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1.
液态下冰芯微粒含量随时间的变化-南极乔治王岛冰芯微粒研究(英) 总被引：1，自引：1，他引：0
KAANG Jian-Cheng WEN Jia-Hong WAAANG Da-Li LIU Lei-Bao YAN Ming Li Yuan-Sheng Han Jian-Kang 《冰川冻土》1998,(4)
Re-measurement of microparticle content of surface 10 m ice core from the top of King George Island Ice Cap shows that, except samples in 8. 5～ 10 m depth, the microparticle content generally decreases 45%～ 85% within first 48 hours at melted state, afterwards, the content change is small. Content at each grain size interval has a decrease, but the main decrease is in particles of <3μm. Though particle content varies with depth, the decreases are much larger in peak areas than in valleys. From the tests, it can be considered that, the reason of particle content decrease at melted state is that some sea salt grains in samples dissolved. The microparticle content of samples in 8. 5～ 10 m depth has not decrease, the reason is that melting and re freezing have occurred at the depth, because the ice temperature is near 0 °C, and there are series of ice layers, the thickest is 7 cm, at that depth. The chemical analyses for same samples at same conditions show that, except irregular changes in NH4,NO, there are small changes in other ions, probably the content changes in micro-grain <3 μm can not obviously cause the chemical content change in samples. 相似文献
2.
Horizontal soil column method was used to determine the horizontal diffusion rate of sandy loam, loam and clay loam under the same bulk density. The results showed that the migration rates of different lithological wet fronts were different. The sandy loam had the fastest migration rate, the loam followed, and the clay loam was the slowest, but the law of change is the same among the three lithologies. The volumetric water content affects the change of Boltzmann parameter λ. When the volumetric water content is between 0.35-0.45 cm~3/cm~3, λ approaches stability. When the volumetric water content is less than 0.35 cm~3/cm~3, the λ value decreases rapidly with the decrease of water content. The water diffusion rate is related to the volumetric water content and particle size. The greater the moisture content is, the greater the diffusion rate will be. The larger the particle size, the larger the diffusion rate. The diffusivity of sandy loam is 10-30 times larger than that of loam and clay loam. The relationship between water content and diffusion rate is in accordance with the exponential function. 相似文献
3.
Permeability Heterogeneity in a Fractured Sandstone–Mudstone Rock Mass in Xiaolangdi Dam Site, Central China 总被引：1，自引：0，他引：1
JIANG Xiaowei WAN Li WANG Xusheng KANG Aibin HUANG Jun and HUANG Guoxing 《《地质学报》英文版》2009,83(5):962-970
Abstract: Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology. Numerous approaches have been proposed to characterize heterogeneity in the last several decades. However, little attention has been paid to correlate permeability heterogeneity with geological information. In the present study, several causes of permeability heterogeneity, that is, lithology, tectonism, and depth, are identified. The unit absorption values (denoted as ω), which are results obtained from the packer test, are employed to represent permeability. The variability of permeability in sandstone–mudstone is so significant that the value of unit absorptions span 3–4 orders of magnitude at any depth with several test sections. By declustering, it has been found that under a similar tectonic history, the means of permeability differ greatly at different formations as a result of different mudrock contents. It has also been found that in the same formation, permeability can be significantly increased as a result of faulting. The well-known phenomenon, the decrease in permeability with depth, is found to be caused by the fractures in the rock mass, and the relationship between permeability and depth can be established in the form of logω–logd. After subtracting the trend of ω with absolute depth, the mean of the residual value at each relative depth can be well correlated with the distribution of mudstone. The methods proposed in this paper can be utilized to research in similar study areas. 相似文献
4.
As to salty soil, salt migrates with water in freezing soils, assembles and crystallizes continuously. Consequently the swelling of the soil volume leads to the phenomenon of salt heaving. It has a practical significance for solving salt-heaving and frost-heaving damage in engineering to deepen the understanding of salt heaving mechanism. In this paper a general overview about new research results at this aspect was presented. And then the study of salt migration and salt heaving mechanism and present salt heaving models were summarized. For further researching the field of salt transfer it is urgent to continually strengthen the salt migration and the numerical simulation study of salt heaving mechanism to expect perfecting the general evaluation of salt heaving prediction models so as to have a better service for engineering. 相似文献
5.
Base on the groundwater yield, water temperature and hydrochemistry change of the groundwater, we can analyze that the summer water content is obviously greater than winter water content where the in and-out wall rock of the Daban Mountain tunnel. The groundwater supply has the extensity and the seasonality. The groundwater content of the middle tunnel wall rock changes relatively steady, mainly supply through horizontal direction. And the total groundwater content is relatively little and steady in winter. The water pressure of the wall rock cranny is little. It has the fluent drainage system to dredge groundwater, which cannot constitute a threat to the tunnel lining. And the cold-proof sluice hole can normally work to drain water. 相似文献
6.
冻融试验对土中含水量分布的影响 总被引：5，自引：0，他引：5
The silty clay and silty loam are two typical soil types obtained from two test sites along the Qinghai-Tibet railway. The two types of soil have been designed various initial dry densities, water eontents, temperature conditions in repeated freezing and thawing tests with free access to water at the bottom. Afterfreeze-thaw cycles, the moisture content in the freeze-thaw zone increases more than that in the unfrozen zone to the peak approximately at the top of the samples. With comparison of the water contents in the frozen and thawed states, the moisture content in the upper freeze-thaw zone in the frozen state is greater than that in the thawed state, while that in unfrozen zone in the frozen state is smaller than that in the thawed state. Within the region of the frost front, the water content in frozen state is smaller than that in thawed state. These findings help to study the freeze-thaw mechanisms deeply and perfect the forecasting module of moisture transferring in freeze-thaw cycles. 相似文献
7.
Yanying SUN Fei LIU Honghan CHEN Wei HE 《中国地球化学学报》2006,25(B08):126-127
The treatment of diesel-contaminated soil with hydrogen peroxide oxidation is investigated in this paper. The factors influencing reactions such as initial oil content, H2O2 dosage, pH-value, catalyst and so on are studied. The results indicate that it is feasible to remediate diesel-contaminated soil by adding oxidant directly at room temperature because of higher absolute removal content although the degradation efficiency is low for the contaminated soil of 1%, 2% and 5% initial oil content. The more the H2O2 dosage, the better the degradation efficiency; it is economical and efficient to add 4 mL H2O2 to 10 g diesel-contaminated soil （2% or so） directly in-situ chemical oxidation （ICO）. For the contaminated soil of 5% initial oil content, when pH-value is 5-8 and H202 dosage is 20 mL, the removal efficiency reaches more than 96%; when pH-value is 1-3 and volume ratios of H2O2 to Fe^2＋ are 1 ： 1, 2：2, the degradation efficiencies are all very high （i.e., 86%-88% or so）. It can be concluded that the degradation efficiencies are comparative when adding 1 mL or 2 mL H2O2 of Fenton Reagent or adding 4 mL of H2O2 only to 10 g diesel-contaminated soil. 相似文献
8.
Prediction criteria for groundwater potential zones in Kemuning District,Indonesia using the integration of geoelectrical and physical parameters 
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下载免费PDF全文 The presence of groundwater is strongly related to its geological and geohydrological conditions.It is,however,important to study the groundwater potential in an area before it is utilized to provide clean water.Werner-Schlumberger’s method was used to analyze the groundwater potential while hydraulic properties such as soil porosity and hydraulic conductivity were used to determine the quality and ability of the soil to allow water’s movement in the aquifer.The results show that the aquifer in the Sekara and Kemuning Muda is at a depth of more than 6 meters below the ground level with moderate groundwater potential.It is also found that the aquifer at depths of over 60 m have high groundwater potential.Moreover,soil porosity in Kemuning is found to be average while the ability to conduct water was moderate.This makes it possible for some surface water to seep into the soil while the remaining flows to the rivers and ditches. 相似文献
9.
Land disposal of fly ash(FA)and sewage sludge(SS)is a major problem due largely to their potentially harmful constituents.In this paper,a potting experiment was performed to evaluate the effects on the plant growth and to discuss in particular the potential hazard to soils and plants according to the characteristics of heavy metal accumulation and migration when FA and SS are used as the amendments of calcific soil in a limestone mining area. The results showed that the application of FA-SS mixture is capable of accelerating the growth of plants and improving the biomass production at either 1:1 or 1:2 FA-SS mixture:soil(w/w).The highest yields were obtained at 1:1(w/w)mixing ratio.When compared with the Element Background Values of Soils in China,the analysis on heavy metals indicated that the contents of Pb,Cr,Hg,Cd,As,Ni,Cu and Zn in the amended soils came up to the second-class environmental quality standards,only Hg and Cd showed significant accumulation.At the same time, though the metal concentrations in roots were higher than those for the control,the concentrations except Cu,Zn in shoots were lower.And all the heavy metal contents in the plants were substantially lower than the toxicity limits. The results indicated that the combined use of FA and SS at a rational rate of application should pose no danger to both soil and food chain based on the characteristics of the FS and SS,heavy metals and calcific soil. 相似文献
10.
Heavy water eoutcnts were determined for brines from Some salt lakes, and for water samples from rivers, springs and oil field by temperature-float method. Because the salt lakes studied are situated in cold, arid region of high altitude, the heavy water content in concentrated brines is much higher than that in rivers and springs due to vigorons evaporation, with a maximum value of 5.9 γ higher than that in running water of Peking. Discussion is also given to the dependence of heavy water variation upon season, depth of lake water, density, the degree of brine metamorphism,and crystallization of minerals containing crystalline water. 相似文献
11.
含盐土渗透系数变化特征的试验研究 总被引：4，自引：0，他引：4
对含盐土的渗透系数进行了室内试验研究.结果表明:在干容重相同的情况下,渗透系数随着含盐量的增加而减小;对同一类型土,随着含盐量的增加,硫酸盐土的渗透系数要比氯盐土渗透系数减小显著;在干容重和盐类相同的情况下,细颗粒含盐土的渗透系数要比粗颗粒含盐土的渗透系数减小显著.在含盐量相同的情况下,同一种土的渗透系数随着干容重的增大而减小.当干容重在一定的范围内时,渗透系数与干容重呈线性关系,但当干容重超过该范围时,渗透系数与干容重呈幂函数关系. 相似文献
12.
超氯盐渍土的工程特性指标研究 总被引：2，自引：0，他引：2
以探讨超氯盐渍土的含盐量与工程特性指标间关系为目的 ,采用室内土工试验与数学分析相结合的方法 ,深入研究了含盐量对塑性指标、抗剪强度的影响以及盐渍土渗透系数与干重度、含水量之间的关系。研究发现 :超氯盐渍土洗盐前后可塑性变化幅度较大 ;抗剪强度随含盐量增加而增大 ;在干重度、含水量与渗透系数三者相互关系中存在界限含水量和界限干重度。所得结论对深入研究盐渍土的工程特性、指导盐田建设将有所裨益 相似文献
13.
盐渍土与盐溶液冻结温度关系的试验研究 总被引：4，自引：2，他引：2
通过不同降温方式的冻结温度试验,明确了降温速率对土体冻结温度的影响,并采用快速降温方法,测定了不同含水率的三种天然氯（亚）盐渍土和黄土的冻结温度,以及不同浓度Na2SO4、NaCl溶液和由溶液配制的黄土的过冷温度和冻结温度,分析了降温速率、含水率、含盐量、盐类对土和溶液相变过程的影响。结果表明,快速降温得到的冻结温度值比缓慢降温得到的值偏低。当含水率低于盐渍土的塑限含水率时,水分是冻结温度的主要制约因素;当含水率大于土的塑限含水率时,天然盐渍土的含盐量对土的冻结温度起控制作用,Na2SO4含量控制含盐土的第一次相变,NaCl含量控制含盐土在低温下的第二次相变;低含盐量黄土含水率低于塑限含水率时,冻结温度随含水率增大而增大,但当含水率高于饱和含水率时,冻结温度随含水率变化不大。含Na2SO4的土和溶液的过冷温度变化规律与冻结温度变化规律类似,且其温度差值较小,通过Na2SO4溶液的冻结温度试验,可近似得到同浓度下含水率为16%只含Na2SO4黄土的冻结温度。 相似文献
14.
含NaCl和Na2SO4双组分盐渍土的水盐相变温度研究 总被引：1，自引：0，他引：1
盐渍土相变温度是判断土体中水分冻结与融化、盐分结晶与溶解的重要参数。不同盐分含量相变温度的差异,给盐渍土在降温过程中的水盐迁移过程及变形规律的模拟带来极大的不确定性。通过降温试验,研究了降温过程中氯盐和硫酸盐综合作用盐渍土中水盐相变温度的变化情况。结果表明：全盐量相同时,盐结晶温度随NaCl和Na2SO4比例的不同而不同。随NaCl的加入,在Na+同离子效应的影响下,Na2SO4更容易结晶,但土体的冰和芒硝共晶点温度下降,使得冰含量显著减少,从而降低了孔隙溶液中固相的产生比例,起到抑制Na2SO4盐渍土盐冻胀变形的作用。当土中只含Na2SO4盐时,随Na2SO4浓度的增加,冰和芒硝共晶点的温度先上升而后缓慢下降,二次相变前冰盐的累积量是导致冰和芒硝共晶点产生这种变化的主要原因。盐渍土三相共晶点温度随NaCl含量的增加呈现上升趋势,这是因为随着NaCl的加入,在发生三相共晶前,孔隙溶液发生相变的固相含量减少,从而使孔隙结构对三相共晶点的影响减小。此外,含有NaCl与Na2SO4双组分的盐渍土,水分和盐分可能以单固相、双固相以及三固相状态析出。研究结果可为深入认识盐渍土的相变规律及物理性质提供理论支撑。 相似文献
15.
盐渍土化学固化法是解决盐渍土盐胀、溶陷和腐蚀等不良工程问题的有效方法之一。通过无侧限抗压强度试验、X射线衍射试验、化学成分分析和扫描电镜试验研究了石灰粉、煤灰、水玻璃联合固化硫酸盐渍土的强度特征,分析探讨了其固化机制。试验结果表明：石灰含量小于8%时,石灰、粉煤灰、水玻璃联合固化硫酸盐渍土的抗压和抗剪强度较石灰粉煤灰固化土有大幅度提升,固化土强度随水玻璃浓度几乎呈线性增长。水玻璃固化硫酸盐渍土强度增加的机制在于：水玻璃的碱激发粉煤灰作用和水玻璃与盐渍土中化学成分的吸附作用所生成各类凝胶的填充和包裹,使得骨架颗粒的接触面积增大,颗粒之间的孔隙逐步减小,骨架颗粒由点接触变为面接触,固化盐渍土通过凝胶而黏结成为一个紧密的空间网状整体结构,土体强度得以提高。同时,复杂的物理化学作用大幅度降低了固化盐渍土中 含量,有效地抑制了硫酸盐渍土的盐胀特性。 相似文献
16.
土-水特征曲线（SWCC）在非饱和土力学中扮有重要的角色,是非饱和土力学研究的核心问题。以西北地区黄土中含有的典型硫酸钠盐为变化因素,采用滤纸法测得了兰州黄土及不同含盐量黄土状硫酸钠盐渍土的基质吸力并绘制土-水特征曲线,通过试验测试和理论分析来解释硫酸钠盐分对黄土状硫酸钠盐渍土基质吸力的影响规律,以期为工程实践提供一定的理论依据。结果表明：相同含水率下硫酸钠盐渍土的含盐量越高,基质吸力越大。以非饱和土力学理论和表面物理化学理论为基础,考虑了土中的盐分对基质吸力的毛细部分及吸附部分的影响,得到了土中含盐量与基质吸力关系的半经验公式。利用该公式计算得到不同含盐量硫酸钠盐渍土的土-水特征曲线,计算曲线与试验曲线吻合程度较高,表明该公式可以很好地描述盐渍土中不同含盐量与基质吸力的关系。 相似文献
17.
泄滩滑坡碎块石土饱和与非饱和水力学参数的现场试验研究 总被引：7，自引：1，他引：6
碎块石土由于块石含量较高,块石粒径较大,其水力学参数的确定具有一定困难。首先,采用双套环法对三峡库区泄滩滑坡的滑体碎块石土饱和渗透系数进行了原位试验,并根据土层孔隙率、颗粒级配等因素采用相关经验公式对试验结果进行了分析。其次,结合使用张力计和体积含水率仪对其土水特征曲线进行了现场模拟试验,并采用Fredlund模型对试验结果进行了拟合分析。最后,根据土水特征曲线和饱和渗透系数,采用经验公式估算了其非饱和渗透系数。试验及分析表明,该滑坡的碎块石土层的饱和渗透系数为(1.78～3.2)×10-2 cm/s,为强渗透性;材料的细颗粒含量越少,有效粒径及控制粒径越大,不均匀系数越小,相应的渗透系数越大。相关研究成果可以为泄滩滑坡非饱和非稳定渗透计算提供参数依据,并对同类型土体非饱和水力学参数的确定具有一定的借鉴意义。 相似文献
18.
含盐量对石灰固化滨海盐渍土微结构参数的影响 总被引：1，自引：1，他引：0
因土中含有较多的氯盐,引起了石灰固化滨海盐渍土的微结构变化。采用Leica QWin5000图形处理软件对石灰固化滨海盐渍土的SEM照片进行统计,证实随着含盐量的增加,固化土颗粒的等效直径、扁圆度、面积比和充填比等微结构参数呈近线性变化。含盐量增加使得固化土颗粒的粒度分维值增加,颗粒的均一化程度越来越差;而颗粒定向分维则先升、后降、再逐渐趋于一个稳定值,即固化土颗粒的排列方向保持不变。固化土颗粒级配测试结果也与上述变化规律相吻合。 相似文献
19.
含水量对冻结含盐粉土单轴抗压强度影响的试验研究 总被引：7，自引：4，他引：3
采用取自甘肃省白银市平川区黄河岸边的天然盐渍土,用蒸馏水洗去土中的盐分,配制成NaCl/Na2SO4含量为1.5%,含水量不同的试样,研究了冻结条件下含水量对冻结含盐粉土单轴抗压强度、破坏应变的影响.结果表明:当含水量较小时,随着含水量的增加,冰的胶结作用增强,并与土颗粒、盐晶体一起承受荷载,冻结含盐土的单轴抗压强度不断增大;当含水量超过某一值时,试样更多地呈现出冰的性质,而冰的强度远远小于矿物颗粒的强度,单轴抗压强度随含水量的增加而减小.随着含水量的变化,含盐土的破坏应变与单轴抗压强度有相似的变化规律. 相似文献
20.
砂浆孔隙溶液水盐相变特性是研究其水-热-盐耦合模型以及水泥基材料损伤机理的关键理论基础。为探究河西走廊盐渍土地区砂浆孔隙溶液水、盐相变规律,首先利用差示扫描量热法测定水盐相变过程中热流、相变温度等热参数;其次基于热量守恒和水分质量平衡方程,初步实现水盐分离;然后分别计算不同温度下的冰、盐晶和未冻水含量,揭示了低温下砂浆孔隙溶液水盐相变机理;最后结合微观扫描和物质能谱图,明晰了砂浆内部劣化机制。研究结果表明:随着盐浓度增大,砂浆孔隙溶液冻结温度降低、相变时间延后、水盐相变顺序调换及未冻水含量向低温方向移动;相同盐浓度下,氯化钠对砂浆孔隙溶液冻结温度的降幅最大,混合盐次之,硫酸钠最小;砂浆在低温盐侵蚀下遭受物理化学耦合作用,其中氯化钠对砂浆破坏性最大,混合盐次之,硫酸钠劣化相对较轻。 相似文献