An approximate method for evaluating the shear band thickness in saturated soils

A formula for the thickness of a shear band formed in saturated soils under a simple shear or a combined stress state has been proposed. It is shown that the shear band thickness is dependent on the pore pressure properties of the material and the dilatancy rate, but is independent of the details of the combined stress state. This is in accordance with some separate experimental observations. Copyright © 2004 John Wiley & Sons, Ltd.     

Elastic solutions for stresses in a transversely isotropic half‐space subjected to three‐dimensional buried parabolic rectangular loads

In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half‐space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half‐space, induced by three‐dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian co‐ordinate system for a transversely isotropic half‐space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half‐spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright © 2002 John Wiley & Sons, Ltd.     

Magnitude of σ1, σ2, and σ3 at mid-crustal levels in an orogenic belt: Microboudin method applied to an impure metachert from Turkey

We revised an equation for estimating palaeostress magnitude using the microboudin technique by incorporating the influence of time on the fracture strength of minerals. The equation was used to estimate triaxial palaeostresses from a rare sample of metachert from Turkey that contains microboudinaged, columnar tourmaline grains in a wide range of orientations within the foliation plane. The estimated principal palaeostresses are σ₁ = 605 MPa, σ₂ = 598 MPa, and σ₃ = 597 MPa. As the microboudinage is considered to have occurred immediately before the rock encountered the brittle-plastic transition during exhumation, these stress values correspond to conditions at approximately 18 km depth and 300 °C within a Cretaceous orogenic belt.     

Effect of Inter-Column Spacing on Soil Stresses due to Vibro-Installed Stone Columns: Interesting Findings

This paper reveals the interesting relation between the inter-column spacing and the corresponding alteration of soil state of stresses due to the vibro-installation technique. This relation is inferred from analyses for load settlement records of various field load tests, performed for stone columns arrangements with different inter-column spacing values. In order to have adequate confidence in the findings, a well-documented case history, involving three columns patterns along with their relevant field and laboratory test results, is utilized for this study. Moreover, a well-tested finite element model, capable of simulating both elasto-plastic and time dependent soil deformations as well as pore water pressure building and dissipation, is employed in the analysis. Instead of determining the soil response to the test load, based on known initial soil stresses and material properties, the analysis is inversely posed to determine the soil initial stresses, based on the recorded settlements and the post-installation material properties. The alteration in the soil state of stress is represented by the increase in the post-installation horizontal to vertical stress ratio, K*, as a function of the inter-column spacing. It is found that this alteration experiences a systematic decrease in its magnitude as the inter-column spacing increases.     

广西合浦海水珍珠变黄机理新议

海水珍珠缓慢变黄的传统解释是无机相文石不稳定向方解石转化这个不可逆过程造成的.然而作者通过肉眼观察、光学显微镜观察、H2O2漂白体系使变黄的海水珍珠重新变白实验及X射线粉晶衍射分析,均表明传统解释可能存在错误,变黄的海水珍珠无机相没有发生明显的相变,故推测珍珠内有机相的变化是珍珠变黄的主要原因.     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

États de contraintes et mécanismes d'ouverture et de fermeture des bassins permiens du Maroc hercynien. L'exemple des bassins des Jebilet et des RéhamnaStates of stresses and opening/closing mechanisms of the Permian basins in Hercynian Morocco. The example of the Jebilet and Réhamna Basins

The fracturing analysis in the Permian basins of Jebilet and Rehamna (Hercynian Morocco) and the underlying terranes allowed us to suggest a model for their opening. Three tectonic episodes are distinguished: a transtensional episode NNE–SSW-trending (Permian I), occurring during the opening along sinistral wrench faults N70–110-trending, associated with synsedimentary normal faults; a transpressive episode ESE–WNW-trending (Permian II), initiating the closure, the normal faults playing back reverse faults and the N70 trending faults dextral wrench faults; a compressional episode NNW–SSE (post-Permian, ante-Triassic), accentuating the closure and the deformation and putting an end to the Tardi-Hercynian compressive movements. To cite this article: A. Saidi et al., C. R. Geoscience 334 (2002) 221–226.     

现代水文与空间数据采集技术

从基本定义、研究对象、研究领域、研究手段、研究方法、研究目的以及数据采集、服务等多个不同层面，对传统水文(学)和现代水文(学)进行了比较，分析了二者的特征和区别，论述了从传统水文向现代水文转变是现代水利的必然要求，而空间数据采集技术是实现这一转变极其重要的途径和手段。     

基于自平衡力的弹塑性动力反应分析方法

本文给出了一个基于自平衡力的弹塑性结构动力反应分析的新方法，详细叙述了方法的原理和过程，并对用改进的Ｔａｋｅｄａ滞变模型描述的梁单元框架结构给出了具体的分析方法。这个方法与传统的方法不同，在分析中不必修正结构的刚度矩阵，而代之以计算代表塑性铰变形引起的应力重分布的动力自平衡力，因而大大地节省了计算机时，最后通过算例对本文方法进行了验证。