高山区雪堆储雪的实验和模拟计算     

王兴  王飞腾  任贾文  秦大河 《冰川冻土》2021,43(6):1617-1627

随着全球气候变暖,滑雪运动呈现出对气候变化高度的敏感性和依赖性,各地滑雪季将不同程度地缩短。储雪作为一种应对气候变化的方法在雪务保障中逐渐得到研究和应用。在新疆阿勒泰地区吉木乃县开展储雪实验,应用谐波反应法研究了雪堆融化量与外界空气温度、太阳辐射和绝热保温结构热学性能之间的定量关系。实验中,覆盖两层绝热保温材料雪堆1的平均融化量为18.0 kg·d^-1（相当于初始质量的0.85%）,未覆盖绝热保温材料雪堆2的平均融化量为120.8 kg·d^-1（相当于初始质量的6.67%）。模拟期间观测到的雪堆1质量减少了1 438.0 kg,对应的模拟值为1 520.8 kg。谐波反应法可以为评价绝热保温结构的热学性能和提前确定储雪量提供重要的参考依据。由于许多物理过程都未考虑,导致模拟的雪堆融化量与实际融化量之间存在不确定性。雪堆所用绝热保温结构的性能可以用反射率、总传热系数、衰减度和延迟时间来衡量。  相似文献   

积雪变化对中国森林凋落物分解影响研究进展     

张鹏  孙鸿儒  贾丙瑞 《冰川冻土》2021,43(6):1840-1847

森林凋落物的分解对于维持生态系统物质循环和养分平衡具有重要意义,并受到不同积雪厚度下冻融格局的影响。冻融期（包括冻结过程期、完全冻结期、融化过程期）是冻土区凋落物分解的重要时期,该时期分解的凋落物量约占全年分解总量的一半。积雪减少通常会导致土壤温度降低、冻融循环次数增加,进而影响凋落物分解。通过综述近10年来积雪变化对我国森林凋落物分解影响的研究成果发现,积雪厚度减少在冻融期通常会抑制凋落物质量损失、碳元素释放和纤维素降解,生长季则起到促进作用,从全年来看多数表现为抑制作用。因此,冻融作用造成凋落物的物理破坏,对其分解的促进作用主要发生在后续生长季。积雪厚度减少在冻融期通常抑制氮元素释放,生长季和全年则无明显规律;磷元素和木质素目前研究还存在很大差异。最后,进一步阐述了积雪变化对凋落物分解影响研究存在的问题及未来研究发展方向。  相似文献   

粗砂砾石地层中高压旋喷桩隔水帷幕施工技术          下载免费PDF全文

张红涛 《探矿工程》2021,48(6):113-117

太原万达广场A2区商住楼基坑工程部分区域为粗砂砾石地层,基坑隔水帷幕中深层搅拌桩无法有效使用。提出了在粗砂砾石地层采用高压旋喷桩隔水帷幕的施工技术方案,采用双套管锚杆钻机引孔、单管高压喷射工艺进行施工,成功实施了这一工程。经检查,喷射注浆体相互咬合良好,有效桩径内水泥含量均匀无夹块现象,隔水帷幕止水效果良好。  相似文献   

护坡桩+微型钢管桩复合土钉墙联合支护体系研究应用          下载免费PDF全文

孙剑  范民浩  李鑫 《探矿工程》2021,48(10):116-124

本文提出了一种新的联合支护体系——护坡桩+微型钢管桩复合土钉墙支护体系,成功解决了基坑周边无放坡空间需垂直开挖、基坑深度大、要求位移小、支护费用高等技术难题,做到了施工便利,对控制边坡位移变形、增强边坡整体稳定性、保证在基坑开挖工程中不发生对周围环境的影响具有良好的作用。采用这种支护方式对北京一工程进行设计施工探讨,经工后监测效果良好,大大地提高了边坡的安全稳定性,从而验证了这一支护形式的可行性,其在深基坑支护中具有常规土钉墙和护坡桩无法相比的技术与经济优势,可供其他类似工程参考,具有较高的适用推广价值。  相似文献   

复杂地质条件和敏感环境中基坑设计实践及关键技术          下载免费PDF全文

邵晨晨 《探矿工程》2021,48(6):102-108

上海某国际金融大厦深大基坑项目北侧紧邻运营轨道交通8号线区间隧道,最近处仅7.87 m,南侧与现有世博共同管沟净距2.0~3.0 m,基坑变形控制要求高,周边环境敏感。同时,本项目位于黄浦江畔,场地浅层为典型的淤泥质软土地层,下部为富含承压水粉（砂）土层,且微承压水层与第一、第二承压水层互为连通,止水帷幕无法隔断承压水层,地质条件复杂。设计采用分坑施工、被动区加固、预应力伺服钢支撑系统、抽灌一体化降水方案、超深地下连续墙、跟踪注浆、型钢垫层等技术方案。实测结果表明,区间隧道的最大变形6.52 mm,共同管沟的最大变形15.3 mm,其最大变形均满足变形控制要求,确保了运营区间隧道和共同管沟的安全。  相似文献   

一次江淮气旋暴雪的积雪特征及气象影响因子分析   总被引：4，自引：4，他引：0  

杨成芳  刘畅 《气象》2019,45(2):191-202

利用自动站、人工加密观测及常规观测资料,通过对2017年2月21—22日一次江淮气旋暴雪过程积雪特征的分析,揭示了近地面气象要素对积雪深度的复杂影响。结果表明:(1)江淮气旋系统特有的空间结构导致山东南、北地区的降雪量和积雪深度不均衡分布。(2)积雪深度具有时效性,在降雪结束时达到峰值,因温度的变化导致峰值不一定维持到次日08时。(3)积雪深度是近地面多气象要素共同作用的结果,降水相态、降雪量、降雪强度、气温、地温和风速均有影响。主要表现为:雨夹雪在转为纯雪之前可产生不超过1 cm的积雪,如果不转雪则不会产生有量积雪;各地降雪含水比差异较大,全省平均为0. 5 cm·mm~(-1),低于全国平均值;在降雪不融化的情况下,降雪量、降雪强度越大则积雪越深,降雪强度大是气温和地温都高于0℃时产生积雪的必要条件;地温和气温越低对积雪形成越有利,积雪开始产生时的地温最高阈值多在0℃左右,地温先突降后缓升是积雪产生前后的共性特征,积雪产生后1～2 h内地温略有上升并逐渐趋于稳定;积雪产生时气温一般低于0℃,气温高于0℃时大部分降雪融化;有利于产生积雪的平均风力多不超过2级,极大风则在3～4级以下。  相似文献   

我国中东部平原地区临界气温条件下降水相态判别分析   总被引：1，自引：0，他引：1  

陈双  谌芸  何立富  郭云谦 《气象》2019,45(8):1037-1051

基于2001—2013年地面观测和探空资料,对地面气温位于0～2℃(以下称临界气温)我国降雪的时空分布及其与降雨的垂直热力特征进行了研究,引入了决策树判别方法对上述条件下雪和雨进行了判别分析,结果表明:临界气温下降雪出现频率总体高于降雨、雨夹雪出现频率,且在我国华北南部至江南北部的中东部地区分布较多,年均可达7.69～15.38站次;临界气温下,降水相态为雨或雪对应的平均温度廓线最大差异位于650 hPa附近,且地面气温较低时,平均温度差异更明显,平均湿度廓线差异则主要位于低层,且在地面气温较高时,平均湿度差异更明显;临界气温下,降水相态为雨时,地面上空存在暖层样本占比,较降水相态为雪时更高,且降雨时暖层主要位于中层,降雪时暖层则主要位于低层,降雨时其暖层强度显著大于降雪时暖层强度;在临界气温下雨雪判别分析中,地面气温能显著提升判别准确率,湿球温度能在一定程度上提升判别准确率,基于云顶温度、中层融化参数、低层湿球温度构建的决策树判别模型,判别准确率达到91.86%,能较好地解决临界气温下雨和雪的判别问题。  相似文献   

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns     

Jane Assini 《水文科学杂志》2013,58(4):738-755

Abstract

This study examined the end-of-winter snow storage, its distribution and the spatial and temporal melt patterns of a large, low gradient wetland at Polar Bear Pass, Bathurst Island, Nunavut, Canada. The project utilized a combination of field observations and a physically-based snowmelt model. Topography and wind were the major controls on snow distribution in the region, and snow was routinely scoured from the hilltop regions and deposited into hillslopes and valleys. Timing and duration of snowmelt at Polar Bear Pass were similar in 2008 and 2009. The snowmelt was initiated by an increase in air temperature and net radiation receipt. Inter-annual variability in spatial snowmelt patterns was evident at Polar Bear Pass and was attributed to a non-uniform snow cover distribution and local microclimate conditions. In situ field studies and modelling remain important in High Arctic regions for assessing wetland water budgets and runoff, in addition to model parameterization and validation of satellite imagery.

Editor Z.W. Kundzewicz

Citation Assini, J. and Young, K.L., 2012. Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns. Hydrological Sciences Journal, 57 (4), 738–755.  相似文献   

Snow interception modelling: Isolated observations have led to many land surface models lacking appropriate temperature sensitivities     

Jessica D. Lundquist  Susan Dickerson-Lange  Ethan Gutmann  Tobias Jonas  Cassie Lumbrazo  Dylan Reynolds 《水文研究》2021,35(7):e14274

When formulating a hydrologic model, scientists rely on parameterizations of multiple processes based on field data, but literature review suggests that more frequently people select parameterizations that were included in pre-existing models rather than re-evaluating the underlying field experiments. Problems arise when limited field data exist, when “trusted” approaches do not get reevaluated, and when sensitivities fundamentally change in different environments. The physics and dynamics of snow interception by conifers is just such a case, and it is critical to simulation of the water budget and surface albedo. The most commonly used interception parameterization is based on data from four trees from one site, but results from this field study are not directly transferable to locations with relatively warmer winters, where the dominant processes differ dramatically. Here, we combine a literature review with model experiments to demonstrate needed improvements. Our results show that the choice of model form and parameters can vary the fraction of snow lost through interception by as much as 30%. In most simulations, the warming of mean winter temperatures from −7 to 0°C reduces the modelled fraction of snow under the canopy compared to the open, but the magnitude of simulated decrease varies from about 10% to 40%. The range of results is even larger when considering models that neglect the melting of in-canopy snow in higher-humidity environments where canopy sublimation plays less of a role. Thus, we recommend that all models represent canopy snowmelt and include representation of increased loading due to increased adhesion and cohesion when temperatures rise from −3 to 0°C. In addition to model improvements, field experiments across climates and forest types are needed to investigate how to best model the combination of dynamically changing forest cover and snow cover to better understand and predict changes to albedo and water supplies.  相似文献   

Effect of snow and soil frost melting on the concentrations of suspended solids and phosphorus in two rural watersheds in Western Finland     

Seppo Rekolainen 《Aquatic Sciences - Research Across Boundaries》1989,51(3):211-223

Hydrological processes are known to have a considerable effect on nutrient transport from agricultural land to watercourses. In cold temperate regions peak discharges are caused not only by storm conditions but also by melting of snow and frost. The objective of this work was to investigate the effects of snow and frost melt on concentrations of phosphorus and suspended solids. The samples were taken using flowweighted automatic sampling techniques from two agricultural drainage basins. During the beginning of the snowmelt period the concentration of suspended solids was rather low by comparison with the total phosphorus concentration and the discharge. The different behaviour compared with the relationships found during storm conditions was probably caused by continuous extraction of the soil surface by low ionic concentration melt water, and to some extent by leaching from plant residues. The gradual decrease of total phosphorus concentration during the frost thawing period could be attributed to the gradually increasing proportion of the subsurface and ground water discharge in the runoff.  相似文献