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1.
土壤粒径分布是最基本的土壤物理性质。作为许多预测模型的输入参数,准确描述土壤的粒径分布是保证模拟质量的前提。评价了对数正态分布、三次样条、逻辑生长、改进逻辑生长以及van Genuchten方程等经验模型在描述土壤粒径分布中的适用情况。结果表明,改进的逻辑生长曲线模型预测效果最好,而广泛采用的对数正态分布的结果最差。其它3种模型的效果介于两者之间。根据5种粒径分布模型的模拟结果,利用分形方法来预测土壤水分特征曲线也得到了类似的结论。 相似文献
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Empirical, theoretical or hybrid methods can be used for the vulnerability analysis of structures to evaluate the seismic
damage data and to obtain probability damage matrices. The information on observed structural damage after earthquakes has
critical importance to drive empirical vulnerability methods. The purpose of this paper is to evaluate the damage distributions
based on the data observed in Erzincan-1992, Dinar-1995 and Kocaeli-1999 earthquakes in Turkey utilizing two probability models—Modified
Binomial Distribution (MBiD) and Modified Beta Distribution (MBeD). Based on these analyses, it was possible (a) to compare
the advantages and limitations of the two probability models with respect to their capabilities in modelling the observed
damage distributions; (b) to evaluate the damage assessment for reinforced concrete and masonry buildings in Turkey based
on these models; (c) to model the damage distribution of different sub-groups such as buildings with different number of storeys
or soil conditions according to the both models. The results indicate that (a) MBeD is more suitable than the MBiD to model
the observed damage data for both reinforced concrete and masonry buildings in Turkey; (b) the sub-groups with lower number
of stories are located in the lower intensity levels, while the sub-groups with higher number of stories depending on local
site condition are concentrated in the higher intensity levels, thus site conditions should also be considered in the assessment
of the intensity levels; (c) the detailed local models decrease the uncertainties of loss estimation since the damage distribution
of sub-groups can be more accurately modelled compared to the general damage distribution models. 相似文献
3.
辽东湾北部浅海区底泥砷元素形态特征 总被引：3，自引：1，他引：2
依据2006年辽东湾浅海评价资料,分析了辽东湾北部浅海底泥的砷元素全量和各形态的含量,对砷元素全量和存在形态的分布特征及相关性进行了系统研究,并探讨了其环境生态效应.结果表明:底泥中的砷含量为较高水平,存在形态主要为残渣态、腐植酸结合态和铁锰氧化态,而水溶态、碳酸盐结合态、离子交换态和强有机结合态含量较少.除砷的强有机结合态以外,全量和其他6种形态有很好的相关性,分布特征一致,高值区都分布在锦州湾及附近.并且生态效应明显,底泥中砷的腐殖酸结合态、铁锰氧化态、离子交换态与脉红螺中砷有显著相关性,碳酸盐结合态与锯缘青蟹和口虾蛄中砷有一定的相关性. 相似文献
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It is generally agreed that particle size distributions of sediments tend ideally to approximate the form of the lognormal probability law, but there is no single widely accepted explanation of how sedimentary processes generate the form of this law. Conceptually, and in its simplest form, sediment genesis involves the transformation of a parent rock mass into a particulate end product by processes that include size reduction and selection during weathering, transportation, and deposition. The many variables that operate simultaneously during this transformation can be shown to produce a distribution of particle sizes that approaches asymptotically the lognormal form when the effect of the variables is multiplicative. This was first shown by Kolmogorov (1941). Currently available models combine breakage and selection in differing degrees, but are similar in treating the processes as having multiplicative effects on particle sizes. The present paper, based on careful specification of the initial state, the nth breakage rule and the nth selection rule, leads to two stochastic models for particle breakage, and for both models the probability distributions of particle sizes are obtained. No attempt is made to apply these models to real world sedimentary processes, although this topic is touched upon in the closing remarks. 相似文献
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Mathematical models and their targets are considered. The results provide an explanation why the shape of the density distribution function is dependent upon both size of the geological object and number of observations. These results have importance both for preparative and interpretative phases of prospecting. 相似文献
6.
Statistical models are proposed for the distribution of directions in three dimensions that are thought to point toward a single source. These models are based on the Fisher distribution. The method of maximum likelihood is used to obtain an estimate of position of the source and to provide corre-sponding confidence regions. When applied to shatter cone data from the Slate Islands, northern Lake Superior, the method yields estimates comparable with those obtained by Stesky and Halls (1982), as well as statistically valid confidence regions. 相似文献
7.
Joints are conduits for groundwater, hydrocarbons and hydrothermal fluids. Robust fluid flow models rely on accurate characterisation of joint networks, in particular joint density. It is generally assumed that the predominant factor controlling joint density in layered stratigraphy is the thickness of the mechanical layer where the joints occur. Mechanical heterogeneity within the layer is considered a lesser influence on joint formation. We analysed the frequency and distribution of joints within a single 12-m thick ignimbrite layer to identify the controls on joint geometry and distribution. The observed joint distribution is not related to the thickness of the ignimbrite layer. Rather, joint initiation, propagation and termination are controlled by the shape, spatial distribution and mechanical properties of fiamme, which are present within the ignimbrite. The observations and analysis presented here demonstrate that models of joint distribution, particularly in thicker layers, that do not fully account for mechanical heterogeneity are likely to underestimate joint density, the spatial variability of joint distribution and the complex joint geometries that result. Consequently, we recommend that characterisation of a layer’s compositional and material properties improves predictions of subsurface joint density in rock layers that are mechanically heterogeneous. 相似文献
8.
P S Moharir 《Journal of Earth System Science》1992,101(4):347-359
Compound Poisson process models have been studied earlier for earthquake occurrences, with some arbitrary compounding distributions.
It is more meaningful to abstract information about the compounding distribution from the empirical observations on the earthquake
sequences. The difinition of a compound distribution can be interpreted as an integral transform of the compounding distribution.
The latter distribution can therefore be estimated by inverting the integral transform. Alternatively, from the moments of
the observable random variablesviz. (a) the number of earthquakes per unit time or (b) the waiting times for subsequent earthquakes, the moments of the compounding
distribution can be obtained. This information can be converted into a statement about the compounding distribution. 相似文献
9.
Models for massive Caledonian sulfide deposits, formed in island are and ocean floor environments, are defined in terms of
their deposit size and grade distribution, as well as the relation between the total amount of sulfides that could be potentially
concentrated and the amount likely to be found in the largest deposit. Given the mineral resource and geological attributes
of the island are and ocean floor models, the similarity between the models and unknown areas with a potential for these types
of sulfide concentrations can be evaluated. This similarity is expressed as a favorability index whose distribution is probabilistically
combined with the metal distribution of the model.
This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications
in Resource Studies” held at Taita Hills, Kenya, November 8–15, 1977. 相似文献
10.
Xavier Emery 《Mathematical Geology》2005,37(2):163-181
The multigaussian model is used in mining geostatistics to simulate the spatial distribution of grades or to estimate the recoverable reserves of an ore deposit. Checking the suitability of such model to the available data often constitutes a critical step of the geostatistical study. In general, the marginal distribution is not a problem because the data can be transformed to normal scores, so the check is usually restricted to the bivariate distributions. In this work, several tests for diagnosing the two-point normality of a set of Gaussian data are reviewed and commented. An additional criterion is proposed, based on the comparison between the usual variogram and the variograms of lower order: the latter are defined as half the mean absolute increments of the attribute raised to a power between 0 and 2. This criterion is then extended to other bivariate models, namely the bigamma, Hermitian and Laguerrian models. The concepts are illustrated on two real data-sets. Finally, some conditions to ensure the internal consistency of the variogram under a given model are given. 相似文献
11.
Precise statistical models are proposed for the distribution of paleocurrent directions in distributary systems. These models are based on a von Mises distribution for directions of paleocurrents in a system. The method of maximum likelihood is used to obtain an estimated position and confidence regions for the apex of the system. Both axial data (where only the trend of the paleocurrent is known) and directional data (where the direction of paleoflow is known) can be used. These models have been applied to two fluvial distributary systems in flat-lying Miocene deposits in the Ebro Basin, northern Spain. The estimate of the position of the apex of one of these systems is in good agreement with the position at the basin margin predicted from sedimentary facies information. The estimate of the position of the apex of the second system lies outside of the sedimentary basin; this result is considered to indicate that the distributary system had several feeder points along the basin margin, a situation which is predicted also from facies distributions. This statistical procedure can be used successfully on small data sets of around a hundred paleocurrent readings provided that they are scattered evenly across the area or lie in a wide arc. 相似文献
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为了研究地表动态沉陷规律,基于正态分布时间函数,结合地表沉陷预测公式,构建了能够进行任意点任意时刻地表动态沉陷预测的函数模型,分析曲线形态系数对时间函数和计算误差的影响,讨论正态分布时间函数的时空完备性,建立了基于时间函数的地表动态下沉计算公式。以辛置煤矿五采区开采为例,利用空间曲面拟合方法求取了地表动态沉陷预测参数,并对特征点的下沉趋势进行了预测。结果表明,地表沉陷预测时曲线形态系数δ > 2为其合理取值,理论预测相对中误差不会超过±4.55%,且随着δ的增大,预测误差逐渐减小;正态分布时间函数在地表下沉、下沉速度以及加速度方面均体现了地表沉陷时空分布的完备性。基于叠加原理的空间曲面拟合求参方法能够进行预测参数的自动求取,地表特征点下沉趋势预测最大中误差为±64 mm,相对中误差为±5.7%,理论值与实测值相吻合,基于正态分布时间函数的预测模型能够体现地表动态下沉的时空分布特征。 相似文献
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Hydrocarbon source rock obviously controls the formation and distribution of hydrocarbon reservoirs.Based on the geological concept of "source control theory",the concept of a hydrocarbon distribution threshold was put forward.This means the maximum range for hydrocarbon controlled by the source rock conditions to migrate in the hydrocarbon basins.Three quantitative analysis models are proposed on this basis,namely the hydrocarbon accumulation probability,maximum hydrocarbon scale threshold and reserve distribution probability,which respectively refer to the probability of forming a hydrocarbon reservoir,the possible maximum scale of the hydrocarbon reservoir and the percentage of reserve distribution in a certain area within the hydrocarbon distribution threshold.Statistical analysis on 539 hydrocarbon reservoirs discovered in 28 hydrocarbon source kitchens from seven sedimentary basins and sags of eastern China shows the maximum reservoir scale possibly formed in the hydrocarbon basin,hydrocarbon accumulation probability and oil and gas reserve distribution probability are all controlled by the characteristics of the hydrocarbon source rock.Generally,as the distances from the hydrocarbon source rock center and hydrocarbon discharge boundary get longer and the hydrocarbon discharge intensity of hydrocarbon source rock center gets smaller,there will be lower probability of hydrocarbon accumulation.Corresponding quantitative models are established based on single factor statistics and multivariate analysis.Practical application in the Jiyang Depression shows that the prediction from the quantitative analysis model for the hydrocarbon distribution threshold agree well with the actual exploration results,indicating that the quantitative analysis model is likely to be a feasible tool. 相似文献
17.
基于影响因素分布模型的滑坡稳定性敏感分析 总被引：1，自引：0，他引：1
提出了基于影响因素分布模型的滑坡稳定性敏感分析方法,该法用于分析影响因素在整个定义域内对滑坡稳定性的敏感程度,以滑坡影响因素为子序列,以其稳定性系数为目标序列,根据子序列的累积分布函数求影响因素区间概率函数,与目标序列差值乘积加和得到敏感性综合决策值。以三峡库区奉节县太山庙滑坡为例,经类比统计得到滑带土抗剪强度参数的分布函数,通过经验分析得到地震水平加速度和库水位变化的分布函数,应用该法计算得到影响因素中对滑坡稳定性最敏感的因素。以内摩擦角为例,分析了影响因素方差与滑坡稳定性敏感分析结果的关系。 相似文献
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随着贯通式潜孔锤全孔反循环钻进技术及配套装备的不断发展和完善,其应用日益广泛,用于油气勘探开发气体钻井领域时施工井眼直径和井深大,合理工艺参数的确定十分关键。基于贯通式潜孔锤双壁钻具系统的结构特点,研究建立了中心反循环排渣通道和环状注气通道内压力分布模型,介绍了潜孔锤内部和反循环钻头上压耗计算方法。系统压力分布模型的建立为确定合理注气参数奠定了基础,为高压注气设备的合理选配提供了依据,对保证良好的钻进效果具有重要的意义。 相似文献