Rigid‐plastic seismic design of reinforced concrete structures

In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed—the Rigid‐Plastic Seismic Design (RPSD) method. This is a design procedure based on Non‐Linear Time‐ History Analysis (NLTHA) for systems expected to perform in the non‐linear range during a lifetime earthquake event. The theoretical background is the Theory of Plasticity (Rigid‐Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required structural strength with respect to a pre‐defined performance parameter using a rigid‐plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing required strength throughout the structure. Any artificial considerations intended to adjust results according to empirical observations are avoided, which, from a conceptual point of view, is considered to be an advantage over other simplified design procedures for seismic design. The procedure is formulated using a step‐by‐step format followed by a design example of a 4‐storey‐R/C‐plane‐frame. Results are compared with refined NLTHA and found to be extremely encouraging. Copyright © 2006 John Wiley & Sons, Ltd.     

气候变化国家评估报告(Ⅱ):气候变化的影响与适应

Significant and various impacts of climate change have been observed in China, showing both positive and adverse effects, dominantly the latter, in different sectors and regions. It is very likely that future climate change would cause significant adverse impacts on the ecosystems, agriculture, water resources, and coastal zones in China. Adoption of adaptive measures to climate change can alleviate the adverse impact, therefore such measures should be incorporated into the medium-and long-term national economic and social development plans. Because China has done relatively limited research on impact assessment and our understanding of climate change is incomplete, the current impact assessment methodologies used and results obtained contain many uncertainties. To reduce the uncertainties and develop effective and practical climate change adaptive measures in China, it is necessary to emphasize regional case studies on adaptive measures, enlarge the scope of climate change research, and strengthen the assessment of the impacts resulted from extreme weather/climate events.     

Compressibility behaviour of lime-stabilized clay

Lime stabilization reactions result in the formation of inter-particle cementation bonds that improves strength and reduce compressibility of clay soils. Though several studies in the past have focused on the impact of lime stabilization on the strength behaviour, few studies have examined the impact of lime stabilization on the compressibility behaviour of clay soils. The present study examines the compressibility behaviour of lime-stabilized soils in light of the frameworks proposed for saturated cemented clays. Cementation bonds formed during the lime stabilization reactions imparted yield stress in the range of 3900–5200 kPa to the artificially cemented specimens. The compression behaviour of these artificially cemented specimens in the pre-yield stress and post-yield stress regions conformed to the framework proposed for saturated cemented soils.     

广西地质构造稳定性分析与评价

文章简述了广西现代地貌、活动断裂、活动盆地特征及地震活动概况 ,将广西地质构造稳定程度划分为稳定、较稳定、较活动 3个一级区和相应的 10个二级带 ,提出今后可能发生 5～ 6级地震的危险地区。     

GCM STUDIES ON ANTHROPOGENIC CLIMATE CHANGE IN CHINA*

Impacts of human activities on climate change as simulated by the general circulation models (GCMs)in China for the recent ten years have been summarized and reviewed in this paper.The researches show that it might be getting warmer over China due to the greenhouse effects.The atmospheric circulation and precipitation also might be changed due to the greenhouse effects.The assessments and evaluations of the models over the globe and China have also been presented in this paper.     

昆明世博会艺术广场后山高陡边坡整治工程

中国 1999昆明世博会艺术广场后山边坡整治工程 ,实施于一废弃采石场 ,不良地质现象十分发育。工程要求安全可靠 ,又与所在自然环境匹配相融 ,采取了清方、喷锚防护加固、截排表水及坡面整饰措施 ,取得了良好整治效果。     

矿渣胶凝材料固化软土的力学性状及机制

利用矿渣胶凝材料固化软土,既可利用工业废渣,又能减少水泥的用量。以矿渣胶凝材料固化黏土、砂土二种软土。发现矿渣胶凝材料加固软土的效果远好于水泥、石灰,其9 %掺量的固化土28 d的无侧限强度达到2.0 MPa以上,普遍高于15 %掺量的水泥固化土,且其28 d固化土的软化系数普遍高于90 %以上,固化黏土后CBR值远高于同掺量的石灰固化土。X衍射结构分析表明,矿渣胶凝材料水化时产生的高强难溶的矿物晶体是其固化软土效果好的主要原因。因此,矿渣胶凝材料是一种性能优异的软土加固材料。     

固化疏浚淤泥做堤防填筑材料的试验研究

固化疏浚淤泥作为堤防填筑材料,既解决淤泥的处置,又可解决堤防建设中填土的缺乏。用灰渣胶凝材料（HAS）固化淤泥并测试固化淤泥土的主要物理力学性质,发现掺6 %灰渣胶凝材料固化后的淤泥土,在自然堆积28 d后的液塑限达到60 %,有机质含量降低到2 %,淤泥由原来的有机质高液限黏土（CHO）变成高液限粉质黏土（MH）,其28 d的无侧限抗压强度普遍大于1.4 MPa,凝聚力c≥100 kPa,内摩擦角?＞35°,渗透系数小于10-6 cm/s,远高于提防填筑材料的标准,表明灰渣胶凝材料固化改性淤泥成为堤防填土是可行的。     

古尔班通古特沙漠短命植物分布及其沙面稳定意义

Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation,describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes,analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert.Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.     

古尔班通古特沙漠短命植物分布 及其沙面稳定意义

从植被稳定沙面的角度出发,通过2002年对古尔班通古特沙漠南部沙垄表面植物种类、高度和盖度等的系统监测,阐明短命植物在单个沙丘上的时空分布规律。并对气象资料和人类活动扰动沙面后短命植物的自然侵入等进行综合分析,探讨沙面稳定中短命植物的重要作用。研究区总计有45种植物,其中短命植物29种。4月初短命植物萌动出土,在两个月左右的时间完成整个生长发育过程。4、5、6三个月正是北疆沙漠风沙活动强盛期,大部分沙垄表面乔灌木和长营养期草本植物盖度不足10%,而短命植物盖度则分别达到13.9%、40.2% 和14.1%,是古尔班通古特沙漠植被稳定沙面的主要贡献者。对工程行为扰动沙面后的植物恢复调查显示,短命植物是首先入侵的先锋植物。