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1.
Thermal and physical properties of reconsolidated crushed rock salt as a function of porosity and temperature 总被引：1，自引：1，他引：0
Crushed salt can be used as backfill to bury and conduct heat away from radioactive waste in salt repositories. As the crushed salt compacts during reconsolidation, its thermal, mechanical and hydrologic properties will change in a manner related to the porosity. Measurements of crushed salt thermal properties are conducted to evaluate such relationships. A simple mixture theory model is presented to predict thermal conductivity of consolidating salt in repository conditions. Experimental work was completed to evaluate the model by measuring thermal conductivity, thermal diffusivity and specific heat of crushed salt as a function of porosity and temperature. Sample porosity ranged from 0 to 46 %, and measurements were made at ambient pressure, from room temperature to 300 °C. These are the temperature conditions expected in a radioactive waste storage facility. Crushed salt thermal conductivity decreases with increasing porosity and temperature. Thermal diffusivity showed little porosity dependence but decreased with increasing temperature. Specific heat also shows little porosity dependence but increases with increasing temperature. Fracture porosity in deformed bedded salt cores appears to reduce thermal conductivity more dramatically than inter- and intra-granular porosity in consolidated salt. A long-term effort to dry crushed salt at high temperatures resulted in a 0.48 weight-percent loss of water that had resided at grain boundaries and in intra-granular fluid inclusions. While this loss does not significantly affect thermal properties, the release of this water volume could impact the mechanical response of the reconsolidating salt and host rock. 相似文献
2.
煤岩热物性参数是矿井降温、防灭火治理工作所需要的重要基础资料。以重庆永川煤矿为研究对象,采用井下现场测定和实验室测试对该矿目前采掘区域内煤岩密度、比热、导热系数、导温系数以及原始温度、地温梯度等参数进行了测试。测试结果表明,在矿井标高-400 m水平,煤岩样的密度、比热、导热系数、导温系数均处在正常范围之内;在标高-357~-438 m,煤岩密度、比热、导热系数、导温系数不随标高的变化而变化。在标高-400 m水平,煤岩原始温度为35~36℃;矿井恒温带深度以下,-400 m水平以上的地温梯度为2.32/℃ hm,-400 m水平以下的地温梯度值为2.65/℃ hm,存在一个稍微递增的趋势,但仍然处于正常地温梯度范围。结合矿井地勘资料确定煤岩原始温度的实测值较理论计算值偏小,但误差不超过3%,精度符合工程实际要求。 相似文献
3.
Heat transport in serpentinites 总被引：1，自引：0，他引：1
The thermal transport properties thermal conductivity and thermal diffusivity were examined for a variety of serpentinites as a function of temperature at ambient pressure. The thermal transport properties of serpentinites show an extraordinary behavior. Besides the common 1/T decrease in thermal transport properties with increasing temperature, which can be related to an increase in phonon–phonon interactions with increasing temperature, an oscillation of thermal conductivity is observed with maxima around 450 and 850 K. This oscillation is linkable to water release of surficially bounded water and water in pores (450 K) and the dehydration of serpentinite (850 K). The oscillations are explained by advective heat transfer during dehydration, reaching up to 30% of the overall heat transport. The dehydration of serpentinites was examined by XRD and Thermo-Gravimetry and Differential Thermal Analysis/Differential Scanning Calorimeters (TG/DSC) investigations, indicating that the dehydration reaction is kinetically hindered and the crystallization of the product phases are observed at ≈1060 K, more than 200 K above the equilibrium of dehydration reactions. The conductive heat transfer by phonons shows a minor temperature variation and dominates thermal diffusivity. Ultrasonic sound velocities as a function of temperature [J. Geophys. Res. 102 (1997) 3051] were used to derive the mean free path length of phonons, which decreases from 0.28 to 0.2 nm at high temperatures. This is in the same order of magnitude as the interatomic distance of O–O, Al–O and Si–O restricting the minimum distance for phononic movement. A high anisotropy in thermal transport properties of single crystallites is concluded from its structure and elastic behaviour. However, the examined samples are macroscopically isotropic. The pressure and temperature dependence of conductive heat transport of an average serpentinite is given by λ=(1/(A+BT))(1+βP) W/m K, with A=0.3638 m K/W, B=0.000244 m/W and β=0.148 GPa−1. 相似文献
4.
Influence of soil moisture content on surface albedo and soil thermal parameters at a tropical station 总被引：1，自引：0，他引：1
Half hourly data of soil moisture content, soil temperature, solar irradiance, and reflectance are measured during April 2010 to March 2011 at a tropical station, viz., Astronomical Observatory, Thiruvananthapuram, Kerala, India (76°59’E longitude and 8°29’N latitude). The monthly, seasonal and seasonal mean diurnal variation of soil moisture content is analyzed in detail and is correlated with the rainfall measured at the same site during the period of study. The large variability in the soil moisture content is attributed to the rainfall during all the seasons and also to the evaporation/movement of water to deeper layers. The relationship of surface albedo on soil moisture content on different time scales are studied and the influence of solar elevation angle and cloud cover are also investigated. Surface albedo is found to fall exponentially with increase in soil moisture content. Soil thermal diffusivity and soil thermal conductivity are also estimated from the subsoil temperature profile. Log normal dependence of thermal diffusivity and power law dependence of thermal conductivity on soil moisture content are confirmed. 相似文献
5.
热扩散系数是多年冻土对外界热扰动敏感程度的重要影响参数之一,也是寒区工程设计与建设的关键基础数据。基于瞬态平面热源法导热系数测试结果和质量加权法计算获取的比热容理论值,计算获得青藏工程走廊西大滩—唐古拉山沿线典型类别土样热扩散系数,分析对比了走廊带内冻融土热扩散系数的分布特征和参数影响规律,提出了基于经验拟合公式法和RBF神经网络方法的冻融土热扩散系数预测模型,并比较了不同预测模型的预测效果。研究结果表明:青藏工程走廊带内土的热扩散系数与粒径整体呈正相关性,融土热扩散系数按黏性土、粉土、全风化岩类、砂土及碎石土依次增大,冻土热扩散系数按黏性土、全风化岩类、粉土、碎石土及砂土依次增大;热扩散系数与容重及天然含水率相关性随土类及冻融状态差异明显,冻、融土热扩散系数呈显著正线性关系;以融土热扩散系数为拟合参数的冻土热扩散系数三元预测模型的预测精度明显高于二元经验公式;RBF神经网络模型在冻、融土热扩散系数预测中均具有最优的预测精度,为最佳预测模型。 相似文献
6.
岩石热导率是地热理论和应用研究中十分重要的参数,对于地热资源评估、大地热流分析、深部热状态及岩石圈热结构等相关研究提供了基础数据支撑。本文从二连盆地白音查干凹陷和乌利亚斯太凹陷采集了98块基本覆盖白垩系各地层的钻井岩芯样品,在实验室条件下对它们进行了岩石热导率测试,并收集了前人对31个样品的测试结果,进而结合孔隙度、钻孔实测温度和深度数据,对实验室条件下的测试数据进行了饱水校正和温压校正。测试样品包括泥岩、砂岩、砾岩、片岩和玄武岩,孔隙度在2%~20%之间,采样深度在117.8~3159.5m范围内,对应的温度和压力范围分别为13.5~118.6℃、2.89~77.41MPa。实测结果表明5种不同岩性岩石样品的热导率变化范围为0.89~4.91W/(m·K)。经过饱水和温压校正后,泥岩、砂岩、砾岩、页岩和玄武岩的平均热导率分别为2.08±0.36W/(m·K)、2.28±0.50W/(m·K)、2.53±0.44W/(m·K)、4.16±0.76W/(m·K)、1.33±0.09W/(m·K)。5种岩性中片岩平均热导率值最大,玄武岩平均热导率值最小,沉积岩介于两者之间,总体上具有随深度增大而增加的趋势。饱水、温度和压力校正后的热导率比干样热导率高。结合研究区内各个地层砂岩和泥岩所占比计算得到白音查干凹陷和乌里雅斯太凹陷白垩系地层热导率分别为2.00W/(m·K)和2.17W/(m·K)。结合钻孔测温数据,计算得到二连盆地大地热流值介于74~85mW/m^2,明显高于中国大陆地区平均热流值61.5mW/m^2。本文的研究成果对二连盆地以及华北北缘的地热资源,深部热状态和岩石圈结构都有意义。 相似文献
7.
低温低压条件下辉石粉末的热导率实验分析:对月球及火星表面热环境研究的指示 总被引：1，自引：0，他引：1
在真空条件下矿物粉末热导率的实验测量,可为我们研究月球及行星表面的热属性和热演化,解译热红外和微波探测数据,开展月球及行星探测载荷设计提供重要的数据参数。本研究主要采用改造后的Hot Disk TPS 2500S导热仪对辉石粉末的热导率进行测量。同时,分析了真空度、温度对辉石粉末热导率的影响。实验结果表明:1)热导率随着真空度的降低呈下降趋势,大气压力在1000Pa时,辉石粉末热传导机制发生明显改变。在低压条件下(1000Pa)热导率随真空度的变化趋于平缓;2)辉石粉末热导率随温度的升高而增大,但是增大的幅度在低压和常压条件下存在明显差异。根据实验结果,提出了低压条件下辉石粉末热导率随真空度和温度变化的关系式。本研究表明,在月球和火星表面热环境的研究中,温度和压力对热导率的影响程度是不同的。上述结果对未来开展地外样品的热导率测量提供了重要的参考。 相似文献
8.
In this paper a thermogravimetry-differential thermal analysis method coupled with chromatography （TG-DTA-GC） has been adopted to simulate the generation of gaseous hydrocarbons from different hydrocarbon source rocks such as coals, mudstones, and carbonate rocks with different maturities. The temperature programming for thermal simulation experiment is 20℃/min from ambient temperature to 700℃. As viewed from the quantities and composition of generated gaseous hydrocarbons at different temperatures, it is shown that low-mature coal has experienced the strongest exothermic reaction and the highest loss of weight in which the first exothermic peak is relatively low. Low-mature coal samples have stronger capability of generating gaseous hydrocarbons than high-mature samples. The amounts and composition of gaseous hydrocarbons generated are closely related not only to the abundance of organic carbon in source rocks, but also to the type of kerogen in the source rocks, and their thermal maturity. In the present highly mature and over-mature rock samples organic carbon, probably, has already been exhausted, so the production of gaseous hydrocarbons in large amounts is impossible. The contents of heavy components in gaseous hydrocarbons from the source rocks containing type- Ⅰ and - Ⅱ kerogens are generally high ; those of light components such as methane and ethane in gaseous hydrocarbons from the source rocks with Ⅲ-type kerogens are high as well. In the course of thermal simulation of carbonate rock samples, large amounts of gaseous hydrocarbons were produced in a high temperature range. 相似文献
9.
Time series of soil surface and subsurface temperatures, soil heat flux, net radiation, air temperature and wind speed were
measured at two locations in Kalpakkam, coastal southeast India. The data were analysed to estimate soil thermal diffusivity,
thermal conductivity, volumetric heat capacity and soil heat flux. This paper describes the results and discusses their implications. 相似文献
10.
B. P. Singh 《Physics and Chemistry of Minerals》2005,32(7):480-484
The variations in isothermal bulk modulus with an increase in temperature are found to be related linearly with the change
in thermal pressure for geophysical minerals, such as MgO, CaO, Al2O3, MgAl2O4 and Mg2SiO4. Analysis of the relationship yields a value of the Anderson–Gruneisen parameter for each mineral in close agreement with
known values. An important finding of the present study is the derivation of an isobaric equation of state representing the
relationship between volume and temperature at ambient pressure. This equation for isobaric volume expansion looks like the
Birch equation for isothermal compression. The calculated values of volume expansion for the minerals at high temperatures
present close agreement with the available experimental data. The formulation developed in the present study has also been
used to predict the volumes at simultaneously elevated temperatures and pressures for CaSiO3 perovskite and NaCl minerals, in good agreement with the experimental values. 相似文献
11.
Hauke Marquardt Steffen Ganschow Frank R. Schilling 《Physics and Chemistry of Minerals》2009,36(2):107-118
Knowledge of heat transport properties as a function of mineral- and rock-composition and temperature is of major relevance
to understand and model heat transfer in the Earth’s interior. A systematic study on 13 natural and 4 synthetic garnets was
carried out in an attempt to obtain a better systematic understanding of the processes that affect the heat transport in minerals,
especially the effect of chemical substitution in solid solution series. It is found that substitution significantly lowers
the thermal diffusivity from end-member values for both synthetic and natural garnets with a minimum of thermal diffusivity
at an intermediate composition. The thermal diffusivity as a function of the degree of substitution can be described by the
approach of Padture and Klemens (J Am Ceram Soc 80 (4):1018–1020, 1997). With increasing temperature the thermal diffusivity decreases due to phonon-phonon-scattering effects. A quantitative analysis
of the high-temperature behaviour was carried out by using the model of Roufosse and Klemens (J Geophys Res 79 (5):703–705,
1974), which takes a lower limit of thermal diffusivity at elevated temperatures into account. The model allows for an extrapolation
of the deduced room temperature thermal diffusivities to higher temperatures. Furthermore, the model was modified to determine
the high temperature limit of the thermal diffusivity for all investigated natural garnets D
min to be 0.64 ± 0.03 mm2/s. 相似文献
12.
高温作用会导致岩石内部结构发生变化,并对其热物理性质有着显著影响。因此,研究高温作用后岩石热物理性质的变化规律对地热系统及存在热流传播问题的地下工程具有指导意义。试验利用高温炉和Hot Disk热常数分析仪研究了高温作用后砂岩热物理性质的变化特征。研究表明:砂岩的热导率、比热、热扩散率随温度整体呈下降趋势,可分为25℃~100℃,100℃~400℃,400℃~600℃,600℃~900℃四个阶段;25℃~100℃,砂岩热导率、比热、热扩散率因附着水蒸发急剧减小;100℃~400℃,砂岩热导率、热扩散率变化平缓,比热因含水量的降低减小得较快;400℃~600℃,砂岩中结晶水、结构水的蒸发及石英的相变导致微裂隙发育、延伸,进而引起热导率、比热、热扩散率持续下降;600℃~900℃,砂岩中矿物发生分解、熔融破裂,热破裂进一步增加与扩展,这个阶段内热导率、比热迅速下降,但热扩散率基本稳定。 相似文献
13.
Reliable estimates of soil thermal properties such as heat capacity, thermal conductivity, and diffusivity are important in analysis of heat transmission through soils in applications such as shallow geothermal applications, buried electrical conduits, and in general heat/fluid flow analyses. A number of analytical, numerical and experimental methods are available to determine the soil thermal properties. In this paper, the analytical and numerical methods developed on the basis of one-dimensional heat conduction equation are used to estimate the apparent thermal diffusivity of soil. Three of the four analytical methods, Amplitude, Phase, and Arctangent provide explicit equations for the apparent thermal diffusivity. Two methods, Harmonic and Numerical, make use of large number of temperature measurements to implicitly solve for the apparent thermal diffusivity. The temperature time series data monitored at different depths in two field sites in Melbourne, Australia for more than 2 year period were used to estimate the apparent thermal diffusivity of soil down to 2 m depth. The apparent thermal diffusivity was calculated using all five methods and compared with laboratory experimental results. The effectiveness of each method in predicting the thermal diffusivity was compared and observed discrepancies were discussed. Finally, the observed soil temperature data for a 12 month period are used to model the temperature variation in the ground analytically using Harmonic method and the model prediction for the following 12 month was compared independently with the field measurements. The analytical model prediction is found to be in good agreement with the field monitored data. 相似文献
14.
Tubing Yin Xibing Li Kaiwen Xia Sheng Huang 《Rock Mechanics and Rock Engineering》2012,45(6):1087-1094
The effect of thermal treatment on the dynamic fracture toughness of Laurentian granite (LG) was investigated in this work. Notched semi-circular bend (NSCB) LG specimens are heat treated at temperatures up to 850?°C. The micro-cracks in the rock samples induced by thermal treatment are examined by scanning electron microscope (SEM). The microscopic observations are consistent with the subsequent P-wave velocity measurements, which shows that the P-wave velocity decreases with the treatment temperature monotonically when the temperature is higher than 250?°C. Dynamic fracture toughness measurements are then carried out on these samples with the dynamic load exerted by a modified split Hopkinson pressure bar (SHPB) system. The relationship between fracture toughness and treatment temperature is investigated. Experimental results show that fracture toughness increases with the loading rate but decreases with the treatment temperature. However, when the heating temperature is below 250?°C and above 450?°C, the dependence of dynamic fracture toughness on the temperature is different from other temperatures, which can be explained by the physical processes at the microscopic level of the rock due to heating. At treatment temperatures below 250?°C, the thermal expansion of grains leads to an increase in the toughness of the rock. At treatment temperatures above 450?°C, the sources of weakness such as grain boundaries and phase transition of silicon are depleted, and as a result the decrease in fracture toughness is not as significant as other treatment temperature ranges. 相似文献
15.
中国大陆科学钻探主孔100～2000m岩石热导率及其各向异性：对研究俯冲带热结构的启示 总被引：10，自引：6，他引：10
系统研究了中国大陆科学钻探工程主孔100～2000米岩石的热导率和生热率特征。初步研究了岩石热导率随矿物组成的变化关系、岩石热导率的各向异性及其影响因素。主孔2000米的岩心热导率介于1．873～4．062Wm^-1K^-1之间，平均热导率2．967Wm^-1K^-1。整体上热导率出现的频率主峰分布在2．8～3.0Wm^-1K^-1。榴辉岩热导率随着其退变质程度的增加而降低，新鲜榴辉岩热导率集中分布于3．6～3．7Wm^-1K^-1，角闪石化榴辉岩的热导率分布在3．1～3.2Wm^-1K^-1，强退变的榴辉岩热导率分布于2．4～2．5Wm^-1K^-1。片麻岩热导率主要分布于2．8～3.0Wm^-1K^-1。从垂向上看，主孔100～735米主要由榴辉岩组成，热导率整体比较大，平均3.265Wm^-1K^-1；1200～1600米主要以花岗质片麻岩为主，热导率比其它层位偏低，平均2．755Wm^-1K^-1。通过对面理发育的样品进行测试，东海地区各类岩石的热导率具有较明显的各向异性。榴辉岩和片麻岩热导率的各向异性平均值分别为4、66％和22．99％，超基性岩的热导率平均值为3．322Wm^-1K^-1，各向异性16．08％。岩石热导率在垂直于面理的方向上具有最小值，在平行于面理的方向上具有最大值。上述资料对超高压地体热结构特征的研究提供了重要数据基础。 相似文献
16.
The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients: aa = 5.8(3) × 10-5, ab = 5.8 (1) × 10-5, ac% = 5.2(1) × 10-5, and av = 7.4(1) × 10-3 ℃-1, in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles a, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively. 相似文献
17.
随着煤炭开采深度的增大,矿井高温问题日益突出,因此必须对矿区的地温场特征进行研究。基于安徽淮北和淮南煤田煤系所测定的127块岩石样品的热导率数据,结合区内前人的研究成果,全面报道两淮煤田岩石热导率参数及其特征,并分析热导率对现今地温场的影响。结果表明:两淮煤田煤系岩石热导率变化范围为0.37~4.36 W/(m·K),平均值为2.54 W/(m·K);热导率与岩性、埋藏深度、地层时代和密度等密切相关,砂岩的热导率普遍大于泥岩和煤,热导率和深度、密度均表现为正相关关系;岩石导热性的差异对区内地温场的影响较大,导热性差的松散层和煤层往往会造成地温异常,且上覆松散层愈厚其地温愈高。 相似文献
18.
The thermal conductivity (TC) of metal and rock samples was determined, under ambient conditions, using standard X-ray diffraction equipment in which only the diffractometer sample holder had been modified from the original. As the method is comparative, standard reference materials were used: a copper standard for the analysis of metals and marble for the rock specimens. The marble was analyzed beforehand using a quick thermal conductivity meter QTM. In experimental measurements of TC the mean reproducibility value appears to be about 4% while the accuracy is about 5% for the examined rocks, and better for metals. 相似文献
19.
The bowing potential of granitic rocks: rock fabrics, thermal properties and residual strain 总被引：1，自引：0，他引：1
The bowing of natural stone panels is especially known for marble slabs. The bowing of granite is mainly known from tombstones
in subtropical humid climate. Field inspections in combination with laboratory investigations with respect to the thermal
expansion and the bowing potential was performed on two different granitoids (Cezlak granodiorite and Flossenbürg granite)
which differ in the composition and rock fabrics. In addition, to describe and explain the effect of bowing of granitoid facade
panels, neutron time-of-flight diffraction was applied to determine residual macro- and microstrain. The measurements were
combined with investigations of the crystallographic preferred orientation of quartz and biotite. Both samples show a significant
bowing as a function of panel thickness and destination temperature. In comparison to marbles the effect of bowing is more
pronounced in granitoids at temperatures of 120°C. The bowing as well as the thermal expansion of the Cezlak sample is also
anisotropic with respect to the rock fabrics. A quantitative estimate was performed based on the observed textures. The effect
of the locked-in stresses may also have a control on the bowing together with the thermal stresses related to the different
volume expansion of the rock-forming minerals. 相似文献
20.
为分析天津地区地层热物性参数的地区分布特征和平面分布规律,布置88个勘查孔、现场采集1 076个岩土样、室内分析热导率、比热容、热扩散系数等地层热物性实验,对测试数据进行统计分析。结果表明:天津市岩土体热导率在1.26~1.70 W/(m·K),比热容在2 050~2 090 J/(kg·K),热扩散系数在0.45×10-6~0.74×10-6 m2/s。同一地区不同岩性的比热容,黏土最大、粉砂最小,热导率刚好相反,热扩散系数与比热容规律相同;不同地区同一岩性的热物性参数差别不大。天津市比热容与热导率呈现大致相反的趋势,热导率高值区位于蓟县、宝坻和宁河的东部、武清西部、静海南部以及滨海新区的中部地区;比热容高值区位于蓟县、宝坻和宁河西部、武清东部、静海北部以及滨海新区大部分地区。 相似文献