Ground Penetrating Radar in the Northern Great Lakes: A Trial Survey of a Contact Period Occupation in Marquette County,Michigan

ABSTRACT

Timing, inclement weather, and limited budgets can obstruct archaeological survey efforts. Here, we ameliorate some of these with use of ground penetrating radar (GPR) at the Goose Lake Outlet #3 (GLO#3) site (20MQ140). GPR surveys to guide survey and excavation efforts in these well-drained sandy soils are limited. GPR imagery exhibited false positives; however, shovel probes, subsequent site excavation, and artifact analysis led to numerous discoveries at this protohistoric site—including glass trade beads dating to the 1630s. These discoveries solidify evidence for some of the earliest European-made trade items in the region and provide further confirmation for placement of an Indian trail and ancient travel corridor between Lake Superior and Lake Michigan. Two ¹⁴C samples obtained from moose-bone in features with trade goods fall within the expected occupation range of 1633–1668 and 1615–1647. Several anomolies, possible hearth clusters were seen on the GPR imagery; however, many features remained invisible.     

A PROCEDURE FOR COMBINING VERTICAL AND HORIZONTAL SEISMIC ACTION EFFECTS

The vertical component of earthquake ground motion has generally been neglected in the earthquake-resistant design of structures. This is gradually changing due to the increase in near-source records obtained recently, coupled with field observations confirming the possible destructive effect of high vertical vibrations.

In this paper, simple procedures are suggested for assessing the significance of vertical ground motion, indicating when it should be included in the determination of seismic actions on buildings. Proposals are made for the calculation of elastic and inelastic vertical periods of vibration incorporating the effects of vertical and horizontal motion amplitude and the cross-coupling between the two vibration periods. Simplified analysis may then be used to evaluate realistic vertical forces by employing the vertical period of vibration with pertinent spectra without resorting to inelastic dynamic analysis.

Finally, a procedure is suggested for combining vertical and horizontal seismic action effects which accounts for the likelihood of coincidence, or otherwise, of peak response in the two directions.     

FUZZY PATTERN CLASSIFICATION OF STRONG GROUND MOTION RECORDS

Classification of earthquake strong ground motion (SGM) records is performed using fuzzy pattern recognition to exploit knowledge in the data that is utilised in a genetic algorithm (GA) search and scaling program. SGM records are historically treated as “fingerprints” of certain event magnitude and mechanism of faulting systems recorded at different distances on different soil types. Therefore, databases of SGM records of today present data of complex nature in high dimensions (many of the dimensions—or SGM parameters in time and frequency domain—are presently available from different archives). In this study, simple ground motion parameters were used but were combined and scaled nonlinearly such that the physical properties of the data could be preserved while reducing its dimensionality. The processed data was then analysed using fuzzy c-means (FCM) clustering method to explore the possibility of meaningfully representing earthquake SGM data in lower dimensions through finding subsets of mathematically similar vectors in a benchmark database. This representation can be used in practical applications and has a direct influence on the processes of synthesising ground motion records, identifying unknown ground motion parameters (e.g. soil type in this study), improving the quality of matching SGM records to design target spectra, and in rule generalisation for response. The results showed that the stochastic behaviour of earthquake ground motion records can be accurately simplified by having only a few of motion parameters. The very same parameters may also be utilised to derive unknown characteristics of the motion when the classification task on “training” records is performed carefully. The clusters are valid and stable in time and frequency domain and are meaningful even with respect to seismological features that were not included in the classification task.     

SEISMIC AMPLIFICATION AT A SOFT SOIL SITE WITH LIQUEFIABLE LAYER

It is well known that local soil conditions play a key role in the amplification of earthquake waves. In particular, a liquefiable shallow soil layer may produce a significant influence on ground motion during strong earthquakes. In this paper, the response of a liquefiable site during the 1995 Kobe earthquake is studied using vertical array records, with particular attention on the effects of nonlinear soil behaviour and liquefaction on the ground motion. Variations of the characteristics of the recorded ground motions are analysed using the spectral ratio technique, and the nonlinearity occurring in the shallow liquefied layer during earthquake is identified. A fully coupled, inelastic finite element analysis of the response of the array site is performed. The calculated stress-strain histories of soils and excess pore water pressures at different depths are presented, and their relations to the characteristics of the ground motions are addressed.     

论磨制石器工业的资源问题

资源研究是新石器时代以降磨制石器工业研究的一个重要的环节。本文从可用性和可获得性两个方面来分析磨制石器资源的特点。在磨制石器的生产中,原料的大小和形状成为非常重要的原料选取的根据。资源研究的立足点应该是生产型遗址,从生产型遗址出发可以获得比较确信的资源产地信息。     

明代都匀卫学、府学建置背景探析

明初,诏令天下府、州、县、卫、司建立学校。终明之世,明王朝相继在都匀设卫置府,建立卫、府学,开办儒学教育,培养才俊。本文对明代都匀卫、府学建置背景进行考察,旨在从教育这一视角了解明代都匀地区概貌。     

城市增智型游憩场所空间结构研究

随着休闲社会的发展,城市居民的生活逐步进入追求生活质量的阶段,其日常生活方式和内容也越来越休闲-娱乐化。城市增智型游憩场所作为城市居民日常生活休闲娱乐行为的主要场所,它的产生和发展,不仅使人们的休闲、娱乐需求向更高层次迈进,而且也成为衡量城市社会-生活空间质量的重要方面。因此,对休闲-娱乐场所特别是城市增智型游憩场所的空间研究便成为(微)区位研究的核心内容之一。本文从城市社会学、城市地理学等多学科的研究方法角度,概括国内外学者对城市增智型游憩场所的研究现状、研究内容以及其在城市中的空间分布区位的规律性进行了尝试性的探讨。     

读《北福地:易水流域史前遗址》

2007年初,由文物出版社出版的《北福地:易水流域史前遗址》(下称《北福地》)和大家见面了。中易水是海河水系南拒马河的支流,北福地遗址就坐落在此河北岸,西倚太行山脉,东望河北平原。该遗址在1985和1997年分别有过发掘,围绕着这些田野工作提出的问题,特别是为究明北福地一期遗存中甲类和乙类的关系,经过精     

SIGNIFICANT GROUND MOTION PARAMETERS FOR EVALUATION OF THE SEISMIC PERFORMANCE OF SLENDER MASONRY TOWERS

The evaluation of seismic risk of masonry monuments requires to study the combination of vulnerability and hazard. In the present work, the global seismic response of slender masonry towers has been studied by means of a specific 3-D fibre model. Accounting for the particular behaviour of such structures, the hazard should also be described by a suitable measure of intensity of the seismic action. A variety of different parameters relating with the ground acceleration recordings have been investigated for what regards their correlation with the damage indicators of the model. The combination of the peak ground velocity of the horizontal component and of the significant duration is an effective measure of intensity. This measure can be improved by considering the accord of the frequency content of the ground motion with the dynamical characteristics of the tower. Since in some cases the effect of the vertical component proved to be important, a further improvement can be obtained by taking into account also the vertical ground motion intensity.     

EUROCODE 8 DESIGN RESPONSE SPECTRA EVALUATION USING THE K-NET JAPANESE DATABASE

The Eurocode 8 (EC8) currently proposes two standard shapes for the design response spectra. Type 1 spectra are enriched in long period and are suggested for high seismicity regions. Conversely, Type 2 spectra are proposed for low to moderate seismicity areas (like France), and exhibit both a larger amplification at short period, and a much smaller long period contents, with respect to Type 1 spectra. These propositions, however, were constrained using few events mostly recorded on analogical instruments. In the present study, we use the Japanese high quality digital K-net array in order to evaluate the proposed ECS response spectra. Furthermore, all K-net stations have geotechnical characterisation. We first constructed a database of shallow events, depth less than 25 km, to avoid subduction related records. The database spans six years of seismicity from 1996 until 2003. Thus, 591 events were selected with moment magnitude between 4 and 7.3, recorded at 691 stations, giving a total of 6812 two horizontal components accelerograms. Using these records, we computed spectral ground-motion prediction equations and we used them to review the shape of the proposed EC8 spectra. In particular, we studied the plateau-PGA ratio level, the period interval where this plateau is constant, and site amplification effects. The results show surprisingly that the Type 2 rock better envelope the Japanese data. Another interesting observation is that the K-net data corresponding to all soil classes are rich in short periods around 0.1 s. This characteristic has not been observed in other worldwide databases. Normalised empirical predictions show a widening of the plateau as the soil conditions degrade. This suggests that the Type 2 EC8 spectra do not cover enough the long periods for EC3-soil classes C, D and E. Finally, the computed ground-motion prediction equations show that the peak ground acceleration (PGA) is nearly invariant to the soil conditions. Soil effects are mainly seen in the shape and plateau level.