中国砂质海岸分布特征与存在问题   总被引：10，自引：0，他引：10  

李震  雷怀彦 《海洋地质前沿》2006,22(6):1-4

中国东部砂质海岸分布范围广泛,地形发育多样,风沙灾害、海岸侵蚀等地质灾害问题多发,严重影响了沿海地区的社会经济发展。了解沙质海岸的分布特征,做好砂质海岸的研究防护工作,对促进海洋经济持续稳定的发展有着十分重要的作用。  相似文献   

长输管道抗震研究的新进展   总被引：2，自引：0，他引：2  

陈贵清  郝婷玥  吴班  王兴国 《地震工程与工程振动》2006,26(3):193-196

本文主要从以下4个方面:地震对长输管道的危害、长输管道震害的研究方法、管道抗震分析和管道抗震的措施,介绍了近几年长输管道抗震方面的研究进展,指出了今后长输管道的研究方向。  相似文献   

Geomorphological evidence from the Lleyn Peninsula constraining models of the magnitude and rate of isostatic rebound during deglaciation of the Irish Sea Basin     

Danny McCarroll 《Geological Journal》1995,30(2):157-163

A stepped series of sand and gravel terraces on the Lleyn peninsula of North Wales is used to test the magnitude and rate of isostatic depression required by the recently proposed glacimarine model of deglaciation of the Irish Sea Basin. A relative sea-level fall of 70 m is required while the ice remained pinned at the north Lleyn coast. Even taking the maximum known rate of isostatic uplift, the margin would have to remain stationary for 1400 years. It seems more reasonable to interpret the Lleyn terraces, and similar features around the Irish Sea Basin, as glacifluvial and glacilacustrine.  相似文献   

黔中乌当盆地阶地沉积特征及其对盆地演化的指示   总被引：1，自引：0，他引：1  

蒋玺  陈文奇  宁凡  郑军  罗维均  周涌 《地理研究》2020,39(6):1242-1254

黔中乌当盆地是贵州省山间盆地的典型代表,四级河流阶地清晰地记录了新构造运动中区域地壳抬升和盆地演化。通过阶地沉积物砾组统计、粒度分析、光释光（OSL）测年,探讨盆地的发育和演化。结果显示,阶地砾石排列指示盆地水系古流向与现代河流基本一致,砾石磨圆度变化大,分选较差,岩性继承了区域地层。砾石组合特征反映了构造抬升期盆地内强烈的冲刷剥蚀。漫滩沉积物粒度表明盆地在稳定阶段河流水动力整体呈增大趋势。T4和T3发育阶段区域以冲刷剥蚀为主并塑造了盆地雏形。T2阶地沉积特征及测年结果（177.4 ka~87.6 ka）表明中更新世末期持续数万年的沉积夷平作用使盆地基本成型。T1阶地形成时代约25ka,指示了黔中地区最近一次构造抬升和盆地的最终定型。  相似文献   

厦门岛东海岸的蚀退与防护   总被引：5，自引：0，他引：5  

高智勇  蔡锋  和转  苏贤泽 《台湾海峡》2001,20(4):478-483

根据波浪输沙和地形对比，对厦门岛东部海岸的岸滩侵蚀动态及演变趋势进行探讨，并根据其海岸特点提出相应的防护对策。  相似文献   

南麂列岛海洋自然保护区潮间带小型生物初步研究   总被引：3，自引：3，他引：3  

林岿璇  张志南  韩洁 《中国海洋大学学报(自然科学版)》2003,33(2):219-225

20 0 1年 10月对浙江省南麂列岛国家海洋自然保护区潮间带进行小型生物采样调查。大沙岙沙滩小型生物丰度较低 ,中潮带为 2 91.9ind· 10 cm-2 ,低潮带为 5 16.8ind· 10 cm-2 。线虫是最优势类群 ,线虫 /桡足类比分别为 3.2 7和 1.0 6,表明沙滩环境质量良好 ,未受到有机质污染。岩相潮间带有 4种大型底栖海藻。附植小型生物平均丰度为 36.1ind· g-1dw algae,桡足类为最优势类群。附植大型底栖动物丰度 4 4 .6ind· g-1dwt algae,大于小型生物丰度。  相似文献   

Explicit stress–strain equations for modeling frictional materials     

Kenneth J. Xu  Martin D. Liu  Buddhima Indraratna 《Marine Georesources & Geotechnology》2018,36(6):722-734

In this paper, a comprehensive study on simulating the shearing behavior of frictional materials is performed. A set of two explicit equations, describing the relationship among the shear stress ratio and the distortional strain and the volumetric strain, are formulated independently. The equations contain three stress parameters and three strain parameters and another parameter representing the nonuniformity of stress and strain during softening. All the parameters have clear physical significance and can be determined experimentally. It is demonstrated that the proposed equations have the capacity of simulating the complicated shearing behavior of many types of frictional materials including geomaterials. The proposed equations are used to simulate the stress–strain behavior for 27 frictional materials with 98 tests. These materials include soft and stiff clays in both reconstituted and structured states, silicon sands and calcareous sands, silts, compacted fill materials, volcanic soils, decomposed granite soils, cemented soils (both artificially and naturally cemented), partially saturated soils, ballast, rocks, reinforced soils, tire chips, sugar, wheat, and rapeseed. It has been demonstrated that the proposed explicit constitutive equations have the capacity to capture accurately the shearing behavior of frictional materials both qualitatively and quantitatively. A study on model parameters has been performed.  相似文献   

Development of the cyclic p–y curve for a single pile in sandy soil     

Sung-Ha Baek  Joonyoung Kim  Seung-Hwan Lee 《Marine Georesources & Geotechnology》2018,36(3):351-359

Pile foundations that support transmission towers or offshore structures are dominantly subjected to cyclic lateral load induced by wind and waves. For a successful design, it is crucial to investigate the effect of cyclic lateral loads on the pile behavior that is loaded laterally. Although the p–y curve method is generally utilized to design the cyclic laterally loaded pile foundations, the effect of cyclic lateral loads on the pile has not been properly implemented with the p–y curve. This reflects a lack of consideration of the overall stiffness change in soil–pile interaction. To address this, a series of model pile tests were conducted in this study on a preinstalled aluminum flexible pile under various sandy soil conditions. The test results were used to investigate the effect of cyclic lateral loads on the p–y behavior. The cyclic p–y curve, which properly takes into account this effect, was developed as a hyperbolic function. Pseudo-static analysis was also conducted with the proposed cyclic p–y curve, which showed that it was able to properly simulate cyclic laterally loaded pile behavior in sandy soil.  相似文献   

Physical determinants of intertidal communities on dissipative beaches: Implications of sea-level rise     

Tsuyuko Yamanaka  Dave RaffaelliPiran C.L. White 《Estuarine, Coastal and Shelf Science》2010

Sea-level rise is likely to cause significant changes in the morphodynamic state of beaches in the higher latitudes, resulting in steeper beaches with larger particle sizes. These physical changes have implications for beach invertebrate communities, which are determined largely by sediment particle size, and hence for ecosystem function. Previous studies have explored the relationships between invertebrate communities and environmental variables such as particle size, beach slope and exposure to wave action, and often these physical variables can be integrated in various indices of morphodynamic state. Most of these studies incorporated a full range of beach types that included wave-dominated surf beaches, where the wave action is harsh enough to enable reliable estimates of breaker height, a parameter included in several of the indices, and concluded that more dissipative beaches with gentler slopes and finer particle sizes often support a higher number of species and greater abundance than more reflective beaches. Whether these predictions remain valid for less wave-dominated beaches, where breaker height is more difficult to determine, is uncertain. In the present study, the abundance of meio- and macrofauna was quantified across a range of beaches in the UK, which are generally towards the lower energy end of the morphodynamic gradient, and their relationships with beach physical properties explored. No significant relationships were found between abundance and the standard morphodynamic indices, but significant relationships were found for both macro- and meiofaunal abundance when these indices were combined with an exposure index (derived from velocity, direction, duration and the effective fetch). All the relationships identified between abundance and combined morphodynamic indices indicated a higher abundance of both macro- and meiofauna on the more dissipative beaches. The reverse was however found for species richness. If predictions that accelerated sea-level rise will move beaches towards a more reflective morphodynamic state are correct, this could lead to declines in the abundance of meio- and macrofauna, with potential adverse consequences for ecosystem functioning.  相似文献   

粒度特征揭示的中全新世以来毛乌素沙地演化过程   总被引：1，自引：1，他引：0  

刘振宇  靳鹤龄  刘冰  薛文萍 《中国沙漠》2019,39(1):88-96

通过对毛乌素沙地现代固定沙丘、半固定沙丘、半流动沙丘和流动沙丘的粒度特征分析,发现研究区沙地变化敏感粒度是>245 μm的沉积物粒度组分,尝试性地将其用于地质时期沙地演化研究。结合区域典型风成砂-古土壤剖面的沉积相特征,探讨了中晚全新世以来毛乌素沙地的时间演化过程及其特征。结果表明：中全新世以来毛乌素沙地存在多次活化扩张和固定萎缩事件,除7.5 ka BP前为流动沙地占优势以外,其余阶段多在半流动沙地、半固定沙地和固定沙地之间频繁转换,即使在全新世适宜期古土壤大规模发育期间仍存在局地短时间的沙地活化事件。  相似文献