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21.
Toyoaki Nogami 《地震工程与结构动力学》1985,13(3):321-336
A simple approach to analyse the flexural vibration of grouped piles was developed. In this approach, a pile group is replaced by a single pile for the evaluation of the pile-head flexibility matrix. Parametric studies were conducted for various conditions of grouped piles. Various features of flexural vibration of pile groups were found. The charts presented in this paper enable quick estimations of dynamic group effects to be made in a manner similar to that widely used for the evaluation of static group effects. 相似文献
22.
Hydrological characteristics of englacial and subglacial drainage systems in Gulkana Glacier, Alaska, were examined by analysing temporal variations of discharge and sediment load in the proglacial Phelan Creek in 2001. From data plots on semi‐log paper, it appeared appropriate to separate both discharge and sediment load into fast and slow components. The two components were possibly produced by two different drainage systems: an englacial and subglacial, ‘channellized’ system in the ablation zone, and a subglacial, ‘distributed’ system in the accumulation zone. The data indicate the occurrence of an event during which part of the ‘distributed’ drainage system changed into the ‘channellized’ drainage system. The daily time‐series of discharge and sediment load were represented using a tank model. In the model, the drainage from an additional tank was added, supposing that a subglacial reservoir full of water and sediment collapsed slowly when the subglacial drainage system changed from distributed to channellized. The simulation with the collapsed tank gave much more reasonable results than those with no collapsed tank. The contribution of the collapsed tank to total sediment load is 24%, which is much larger than 9% to total discharge. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
23.
The D/H and 18O/16O ratios of water in the active crater lake situated on the Kusatsu-Shirane volcano, Japan are about 20 and 6‰, respectively, higher than local meteoric water. The ratios show seasonal variations superimposed on a gradual change over nine years. The isotopic ratios started to increase in early 1990 and decrease in the spring of 1995. The seasonal variation which is high in winter and low in summer correlates with the temperature difference between lake water and ambient air. The large temperature difference in winter enhances the evaporation of lake water and produces the enriched isotopic ratios relative to the ratios in summer. The accumulation of snow and the decrease in the flux of meteoric water into the lake strengthens the winter-time isotopic enrichment. The enriched isotopic ratios of the lake water over a long time result from the addition of an end member with heavy isotopic ratios contained in a thermal fluid supplied to the lake. Considering the water balance in the lake, the isotopic ratios of the thermal fluid were found to be close to the lake water itself, suggesting the circulation of the lake water seeping through lake floor. Based on the correlation between Cl−concentration and the isotopic ratios, the contribution by the heavy end member was estimated to be 25–36% relative to the enrichment by evaporation. The heavy end member could be a liquid phase evolved from a parental fluid, which is a mixture of local meteoric water and a magmatic fluid as found in high-temperature volcanic gases. 相似文献
24.
A transfer matrix method is applied for the analysis of non-linear pile group responses. The expression for the transfer matrix is obtained by idealizing the non-linear pile group as a group of piles attached to a piecewise linear “Winkler model for a pile group”. This Winkler idealization is essential to apply a transfer matrix method for the pile group response analysis. The parameters of this Winkler model can be defined from unit load transfer curves obtained for a single pile. In the limited studies carried out, it is found that the present approach predicts the response of pile groups reasonably well. 相似文献
25.
A soil medium at the side of an embedded structure is treated as mutually uncoupled horizontal layers of a unit thickness. A plane strain condition is assumed within each individual layer such that the medium responses do not vary along the thickness. According to previous work by the authors and also a new formulation given herein, the impedance of the above layer at the structure can be produced by frequency-independent simple mechanical models for all three modes of foundation responses. Similar frequency-independent models are also presented for the impedance at the foundation base. These models are made of two different basic elements and a mass interconnected in series. Their arrangements directly indicate the wiring of electric circuits which generate signals corresponding to the transient soil–structure interaction responses. To all intents and purposes, electric circuits do not loose time in responding to the inputs. Therefore, they allow us to simulate the soil–structure interaction response in shake table model tests, which are commonly conducted at relatively high excitation frequencies for earthquake simulation. 相似文献
26.
Tadashi Shimamura Shohei Yanagita Kazuo Yamakoshi Ken&#x;ichi Nogami Okio Arai Yuji Tazawa Koichi Kobayashi 《Earth and Planetary Science Letters》1979,42(3):379-382
Isotopic compositions of potassium and calcium in individual magnetic spherules were determined. No significant anomaly was observed for potassium within twice the statistical error (2σ), although for calcium isotopes enrichments of46Ca,44Ca and42Ca were observed in one spherule. The relative excess of46Ca,44Ca and42Ca in the spherule agrees with the relative yield of spallogenic calcium isotopes observed in iron meteorites. This fact indicates that the enrichment in the calcium isotopes was caused by cosmic ray irradiation of the spherule in outer space. 相似文献
27.
Baranov proposed an approach for the treatment of the subgrade in the dynamic response analysis of a rigid foundation which is partially embedded. The approach is based on a Winkler approximation together with wave equation solutions developed for simplified conditions. The paper extends and modifies Baranov's approach so as to be applicable to surface foundation problems, by introducing an internal coupling mechanism. Closed form expressions are presented for the steady state harmonic responses of a massless rigid footing and an elastic beam on the surface of the presented subgrade model. These expressions can accommodate the inhomogeneity of the subgrade in a straightforward manner. The model is found to perform well in reproducing the continuous subgrade medium behaviour. The dynamic responses of structures are often highly dependent on the subgrade modelling and therefore great caution is needed in modelling the subgrade. 相似文献
28.
We have proposed a time-weighted measurement using blue rayon that selectively adsorbs and concentrates polycyclic aromatic hydrocarbons (PAH), e.g. benzo(a)pyrene (BaP). Though the method was demonstrated to be a convenient way to monitor PAH, the amount adsorbed to the blue rayon depends on the intensity of water stream and the level of PAH. The intensity of water stream was measured by ‘plaster ball’ method, while TWA of PAH in water was measured by a portable sampler using solid phase extraction cartridge. A level of BaP measured by the original blue rayon technique was corrected in this way by the water stream intensity, which correlated well with the TWA of BaP measured by the portable sampler. The improved blue rayon hanging method was applied to several field sites in the Seto Inland Sea of Japan. TWA of BaP ranged from 0.08 to 3.78 ngl−1. These results showed the possibility that the method could be used to evaluate pollution in aquatic environment. 相似文献
29.
Humic compounds are one of the major substances that affect the COD value of the surface water of Lake Kojima. The humic compounds in the lake water were studied with a spectrofluorophotometer. The 3-dimensional fluorescence spectrum suggests that two kinds of fluorescent substances exist in the lake water. One shows an fluorescence excitation maxim (Ex) at about 240 nm and an emission maxim (Em) at 413 nm. The other has an Ex at 330 nm and an Em at 418 nm. The former peaks are associated with humic acid and the latter peaks are associated with fulvic acid. These peak intensities are proportional to the COD values. The fulvic acid in the lake water may be enriched by the effluent from domestic water treatment plants. 相似文献
30.
Masako Nogami Takeshi Matsuno Takehiro Nakamura Tadashi Fukumoto 《Journal of Oceanography》2000,56(3):319-329
We have observed the temporal variation of oxygen deficient water with short time scale (less than a few days) in the central area of Ohmura Bay, Kyushu, Japan, in summer, 1995 and 1996. The vertical profiles of temperature were similar to those of dissolved oxygen. We noticed a linear relation between temperature and dissolved oxygen in the bottom layer, and applied the T-DO relation to estimate the net oxygen consumption rate, rather than direct evaluation of the advection and diffusion. Oxygen consumption rate just above the bottom was estimated to be about 0.21 g O2 m–3day–1 in July 1995, and about 0.28 g O2 m–3day–1 in August 1996. The net oxygen consumption rate estimated for the bottom layer below the second thermocline was about 0.61 g O2 m–3day–1 with variability from 0.55 to 0.66 g O2 m–3day–1 during July 25 to 29, 1995. This is was about 0.64 g O2 m–3day–1 with variability from 0.18 to 1.4 g O2 m–3day–1 during August 22 to 30, 1996. The net oxygen consumption rates are about half of those measured with a closed system in the Seto Inland Sea. 相似文献