基于新型损伤定义的岩石损伤统计本构模型探讨   总被引：10，自引：2，他引：8  

曹文贵  张升  赵明华 《岩土力学》2006,27(1):41-46

针对几何损伤理论中损伤定义的局限性与不足,对岩石损伤定义进行了改进;在此基础上,将在应力作用下的岩石材料抽象为破坏与未破坏两部分,并根据这两部分不同的受力情况,建立出新型损伤模型;其次,利用统计损伤理论,建立出岩石统计损伤演化方程,进而建立起基于特定围压下的岩石损伤统计本构模型;然后,通过探讨模型参数与围压的经验关系,对模型进行合理修正,从而建立了反映不同围压条件下的岩石损伤统计本构模型,并通过探讨模型参数的物理意义,初步建立了反映岩石软化与硬化特性相互转化的临界物理力学参数的确定方法。该模型能够反映岩石软化与硬化特性相互转化的特征,与试验结果进行比较分析表明,该模型与实测结果吻合良好。  相似文献   

Fire decreases near‐surface hydraulic conductivity and macropore flow in blanket peat          下载免费PDF全文

Joseph Holden  Catherine Wearing  Sheila Palmer  Benjamin Jackson  Kerrylyn Johnston  Lee E. Brown 《水文研究》2014,28(5):2868-2876

Many peatlands have been subjected to wildfire or prescribed burning, but it is not known how these fires influence near‐surface hydrological processes. Macropores are important flowpaths in the upper layers of blanket peat and were investigated through the use of tension disc infiltrometers, which also provide data on saturated hydraulic conductivity. Measurements were performed on unburnt peat (U), where prescribed burning had taken place 2 years (B2), 4 years (B4) and >15 (B15+) years prior to sampling, and where a wildfire (W) had taken place 4 months prior to sampling. Where there had been recent burning (B2, B4 and W), saturated hydraulic conductivity was approximately three times lower than where there was no burning (U) or where burning was last conducted >15 years ago (B15+). Similarly, the contribution of macropore flow to overall infiltration was significantly lower (between 12% and 25% less) in the recently burnt treatments compared to B15+ and U. There were no significant differences in saturated hydraulic conductivity or macropore flow between peat that had been subject to recent wildfire (W) and those that had undergone recent prescribed burning (B2 and B4). The results suggest that fire influences the near‐surface hydrological functioning of peatlands but that recovery in terms of saturated hydraulic conductivity and macropore flow may be possible within two decades if there are no further fires. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Cavity expansion in strain hardening frictional soils under drained condition          下载免费PDF全文

S.L. Chen  Y.N. Abousleiman 《国际地质力学数值与分析法杂志》2018,42(1):132-142

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Coupling of BEM with a large displacement and rotation algorithm     

Pooyan Asadollahi  Fulvio Tonon 《国际地质力学数值与分析法杂志》2011,35(7):749-760

In stability analysis of rock blocks, the deformability of the blocks can conveniently be simulated using the boundary element method (BEM). However, all boundary conditions are given as stresses. Thus, the displacement solution is not unique. In this paper, an algorithm is proposed to remove rigid body motions in the solution of the boundary form of Somigliana identity discretized by the direct BEM formulation. The algorithm is applied to the calculation of the normal stiffness of rock blocks and coupled with BS3D, large displacement and rotation algorithm for the general stability of rock blocks. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Discrete element method analysis of non‐coaxial flow under rotational shear     

Zhaoxia Tong  Pengcheng Fu  Yannis F. Dafalias  Yangping Yao 《国际地质力学数值与分析法杂志》2014,38(14):1519-1540

This study focuses on non‐coaxial flow behavior of cohesionless soil undergoing cyclic rotational shear, with a special interest in the effects of particle‐scale characteristics. To this end, we perform a series of 2D discrete element simulations with various particle shapes, inter‐particle coefficient of friction, initial density, and stress ratios. The validity and efficacy of the numerical model is established by systematically comparing numerical simulation results with existing laboratory testing results. Such comparison shows that the numerical simulations are capable of capturing mechanical behavior observed in laboratory testing under rotational shear. We further demonstrate and quantify a strong yet simple relationship between the deviatoric part of the normalized strain increment and the non‐coaxial angle, denoted by and ψ, respectively. This quantitative correlation between ψ and is independent of applied stress ratio, initial and current void ratio, and the number of cycles applied, but dependent on the principal stress orientation and particle‐scale characteristics. At the same , specimens with higher inter‐particle friction angle or smaller particle aspect ratio show greater non‐coaxial angles. A simple model is able to fit this ψ‐ relationship well, which provides a useful relationship that can be exploited in developing constitutive models for rotational shearing. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Laboratory studies of the HNCO molecular spectrum for precise spectroscopy of dark clouds     

A. V. Lapinov  G. Yu. Golubiatnikov  V. N. Markov  A. Guarnieri 《Astronomy Letters》2007,33(2):121-129

Detailed studies of the internal motions of dark clouds using spectral lines of many molecules require a laboratory frequency accuracy of the order of a few m s^?1. Based on our laboratory studies of the HNCO rotational spectrum in the ground vibrational state, we have increased significantly the accuracy of frequency calculation in a wide range of quantum numbers. We have achieved an (1σ) uncertainty for rotational transitions in the K _a = 0, 1 states recalculated to the Doppler velocity scale ≤2 m s^?1 for all frequencies <1.1 THz. This value allows radio-astronomical measurements with an accuracy comparable to that of the highest-precision observations based on spectral lines of other molecules.  相似文献   

A new approach to anisotropic,bounding surface plasticity: general formulation and simulations of natural and reconstituted clay behaviour     

A. Gajo  D. Muir Wood 《国际地质力学数值与分析法杂志》2001,25(3):207-241

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孟加拉湾风暴暴雨的能量分析   总被引：1，自引：0，他引：1  

许美玲  段旭  张秀年 《成都信息工程学院学报》2006,21(2):277-282

利用MMSV3中尺度数值预报模式对2004年5月18-19日造成云南暴雨过程的孟湾风暴进行了数值模拟，在模拟结果与实况较为一致的基础上，利用辐散风和旋转风动能平衡方程，分析盂湾风暴的能量收支和转换特征，揭示孟加拉湾风暴维持的机制及其与外围暴雨增幅的关系。  相似文献   

Compaction process in sedimentary basins: the role of stiffness increase and hardening induced by large plastic strains     

V. Deud  L. Dormieux  S. Maghous  J. F. Barthlmy  D. Bernaud 《国际地质力学数值与分析法杂志》2004,28(13):1279-1303

This paper is devoted to the simulation of large strain compaction process in sedimentary basins. Special attention is paid to the effects of large porosity changes on the elastic and plastic mechanical properties of the sediment material. The latter are introduced in the constitutive behaviour in the framework of a micromechanical reasoning. In particular, the proposed approach avoids the problem of negative porosities that are predicted by classical models under high confining pressures. Some closed‐form solutions are presented in the simplified case of one‐dimensional compaction. While the influence of stiffness increase is shown to be negligible as regards the compaction law, it proves to affect significantly the stress and porosity profiles. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

关于地震动转动分量的研究   总被引：2，自引：0，他引：2  

何超  罗奇峰  洪钟 《地震研究》2011,34(1)

列举了多次地震中的地震动转动现象,概括了国内外对地震动转动分量的产生、传播、合成方法及其对结构的作用等方面的研究成果.还介绍了由地震动平动分量计算转动分量的弹性波动方法,并讨论了其局限性;还介绍了欧洲规范对转动分量的部分规定,指出有必要在结构抗震设计中考虑转动分量的作用.此外,在转动分量的产生、对结构的作用及数值模拟方面还做了一些假设与解释.  相似文献