Numerical prediction of blast‐induced stress wave from large‐scale underground explosion     

Chengqing Wu  Yong Lu  Hong Hao 《国际地质力学数值与分析法杂志》2004,28(1):93-109

This paper presents a numerical model for predicting the dynamic response of rock mass subjected to large‐scale underground explosion. The model is calibrated against data obtained from large‐scale field tests. The Hugoniot equation of state for rock mass is adopted to calculate the pressure as a function of mass density. A piecewise linear Drucker–Prager strength criterion including the strain rate effect is employed to model the rock mass behaviour subjected to blast loading. A double scalar damage model accounting for both the compression and tension damage is introduced to simulate the damage zone around the charge chamber caused by blast loading. The model is incorporated into Autodyn3D through its user subroutines. The numerical model is then used to predict the dynamic response of rock mass, in terms of the peak particle velocity (PPV) and peak particle acceleration (PPA) attenuation laws, the damage zone, the particle velocity time histories and their frequency contents for large‐scale underground explosion tests. The computed results are found in good agreement with the field measured data; hence, the proposed model is proven to be adequate for simulating the dynamic response of rock mass subjected to large‐scale underground explosion. Extended numerical analyses indicate that, apart from the charge loading density, the stress wave intensity is also affected, but to a lesser extent, by the charge weight and the charge chamber geometry for large‐scale underground explosions. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

武汉区域气象中心数值预报业务并行计算机系统     

龚贤创  范宏飞  余康庆  王宏记 《成都信息工程学院学报》2002,17(4):236-239

对武汉区域气象中心并行计算机系统进行了详细地介绍，分析了并行计算机体系结构、网络和存储系统特点；给出了在并行计算机SP上实现数值预报业务并行化的部分结果；对数值预报模式在串、并行编程环境下的结果进行了分析比较。  相似文献   

测绘科技进步的研究与测算     

卢萍 《地理信息世界》2001,(3)

科技进步是测绘事业发展的动力 ,讨论运用科技进步的评价指标 ,对测绘单位的科技进步速度和对经济增长的贡献等进行测算和分析 ,可以为测绘规划管理及决策提供参考。  相似文献   

DCMT光电扫描主测微器的设计与研究     

李志刚  李焕信  方福胜  朱紫  许林生 《时间频率学报》1993,(1)

DCMT主测微器不同于其它类型的子午环测微器,它具有自校准测定仪器参数的功能。该测微器采用了活动光栅的方案,其优点是能观测近极星和各类准直像;活动光栅另一个显著优点是不同赤纬星几乎可用相同的观测时间.对“V”形光栅的工作原理和误差进行了详细讨论,并给出了一组严格的公式。其系统误差来源有:光栅形状改正、光栅驱动方向相对于光栅的倾斜、光栅驱动方向相对于赤径方向的倾斜、星径曲率改正。  相似文献   

Dynamical History of the Earth–Moon System     

G. A. Krasinsky 《Celestial Mechanics and Dynamical Astronomy》2002,84(1):27-55

Differential equations describing the tidal evolution of the earth's rotation and of the lunar orbital motion are presented in a simple close form. The equations differ in form for orbits fixed to the terrestrial equator and for orbits with the nodes precessing along the ecliptic due to solar perturbations. Analytical considerations show that if the contemporary lunar orbit were equatorial the evolution would develop from an unstable geosynchronous orbit of the period about 4.42 h (in the past) to a stable geosynchronous orbit of the period about 44.8 days (in the future). It is also demonstrated that at the contemporary epoch the orbital plane of the fictitious equatorial moon would be unstable in the Liapunov's sense, being asymptotically stable at early stages of the evolution. Evolution of the currently near-ecliptical lunar orbit and of the terrestrial rotation is traced backward in time by numerical integration of the evolutional equations. It is confirmed that about 1.8 billion years ago a critical phase of the evolution took place when the equatorial inclination of the moon reached small values and the moon was in a near vicinity of the earth. Before the critical epoch t _cr two types of the evolution are possible, which at present cannot be unambiguously distinguished with the help of the purely dynamical considerations. In the scenario that seems to be the most realistic from the physical point of view, the evolution also has started from a geosynchronous equatorial lunar orbit of the period 4.19 h. At t < t _cr the lunar orbit has been fixed to the precessing terrestrial equator by strong perturbations from the earth's flattening and by tidal effects; at the critical epoch the solar perturbations begin to dominate and transfer the moon to its contemporary near-ecliptical orbit which evolves now to the stable geosynchronous state. Probably this scenario is in favour of the Darwin's hypothesis about originating the moon by its separation from the earth. Too much short time scale of the evolution in this model might be enlarged if the dissipative Q factor had somewhat larger values in the past than in the present epoch. Values of the length of day and the length of month, estimated from paleontological data, are confronted with the results of the developed model.  相似文献   

天文(重力)水准的新手段及其计算方法     

张赤军 《大地测量与地球动力学》2002,22(4):31-34

介绍当今确定天文大地垂偏差的新仪器－CCD自动天体测量仪和确定两点间高程异常差的新方法，该方法用单极坐标代替繁琐的双极坐标进行计算，讨论了天文重力水准的误差及垂线偏差非线性影响等问题，估计在不久的将来，用这一手段施测山区似大地水准面的精度可望达到厘米级。  相似文献   

概论机场能见度的准确预报     

张晓晖 《成都信息工程学院学报》2002,17(3):166-169

通过对影响能见度的因素的分析，提出了一种能见度预报方法－综合分析法，极大地提高了能见度的预报准确率。  相似文献   

P-T-t-deformation paths recorded by kinzigites during diapirism in the western Variscan belt (Golfe du Morbihan, southern Brittany, France)     

C. AUDREN  C. TRIBOULET 《Journal of Metamorphic Geology》1993,11(3):337-356

Abstract The high-grade metamorphic rocks of southern Brittany underwent a complex tectonic evolution under various P-T conditions (high-P, high-T), related to stacking of nappes during Palaeozoic continentcontinent collision. The east to west thrusting observed in the whole belt is strongly perturbed by vertical movements attributed to the ascent of anatectic granites in the high-T area. The field reconstruction of subvertical, closed elliptical structures in gneisses and migmatites, associated with the subhorizontal, doubly radial pattern of stretching lineation in the mica schists, suggests the existence of an elliptical diapiric body buried at depth beneath the present erosion level. Deformation is associated with a complex P-T evolution partly recorded in aluminous gneisses (kinzigites, e.g. morbihanites). A chronology of successive episodes of mineral growth at different compositions is established by detailed studies of the mineral-microstructure relationships in X-Z sections, using the deformation-partitioning concept (low- and high-strain zones). Several thermometric and barometric calibrations are applied to mineral pairs either in contact or not in contact but in equivalent microstructiiral positions with respect to the deformation history. This methodology provides a continuous microstructural control of P-T variations through time and leads to three P-T-t-d paths constructed from numerous successive P-T estimations. Path 1 is a clockwise retrograde path preserved in low-strain zones, which records general exhumation movements after crustal thickening. Paths 2 and 3 are clockwise prograde/retrograde paths from high-strain zones; they are interpreted and discussed in the light of models of crustal anatexis and upward movement of magma (diapirism). Deformation and P-T effects induced by diapirism can be distinguished from the general deformation-metamorphic history of a belt, and would seem to be produced during a late stage of its history. The present microstructural-petrological approach to defining successive mineral equilibria in relation to progressive deformation steps provides a far more accurate evaluation of the metamorphic evolution than is possible by ‘standard’thermobarometry.  相似文献   

Viscoelastodynamics of A Stratified, Compressible Planet: Incremental Field Equations and Short- and Long-Time Asymptotes     

Detlef Wolf 《Geophysical Journal International》1991,104(2):401-417

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土地征用制度改革的探索   总被引：1，自引：0，他引：1       下载免费PDF全文

秦泗彦  田宏红  张传亮 《山东国土资源》2003,19(6):29-31,41

征地补偿安置是当前群众反映最强烈并迫切要求解决的问题。要解决该问题必须进行土地征用制度改革．由政府按照市场公平原则向农民集体征购土地，实行统一的土地征购制度。  相似文献