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21.
本文考虑液固耦联及底板几何非线性与土壤弹性,建立了液-固-土耦合的储液罐翘离分析力学模型。算例表明,恢复力矩与翘离角之间的关系可以表达为分段线性,翘离将使地震响应增大。 相似文献
22.
The separation of the influence of nutrients and climate on the varve time-series of baldeggersee, Switzerland 总被引:7,自引:2,他引:7
The varve data-set from a freeze-core taken in the deepest part of Baldeggersee was subjected to different multivariate statistical
analyses in order to estimate the amount of variance in the varve thickness measures explicable by past climate and by the
trophic state of the lake. A comparison of two different time-periods (1902 to1992 versus 1920 to 1980) revealed that the
lake restoration programme since 1982 has had a significant impact on the formation of the seasonal layers. Results of the
partitioning of the variance in the varve thickness measures showed that about two thirds of the variance are unexplained
by a climate and trophic state model and that trophic state explains 6%, whereas climate accounts for about 28% of the variance
before the effect of lake restoration had a strong impact on the varves. Among the climate parameters the amount of annual
precipitation is a strong predictor for explaining the thickness of both dark layer and total couplet thickness, whereas summer
precipitation is important for the thickness of the light layer. 相似文献
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Yang Wunian Zhu Zhangsen Institute of Remote Sensing GIS Chengdu University of Technology Chengdu Sichuan Liu Xinzhu Yang Wencai 《《地质学报》英文版》1997,71(3):344-354
The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field of each of the different stages in the complexdeformation of an area can be reconstructed in three steps: (1) geological structures formed atdifferent times are distinguished in remote sensing image interpretation; (2) structuraldeformation fields at different stages are determined by analyzing relationships betweenmicrostructures (joints and fractures) and the related structures (folds and faults); and (3)tectonic stress fields at different stages are respectively recovered through a study of the featuresof structural deformation fields in different periods. Circular structures and related circlular and radial joints are correlated in space to con-cealed structural rises. The authors propose a new method for establishing a natural model ofthe concealed structural rises and calculating the tectonic stress field by using quantitative dataof the remote sensing information of circular structures and related linear structures. 相似文献
25.
煤层倾角与覆岩变形破裂分带 总被引:7,自引:0,他引:7
地下采煤中三带(冒落带、裂隙带、弯曲带)高度的判断是预测采空引起地表变形破坏程度的依据。在诸多的影响因素中, 煤层倾角是控制三带高度的最主要因素。建立在实测统计基础上的经验范围值用于三带高度的判断带有一定的人为性。急倾斜煤层中冒落带和裂隙带高度随煤层倾角变化的规律已被褐示[7].通过弹塑性岩石材料的非线性有限元模拟, 本文提出了利用应力重分布图判断中、缓倾角煤层采空区覆岩三带高度的方法, 并应用于实际工程。 相似文献
26.
I.Y. Malchikova 《冰川冻土》2004,26(Z1):206-209
The development of North Transbaikalye mineral resources (e. g. the Chiney deposit of iron titanium-vanadium-magnetite ores and Udokan copper deposits) is impossible without the establishment of industrial and transport infrastructure, one component of which are linear engineering constructions (drive railways, by-line auto roads, platform passages, protecting constructions, and others). However,on condition of spreading permafrost rocks this is conjugated with certain ecological risk just as from the transport network objects so for the objects themselves. A special attention is paid in the paper to considering of problems of projecting and constructing railways on the Udokan ridge. 相似文献
27.
A procedure for developing equations that estimate the isolator displacement due to strong ground motion is applied to buildings isolated with the friction pendulum system. The resulting design equations, based on rigorous non‐linear analysis, offer an alternative to the iterative equivalent‐linear methods used by current U.S. building codes. The governing equations of the system are reduced to a form such that the median normalized displacement of the system due to an ensemble of ground motions is found to depend on only the isolation period—a function of the curvature of the isolator—and the friction force at incipient slip normalized by peak ground velocity. The normalization is effective in minimizing the dispersion of the normalized displacement for an ensemble of ground motions, implying that the median normalized displacement is a reliable estimate of response. The design equations reflect the significant (20 to 38%) increase in displacement when the excitation includes two lateral components of ground motion instead of just one component. Equivalent‐linear methods are shown to underestimate by up to 30% the exact median displacement determined by non‐linear response history analysis for one component of ground motion, and building codes include at most a 4.4% increase for a second component. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
28.
Two approximate methods for decomposing complicated inelastic dynamic responses of wall buildings into simple modal responses are presented. Both methods are based on the equivalent linear concept, where a non‐linear structure is represented by a set of equivalent linear models. One linear model is used for representing only one vibration mode of the non‐linear structure, and its equivalent linear parameters are identified from the inelastic response time histories by using a numerical optimizer. Several theoretical relations essential for the modal decomposition are derived under the framework of complex modal analysis. Various numerical examinations have been carried out to check the validity of the proposed modal decomposition methods, and the results are quite satisfactory in all cases. Fluctuating bending moment and shear at any location along the wall height contributed by each individual vibration mode can be obtained. Modal contributions to shear and flexural strength demands, as well as the corresponding modal properties, under various seismic loading conditions can also be identified and examined in detail. Furthermore, the effects of higher vibration modes on seismic demands of wall buildings are investigated by using the modal decomposition methods. Several new insights into the complicated inelastic dynamics of multi‐story wall buildings are presented. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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