地震面波产生的地震动转动分量研究   总被引：7，自引：0，他引：7  

李宏男  孙立晔 《地震工程与工程振动》2001,21(1):15-23

本文利用弹性波动理论对地面转动分量，即瑞利（Rayleigh)波和乐夫（Love)波产生的转动分量进行了研究，给出了相应的计算公式和计算方法，特别注意到面波的散射效应对转动分量的影响，并将这一特性引入到转动分量的求取中，使问题的解决更切合于实际，最后选取实际地震记录，利用得到的公式计算出地震面波产生的转动分量。  相似文献   

Unrestricted Planar Problem of a Symmetric Body and a Point Mass. Triangular Libration Points and Their Stability     

Krzysztof Goździewski  Andrzej J. Maciejewski 《Celestial Mechanics and Dynamical Astronomy》1999,75(4):251-285

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Numerical local analysis of relevant internal variables for constitutive modelling of granular materials     

Yuhanis Yunus  Eric Vincens  Bernard Cambou 《国际地质力学数值与分析法杂志》2010,34(11):1101-1123

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Development in modeling cyclic loading of sands based on kinematic hardening     

Mohammad Maleki  Bernard Cambou  Philppe Dubujet 《国际地质力学数值与分析法杂志》2009,33(14):1641-1658

In this paper, there is presented an elastoplastic constitutive model to predict sandy soils behavior under monotonic and cyclic loadings. This model is based on an existing model (Cambou‐Jafari‐Sidoroff) that takes into account deviatoric and isotropic mechanisms of plasticity. The flow rule used in the deviatoric mechanism is non‐associated and a mixed hardening law controls the evolution of the yield surface. In this research the critical state surface and history surface, which separates the virgin and cyclic states in stress space, are defined. Kinematic hardening modulus and stress–dilatancy law for monotonic and cyclic loadings are effectively modified. With taking hardening modulus as a function of deviatoric and volumetric plastic strain and with defining the history surface and stress reversal, the model has the ability to predict the sandy soils' behavior. All of the model parameters have clear physical meanings and can be determined from usual laboratory tests. In order to validate the model, the results of homogeneous tests on Hostun and Toyoura sands are used. The results of validation show a good capability of the proposed model. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

强质子耀斑活动区的形态和旋转特征     

周树荣 《中国天文和天体物理学报》1996,(3)

本文研究结果表明：同一黑子群在日面期间的顺或反时针方向的旋转运动会先后并存．质子耀斑前1～2无，黑子群的旋转角速度达到极大．耀斑后，磁绳的松弛，黑子群可能会反向旋转，强的剪切过程和质子耀斑可能会再度出现．强质子耀斑活动区的共同特征是：（1）形态为单个团状结构δ型黑子，即众多异极性本影核紧锁在同一黑子半影中；（2）黑子面积＞1000×10－6半球面积，日面跨度＞10°；（3）黑子群都有快速的旋转运动．这类活动区，如果在日面西部活动性明显地增强，那么这个活动区在未来转到日面边缘及其背后、或再次从日面东边缘转出时，定能再次爆发耀斑和伴随较强质子事件。  相似文献   

单机械手夹持状态下钻杆运移平稳性分析          下载免费PDF全文

李昊轩  王清岩  金赠伍  李苓豪  郭乃铭 《探矿工程》2022,49(3):76-82

本文主要针对一种新型的可以保留钻杆旋转自由度的机械手,研究其运移钻杆时的稳定性和安全性是否满足要求。该机械手通过蓄能器提高了停泵保压效果,通过滚轮结构保留了钻杆的旋转自由度。本文建立了机械手的多体动力学模型及配套的液压控制回路,并进行机-液联合仿真分析。在分别改变钻杆直径和液压回路压力的条件下,观察机械手夹紧效果。通过仿真得到了钻杆的夹紧力变化曲线及钻杆重心位置变化曲线,确定了液压系统的许用压力范围,并验证了单机械手夹持状态下钻杆运移平稳性满足要求。  相似文献   

描述饱和黏性土应变软化的弹塑性双面模型     

张涛  李涛  冯硕 《岩土力学》2022,43(10):2757-2767

常规三轴压缩试验中具有较强结构性的黏性土在围压较低时其应力−应变关系会呈现应变软化现象,一般还伴有塑性变形,通常土体内部结构损伤是应变软化产生的主要原因。考虑到采用经典塑性理论描述材料的应变软化不仅会违背 Drucker 的稳定性假设,而且也不能描述卸载塑性。因此,基于修正剑桥模型及 Li 和 Meissner 提出的塑性硬化准则,建立了一个描述饱和黏性土不排水应变软化的弹塑性双面模型。该模型以应力−应变曲线的峰值点分界,将应变硬化和应变软化分别作为独立的加载事件进行分析,同时引入新的结构性参数表征剪切过程中土体结构损伤导致的塑性刚度衰退。对不同固结状态饱和结构性黏土的三轴固结不排水压缩试验结果的模拟表明,所建模型能够较好地描述饱和黏性土的不排水应变软化特性。  相似文献   

Polygonal deformation bands     

《Journal of Structural Geology》2015

We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are shear deformation bands that developed under shallow burial conditions via strain hardening in dm-wide zones. The edges of the polygons are 1–5 m long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain <0.005). The individual shear deformation bands show abutting T-junctions, veering, curving, and merging where they mechanically interact. Crosscutting relationships are rare. The interactions of the deformation bands are similar to those of mode I opening fractures. The documented fault networks have important implications for evaluating the geometry of km-scale polygonal fault systems in the subsurface, top seal integrity, as well as constraining paleo-tectonic stress regimes.  相似文献   

The anomalous demagnetization of pyrrhotite     

George F. Thomson 《Geophysical Journal International》1990,103(2):425-430

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Invariant rotational curves in Sitnikov's Problem     

J. Martínez Alfaro  Cristina Chiralt 《Celestial Mechanics and Dynamical Astronomy》1993,55(4):351-367

The Sitnikov's Problem is a Restricted Three-Body Problem of Celestial Mechanics depending on a parameter, the eccentricity,e. The Hamiltonian,H(z, v, t, e), does not depend ont ife=0 and we have an integrable system; ife is small the KAM Theory proves the existence of invariant rotational curves, IRC. For larger eccentricities, we show that there exist two complementary sequences of intervals of values ofe that accumulate to the maximum admissible value of the eccentricity, 1, and such that, for one of the sequences IRC around a fixed point persist. Moreover, they shrink to the planez=0 ase tends to 1.  相似文献