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991.
不同边界条件对多年冻土上限影响的模型试验研究 总被引:17,自引:10,他引:17
在全球气候转暖对多年冻土影响的情景下,开展了在多模式下气温升高对冻土上限的影响试验研究。针对不加抛石遮阳棚、加抛石、加抛石遮阳棚3种情况,地表温度均采取基本温度加2次不同升温冻融循环,每次温控指标逐级提高0.5℃,即地表温度3次变化依次按照-16.1~5.8~-13.3℃、-15.6~6.3~-12.8℃、-15.1~6.8~-12.3℃进行,结果表明,加抛石及遮阳棚对多年冻土上限有着明显的影响,冻土上限的变化与气温基本上呈正相关,为寒区道路工程设计与施工提供了理论参考依据。 相似文献
992.
对本省钽铌矿床根据矿床成因采取四级划分原则进行了详细分类,按成矿作用分内生矿床和外生矿床二大类,按矿床成因及成矿地质条件分二个亚类,根据成矿阶段分七种矿床类型,根据与矿化有关的母岩体的标型矿物分十四种矿体类型,其中蚀变的花岗岩型钽铌矿床是主要类型,其次是伟晶岩型钽铌矿床,细晶岩型矿床因矿物细小,目前尚难利用.各种类型钽铌矿床(点)主要是位于构造隆起带内,分布于怀玉山、武功山、武夷山、于山和九岭等5个钽铌成矿带中.从华力西期至燕山期均有产出,其中以燕山中期为主要成矿期. 相似文献
993.
994.
995.
活性白云粉生产工艺及其物化性能研究 总被引:1,自引:0,他引:1
活性白云粉(ABP)是在白云岩经过破碎、细粉碎、表面改性的基础上得到的一种新型改性功能填料。本文利用河南辉县市的拍石头和张村两地产出的白云岩作为实验原料,对其表面改性的实验方法、改性剂选择及用量、改性条件及改性效果等方面进行了一定的探讨,并且对改性前后的白云石粉体的粒度、比表面积等性能及红外光谱特征做了对比研究。生产工艺和物性测试研究表明:活性白云粉代替轻质碳酸钙作橡胶填料前景广阔;与轻钙相比,活性白云粉的粒度不够均匀,经优化和改善生产工艺条件,可望进一步提高其应用价值。 相似文献
996.
笔者从地下地质工程和上水库工程地质调查这两个特殊问题论述了工程物探应用的对策和实效,具有一定的实用性和理论依据,对今后在抽水蓄能电站工程地质勘察中应用工程物探有一定的参考意义。 相似文献
997.
Wu Fu-chun Song Li-sheng Zhu Xing-guo Wang Feng Jing Bei-ke Dong Xing-hong Fang Wei Zuo Yong-qing 《地震学报(英文版)》2001,14(4):434-439
Based on the analysis of the induced earthquakes in China and abroad, we get some ideas about earthquakes induced by pumping
water out of a well or injecting water into a well. The induced earthquakes usually occur near the well, and they are generally
small earthquakes. The earthquake sources are shallow, and they belong to the main shock-after shock type of earthquake or
the swarm-type of earthquake. The magnitude and the quantity of the induced earthquakes obviously depend on the pressure and
the quantity of water pumped or injected. These earthquakes happen as soon as pumping or injecting occurrence, or after ten
or twenty days, they may occur at the time of injecting mud or injecting high pressure water when a well is being drilled,
or at the time when the ground water is being normally exploited. A large quantity of hot water has been exploited since 1990
in Xi’an, and the quantity of water exploited has been increasing year by year, as a result the groundwater level has been
dropping with the water pumped out and the water level is high in summer and low in winter. The earthquakes in Xi’an region
belong to the solitary-type and they spread outside Xi’an city where the wells are concentrated but no earthquake happens.
The seismic frequency and the energy released have no relation with the quantity of water exploitation or the water level
in the well. It is considered that geothermal exploitation does not induce earthquakes in and around Xi’an because of its
specially geological condition.
Foundation item: Project sponsored by the Landslide Office of Shaanxi Province and Society of Disaster Reduction of Shaanxi Province. 相似文献
998.
A new formulation is proposed to model pounding between two adjacent structures, with natural periods T1 and T2 and damping ratios ζ1 and ζ2 under harmonic earthquake excitation, as non‐linear Hertzian impact between two single‐degree‐of‐freedom oscillators. For the case of rigid impacts, a special case of our analytical solution has been given by Davis (‘Pounding of buildings modelled by an impact oscillator’ Earthquake Engineering and Structural Dynamics, 1992; 21 :253–274) for an oscillator pounding on a stationary barrier. Our analytical predictions for rigid impacts agree qualitatively with our numerical simulations for non‐rigid impacts. When the difference in natural periods between the two oscillators increases, the impact velocity also increases drastically. The impact velocity spectrum is, however, relatively insensitive to the standoff distance. The maximum relative impact velocity of the coupled system can occur at an excitation period Tn* which is either between those of the two oscillators or less than both of them, depending on the ratios T1/T2 and ζ1/ζ2. Although the pounding force between two oscillators has been primarily modelled by the Hertz contact law, parametric studies show that the maximum relative impact velocity is not very sensitive to changes in the contact parameters. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
999.
Abstract: The Dajing Cu–Sn–Ag–Pb–Zn ore deposit, Inner Mongolia of China, is a fissure‐filling hydrothermal ore deposit that occurs within the Upper Permian Linxi group. No magmatic pluton and volcanic rocks outcrop on the surface of the deposit. Most of ore veins show clear‐cut boundary with country rocks. Wallrock alterations that include silicification, carbonation, chlori–tization, and sericitization are generally weak and occur in the close vicinity of ore veins. Mineralization is divided into three stages: (1) cassiterite–arsenopyrite–quartz stage, (2) sulfide stage, and (3) Pb–Zn–Ag–carbonate stage. These mineralization stages have distinct ranges of homogenization temperatures, 290–350C for Stage 1, 260–320C for Stage 2, and 150–250C for Stage 3. However, salinities for Stages 1, 2, and 3 overlap and range between 2.2 and 10.4 wt % NaCl equivalent. The dD values relative to V‐SMOW of inclusion water from quartz are lower than –88% and centered at –100 to –130%. The δ34S values relative to CDT of sulfide ore minerals and δ13C values relative to PDB of carbonate gangue minerals, vary from –0.3 to +2.6%, and from –7.0 to –2.9%, respectively. Integrated isotopic data point to two major contributions to the mineralizing fluid that include a dominant meteoric‐derived water and the other from hypogene magma for sulfur and carbon species. Analyses of inclusion gas and liquid compositions are performed. The H2O and CO2 are the two most abundant gaseous components, whereas SO42‐ and Cl‐, and Na+, Ca2+, and K+ are the major anions and cations, respectively. A linear trend is shown on the gaseous H2O versus CO2 plot. Phase separation is excluded as cause for the trend on the basis of isotope data and fluid inclusion microthermometry. In addition, a weak wallrock alteration does not support fluid‐rock interaction as an efficient mechanism. Hence, the linear H2O–CO2 trend is interpreted in terms of absorption or dilution of CO2–dominant magmatic vapor by meteoric‐derived water. Cooling effects resulting from dilution may have caused precipitation of ore minerals. Major and trace element compositions of regional granites show a high‐K calc–alkaline characteristics and an arc–affinity. Lead isotopic compositions of galena samples from the Dajing deposit exhibit elevated U/Pb and Th/Pb ratios. These characteristics indicate a common source of supra subduction zone mantle wedge for regional granites and metals from the Dajing deposit. 相似文献
1000.