Inelastic constitutive properties and shear localization in Tennessee marble     

D. J. Holcomb  J. W. Rudnicki 《国际地质力学数值与分析法杂志》2001,25(2):109-129

The inelastic response of Tennessee marble is modelled by an elastic plastic constitutive relation that includes pressure dependence of yield, strain‐softening and inelastic volume strain (dilatancy). Data from 12 axisymmetric compression tests at confining pressures from 0 to 100 MPa are used to determine the dependence of the yield function and plastic potential, which are different, on the first and second stress invariants and the accumulated inelastic shear strain. Because the data requires that the strain at peak stress depends on the mean stress, the locus of peak stresses is neither a yield surface nor a failure envelope, as is often assumed. Based on the constitutive model and Rudnicki and Rice criterion, localization is not predicted to occur in axisymmetric compression although faulting is observed in the tests. The discrepancy is likely due to the overly stiff response of a smooth yield surface model to abrupt changes in the pattern of straining. The constitutive model determined from the axisymmetric compression data describes well the variation of the in‐plane stress observed in a plane strain experiment. The out‐of‐plane stress is not modelled well, apparently because the inelastic normal strain in this direction is overpredicted. In plane strain, localization is predicted to occur close to peak stress, in good agreement with the experiment. Observation of localization on the rising portion of the stress–strain curve in plane strain does not, however, indicate prepeak localization. Because of the rapid increase of mean stress in plane strain, the stress–strain curve can be rising while the shear stress versus shear strain curve at constant mean stress is falling (negative hardening modulus). Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Velocity and attenuation of elastic waves in finely layered porous rocks   总被引：5，自引：0，他引：5  

B. Gurevich  S. L. Lopatnikov 《Geophysical Journal International》1995,121(3):933-947

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甘蔗“新台糖10号”农艺性状试验     

杨景  袁栋 《广东海洋大学学报》1997,(1)

以“粤糖63／237”为对照品种进行新植、宿根共3年的对比试验，结果表明，“新台糖10号”的新植、宿根的蔗茎产量及蔗糖份均高于对照品种。“新台糖10号”是适合遂溪县蔗区种植的早熟、高产、高糖以及宿根性好的甘蔗品种。  相似文献   

Limits on the chirality of interstellar and intergalactic space     

Maurice Goldhaber  Virginia Trimble 《Journal of Astrophysics and Astronomy》1996,17(1-2):17-21

We raise the question of whether velocities of left and right circularly-polarized photons might be different (for reasons other than the well-known Faraday effect). Such a difference could manifest itself either in the time profiles of pulsed or bursting astronomical sources or in the rotation of the direction of polarization of linearly polarized radiation from them. The existing observations of pulsars, gamma ray bursters, and quasar jets are used to set limits to the difference in speed, between 10^-17and 10^-32  相似文献   

Transport properties and microstructural characteristics of a thermally cracked mylonite     

M. Le Ravalec  M. Darot  T. Reuschlé  Y. Guéguen 《Pure and Applied Geophysics》1996,146(2):207-227

An experimental study was carried out on a granitic mylonite (La Bresse, France) to analyze the influence of pore microstructure on transport properties. Different crack networks were obtained by a controlled thermal treatment. Microstructures were analyzed by means of gas adsorption and mercury porosimetry. Transport properties have been investigated by measuring gas permeability and electrical conductivity. The dependence of permeability on confining pressure shows an exponential decrease, characteristic of a porosity made of cracks. Correlations between measured parameters have been analyzed by comparing them with relations deduced from theoretical models. Linking the formation factor to the porosity leads to a rather low tortuosity value (about 2.4), characterizing a medium with a well connected porosity. Correlation between permeabilityk and formation factorF leads to a power-law relationk F ^–n wheren2.9, which is consistent with a crack model describing the behavior of the thermally treated rock.  相似文献   

关于GIS工具软件可视化设计的几点注记     

秦志远  蔡少华 《测绘学院学报》1998,(1)

文中从实用的角度 ,结合具体实践 ,对 GIS工具型软件可视化设计及实现阶段的基本问题 ,提出了 Visual C++5.0软件环境中有效的解决方法。  相似文献   

碎屑岩储层的两种不同成岩序列   总被引：11，自引：1，他引：10  

郑浚茂  赵省民 《地质论评》1998,44(2):207-212

碎屑岩储层的成岩作用可分为两大序列,即连续埋藏成岩序列和间断埋藏成岩序列。前者表现为沉积物沉积后一直下沉,其各种成岩事件的演化受埋深的控制,储层孔隙度的演化及储集性也随埋深变化而具有明显的分带性;后者表现为多种成岩事件的演化主要受构造运动的影响,成岩演化复杂,其储层的储集性受不整合面控制。  相似文献   

Positive and negative impacts of longwall mine subsidence on a sandstone aquifer   总被引：3，自引：0，他引：3  

C. J. Booth  E. D. Spande  C. T. Pattee  J. D. Miller  L. P. Bertsch 《Environmental Geology》1998,34(2-3):223-233

 Subsidence due to longwall underground coal mining changes the hydraulic properties, heads, yields, and in some cases the groundwater chemistry of overlying bedrock aquifers. A 7-year study of a sandstone aquifer overlying an active longwall mine in Illinois has supported a comprehensive model of these impacts. Subsidence caused increases in permeability and storativity over the longwall panel. These changes initially caused a major decline in water levels in the sandstone, but the aquifer recovered slightly within a few months and fully within several years after mining. The enhanced hydraulic properties combined with potentiometric recovery resulted in a zone of greater well yield. However, at sites with very poor transmissivity and inadequate recharge pathways, recovery may not occur. Also, at the study site, the physical enhancement was accompanied by a deterioration in groundwater quality from slightly brackish, sodium bicarbonate water to more brackish water with increased sulfate levels. Received: 17 March 1997 · Accepted: 9 September 1997  相似文献   

泥页岩的X射线衍射定向指数与理化性能及井壁稳定的关系   总被引：1，自引：0，他引：1  

沈守文  沈明道  梁大川  张国钊 《沉积学报》1998,(2)

首次提出了泥页岩Ｘ射线衍射定向指数的测定方法,探讨了定向指数与矿物成分,定向指数与泥页岩理化性能（密度、回收率、膨胀率、阳离子交换容量等）的关系。并在定向指数的基础上,提出了综合指数的概念,然后以定向指数和综合指数为主要依据,对坍塌地层泥页岩进行了分类。这对于钻井工程上研究井壁稳定的机理,预防井壁失稳,具有重要的理论意义和实用价值。  相似文献   

南京地质环境的基本特征和几个主要环境岩土工程问题   总被引：19，自引：2，他引：17  

罗国煜  张晓昭 《高校地质学报》1998,4(2):189-197

环境问题已成为全球热点,本文提出了关于人类社会面临的两类环境问题的概念,即污染和生态破坏及环境岩土工程问题,论述了南京市的地质环境特点,剖析了南京市的几个主要环境岩土工程问题。这对深化环境问题的认识,促进南京经济建设的发展,推动南京环境岩土工程问题瓣研究有积极意义。  相似文献