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

X. B. Lu  Wang Shuyun  Wang Yihua  Peng Cui 《国际地质力学数值与分析法杂志》2004,28(15):1533-1541

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.  相似文献   

Plane of elastic non-resisting tension material under foundation structures     

A. Baratta  I. Corbi 《国际地质力学数值与分析法杂志》2004,28(6):531-542

In the frame of 2D-static problems one approaches the problem of elastic-NRT (not-resisting tension) semi-plane loaded on its limit line. This problem is intended to model the stress situation induced in the soil by a foundation structure. The solution, in terms of activated stress field, is searched for in the class of stress fields satisfying equilibrium and admissibility conditions, by applying an energy approach. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

毫秒级快速尖峰辐射事件的时间和频率特性     

马媛  谢瑞祥 《天文研究与技术》2001,(1):26-31

介绍了太阳22周峰年期间云南天文台米波射电频谱仪的观测结果。主要对1557个单个Spike的时间和频率分布作了统计分析，着重指出太阳快速精细结构的观测特征并定性地指出其产生机制。  相似文献   

Microboudin structures of piemontite along the Sambagawa metamorphic belt, Japan: implications for lateral variation of differential stress during regional metamorphism     

T. Masuda  T. Shibutani  T. Ochiai  S. Akagi  H. Yamaguchi  Y. Kugimiya  N. Kimura  T. Miyake 《Journal of Metamorphic Geology》2004,22(3):199-205

Evidence is presented of a lateral variation in differential stress during metamorphism along a regional metamorphic belt on the basis of the proportion of microboudinaged piemontite grains (p) in a quartz matrix in metacherts. It is proposed that p is a practical indicator of relative differential stress. Analysis of 123 metacherts from the 800 km long Sambagawa metamorphic belt, Japan, reveals that p‐values range from < 0.01 to 0.7 in this region. Most samples from Wakayama in the mid‐belt area have p‐values of 0.4–0.6, whereas those from western Shikoku have p‐values of < 0.1. This difference cannot be explained by variations in metamorphic temperature, and is instead attributed to a regional, lateral variation in differential stress during metamorphism.  相似文献   

Structures in the phase space of a four dimensional symplectic map     

Ch. Skokos  G. Contopoulos  C. Polymilis 《Celestial Mechanics and Dynamical Astronomy》1996,65(3):223-251

We numerically investigate the projections of non periodic orbits in a 4-dimensional (4-D) symplectic map composed of two coupled 2-dimensional (2-D) maps. We describe in detail the structures that are produced in different planes of projection and we find how the morphology of the 4-D orbits is influenced by the features of the 2-D maps as the coupling parameter increases. We give an empirical law that describes this influence.  相似文献   

STUDY ON GIS FOR YIELD ESTIMATION BY REMOTE SENSING IN JILIN MAIZE BELT     

Liu Xiangnan  Huang Fang  Zhou Zhanao 《中国地理科学(英文版)》1996,6(4):351-358

ＳＴＵＤＹ　ＯＮ　ＧＩＳ　ＦＯＲ　ＹＩＥＬＤ　ＥＳＴＩＭＡＴＩＯＮ　ＢＹ　ＲＥＭＯＴＥ　ＳＥＮＳＩＮＧ　ＩＮ　ＪＩＬＩＮ　ＭＡＩＺＥ　ＢＥＬＴＳＴＵＤＹＯＮＧＩＳＦＯＲＹＩＥＬＤＥＳＴＩＭＡＴＩＯＮＢＹＲＥＭＯＴＥＳＥＮＳＩＮＧＩＮＪＩＬＩＮＭＡＩＺ...  相似文献   

Fast iterative solution of large undrained soil‐structure interaction problems     

Kok‐Kwang Phoon  Swee‐Huat Chan  Kim‐Chuan Toh  Fook‐Hou Lee 《国际地质力学数值与分析法杂志》2003,27(3):159-181

In view of rapid developments in iterative solvers, it is timely to re‐examine the merits of using mixed formulation for incompressible problems. This paper presents extensive numerical studies to compare the accuracy of undrained solutions resulting from the standard displacement formulation with a penalty term and the two‐field mixed formulation. The standard displacement and two‐field mixed formulations are solved using both direct and iterative approaches to assess if it is cost‐effective to achieve more accurate solutions. Numerical studies of a simple footing problem show that the mixed formulation is able to solve the incompressible problem ‘exactly’, does not create pressure and stress instabilities, and obviate the need for an ad hoc penalty number. In addition, for large‐scale problems where it is not possible to perform direct solutions entirely within available random access memory, it turns out that the larger system of equations from mixed formulation also can be solved much more efficiently than the smaller system of equations arising from standard formulation by using the symmetric quasi‐minimal residual (SQMR) method with the generalized Jacobi (GJ) preconditioner. Iterative solution by SQMR with GJ preconditioning also is more elegant, faster, and more accurate than the popular Uzawa method. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

再论贺兰山南部北西向构造成因   总被引：3，自引：0，他引：3  

张进  马宗晋  任文军 《地球科学与环境学报》2005,27(1):19-25,29

贺兰山南部分布着多个方向的构造，其中最明显地是一系列的北西向构造，目前这些构造的相互关系以及形成机制还没有得到合理地解释，争论很大；野外构造研究表明，贺兰山南部北西向构造的形成与青铜峡一固原断裂活动有密切的关系，是该断裂由走滑运动向挤压运动转换时的派生构造；从另一角度也说明，在中新生代由青铜峡一固原断裂所限定的地块(卫宁北山)向东运动，而这些北西向构造的形成主要发生在新生代。由于卫宁北山向东运动的动力来源于青藏高原，因此，贺兰山南部北西向构造的形成与青藏高原的演化有密切的联系。所以。作为中国重要地质界限的南北向构造——贺兰山已经被青藏高原的构造活动所叠加。  相似文献   

Biogeochemical characteristics of the Hetai goldfield, Guangdong Province, China     

Li Miao  Ruisong Xu  Yueliang Ma  Jinhong Xu  Jie Wang  Rui Cai  Yu Chen   《Journal of Geochemical Exploration》2008,96(1):43-52

In the Hetai goldfield, Guangdong Province, China, samples including rocks, soils and leaves of four plants (Pinus massoniana, Rhodomyrms tomenlosa, D. linearis var. dichotoma and Embelia laeta) collected from the gold mineralization zone and the background area were analyzed for Au, Ag, Cu, Pb, Zn, Hg, As and physiological parameters. The objective of this investigation is to study the geochemical and biogeochemical characteristics of studied plants, aiming at biogeochemical methods in Au exploration. The goldfield region shows geochemical and biogeochemical anomalies. Abundances of Au in rocks, soils, plants and the leaf pigments in the mineralized area are much higher than those in the surrounding region. The plants display unhealthy physiological and ecological characteristics in the Hetai goldfield area. The cell structures of the goldfield plants were anomalous and aberrant, and there were many nano-metal particles diffused in mitochondria and chloroplasts. Macro- and microscopic evidences of the vegetation in the goldfield areas are distinctly different from the background regions. The strongly anomalies in responses to Au are profound in further geochemical and botanic exploration studies.  相似文献   

引水工程秦巴段隧洞地应力模拟及工程地质问题     

李东林  吴树仁  韩金良  刘景儒 《地质与勘探》2008,44(5):81-86

利用Ansys有限元软件对三峡引水工程秦巴段线路不同深度、不同截面形态隧洞围岩的应力重分布情况进行模拟计算,得到圆形隧洞、城门形隧洞和马蹄形隧洞围岩的应力数值和等值线图.利用库仑一纳维尔强度准则,对花岗岩区及灰岩区隧洞围岩的剪切破坏进行分析;利用三种岩爆应力判别指标,对岩爆进行初步预测;进而对不同深度、不同截面形态的隧洞围岩的稳定性进行分析;最后对引水工程隧洞设计中截面形态的选择给出了初步建议.  相似文献