Strain localization due to structural in-homogeneities in the Central European Basin System     

Mauro Cacace  Ulf Bayer  Anna Maria Marotta 《International Journal of Earth Sciences》2008,97(5):899-913

The large-scale crustal deformations observed in the Central European Basin System (CEBS) are the result of the interplay between several controlling factors, among which lateral rheological heterogeneities play a key role. We present a finite-element integral thin sheet model of stress and strain distribution within the CEBS. Unlike many previous models, this study is based on thermo-mechanical data to quantify the impact of lateral contrasts on the tectonic deformation. Elasto-plastic material behaviour is used for both the mantle and the crust, and the effects of the sedimentary fill are also investigated. The consistency of model results is ensured through comparisons with observed data. The results resemble the present-day dynamics and kinematics when: (1) a weak granite-like lower crust below the Elbe Fault System is modelled in contrast to a stronger lower crust in the area extending north of the Elbe Line throughout the Baltic region; and (2) a transition domain in the upper mantle is considered between the shallow mantle of the Variscan domain and the deep mantle beneath the East European Craton (EEC), extending from the Elbe Line in the south till the Tornquist Zone. The strain localizations observed along these structural contrasts strongly enhance the dominant role played by large structural domains in stiffening the propagation of tectonic deformation and in controlling the basin formation and the evolution in the CEBS.  相似文献   

分布式光纤传感技术在滑坡监测中的应用   总被引：5，自引：1，他引：4  

史彦新  张青  孟宪玮 《吉林大学学报(地球科学版)》2008,38(5)

将分布式光纤传感技术引入滑坡监测,既可得到整个滑坡体的概要特征,又能提高监测效率。FBG与BOTDR是两种最具代表性的分布式光纤传感技术,FBG通过测量其反射光波长的变化获得应变或温度值。BOTDR通过测定后向布里渊散射光的频移实现分布式温度、应变测量。FBG传感器灵敏度高,但只能实现离散点的准分布式测量,BOTDR可实现分布式、长距离、不间断测量,但其空间分辨率不高。笔者提出FBG与BOTDR联合监测滑坡的方案。在巫山残联滑坡,在整个滑坡体上铺设监测光纤,利用BOTDR获得整个滑坡体的概要信息;在滑坡体变形的关键部位———变形缝安装FBG传感器,获得某些关键部位的应变信息,从而实现由点到线再到面的监测,获得滑坡体较完整的应变信息。  相似文献   

Strain analysis in Jurassic argillites of the Monte Sirino area (Lagonegro Zone,southern Apennines,Italy) and implications for deformation paths in pelitic rocks     

S. Mazzoli 《International Journal of Earth Sciences》1995,84(4):781-793

Analysis of strain in Jurassic argillites forming part of the folded and thrusted sedimentary succession of the Lagonegro basin (southern Italian Apennines) has been carried out using ellipsoid-shaped reduction spots as strain markers. Most of the determined finite strain ellipsoids are of oblate type and show a peculiar distribution of the maximum extension direction (X), with maxima either subparallel or subperpendicular to the local fold axes. Using the strain matrix method, two different deformation histories have been considered to assist the interpretation of the observed finite strain pattern. A first deformation history involved vertical compaction followed by horizontal shortening (occurring by a combination of true tectonic strain and volume loss), whereby all strain is coaxial and there is no change in the intermediate axis of the strain ellipsoid. By this type of deformation sequence, which produces a deformation path where total strain moves from the oblate to the prolate strain field and back to the oblate field, prolate strain ellipsoids can be generated and may be recorded where tectonic deformation has not been large enough to reverse pretectonic compaction. This type of deformation history may be of local importance within the study area (i.e. it may characterize some fold hinge regions) and, more generally, is probably of limited occurrence in deformed pelitic rocks. A second deformation sequence considered the superposition of pre-tectonic compaction and tectonic strain consisting of initial layer-parallel shortening followed by layer-parallel shear (related to flexural folding). Also in this instance, volume change during tectonic deformation and tectonic plane strain have been assumed. For geologically reasonable amounts of volume loss due to compaction and of initial layer-parallel shortening, this type of deformation history is capable of producing a deformation path entirely lying within the oblate strain field, but still characterized by a changeover, during deformation, of the maximum extension axis (X) from a position parallel to the fold axis to one perpendicular to it. This type of deformation sequence may explain the main strain features observed in the study area, where most of the measured finite strain ellipsoids, determined from the limb regions of flexural folds, display an oblate shape, irrespective of the orientation of their maximum extension direction (X) with respect to the local structural trends. More generally, this type of deformation history provides a mechanism to account for the predominance of oblate strains in deformed pelitic rocks.  相似文献   

Uniaxial compression and tension tests of anthracite and loading rate dependence of peak strength   总被引：2，自引：0，他引：2  

S. Okubo  K. Fukui  Qi Qingxin 《International Journal of Coal Geology》2006,68(3-4):196-204

The mechanical characteristics of coal under uniaxial compressive stress and uniaxial tensile stress are key factors in investigations of the stability of galleries and coal faces, and are vital considerations for the efficient design of coalmines, disaster prevention, and environmental preservation. These mechanical characteristics have long been a topic of research, but remain insufficiently understood. In this study we performed uniaxial compression tests and uniaxial tension tests on coal, with particular attention to two concerns. The first was to measure the loading rate dependence of the peak strength of coal. Coal shows high sample-to-sample scatter in strength; test methods that are successful in comparatively homogeneous rock types cannot be used for coal. We therefore used an alternative test method that was recently developed by the authors. Anthracite samples were subjected to alternating slow and fast strain rates. Measured variations in stress during this process were used to estimate the loading rate dependence of peak strength. The second objective was to obtain complete stress–strain curves for coal under uniaxial tensile stress. It is difficult to hold samples secure during a tensile test; consequently, such curves have yet to be obtained. This study presents a successful application of the authors' method to the analysis of coal samples, yielding a complete stress–strain curve under tensile stress. The two methods presented here hold promise for application not only to anthracite but also to a wide variety of coals. It is possible to derive the values of the constants used in constitutive equations from the obtained experimental results. Once these equations are determined, they can be incorporated into finite-element software to investigate various time-dependent behaviors of coal and aid in the efficient design of coalmines and the prevention of subsidence and mine disasters.  相似文献   

Experimental and numerical studies of rock salt strain hardening     

M. Hamami 《Geotechnical and Geological Engineering》2006,24(5):1271-1292

The work presented in this paper comes as part of a research program dealing with the thermomechanical behaviour of rock salt. It aims to study laboratory and in-situ long-term behaviour by means of creep tests with deviator and temperature changes. The laboratory results, using a triaxial multi-stages creep tests, highlighted the strain hardening character of rock salt. Furthermore, the in-situ results, using a borehole dilatometer multi-step creep test, have shown that the drilling is carried out in a weakly stressed pillar. The interpretation of the laboratory results, using the J.LEMAITRE law, did not indicate full agreement with all the test results. As a result a ‘double’ J.LEMAITRE model, which takes into account a double strain hardening variable, has been put forward. The validation of this model on the laboratory creep tests is very satisfactory. Furthermore, the activation energy seems satisfactory to represent the influence of the temperature. The in-situ behaviour modelling is clearly more complex than the modelization based on laboratory tests. In fact, it seems that if the rock salt behaviour is maintained by J.LEMAITRE law, it is necessary to vary with the stress, at least, one of the parameters assumed constant in the basic law.  相似文献   

吉林台爆破料应力应变关系的三轴试验研究     

侯新强  张远芳  高盟  慈军  刘红  张之科 《新疆地质》2005,23(2):194-198

通过室内大型三轴实验，研究了吉林台水库爆破料在不同级配下的应力应变关系，得到了在一定击实功下爆破料的最大干密度随细料含量变化的规律，分析了爆破料在不同级配和不同围压下应力与应变的变化规律、轴向应变与体积应变的关系及抗剪强度变化特性．从微观的角度说明了变化规律产生的原因，得出爆破料的抗剪强度随级配的变化而变化的规律．  相似文献   

过硫酸铵氧化容量法测定矿石中锰方法的改进   总被引：5，自引：1，他引：5  

范福南 《岩矿测试》2005,24(3):235-236

采用过硫酸铵氧化容量法测定锰时,可在低酸度(0.18mol/LH2SO4、0.29mol/LH3PO4)和大体积(300mL)溶液中氧化Mn2 至Mn7 。所测得的结果十分稳定,回收率为100%。采用管理样分析验证方法,其结果与铋酸钠容量法结果一致。对于w(Mn)=11.36%的试样进行10次分析测定,RSD=0.33%。方法可测定w(Mn)≥0.01%的常见矿种样品。  相似文献   

绿片岩三轴流变力学特性的研究(Ⅰ):试验结果   总被引：17，自引：4，他引：17  

徐卫亚  杨圣奇  杨松林  谢守益  邵建富  王义锋 《岩土力学》2005,26(4):531-537

为了解锦屏一级水电站坝基绿片岩的流变力学特性，采用岩石全自动流变伺服仪对绿片岩进行了三轴压缩流变试验。基于试验结果，研究了绿片岩在不同围压作用下的轴向应变以及侧向应变随时间的变化规律，讨论了流变特性对岩石应力一应变曲线的影响，探讨了不同应力水平下的轴向以及侧向流变速率变化趋势，分析了不同围压下流变的破裂机制，掌握了绿片岩三轴流变的基本规律，从而为该水电站工程流变数值分析时参数的辨识提供了可靠的依据。  相似文献   

抽水引起的含水层水平应变──地裂缝活动新机理   总被引：13，自引：0，他引：13  

王庆良  刘玉海  陈志新  王文萍 《工程地质学报》2002,10(1):46-50

基于Darcy -Gersevanov广义渗流关系式 ,本文首先导出了单井定流量抽水引起的泰斯承压含水层水平运动和应变解析表达式 ,并据此提出了抽水诱发地裂缝活动的含水层水平应变新机理 ,其主要观点为 :受井栅的约束阻挡作用 ,抽水活动将在含水层内部形成近井径向挤压区和远井径向拉张区两个应变区域 ,随着抽水时间的增长 ,近井径向挤压区将逐渐向外扩展 ;当地裂缝及其下伏断层或裂隙位于抽水活动引起的径向拉张应变区域时 ,地裂缝将出现加速活动 ;反之 ,当地裂缝处于抽水活动引起的径向挤压应变区域时 ,地裂缝活动反而受到抑制。上述地裂缝活动机理通过大同机车工厂现场抽水实验得到了初步证实。  相似文献   

Pseudodynamic tests on rubber base isolators with numerical substructuring of the superstructure and strain‐rate effect compensation     

F. J. Molina  G. Verzeletti  G. Magonette  Ph. Buchet  V. Renda  M. Geradin  A. Parducci  M. Mezzi  A. Pacchiarotti  L. Federici  S. Mascelloni 《地震工程与结构动力学》2002,31(8):1563-1582

A pseudodynamic testing procedure has been applied by which the seismic response of a base‐isolated building is obtained by using as specimen the isolators, while the superstructure is numerically simulated. The procedure also takes advantage of the continuous pseudodynamic testing capabilities of the ELSA laboratory, which increase the accuracy of the results and reduce the strain‐rate effect of the rubber bearings. A simple proportional correction of the measured forces compensates the remaining strain‐rate effect due to the unrealistic speed of the test. The correction factor is obtained by means of a characterizing test on the specific rubber isolators. The developed method has been successfully applied to the prediction of the seismic response of a base‐isolated four‐storey building submitted to several specified accelerograms. The results for those earthquakes as well as the effects of some changes of the parameters of the system are discussed. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献