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考虑核电厂地基-基础的动力相互作用,应用显式动力有限差分法分析了地震作用下极软岩、较软岩、坚硬岩上核电厂建筑结构基础的地震响应特征,比较了岩石坚硬程度对基础加速度反应谱的影响。研究表明：随着岩石坚硬程度的提高,核电厂建筑物结构基础的地震响应有增加的趋势;在周期轴上,基础处的加速度反应谱曲线会随着岩石坚硬程度的提高逐渐向短周期（高频段）方向移动。在高频段,建造于较坚硬岩石上基础结构的加速度反应谱值偏大;在中等频段,建造于较软岩石上基础结构的加速度反应谱值偏大;在低频段,岩石坚硬程度对加速度反应谱的影响不显著。 相似文献
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下扬子区三叠纪古地理演化 总被引：2，自引：2，他引：0
下扬子区在三叠纪期间接受了早-中三叠世海相碳酸盐沉积、中-晚三叠世海陆交互相和陆相湖沼沉积.沉积相带的空间分布和古地理格局的变迁明显地受到区域构造的控制.区内盆地发育与演化是在华南板块与扬子板块、扬子板块与华北板块相互作用的背景下进行的.早-中三叠世末期的印支运动是下扬子区构造-古地理格局改变的决定性因素,使下扬子海盆闭合,沉积类型由海相沉积变为陆相沉积.下扬子区三叠纪古地理的演化特征也为板块碰撞提供了沉积证据. 相似文献
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Using the database of automatic hydrometeorological stations, installed in the Don RIver delta and Taganrog Bay seashore, the sources of the anomalois scale water negative surge and salinization of the Azov Sea under conditions of low river flow in 2015–2016 are studied. The new schemes of stratification and advection of salty sea waters in the Don River mouth under different weather conditions, water discharge and levels are given. 相似文献
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土压缩模量预测回归分析方法 总被引：1，自引：0，他引：1
在土压缩模量Es的分析计算中,常用的分析方法是根据土的e-p曲线试验资料建立公式求解,本文引入了数学上的回归分析方法来探讨Es与其它各项物理力学指标参数之间的相关关系,旨在找出对Es影响最显著的指标参数,并建立最优回归方程式,以此来预测Es。研究结果表明:该方法通用性强,应用范围广,亦可推广应用于其它相关领域。 相似文献
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岫岩陨石坑是中国第一个被证实并被国际学术界认可的陨石坑,是极为珍贵的地质遗迹及自然遗产,具有重要的科学价值与开发利用价值。岫岩陨石坑范围应定为地质遗迹重点保护区,根据地貌单元、遗迹点分布特点及人文因素,将保护区划分为地质遗迹景观区、居民点保留区和自然生态区等3个分区;借鉴国外对陨石坑遗迹保护开发的经验和岫岩陨石坑的现状,提出了进行保护和开发的路线;针对地质遗迹景观区基础设施建设、居民点保留区和自然生态区功能性升级、场馆的建设等问题提出相应的措施与建议。 相似文献
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Reaction of zoning of garnet 总被引：1，自引：0，他引：1
Timothy P. Loomis 《Contributions to Mineralogy and Petrology》1975,52(4):285-305
Compositional zoning of garnet in metamorphic or igneous rocks preserves evidence of the equilibration history of the sample and can be interpreted in terms of a growth-fractionation, diffusion-exchange, or diffusion-reaction model. Diffusion zoning is usually assumed to result from exchange reactions between garnet and other phases as the partitioning coefficient varies in response to changing environmental conditions, primarily temperature. However, in many natural environments where garnet grew originally in divariant equilibrium with other phases, changing conditions can promote continuous or “divariant” reactions and consequent compositional shifts of phases that can be much greater in some systems showing these reactions than those related to the small changes of partitioning. Diffusional zoning related to overstepping of these continuous reactions must be related to incongruent reaction and necessitates formulation of a kinetic diffusion-reaction model involving moving phase boundaries as well as solid-state diffusion. Three samples containing zoned garnets from the metamorphic aureole around the Ronda ultramafic intrusion in southern Spain are used to illustrate two possible models of diffusion-reaction processes. The examples are particularly informative because the reactions are demonstrably irreversible and evidence of the reaction system is preserved. Partitioning data indicates that compositions of product phases are not in equilibrium with the original garnet and do not vary with extent of reaction; therefore, exchange reactions with garnet were not possible and garnet changed composition only by incongruent reaction. After a small amount of reaction, Mg/Fe of the rim composition approaches a value apparently in equilibrium with product phases, but the garnets are zoned inward to the original garnet composition preserved in the interior. Grossularite content is approximately constant and spessartite content variable but small, thus, the rim composition of pyrope or almandine is assumed to be fixed by the external reaction process and is taken as a boundary condition in the following models. The zoning profile of pyrope or almandine component between the fixed rim and core compositions (assumed to extend to ∞) is described in semiinfinite, half-space models appropriate for large garnets with narrow rims. The first model corresponds to a reaction system in which all garnet compositions are metastable (case 1) and zoning depends on the independent variables of the diffusion constant, velocity of the interface between garnet and matrix, and time. The second model, corresponding to systems in which the initial garnet composition is metastable but an equilibrium composition is stable (case 2), depends on the independent variables diffusion constant, time, and a function of reaction compositions. In case 1 the consumption velocity is assumed constant and a steady state zoning profile is reached at large time, whereas, in case 2, the velocity decreases with the concentration gradient and steady state is not possible. The models were tested using a reaction time estimated from cooling models of the aureole, mass of garnet consumed, determined petrographically, and phase compositions. The two cases are somewhat independent in that different parameters are independent variables. The estimate of the diffusion constant of 10?18±2 cm2/sec (assumed to be a mutual or binary coefficient for almandine and pyrope) is considered reasonable for the temperature range of reaction (probably 600–900° C), and the two models are consistent considering the probable error and possible real temperature differences. It is obvious that details of the metamorphic reaction system must be known to successfully apply diffusion models. Kinetic models, involving consumption or growth of the phase as well as diffusion are probably necessary when dealing with natural rocks. Several possible and interesting complications, such as cross coupling between components, can be investigated if more data were available. Experimental determination of diffusion constants allow natural reaction rates to be estimated by this method. Diffusion zoning is an important consideration that could increase the efficiency of experimentation with chemically recalcitrant phases. 相似文献
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M. D. Sharma 《Journal of Earth System Science》2004,113(2):247-257
Three dimensional scattering of near-field is studied for dilatation and rotation in the time domain. The perturbation method
is applied to solve the equation of motion for the first order scattering from a weak inhomogeneity in an otherwise homogeneous
medium. The inhomogeneity is assumed close enough to the point source so that the near-field intermediate wave is dominating
over the far-field sphericalP andS pulses. The integral expressions are derived to relate dilatation and rotation of scattering to the radial fluctuations of
velocities and density in the inhomogeneity. These integrals are solved to calculate the strains of scattering from (a part
of) an inhomogeneous spherical shell of arbitrary curvature. Variable curvature may allow the shape of inhomogeneity volume
element to change uniformly from spherical to rectangular. Rotation of scattering from a spherical shell is independent ofP wave velocity inhomogeneity. Dilatation of scattering does not involveS wave velocity inhomogeneity but its gradient. The back scattering results are obtained as a special case. Strains are computed
numerically, for hypothetical models to study the effects of various parameters viz., velocity inhomogeneity, distance of
source from inhomogeneity and from receiver, and thickness of inhomogeneity. The curvature of the spherical shell is varied
to study the effects of the shape of inhomogeneous volume element on scattering. 相似文献
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In the period of impounding and running of the Three Gorges Reservoir, the sensitive degrees of change of groundwater table and displacement to the fluctuation of water level are different in different parts of landslides induced by the fluctuation of water level (as the case of Xietan Landslide). According to the relationship between different sensitive degrees of monitoring variables (underground water level and displacement) and quantity of monitoring information, the sensitive zones of groundwater table and displacement to the fluctuation of reservoir water level are divided into different degrees by the approach of fuzzy pattern recognition. The result of numerical subarea of sensitive zone of groundwater table and displacement indicates that the middle and front part of the landslide are the main places with groundwater table affected by the fluctuation of water level of reservoir; the variation of horizontal displacement of surficial part of the middle and front part of the landslide is more sensitive to water impounding and sudden fall of water level; and with the increase of elevation and depth of the landslide, the horizontal displacement changes less and less; the change of vertical displacement of surficial parts of the landslide is most sensitive to the fluctuation of water level of Three Gorges Reservoir; and with the increase of depth, the change of vertical displacement become smaller and smaller. By the means of the numerical subarea regulation of Xietan Landslide, the suggestions to the point layout for monitoring the groundwater table and displacement in the landside of Three Gorges Reservoir are put forward. 相似文献
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《International Geology Review》2012,54(10):1218-1225
Copper deposits of Cuba belong to the Jurassic lead-zinc-copper, Cretaceous copper and Paleogene copper complexes, which differ substantially in their formation conditions. The island is differentiated into a number of metallogenic zones formed at the initial and early stages of the Cuba folded province. Pinar del Rio, Pinos, Trinidad and Oriente zones, of an intrageanticlinal nature, are prospective with respect to copper vein deposits of the lead-Zinc-copper complex. The Sasa and Cauto zones - intrageosynclinal - are prospective with regard to copper-pyrite and copper vein deposits of the Cretaceous complex. A metallogenic study of the island is indicated in planning the exploration of its copper prospects. -- AGI Staff. 相似文献
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以天津海积软黏土为研究对象,对原状土及重塑土进行了不同固结压力、应力路径、加荷速率、排水条件下的三轴剪切试验,以应力比结构性参数与应变的关系来描述结构性衰减,研究了不同加荷模式下的结构损伤特性。结果表明,固结压力小于结构屈服应力时,剪切阶段的初始结构性和损伤速率基本不受固结压力影响,固结压力大于结构屈服应力时,初始结构性和损伤速率则随固结压力的增大而减小;在0相似文献
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边坡滚石运动轨迹分段循环算法 总被引：1，自引：0，他引：1
边坡滚石是在基本建设中常遇到的一种工程灾害。其防护结构的设计依据主要是边坡滚石的运动轨迹,因而要对这种灾害进行防治,首先要确定滚石的运动轨迹。根据落石运动全过程的三个阶段,即滚动(滑动)运动阶段、抛物运动阶段和与坡面碰撞阶段,利用分段循环算法分别得到了三个运动阶段的运动速度计算公式。以某岩质边坡构建相似模型,将该理论公式应用于落石运动轨迹预测,验证了公式的可行性和有效性。与现有方法相比,分段循环算法具有计算原理简单明确、易于使用等优点。该方法可用于斜坡区滚石运动特征的预测,并可作为斜坡区滚石灾害防治的依据。 相似文献
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含瓦斯煤孔隙率和有效应力影响因素试验研究 总被引：1，自引：0，他引：1
以孔隙率基本定义和力学平衡原理为出发点,充分考虑由煤层瓦斯的吸附膨胀和解吸收缩、温度效应的热胀冷缩和煤体骨架受孔隙瓦斯压力的压缩共同引起的本体变形,建立了在压缩条件下(扩容前)的含瓦斯煤孔隙率动态演化模型和以吸附热力学参数及瓦斯压力表达的有效应力方程,并分别根据现场实测孔隙率数据和含瓦斯煤三轴应力试验数据,对所建立的理论模型进行了验证。结果表明,理论计算值与实测资料和试验结论一致性较好,理论模型拟合精度较好,误差不大,所得结论对煤层气开采和矿井瓦斯灾害防治具有一定的指导意义。 相似文献
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结合工程勘察实践及现场载荷试验成果,提出将珊瑚砂分为海洋类珊瑚砂和濒海类珊瑚砂两大类,并在此基础上对珊瑚砂进行了规范定名,通过现场载荷试验对各类珊瑚砂的岩土力学特性进行了研究分析,阐明了各类珊瑚砂的岩土力学特性,对今后进一步研究珊瑚砂的岩土力学特性及工程实践具有一定指导意义. 相似文献
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滑体渗透系数是决定滑坡对降水入渗或库水位波动响应的关键参数。当滑坡区有较丰富的地下水位监测数据时,基于监测数据反演滑体渗透系数是公认的最有效途径之一。然而,反演参数的准确性受制于监测数据的采集频率和时长。确定反演滑体渗透系数的相对最优监测频率和监测时长是获取准确反演结果的前提。本文以三峡库区典型的碎石土滑坡——李家坡滑坡为例,通过渗流场反演模拟和反演结果与监测数据拟合途径,以反演结果的稳定性和离散性为评价指标,分析地下水位监测频率和监测时长对滑体渗透系数反演结果的影响,进而提出水库环境中反演碎石土滑坡滑体渗透系数的相对最佳监测频率和监测时长。研究发现:（1）监测时长不大于810 d、监测频率高于15 d/次时,可以获得水位误差相对最小、且基本稳定的反演结果;（2）监测频率1 d/次和5 d/次、监测时长同为270 d时,或监测频率10 d/次、监测时长540 d时,反演所得渗透系数的稳定性较好、离散性较小;（3） 监测频率15 d/次和30 d/次时,即使监测时长长达1 170 d,反演所得渗透系数的稳定性、离散性依然较差。综合反演水位误差大小、反演渗透系数的稳定性和离散性以及监测成本,认为监测频率5 d/次、监测时长270 d为三峡库区碎石土滑坡相对最佳的监测频率和监测时长。 相似文献
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Matishov G. G. Ilyin G. V. Usyagina I. S. Valuyskaya D. A. Deryabin A. A. 《Doklady Earth Sciences》2018,480(1):679-684
The patterns of the distribution of technogenic radionuclides 137Cs and 90Sr in the water mass and bottom deposits of three fjords of Western Spitsbergen (Isfjorden and its arms Grønfjorden and Billefjorden) were studied. The hydrological processes affecting migration of radionuclides in these water bodies were described. It was shown that the ice sheet of the archipelago that accumulates atmospheric precipitation is a source of radioactive contamination of the marine environment of the coast. Technogenic isotopes were accumulated during nuclear weapon testing in the second half of the twentieth century. The current climatic changes strengthen the role of glaciers in the contamination of arctic seas. It was noted that extrema of the 137Cs and 90Sr specific activity is mainly concentrated in the areas of glacier runoff discharge.
相似文献20.
震后沟道泥石流启动条件——松散堆积体雨中失稳的水力学机制分析 总被引：2，自引：0，他引：2
5.12地震导致大规模的松散崩滑物质堆积于沟道,极大的增加了震后降雨型沟道泥石流爆发的概率。然而,灾后特殊的物源条件和成灾环境改变了传统沟道泥石流的形成机制,给震后沟道泥石流的防治工作带来了巨大的困难。为此,以水文学为基础,在构建松散堆积体潜水位变化水文学模型的前提下,借助水力学理论,分析了沟道堆积体内水力随潜水位变化的规律和特征,研究作用在单元条块堆积体上静水压力和动水压力的计算方法。在合理分段沟道松散堆积体的前提下,基于无限边坡理论完成了对各段堆积体下滑力、基底抗滑力及剩余下滑力的表达构建。结合算例解析了震后降雨条件下堆积体失稳的力学机制。分析表明,震后沟道松散堆积体失稳启动并泥石流化是流域降雨作用下堆积体内潜水位不断抬升、水力环境不断劣化的结果。流域大、沟道窄、堆积深、导水系数小、沟床缓的堆积体因较高的潜水位更易在降雨中失稳,且失稳模式因条块间剩余下滑力差异而分为整体推移启动及解体牵引启动两类。 相似文献