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161.
Shear modulus and damping ratio of grouted sand 总被引:2,自引:0,他引:2
Estelle Delfosse-Ribay Irini Djeran-Maigre Richard Cabrillac Daniel Gouvenot 《Soil Dynamics and Earthquake Engineering》2004,24(6):461-471
An experimental comparative study of three different grouted sands in terms of their effects on the values of two dynamic properties is presented. The dynamic properties studied are the shear modulus and the damping ratio which are determined with resonant column tests and cyclic triaxial tests. The behaviour of a pure Fontainebleau sand is compared with the behaviour of a Fontainebleau sand grouted with a silicate grout, a micro-fine cement grout and a mineral grout. The effects of the grouting treatment, the type of grout, the confining pressure, and the strains, on the shear modulus and the damping ratio are studied. The test results have shown that grouting improves the stiffness of the sand especially for small strains. Whatever the type of material, confining stress improves the shear modulus whereas it has a negligible effect on the damping ratio. When strain increases, the shear modulus decreases and the damping ratio increases. 相似文献
162.
R. Dobry A. Pecker G. Mavroeidis M. Zeghal B. Gohl D. Yang 《Soil Dynamics and Earthquake Engineering》2003,23(6):483-495
A global energy analysis is presented of three static unloading–reloading foundation lateral loading cycles, calculated using the nonlinear finite element (FE) program DYNAFLOW. This simulates seismic action on an offshore pier foundation in the Rion-Antirion Bridge in Greece, located in deep-sea water (65 m). A cyclic horizontal force is applied at a height of 30 m to a rigid raft 78 m in width placed on the surface of an idealized 2-layer soil profile consisting of a 3.5 m man-made gravel layer over soft deep natural clay, with elastic vertical steel inclusions reinforcing the soil. Results of the two-dimensional FE run are used for the energy analysis. It is verified that for the three cycles, the sum of energies associated with the external forces and moments, mostly dissipated through hysteresis loops, is about equal to the sum of the total internal energies dissipated or stored in the system. For the smaller loops almost all energy is dissipated in the soil, while for the largest loop about half of the energy is dissipated by horizontal sliding at the raft-soil interface. Global damping ratios obtained from the areas of the horizontal and rocking moment hysteresis loops are about double of those computed from the corresponding static backbone curves using the Masing criterion. 相似文献
163.
A new damage index to estimate damage to buildings relies on construction costs per square metre, and a replacement ratio which approximates costs relative to the cost of replacing a median-sized family home. Building damage is estimated against a five-point scale with Central Damage Values at 0.02, 0.1, 0.4, 0.75 and 1.0 of the replacement cost.Damage is expressed as damage in House Equivalents (HE) = Replacement Ratio × Central Damage Value. The Damage Index = log2 (HE) provides a simple 0–20 scale covering total damage of less than 1 HE to>1 million HE. For all natural hazard impacts in Australia DI is less than 12.Where the only damage data available are of lesser quality Generic or Qualitative Damage Indices (GDI and QDI) can be used. The various advantages and limitations of the Damage Index are discussed. 相似文献
164.
本文应用模糊优选神经网络理论,建立了边坡稳定性评价模型,综合分析了影响边坡稳定性的各种因素,根据它们作用程度的不同,赋予不同的权值,通过对收集到的边坡稳定性实例进行学习,提出了与优属度有关的函数关系式。可以看出:该方法具有精度高、收敛速度快、权值调整模型好等优点。 相似文献
165.
Stewart Barr 《Area》2003,35(3):227-240
Policymakers are becoming increasingly interested in the means by which individuals can be encouraged to engage in environmental actions around the home. This paper uses evidence from existing empirical research and a large questionnaire survey undertaken by the author to argue that environmental action is open to a range of influences, focusing especially on environmental values, situational characteristics and psychological variables. Accordingly, the paper asserts that strategies for promoting environmentally responsible behaviours (such as energy saving, water conservation and waste recycling) should take account of these factors. The implications for the study of environmental behaviour are considered. 相似文献
166.
河南省飞机人工增雨试验效果检验 总被引:1,自引:0,他引:1
采用区域对比的试验方法,选取1991年至1998年春、秋季试验作业区和对比区内测站逐时历史降水资料,对历史增雨作业效果进行了评估。统计检验结果表明,河南省1991年至1998年春、秋季人工增雨效果分别为20.05%、13.22%,总平均效果为16.63%。 相似文献
167.
168.
1 Introduction The modern surface pollen data provide foundation for the reconstruction of paleoenvironment and paleoclimate using pollen data. So the studies of modern pollen have received more attention in China and other countries. The study objects in… 相似文献
169.
农地价值与农地城市流转决策若干问题探讨 总被引:8,自引:0,他引:8
从资源环境价值观的角度对农地价值的构成进行分析,得出农地不仅具有市场价值,而且具有巨大的非市场价值。以此为基础,对传统决策模式进行理论优化。认为要协调农地保护与城市化之间的关系,促进经济社会的可持续发展,农地城市流转的直接决策者必须将农地的非使用价值与外部性纳入决策框架。 相似文献
170.