程水土流失总量(9 028t/km)不大.在施工过程中,可通过移挖作填、减少弃方、控制施工影响范围、缩短施工期等措施来进一步减弱山区铁路增建工程的水土流失影响,更好地保护山区铁路沿线的生态环境.     

基于“点-轴系统”理论的福厦铁路沿线旅游资源开发研究

近年来迅猛发展的高速铁路在推动区域旅游大发展的同时,也导致区域旅游资源要素的加速整合,迫切需要学术界提供相应的理论支撑与案例研究。以福建省为例,基于“点--轴系统”理论,通过文献搜集与实证调研,对福厦铁路沿线旅游资源基础和特色进行梳理,提出了实现福厦铁路沿线旅游资源优化开发的构想：加强旅游重点节点与重点旅游发展轴线的集聚与辐射作用,完善沿线的旅游交通网络及旅游配套服务设施建设;市场导向与政府主导相结合,建立良性发展的机制;加强福厦铁路沿线四地市的区域旅游合作,共同塑造海峡西岸区域旅游形象。     

Analysis of Field Test High-Speed Railway CFG Pile-Raft Composite Foundation

Based on settlementation control design, CFG pile-raft composite foundation was used in the Shanghai-Nanjing intercity railway embankment test. To explore the settlement control mechanism and bearing characteristics of the CFG pile-raft composite foundation,embankment settlement, pile-soil stress distribution and the dissipation of excess pore water pressure were observed to obtain data through field testing. Composite foundation settlement, lateral deformation of subgrade soil, pile-soil stress distribution along the lateral base and excess pore water pressure changes with time under embankment were analyzed. The change pattern of pile-soil stress ratio and load sharing ratio were studied. Field test results provide the experimental basis for the further theoretical studies and optimized practial design of the soft foundation treatment in the CFG pile - raft structure in the high-speed railway project.     

Numerical study of airflow distribution in air-conditionedtrain in Qinghai-Tibet Railway

To obtain the influence of outer environmental condition on the indoor airflow distribution for the 25T air-conditioned train in Qinghai-Tibet, the Realizable k-ε model is adopted to numerically analyze the indoor temperature and velocity fields of the running train. The results indicate that solar radiation has great effect on the indoor temperature field and it is meaningful for improving the thermal comfort to adjust the air supply parameters with the outer environmental condition. Under different air supply conditions, it is the conjugating relation between the indoor temperature field and velocity field that leads to different thermal comfort in different regions of the running train. In addition, the operating modes exchange under different outdoor environmental conditions is also discussed and some additional functions of the using air-conditioning system are put forward too.     

三江源区退化高寒草甸蒸散的变化特征

为揭示三江源区退化高寒草甸水分收支变化特征,利用涡度相关和微气象方法对青海省果洛州大武镇退化高寒草甸生态系统的年蒸散变化进行了定量研究,并探讨了环境和生物因子对其影响。结果表明:年总蒸散量为481.9mm,年蒸散量约占年降水量的97%。生长季中日均蒸散量为2.3mm·d-1,而非生长季日均蒸散量仅为0.6mm·d-1。温度与蒸散量呈明显的指数关系;该区接收的太阳辐射较强,但净辐射占太阳辐射的比例相对较低(46%),在非冻土时期,蒸散量与净辐射呈线性关系;研究区降水量相对丰沛,与温度和净辐射相比,土壤含水量对蒸散的影响相对较小。本研究说明高寒草甸的退化加剧了生态系统的蒸散量,从而降低了生态系统涵养水分的能力,净辐射和温度是驱动三江源区退化高寒草甸生态系统蒸散最主要的环境因子。     

临策铁路防沙明洞对新月形沙丘沙物质粒度特征的影响分异

本文通过临策铁路防沙明洞影响区内外新月形沙丘各部位粒度特征参数的对比研究,探明了防沙明洞对新月形沙丘粒度特征的影响分异规律。研究表明:(1)防沙明洞改变了影响区内新月形沙丘的自然风场结构,地表沙物质呈现粗粒化、粒径均匀程度提高、粒径分布集中的特点。(2)防沙明洞上风向沙丘各个部位沙物质粗粒化程度均高于下风向沙丘,上风向沙丘迎风坡、下风向沙丘背风坡粒度变化最显著。(3)防沙明洞上风向沙丘运动状态受冬季风控制,风蚀作用强于堆积作用,而下风向沙丘运动状态受夏季风控制,堆积作用强于风蚀作用。     

氮、磷养分添加对高寒草甸土壤酶活性的影响

本试验以典型的青藏高原高寒矮嵩草草甸(Kobresia humilis meadow)为研究平台,以表征土壤碳、氮、磷、硫养分循环的6种土壤酶为研究对象,研究土壤酶以及土壤速效养分在4年氮、磷养分添加的累积效应下的变化规律,分析和评价氮、磷养分添加对土壤养分循环方面的影响。试验结果为:氮、磷养分添加改变了土壤中速效养分的含量;氮添加与010 cm土层中的碱性磷酸酶活性有正效应,磷添加抑制了010 cm土层中的碱性磷酸酶活性;氮、磷养分添加均抑制了010 cm土层中的脲酶活性;氮添加抑制了2个土层中的纤维素酶活性;芳基硫酸酯酶活性和蔗糖酶活性没有表现出显著差异性;1020 cm土层中的几丁质酶活性在氮、磷养分添加处理下均增强,其中磷添加对几丁质酶活性的增幅最显著。结果表明:外源添加的氮在调控磷的矿化方面有促进作用,磷的添加对氮素的释放也有一定的作用;青藏高原高寒草甸受磷限制的程度可能更大。     

Change in soil microbial biomass and regulating factors in an alpine meadow site on the Qinghai-Tibetan Plateau

ABSTRACT

The change in soil microbial biomass (SMB) content and its direct links to soil organic matter (SOM) and environmental factors are not well understood for high-elevation regions. Therefore, this research investigated the temporal variation of SMB and its relationship with SOM and environmental factors in an alpine meadow site on the Qinghai-Tibetan Plateau. The soil organic carbon (SOC) and total nitrogen (TN) contents in alpine meadows showed monthly and seasonal variations and were higher in colder months, and the soil C/N ratio was higher in winter and in autumn than it was in the other seasons (P < 0.05). In addition, the changes in the SMB C and SMB N contents were notable at monthly and seasonal scales, whereas the SMB C and SMB N contents were higher in the winter and spring than they were in the other seasons (P < 0.05); the ratio of SMB C/SOC was higher in spring than it was in the other seasons; the ratio of the SMB N/TN content was higher in cold or cool months than it was in the other months; and the ratio of the SMB C/SMB N was highest in August (P < 0.05). Moreover, the SMB C and SMB N contents were significantly positively correlated to the SOC and TN contents (P < 0.01), and the SMB content was also significantly positively correlated to soil water content and air temperature (P < 0.05), or to soil bulk density and soil pH (P < 0.05). The results suggested that the change in the SMB in the alpine meadows was highly regulated by the SOC and TN and by monthly and seasonal changes in the soil bulk density, the soil pH, soil moisture, and air temperatures.     

大型铁路轴承表面变质层研究

应用显微硬度、光学显微镜、X射线衍射、SEM及 AES等,分析与研究了大型铁路轴承(197 726)表面变质层的成分、组织与残余应力,发现变质层中硬度的变化与磨削热产生的相变及表层碳量下降有关,表面存在很大残余压应力,但分布不均匀。     

高速铁路泥岩地基原位减胀试验研究

以兰新高铁一处典型“弱”膨胀泥岩地基为例,通过现场原位变形监测试验,分别设计了不同减胀措施,研究了不同减胀措施（渗水孔、级配碎石层和重复荷载）与膨胀变形的关系.结果表明：9个消能孔（直径5 cm×深度110 cm）消能后基坑膨胀量分别是7个消能孔、5个消能孔膨胀量的0.42倍和0.26倍,即消能孔数量的增加可有效地消解膨胀泥岩的膨胀能;路基施工时可以采用多次碾压或堆卸载等重复加卸载的方式,也可以有效地消除路基的膨胀能;增设减胀层的方法施工相对简单易行且经济,可以有效地消减膨胀能,是避免膨胀变形量过大的实用工程措施.对变形量控制极为严格的高速铁路实际工程中,对膨胀土地基膨胀性应采取恰当的工程措施.