冻土切削力学特性的试验和理论分析   总被引：5，自引：2，他引：5  

张招祥  余群 《冰川冻土》1994,(2)

利用笔者所研制的冻土切削试验台，在室内对不同冻土在不同温度、含水量、切削速度、切削深度和切刀前角下进行了一系列切削试验。结果表明，切削时，冻土主要呈脆性断裂破坏，其切削过程被认为是刀刃切入和撕裂冻土的结果，切削阻力随冻土温度降低而非线性增加，随切削速度提高而略有增加，随切削深度增加而近似线性增加，最佳切刀前角随切削深度增大有增大趋势。但平均切削阻力与最大切削阻力之比值对不同试验条件基本在０．４－０．６５间变化。同时，根据切削过程机理，从理论上建立了最大切削力模型，此模型考虑了切入和撕裂冻土阻力。  相似文献   

Transport of water in frozen soil: V, Method for measuring the vapor diffusivity when ice is absent     

Yoshisuke Nakano  Allen R. Tice  Thomas F. Jenkins 《Advances in water resources》1984,7(4):172-179

A new experimental method is introduced for determining the relative magnitudes of liquid and vapor diffusion by using a small amount of soluble chemical as a tracer. The theoretical justification of the method is presented for the case where ice is absent. The feasibility of the method is demonstrated by an experiment using marine-deposited clay.  相似文献   

Ultraviolet absorption spectra of some Br-containing haloalkanes     

V. L. Orkin  E. E. Kasimovskaya 《Journal of Atmospheric Chemistry》1995,21(1):1-11

The ultraviolet absorption cross sections were measured for CF₃Br, CF₂ClBr, CF₂Br-CF₂Br, CF₂Br₂, CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃ in the wavelength range 190–320 nm at 295 K. The photolysis is concluded to be the minor atmospheric sink for CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃.  相似文献   

Micromorphological Analysis of Coastal Sediments from Willapa Bay, Washington, USA: A Technique for Analysing Inferred Tsunami Deposits     

Aoibheann A. Kilfeather  Jeffrey J. Blackford  Jaap J. M. van der Meer 《Pure and Applied Geophysics》2007,164(2-3):509-525

Tsunami deposits are provisionally distinguished in the field on the basis of anomalous sand horizons, fining-up and fining-landward, coupled with organic-rich, fragmented `backwash' sediments. In this paper, micromorphological features of a sediment sequence previously interpreted as being of tsunami origin are described. These characteristics are shown to be consistent with the macro-scale features used elsewhere, but show additional details not seen in standard stratigraphies, including possible evidence for individual waves, possibly wave-magnitude progression, organic fragment alignment and intraclast microstructures. Although replication and more complete studies are needed, this analysis confirms the identification of a tsunami in Willapa Bay in ca.1700 AD, while demonstrating a widely applicable technique for confirming or refuting possible tsunami deposits.  相似文献   

论青藏铁路修筑中的冻土环境保护问题   总被引：9，自引：0，他引：9  

吴青柏  施斌 《水文地质工程地质》2002,29(4):14-16,20

本文通过研究已建青藏公路修筑过程中寒区冻土环境和生态环境的破坏特征，分析总结了寒区环境破坏对公路工程的影响。青藏公路工程修建活动极大地改变了冻土环境，使得多年冻土退化，上限加深，诱发了一系列冻胀、融沉、热融滑塌等冻融灾害，使得生态环境原本就很脆弱的寒区环境更加恶化，如植被退化、荒漠化等，同时，冻土环境的破坏也使得工程环境恶化，直接影响青藏公路正常交通运输。因此，在即将进行的青藏铁路修筑工程中，必须深入研究其对冻土环境的影响，对冻土环境问题和环境保护应予以足够的重视。  相似文献   

对岛状融区房建冻害的几点认识——以沱沱河兵站楼房为例     

黄以职  郭东信 《冰川冻土》1992,(1)

座落在岛状融区中的青藏高原沱沱河兵站楼房,由于跨年度施工,楼房各部位季节冻深和融化速度不一,引起不均匀下沉,致使墙体产生严重裂缝。岛状融区是工程地质环境敏感区。在太阳辐射强烈的青藏高原,现行建筑规范中房屋采暖对冻深的影响系数偏小,建议对北外墙中段和角端应比规范规定系数分别增大0.2和0.3。  相似文献   

高围压下冻土强度弱化的机理分析   总被引：7，自引：5，他引：2  

马巍  吴紫汪 《冰川冻土》1999,21(1):27-32

围压作用下,影响冻结砂土强度弱化的主要原因是孔隙冰的压融,矿物颗粒细化的微裂隙的发育。影响冻结粉质粘土强度弱化的主要原因是孔隙冰的压融和微裂隙的发育,这些过程是不独立存在的,而是共同影响,共同作用,从而导致了冻土强度的弱化。  相似文献   

Transport of water in frozen soil IV. Analysis of experimental results on the effects of ice content     

Yoshisuke Nakano  Allen Tice  Joseph Oliphant 《Advances in water resources》1984,7(2):58-66

Effects of ice content on the transport of water in frozen soil are studied experimentally and theoretically under isothermal conditions. A physical law, that the flux of water in unsaturated frozen soil is proportional to the gradient of total water content is proposed. Theoretical justification is made by the use of the two-phase flow theory. The experimental results are shown to support the proposed physical law. The results of this study are presented in two parts and this is the second paper describing the theoretical aspects of the study.  相似文献   

古尔班通古特沙漠南部沙垄水分动态--兼论积雪融化和冻土变化对沙丘水分分异作用     

王雪芹  张元明  蒋进  陈均杰  宋春武 《冰川冻土》2006,28(2):262-268

2004年3月至2005年7月对古尔班通古特沙漠南部典型半固定沙垄土壤水分进行了系统监测,结合气象资料,特别是对冬季积雪和冻土资料的分析,认为该沙漠沙丘土壤水分时空变化规律在很大程度上受积雪融化和季节性冻土的影响.由于冬季稳定存在20~30 cm的积雪于春季融化,使得春季沙丘土壤含水率成为全年最高的季节,从而为早春植物的萌发生长创造了有利的条件.冬季1 m多深的冻土于早春时节由表及里开始消融,沙丘表面融化的雪水在坡面重力作用下,沿难以透水的冻土层上界自坡上向坡下发生迁移,在春夏季形成了垄间最高、坡部次之和垄顶最少的土壤水分空间格局.该研究具有生态学意义,可为古尔班通古特沙漠特殊环境条件下植被恢复与重建提供依据.  相似文献   

Numerical analysis for random temperature fields of embankment in cold regions   总被引：1，自引：0，他引：1  

LIU ZhiQiang    LAI YuanMing  ZHANG MingYi & ZHANG XueFu State Key Laboratory of Frozen Soil Engineering  Cold  Arid Regions Environmental  Engineering Research Institute  Chi- nese Academy of Sciences  Lanzhou  China  School of Civil Engineering  Lanzhou Jiao Tong University  Lanzhou  China  Chongqing Jiao Tong University  Chongqing  China 《中国科学D辑(英文版)》2007,50(3):404-410

The stochastic finite element equations for random temperature are obtained using the first-order per-turbation technique taking into account the random thermal properties and boundary condition, based on heat transfer variational principle. The local average method for 2-D is used to discretize random fields. Then, the random temperature fields of embankment in cold regions are investigated on condi-tion that the thermal properties and boundary condition are taken as random fields, respectively, by using the program, which is written by the methods. The expected value of temperature field and the standard deviation of the temperature field of embankment in cold regions are obtained and analyzed.  相似文献