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1.
George A. Athanasopoulos 《Geotechnical and Geological Engineering》1993,11(1):51-65
Summary Results of resonant column tests were used to determine values of low amplitude shear modulus (G
0) of a remoulded kaolinite clay for different durations of ageing and for different values of consolidation stress (0) and overconsolidation ratio (OCR). It was found that after completion of primary consolidation the values of G
0 increased linearly with the logarithm of time and after a week of confinement the value of normalized rate of secondary increase of shear modulus (N
G
) could be reliably estimated. Values of N
G
were found to derease linearly with the logarithm of OCR and with the logarithm of ageing duration. This similarity of behaviour provided a basis for establishing an equivalency between age and equivalent overconsolidation ratio (OCR)eq. The effects of 0 and OCR on the value of G
0 were also established in a functional form that indicated a stronger influence compared to that predicted by the Hardin Equation. 相似文献
2.
粤北笋洞花岗岩的形成时代、地球化学特征与成因 总被引：25，自引：10，他引：25
笋洞花岗岩体是粤北贵东复式花岗岩体的一个重要组成部分。锆石U-Pb年龄为189.1±0.7Ma,是燕山早期岩浆活动产物。该岩体的主要元素显示富硅、富碱、强过铝质和低 CaO/Na_2O比值等特征;微量元素方面,富集Rb,Th,U,Ce,Sm,Y,亏损 Ba,Sr,P,Ti;LREE轻微富集(LREE/HREE=6.6～8.8,(La/Yb)_N=6.44～10.74),Eu亏损明显(δEu=0.14～0.31);它具有低的ε_(Nd)(t)(-11.4～-9.3),高的δ~(18)O(10.2～12.7‰)、(~(87)Sr/~(86)Sr);(0.72949～0.74923)、~(206)Pb/~(204)Pb(18.180～18.488)、~(207)Pb/~(204)Pb(15.655～15.661)和古老的Nd模式年龄(1762～1933Ma)。上述这些特征表明,笋洞岩体属于典型的壳源型花岗岩,是在地壳伸展-减薄的构造背景下,通过以泥质成分为主的古-中元古代变质沉积岩部分熔融的方式形成。 相似文献
3.
海岸带空间功能分区是优化海岸带开发与保护的基础性工作,在国土空间规划体系中具有重要作用。当前我国海陆功能分区在分区层级、分区方法等方面并不一致,导致海岸带保护与开发利用失衡。本文在梳理国内外海岸带空间功能分区研究的基础上,从陆海统筹角度出发,构建海岸带空间功能分区体系,并以宁波市为例进行验证,在优先划定生态保护区基础上,对海陆空间进行适宜性评价,根据评价结果确定功能分区。结果表明：（1）宁波市海岸带功能区中生态保护区面积占比约为60%,海陆一体发展区占比约为22.3%,海洋发展区占比约为12.5%,陆地发展区占比约为5.2%;(2)宁波市开发利用功能区空间分布与以临港产业、海洋服务业和海洋渔业为基础的海洋经济发展导向相符。海岸带空间功能分区要以生态保护为底线,以优化空间布局为导向,为优化海岸带开发与保护提供有力支撑。 相似文献
4.
G. A. Athanasopoulos 《Geotechnical and Geological Engineering》1994,12(2):122-132
Summary A review is presented of conceptual approaches that are currently in use for interpreting the operation of reinforced soil.
The concepts of enhanced confining pressure and of reduced normal tensile strains are found to be closely related to current
experimental and theoretical investigations as well as to the design methodologies available at present for reinforced soil
applications. Focusing on the enhanced confining pressure concept, analytical expressions are developed that allow the estimation
of the value of equivalent confining stress increase when the properties of soil and reinforcement and the state of stresses
acting on a cylindrical reinforced soil element are known. The derived expressions can also be utilized for estimating the
soil-reinforcement friction angle from the results of triaxial tests on cylindrical samples reinforced with horizontal layers
of reinforcement. 相似文献
5.
6.
TritonX-100－5-Br-PADAP光度法测定铜和镍 总被引：2，自引：0，他引：2
研究了非离子型表面活性剂Ｔｒｉｔｏｎ Ｘ－ １００ 存在下,用５ － Ｂｒ － ＰＡＤＡＰ 光度法测定铜、镍的方法。结果表明：在ｐＨ９ ．０ 的硼砂缓冲介质中,５ － Ｂｒ － ＰＡＤＡＰ 与铜和镍生成紫红色络合物,λＣｕｍ ａｘ ＝ ５７５ ｎｍ ,εＣｕ ＝ １ ．０４ ×１０５ Ｌ·ｍｏｌ－ １·ｃｍ － １ ;λＮｉｍ ａｘ ＝ ５７５ ｎｍ ,εＮｉ ＝ １ ．１４ ×１０５ Ｌ·ｍｏｌ－ １·ｃｍ － １ 。铜和镍的质量浓度分别在０ ～５６０ μｇ／ Ｌ和０ ～４４０ μｇ／ Ｌ符合比尔定律。加入六偏磷酸钠后,由于偏磷酸镍的形成,镍不再与５ － Ｂｒ － ＰＡＤＡＰ 显色,可通过铜及铜镍总量的测定,计算出镍的含量。用该方法实测了钢样中铜和镍的含量,结果与推荐值相符,对铜和镍５ 次测定的ＲＳＤ均小于５ ％ 。 相似文献
7.
8.
Following a comprehensive review of the subject of man-made ground vibrations, measurements of ground vibration caused by vibratory sheetpile driving in recent soil deposits are reported in terms of particle velocities vs. distance from the source of vibration. The measurements were conducted on paved surfaces and sidewalks in the inner urban environment. Reconstructed particle displacement paths indicated, predominantly, vertical vibrations of the Rayleigh type. The attenuation rate of vibrations with distance was compared to published results of other studies and satisfactory agreement was found to exist. Values of particle velocity measured in this study, however, were lower than corresponding values of other studies under comparable values of rated vibratory kinetic energy. This is possibly due to different soil conditions. Average and upper bound linear log–log attenuation relationships are proposed, which fit the results of measurements and are representative of the conditions likely to be encountered in the urban environment. Measurement of vibrations on higher floors of multistory reinforced concrete buildings indicated a significant amplification of vertical vibration and an average curve for amplification magnitude vs. floor level was fitted to the results of measurements. A comparison of measured values of vibration with the observed performance of buildings and with damage threshold values suggested by existing codes and standards indicated that the latter do not provide safety against damage caused by vibratory densification of loose sandy soils. On the other hand, the existing criteria for human exposure to vibrations in buildings, according to the results of this study, seem to adequately define the degrees of human discomfort. 相似文献
9.
G. A. Athanasopoulos P. C. Pelekis G. A. Anagnostopoulos 《Soil Dynamics and Earthquake Engineering》2000,19(4)
The amplitude of vertical ground surface vibrations generated by impact tests on the ground surface was measured at various radial distances from the point of impact at locations of Greece. The results of measurements were analyzed in the frequency domain (in the range from 0–100 Hz) and the attenuation characteristics of soil materials were studied in terms of a frequency-independent attenuation coefficient, a0, of the empirical Bornitz equation. The aim of the study was to investigate the effect of soil stiffness (expressed by the value of low-amplitude shear wave velocity of soil, VSO) on the value of attenuation coefficient, a0. Values of VSO for the tested soils were estimated by applying the methodology of Spectral Analysis of Surface Waves (SASW) technique and utilizing the surface vibration data. An empirical relationship between a0 and VSO1 (VSO1 is the representative value of VSO for the soil profile up to a depth of one wavelength) was established for values of VSO1 ranging from 140 to 1000 m/s. A similar relationship in terms of the low-amplitude shear modulus of soil, GO1, was also established by converting the VSO1 values to GO1 values. The experimental results were compared to values reported in the literature for comparable soil types and frequencies of vibration and a reasonable agreement was found to exist. The proposed empirical relationship can be utilized in many practical applications of soil dynamics requiring the knowledge of the attenuation rate of Rayleigh waves with distance in various types of soils. 相似文献
10.
DJ Karoly JA Cohen GA Meehl JFB Mitchell AH Oort RJ Stouffer RT Wetherald 《Climate Dynamics》1994,10(1-2):97-105
As an example of the technique of fingerprint detection of greenhouse climate change, a multivariate signal or fingerprint of the enhanced greenhouse effect is defined using the zonal mean atmospheric temperature change as a function of height and latitude between equilibrium climate model simulations with control and doubled CO2 concentrations. This signal is compared with observed atmospheric temperature variations over the period 1963 to 1988 from radiosonde-based global analyses. There is a significant increase of this greenhouse signal in the observational data over this period.These results must be treated with caution. Upper air data are available for a short period only, possibly too short to be able to resolve any real greenhouse climate change. The greenhouse fingerprint used in this study may not be unique to the enhanced greenhouse effect and may be due to other forcing mechanisms. However, it is shown that the patterns of atmospheric temperature change associated with uniform global increases of sea surface temperature, with El NinoSouthern Oscillation events and with decreases of stratospheric ozone concentrations individually are different from the greenhouse fingerprint used here. 相似文献