Cyclic testing of unreinforced masonry walls in two‐way bending

An experimental programme was conducted in which eight full‐scale unreinforced masonry walls were subjected to cyclic face loading using a system of airbags. Of the eight walls, six contained a window opening and four were subjected to vertical pre‐compression. Combined supports at the vertical and horizontal edges ensured that under face loading the walls underwent two‐way bending. The test walls were found to possess good post‐peak strength and displacement capacity as well as reasonable energy dissipation characteristics. Significant strength and stiffness degradation and non‐symmetry of strength in the positive and negative displacement directions were also evident. Discussion of the causes of the aforementioned trends and their implications towards the seismic response of masonry walls is provided. Copyright © 2006 John Wiley & Sons, Ltd.     

Shaking table model test and engineering practice of a new gypsum-adobe walls dwelling in Xinjiang autonomous region, China

The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.     

兰州市红古区非天然地震记录特征分析

选取2010年1月至2020年8月期间甘肃区域测震台网记录的兰州市周边地区三分向宽频带数字波形资料,采用震中位置空间分布、波形特征及傅里叶频谱特征对比等多种方法相结合,分析兰州市红古区非天然地震活动的特性.结果显示:该区临近测震台记录的大量地震事件波形特征和傅里叶频谱特征与其他区域地震存在显著差异,符合非天然地震的典型...     

Submerged reefal deposits near a present‐day northern limit of coral reef formation in the northern Ryukyu Island Arc,northwestern Pacific Ocean

High‐resolution single‐channel seismic reflection surveys were carried out in the northern Ryukyu Island Arc during an NT05‐14 cruise of the R/V Natsushima. The survey area is located northeast of Amami Oshima and southwest of Kikai Shima immediately south of the current northern limit of coral reef formation in the northwestern Pacific Ocean. The main purpose of the surveys was to ascertain whether coral reefs formed during glacial periods and, if so, to determine their three‐dimensional distribution. We collected 784 km of high‐resolution single‐channel seismic data during the cruise. The acoustic basement is clearly observed under the Amami Spur, off Amami Oshima. The seismic profiles show two anticlines, each with an axis trending northeast to southwest. Thin Quaternary stratified sediment overlies the acoustic basement in the northwestern and southeastern slope areas, as well as between the anticlinal axes. The stratified sediment can be divided into several sedimentary units. The mound‐shaped reflections are found within the stratified sedimentary units in the central to eastern parts of the spur. Because the mound‐shaped reflections are characterized by strong reflections and chaotic internal structures in profiles, they are considered biogenic ‘reefs’ or banks consisting of coarse‐grained bioclasts. They overlie the acoustic basement or stratified sediment and reach 15 m in thickness and 400 m in width. In contrast, irregularly shaped topographic highs were detected at the shelf edge southwest off Kikai Shima, which are likely to be remnants of coral reefs formed during the last glacial period. Our seismic data indicate probable coral reef formation at low stands during glacial stages, such as the Last Glacial Maximum, even in the northern Central Ryukyus. The occurrence of drowned reefs may indicate that their growth rate was not sufficient to keep up with a rapid rise in sealevel after a glacial period.     

Spatial distribution of surface properties,runoff generation and landscape development in the Zin Valley Badlands,northern Negev,Israel

In?ltration tests, soil mapping and soil property analysis were used to assess the effect of within‐storm rainfall conditions on spatial patterns of surface characteristics relevant for runoff generation, continuity and erosion in the Zin Valley Badlands. Runoff and erosion differ strongly between ridges and slopes. Soils at both locations are susceptible to sealing, but on the sideslopes deep desiccation cracks inhibit continuous ?ow, even during high magnitude rainstorms. The discontinuous nature of runoff has a feedback on surface conditions. Erosion on the ridges maintains shallow soils prone to sealing while in?ltration and deposition on the sideslopes enhance soil depth, a prerequisite for stable desiccation cracks. Some runoff generated on the ridges is transmitted to the valley via rills. On straight sideslopes, rills are single and often discontinuous, indicating limited frequency of continuous runoff. Along concave valley heads, rill systems are well integrated and continuous, concentrating runoff and reducing in?ltration losses along slopes. The longitudinal, V‐shaped valley morphology of small catchments in the Zin Valley Badlands re?ects the long‐term effect of different erosion rates in valley heads and on sideslopes. Over time, valley incision lengthened the sideslopes, reducing the portion of annual rainfall that was runoff‐effective. Once sideslopes reached a critical length that inhibited frequent continuous ?ow, a colluvium with an increased in?ltration capacity developed, reducing runoff frequency even further. Consequently, erosion on the valley sideslopes decreased. Continuous ?ow from ridges to the valley channel remained more common in integrated rill systems in concavities and valley heads, leading to more erosion and retreat of the valley heads. The spatial patterns of runoff and erosion in the Zin Valley Badlands demonstrate that landscape development is strongly affected by processes that lead to differentiation of soil properties on hillslopes with uniform lithology. The patterns of surface characteristics and their role in landscape development are strongly dependent on rainfall conditions, highlighting the need for geomorphologists to identify the dynamic spatial and temporal scales relevant for landscape development. Copyright © 2004 John Wiley & Sons, Ltd.     

柴达木盆地三湖地区北斜坡岩性地层气藏形成的地质条件与预测技术研究

三湖地区北斜坡褶皱发育,相变快,生储盖组合优越,具备形成岩性地层气藏的构造背景和地质务件.由于本区储层厚度薄(1～3m),缺乏三维地震资料,砂体分布难以准确追踪,导致岩性地层气藏勘探难以取得突破.已知气藏解剖和理论研究表明地层含气后会产生特殊的地震响应,通过地震异常信息研究,结合构造、沉积和成藏条件分析,发现驼西地区是岩性圈闭发育带,Tzh2井获得工业气流证明该区带具备形成岩性气区的潜力.