Numerical prediction of blast‐induced stress wave from large‐scale underground explosion

This paper presents a numerical model for predicting the dynamic response of rock mass subjected to large‐scale underground explosion. The model is calibrated against data obtained from large‐scale field tests. The Hugoniot equation of state for rock mass is adopted to calculate the pressure as a function of mass density. A piecewise linear Drucker–Prager strength criterion including the strain rate effect is employed to model the rock mass behaviour subjected to blast loading. A double scalar damage model accounting for both the compression and tension damage is introduced to simulate the damage zone around the charge chamber caused by blast loading. The model is incorporated into Autodyn3D through its user subroutines. The numerical model is then used to predict the dynamic response of rock mass, in terms of the peak particle velocity (PPV) and peak particle acceleration (PPA) attenuation laws, the damage zone, the particle velocity time histories and their frequency contents for large‐scale underground explosion tests. The computed results are found in good agreement with the field measured data; hence, the proposed model is proven to be adequate for simulating the dynamic response of rock mass subjected to large‐scale underground explosion. Extended numerical analyses indicate that, apart from the charge loading density, the stress wave intensity is also affected, but to a lesser extent, by the charge weight and the charge chamber geometry for large‐scale underground explosions. Copyright © 2004 John Wiley & Sons, Ltd.     

Timing of the Nihewan formation and faunas

Magnetostratigraphic dating of the fluvio-lacustrine sequence in the Nihewan Basin, North China, has permitted the precise timing of the basin infilling and associated Nihewan mammalian faunas. The combined evidence of new paleomagnetic findings from the Hongya and Huabaogou sections of the eastern Nihewan Basin and previously published magnetochronological data suggests that the Nihewan Formation records the tectono-sedimentary processes of the Plio-Pleistocene Nihewan Basin and that the Nihewan faunas can be placed between the Matuyama-Brunhes geomagnetic reversal and the onset of the Olduvai subchron (0.78-1.95 Ma). The onset and termination of the basin deposition occurred just prior to the Gauss-Matuyama geomagnetic reversal and during the period from the last interglaciation to the late last glaciation, respectively, suggesting that the Nihewan Formation is of Late Pliocene to late Pleistocene age. The Nihewan faunas, comprising a series of mammalian faunas (such as Maliang, Donggutuo, Xiaochangliang, Banshan, Majuangou, Huabaogou, Xiashagou, Danangou and Dongyaozitou), are suggested to span a time range of about 0.8-2.0 Ma. The combination of our new and previously published magnetostratigraphy has significantly refined the chronology of the terrestrial Nihewan Formation and faunas.     

等温微量热法在土壤微生物研究方面的进展

土壤微生物是陆地生态系统中分解者亚系统的主要组成部分, 参与了包括有机质降解、营养转化、 植物生长的促进或抑制以及各种土壤物理过程在内的一系列反应活动. 土壤微生物则是土壤质量重要的生物指标, 可以用来监控土壤质量的变化. 等温微量热法是一种简便、快速地测量微生物活性的方法, 在土壤微生物代谢热效应的研究领域中广泛应用. 就等温微量热法在土壤微生物活性中的研究进展进行综述: 等温微量热法的简介, 微量热方法与传统方法的比较, 等温微量热法在各种外界环境和土壤条件影响下的土壤微生物活性研究中的应用, 并对等温微量热法在土壤微生物和其它方面的研究进行了展望.     

Species composition and distribution of marine nematode community in the North Taiwan Strait

I~IOW~ne nelnatode is a ban gIOup of benthic OrgAnsrns. Abbot 5 000 spotes Of free-livingnelnatedes have ben dedbo so far, and it has ho estimated that abbot 20 (XX) are as yetunknoWn. Chinese bothologist has Paid attention to marine nelnatodes in China seas in yare. The spatial distribution and shoes commotion of marine nelnatedes in the HUanghe EstUary, Qinhuangdao waters, QingdaO Bay and Xiamen ~ have ho reported (Zhang etal., 1990, 1991, 1993; ac and Li, 1998). ~ new shoes in the…     

台湾以东海区磁异常及磁条带研究

资料显示,在整个台湾以东海区内磁异常几乎全为负磁异常,磁异常分块现象明显。通过对本海区的磁力资料进行分析和研究,表明本海区的地磁异常表现为明显的条带状异常特征。由于受板块差异性运动的影响,以加瓜海脊为界,东西两侧具有不同的磁条带方向,在加瓜海脊以东,磁条带为NW-SE向(120°),而在加瓜海脊以西则为近东西向(80°)。加瓜脊以西地区的扩张时间为45～38Ma,相当于19～16号磁条带;而加瓜脊以东地区的扩张时间为40～35Ma,相当于17～13号磁条带。加瓜脊以西的磁条带相对于以东的磁条带要老,由此推断出加瓜脊以西相对于东侧发生了北向位移。     

A comparison of several wave spectra for the random wave diffraction by a semi-infinite breakwater

A comparison of the diffraction of multidirectional random waves using several selected wave spectrum models is presented in this paper. Six wave spectrum models, Bretschneider, Pierson–Moskowitz, ISSC, ITTC, Mitsuyasu, and JONSWAP spectrum, are considered. A discrete form for each of the given spectrum models is used to specify the incident wave conditions. Analytical solutions based on both the Fresnel integrals and polynomial approximations of the Fresnel integrals and numerical solutions of a boundary integral approach have been used to obtain the two-dimensional wave diffraction by a semi-infinite breakwater at uniform water depth. The diffraction of random waves is based on the cumulative superposition of linear diffraction solution. The results of predicted random wave diffraction for each of the given spectrum models are compared with those of the published physical model presented by Briggs et al. [1995. Wave diffraction around breakwater. Journal of Waterway, Port, Coastal and Ocean Engineering—ASCE 121(1), 23–35]. Reasonable agreement is obtained in all cases. The effect of the directional spreading function is also examined from the results of the random wave diffraction. Based on these comparisons, the present model for the analysis of various wave spectra is found to be an accurate and efficient tool for predicting the random wave field around a semi-infinite breakwater or inside a harbor of arbitrary geometry in practical applications.     

Refraction-Diffraction Mathematical Model for Waves With Lateral Energy Transmission Mechanism and Its Verification

To solve problems concerning wave elements and wave propagation, an effective way is the wave energy balance equation, which is widely applied in oceanography and ocean dynamics for its simple computation. The present papaer advances wave energy balance equations considering lateral energy transmission and energy loss as the governing equation for the study of wave refraction-diffraction. For the mathematical model, numerical simulation is made by means of difference method, and the result is verified with two examples.     

地层学的发展推动油气地质理论研究的进步

自上个世纪50年代以来,地层学经历了彻底的变革,逐渐由“相模式”、“沉积体系”、“地震地层学”发展到目前的“层序地层学”,形成高分辨率层序地层学和事件地层学的理论体系和研究方法。文章围绕层序地层学、高分辨率层序地层学基本方法及理论体系,与含油气系统相关关系进行了讨论。     

Tephra Discovered in High Resolution Peat Sediment and Its Indication to Climatic Event

Floating tephra was deposited together with ice core,snow layer,abyssal sediment,lake sediments,and other geological records.It is of great significance to interpret the impact on the climate change of volcanic eruptions from these geological records.It is the first time that volcanic glass was discovered from the peat of Jinchuan(金川)Maar,Jilin(吉林)Province,China.And it is in situ sediments from a near-source explosive eruption according to particle size analysis and identification results.The tephra were neither from Tianchi(天池)volcano eruptions,Changbai(长白)Mountain,nor from Jinlongdingzi(金龙顶子)volcano about 1 600 aBP eruption,but maybe from an unknown eruption of Longgang(龙岗)volcano group according to their geochemistry and distribution.Geochemical characters of the tephra are similar to those of Jingiongdingzi,which are poor in s.Jica,deficient in alkali,Na20 content is more than K20 content,and are similar to distribution patterns of REE and incompatible elements,which helps to speculate that they originated from the same mantle magma with rare condemnation,and from basaltic explosive eruption of Longgang volcano group.The tephra,from peat with age proved that the eruption possibly happened in 15 BC-26 AD,is one of Longgang volcano group eruption that was not recorded and is earlier than that of Jinglongdingzi about 1 600 aBP eruption.And the sedimentary time of tephra is during the period of low temperature alteration.which may be the influence of eruption toward the local climate according to the correlativity of eruption to local temperature curve of peat cellulose oxygen isotope.