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Alik Ismail-Zadeh Igor Tsepelev Chistopher Talbot Alexander Korotkii 《Tectonophysics》2004,387(1-4):81-103
Numerical studies of ductile deformations induced by salt movements have, until now, been restricted to two-dimensional (2D) modelling of diapirism. This paper suggests a numerical approach to model the evolution of three-dimensional (3D) salt structures toward increasing maturity. This approach is also used here to restore the evolution of salt structures through successive earlier stages. The numerical methodology is applied to study several model examples. We analyse a model of salt diapirs that develop from an initial random perturbation of the interface between salt and its overburden and restore the evolved salt diapirs to their initial stages. We show that the average restoration errors are less than 1%. An evolutionary model of a 2D salt wall loaded by a 2D pile of sediments predicts a decomposition of the salt wall into 3D diapiric structures when the overburden of salt is supplied by 3D synkinematic wedge of sediments. We model salt extrusion feeding a gravity current over the depositional surface and estimate an average rate of extrusion and horizontal velocity of salt spreading. Faulting of the overburden to salt overhangs initiates new secondary diapirs, and we analyse the growth of these secondary diapirs. We also study how lateral flow effects the evolution of salt diapirs. The shape of a salt diapir can be very different if the rate of horizontal flow is much greater than the initial rate of diapiric growth solely due to gravity. We discuss the applicability of the results of the models to the evolution of Late Permian salt structures in the Pricaspian basin (Russia and Kazakhstan). These structures are distinguishable into a variety of styles representing different stages of growth: salt pillows, diapirs, giant salt massifs, 2D diapiric walls and 3D stocks complicated by large overhangs. The different sizes, shapes and maturities of salt structures in different parts of the Pricaspian basin reflect areal differences in salt thickness and loading history. Our results suggest that the numerical methodology can be employed to analyse the evolution of all salt structures that have upbuilt through younger ductile overburdens. 相似文献
114.
Introduction The Great North China, located at longitude 106E to 124E and latitude 31N to 42N, in-cludes three secondary active tectonic blocks, Ordos, Yanshan and North China plain (Figure 1). The geological tectonics of these three secondary blocks is much different from each other. As a stable block with high rigidity, the Ordos block is mostly surrounded by down-faulted basins with an inactive interior since Cenozoic, although the fault zones along its boundary are strongly active wi… 相似文献
115.
Preliminary study on variation characteristics of ocean tide dynamic stress in crust and its relationship with earthquakes 总被引:1,自引:0,他引:1
~~Preliminary study on variation characteristics of ocean tide dynamic stress in crust and its relationship with earthquakes@陆明勇$China Center for Earthquake Disaster Emergency and SAR,Beijing 100049,China
@郑文衡$Huazhong University of Science and Technology,Wuhan 430074,China①Strong earthquake catalogues in China. Earthquake catalogues reported monthly by Center for Analysis and Prediction, CEA.
①YI Zhi-gang. Institute of Crustal Dynamics, China Earthquake Administrati… 相似文献
116.
Concentrated plasticity (CP) models are frequently used in static and dynamic building analysis and have been implemented in available commercial software. This investigation deals with three different CP‐models, a simplified macroelement model (SEM) for a complete building story, a frame element with elasto‐plastic interaction hinges (PH), and a frame element with fiber hinges (FB). The objectives of this work are to evaluate the quality of the earthquake responses predicted by these models and to identify important aspects of their implementation and limitations for their use in dynamic analysis. The three elements are tested in a single‐story asymmetric plan building and in a three‐story steel building. Results show that base shear and global response values are usually computed with better accuracy than interstory deformations and local responses. Besides, the main limitation of elasto‐plastic CP models is to control the displacement offsets that result from perfect elasto‐plastic behavior. On the other hand, calibration of the SEM‐model shows that global responses in steel structures may be computed within 20% error in the mean at a computational cost two orders of magnitude smaller than that of the other CP elements considered. However, the three element models considered lead to increasing levels of accuracy in the dynamic response and their use depends on the refinement of the analysis performed. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
117.
F. Colangelo 《地震工程与结构动力学》2005,34(10):1219-1241
This paper presents pseudo‐dynamic test results on the in‐plane seismic behaviour of infilled frames. Thirteen single‐storey, single‐bay, half‐size‐scale, reinforced concrete‐frame specimens, most of which infilled with non‐structural masonry made of perforated bricks and cement mortar are tested. The infills are in contact with frames, without any connector; openings are not covered. The frames are different in their strength and details, reinforcement grade, and aspect ratio. Seismic input is the 1976 Tolmezzo (Friuli, Italy) ground acceleration, to which specimens are subjected two times: virgin and damaged by the previous test. The global seismic response of initially virgin infilled specimens considerably differs from that of bare specimens. This follows a dramatic change of properties: compared to a bare frame, the initial stiffness increases by one order of magnitude, and the peak strength more than doubles. The peak drift lessens; however, the displacement ductility demand does not. The energy demand is greater. Nevertheless, the influence of infill decreases as damage proceeds. Displacement time histories of damaged specimens are quite similar. At the local level, infill causes asymmetry and concentration of the frame deformation. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
118.
Scalar and vector intensity measures are developed for the efficient estimation of limit‐state capacities through incremental dynamic analysis (IDA) by exploiting the elastic spectral shape of individual records. IDA is a powerful analysis method that involves subjecting a structural model to several ground motion records, each scaled to multiple levels of intensity (measured by the intensity measure or IM), thus producing curves of structural response parameterized by the IM on top of which limit‐states can be defined and corresponding capacities can be calculated. When traditional IMs are used, such as the peak ground acceleration or the first‐mode spectral acceleration, the IM‐values of the capacities can display large record‐to‐record variability, forcing the use of many records to achieve reliable results. By using single optimal spectral values as well as vectors and scalar combinations of them on three multistorey buildings significant dispersion reductions are realized. Furthermore, IDA is extended to vector IMs, resulting in intricate fractile IDA surfaces. The results reveal the most influential spectral regions/periods for each limit‐state and building, illustrating the evolution of such periods as the seismic intensity and the structural response increase towards global collapse. The ordinates of the elastic spectrum and the spectral shape of each individual record are found to significantly influence the seismic performance and they are shown to provide promising candidates for highly efficient IMs. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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挤扩支盘桩极限承载力的预测 总被引:2,自引:0,他引:2
用双曲线方法对110根挤扩支盘桩的极限承载力进行预测,并与直杆桩预测结果进行对比。结果表明由于支盘桩受力性状复杂,加载前期和中期预测精度较高,后期较低,误差超过15%;支盘桩的沉降曲线出现台阶时预测值与实测值误差较大;支盘桩极限承载力的预测精度与工程地质条件和桩本身的参数密切相关,桩身参数和地质条件相同条件下各桩预测精度比较接近。总体上直杆桩的预测结果优于支盘桩。 相似文献