Three-dimensional finite element simulation of fracture propagation in rock specimens with pre-existing fissure(s) under compression and their strength analysis     

Ramin Pakzad  Shanyong Wang  Scott W. Sloan 《国际地质力学数值与分析法杂志》2020,44(10):1472-1494

A FORTRAN program, consistent with the commercially available finite element (FE) code ABAQUS, is developed based on a three-dimensional (3D) linear elastic brittle damage constitutive model with two damage criteria. To consider the heterogeneity of rock, the developed FORTRAN program is used to set the stiffness and strength properties of each element of the FE model following a Weibull distribution function. The reliability of the program is assessed against available experimental results for granite cylindrical specimens with a throughgoing, flat and inclined fissure. The calibration procedure of the material parameters is explained in detail, and it is shown that the compressive to tensile strength ratio can have a substantial influence on the failure response of the specimens. Numerical simulations are conducted for models with different levels of heterogeneity. The results show a smaller load bearing capacity for models with less homogeneity, representing gradual coalescence of fully damaged elements forming throughout the models during loading. The maximum load bearing capacity is studied for various combinations of inclination angles of two centrally aligned, throughgoing and flat fissures of equal length embedded in cylindrical models under uniaxial and multiaxial loading conditions. The key role of the compressive to tensile strength ratio is highlighted by repeating certain simulations with a lower compressive to tensile strength ratio. It is proven that the peak loads of the rock models with sufficiently small compressive to tensile strength ratios containing two throughgoing fissures of equal length are similar, provided that the minimum inclination angles of the models are the same. The results are presented and discussed with respect to the existing experimental findings in the literature, suggesting that the numerical model applied in this study can provide useful insight into the failure behaviour of rock-like materials.  相似文献   

Solution to the rotation of the elastic earth by method of rigid dynamics     

Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》1990,50(2):165-187

Hamiltonian mechanics is applied to the problem of the rotation of the elastic Earth. We first show the process for the formulation of the Hamiltonian for rotation of a deformable body and the derivation of the equations of motion from it. Then, based on a simple model of deformation, the solution is given for the period of Euler motion, UT1 and the nutation of the elastic Earth. In particular it is shown that the elasticity of the Earth acts on the nutation so as to decrease the Oppolzer terms of the nutation of the rigid Earth by about 30 per cent. The solution is in good agreement with results which have been obtained by other, different approaches.  相似文献   

有限元法与伪谱法混合求解弹性波动方程   总被引：6，自引：0，他引：6  

马德堂  朱光明 《地球科学与环境学报》2004,26(1):61-64

在地震波场数值模拟中,有限差分法、有限元法和伪谱法都是常用的基本方法,但它们各有不同的适应性和优缺点,如有限差分法、有限元法都存在减弱网格频散和提高计算效率的矛盾,而伪谱法的网格频散小且计算效率高.有限差分法和伪谱法在处理地表结构复杂或地表剧烈起伏以及地下结构复杂的情况时存在较大的难度,而有限元法可较为理想地拟合起伏地表和任意弯曲界面,且可方便地处理自由边界条件和界面边界条件.尝试将有限元法和伪谱法相结合,形成地震波场数值模拟的一种混合方法,利用二者的优点,克服二者的缺点,达到既减弱网格频散又提高计算精度和效率的目的.并采用所谓的‘过度区域‘技术解决两种不同算法的衔接问题.模拟实例表明,给出的混合模拟方法不失为弹性波场数值模拟的一种有效方法.  相似文献   

阿尔金断裂昌马大坝—宽滩山段全新世活动特征   总被引：9，自引：2，他引：7  

陈柏林  刘建生  王春宇  张永双  刘建民  董诚  吴乃芬 《地质学报》2008,82(4):433-440

阿尔金断裂是我国西部著名的巨型走滑断裂带之一,也是全新世活动断裂和发震断裂。该断裂昌马大坝—宽滩山段运动方式为以左行走滑占主导,伴有弱的垂直运动;在距今2.7ka以来发生过明显的新构造活动（和地震）。在沙坪—宽滩山段全新世左行走滑位移速率为0.9～2.2mm/a,明显低于阿尔金断裂东段昌马大坝以西地区4～5mm/a和中西段9～11mm/a的位移速率。阿尔金断裂东段在肃北和昌马大坝出现二次位移速率的锐减,锐减的部分分别转化为海原活动断裂西段（党河南山断裂）和祁连山北缘活动断裂西段的左行走滑和逆冲,且在位移速率数值上相互之间具有非常好的对应性。阿尔金断裂在肃北位移速率减少部分（4.6mm/a）与海原活动断裂西段（党河南山断裂）的位移速率（4～5mm/a）非常接近,同样阿尔金断裂在昌马大坝位移速率减少部分（3.2mm/a）与祁连山北缘活动断裂的位移速率（3.0mm/a）也非常接近。  相似文献   

基于Poulos弹性理论的被动桩改进算法     

陈福全  黄伟达 《岩土力学》2008,29(4):905-910

传统的Poulos弹性理论仅适合于均质土中土体侧向位移时桩的性状分析,无法考虑土的层状特性。通过引入层状地基中作用一水平集中力的广义Mindlin解和地面作用有竖向荷载时的应力和位移通解,对Poulos方法进行了改进,使之扩展到多层土中,还用于研究堆载条件下的被动桩变形和受力响应。算例分析表明,改进弹性理论要比Poulos方法更为严密、合理,提高了计算精度,应用范围也更广。  相似文献   

冈底斯带东段鲁朗-墨脱地区中新世花岗岩的地球化学、年代学及成因     

耿全如  ;郑来林  ;董翰  ;孙志明  ;欧春生  ;王小伟 《中国区域地质》2008,(1):69-82

冈底斯东段的鲁朗-色季拉和墨脱-崩崩拉一带花岗岩的岩石类型主要为二长花岗岩、黑云母花岗岩、花岗闪长岩、石英闪长岩等。墨脱花岗岩的K—Ar年龄为19-22Ma;鲁朗花岗岩的^40Ar—^39Mr年龄为14-18Ma。岩石地球化学研究结果表明,本区花岗岩主要属于高钾钙碱性系列和钙碱性系列,同时具有某些埃达克岩的特征,表现为高SiO2（65．60％-76．40％）、Al2O3（12．32%-17．23％）、Sr／Y（2．41-86．46）、（La／Yb）。（6．65-56．14）比值,低Y（4．23×10^-6-39．40×10^-6）等特点。呈典型的LREE和LILE富集型分配模式．Eu为正到弱负异常。本区中新世花岗岩主要来源于中下陆壳的硅铝质成分和镁铁质成分的重熔,不同于具埃达克岩成分的冈底斯中新世含矿花岗斑岩。以中新世花岗岩侵位为标志,东喜马拉雅构造结地区的初始伸展可能在22Ma左右,早于冈底斯中段（20Ma左右）。  相似文献   

阿尔金南缘构造带西段辉绿岩墙群的地球化学特征及构造环境   总被引：5，自引：0，他引：5  

覃小锋  夏斌  李江  陆济璞  许华  周府生  胡贵昂  李乾 《岩石矿物学杂志》2008,27(1):14-22

对阿尔金南缘构造带西段辉绿岩墙群的岩石学和地球化学的详细研究表明,该区辉绿岩墙群为拉斑系列岩石,其主量元素以中等TiO2(1.19%～1.59%)、高MgO(5.51%～7.88%)、贫K2O(0.04%～0.84%)和P2O5(0.10%～0.20%)、Na2OK2O为特征;高场强元素(HFSE)丰度特征显示其为E-MORB型或过渡型玄武岩质岩石;稀土元素总量相对较高,轻重稀土元素分馏不显著[(La/Yb)N=1.93～3.61,LREE/HREE=3.01～4.10],在球粒陨石标准化配分模式图上呈略富集型.结合玄武岩构造环境判别图解综合分析推测,它们可能形成于一种裂谷向MORB环境过渡的构造环境,即初始小洋盆构造环境.  相似文献   

Reduction of hydroelastic responses of a very-long floating structure by a floating oscillating-water-column breakwater system     

D.C. Hong  S.Y. Hong  S.W. Hong 《Ocean Engineering》2006,33(5-6):610-634

The hydroelastic responses of a very-long floating structure (VLFS) placed behind a reverse T-shape freely floating breakwater with a built-in oscillating water column (OWC) chamber are analyzed in two dimensions. The Bernoulli–Euler beam equation is coupled with the equations of rigid and elastic motions of the breakwater and the VLFS. The interaction of waves between the floating rigid breakwater and the elastic VLFS is formulated in a consistent manner. It has been shown numerically that the structural deflections of the VLFS can be reduced significantly by a suitably designed reverse T-shape floating breakwater.  相似文献   

Analytic Solution of Interaction Between Surface Waves and Floating Elastic Plates with Elastic End-Restraints     

赵存宝张嘉钟  邢海燕黄文虎 《中国海洋工程》2007,21(1):23-38

Based on the dynamic theories of water waves and Mindlin plates,the analytic solution of interaction between surface waves and two-dimensional floating elastic plates with edge-restraint is constructed by use of the Wiener-Hopf technique.Firstly,without regard for elastic edge restraint,the wave-induced responses of elastic floating plate analyzed by the present method are in good agreement with the results from literature and experimental results.Therefore,it can be shown that the present method is valid.Secondly,three end-restraint cases(i.e.,the left-end elastic restraints,the both-end elastic restraints,and the right-end elastic restraints)are proposed to reduce the vibration of floating plates,in which the spring is used to connect the sea bottom and the floating plate's left(or right)edge.The relations between the spring stiffness and the parameters of wave-induced responses of floating plates are discussed.Moreover,the effective method to reduce the vibration of floating elastic plates can be obtained through comparison.  相似文献   

鲜水河断裂带炉霍段的水平运动及地震的重复性研究   总被引：5，自引：0，他引：5       下载免费PDF全文

杜其方 《地震地质》1989,11(4):31-42

本文讨论了鲜水河活动断裂带炉霍段的水平断错、古地震遗迹与地震重复间隔等问题。晚更新世以来断裂的平均滑动速率为13毫米/年。全新世中期以来大震的重复间隔时间小于600年  相似文献