新疆天山中段两次Ms6.0地震前异常特征的聚类分析

分别选取2011-11-01精河Ms6.0地震和2012-06-30新源-和静Ms6.6地震自2009-01以来100 km范围内ML3.0以上地震, 使用CAP和P波初动方法计算震源机制解,并对主震前震源机制解进行聚类分析。结果表明,震中附近震前半年左右,震区周围地震断层性质逐渐由紊乱变为统一;最大主压应力P轴方位由随机逐步呈现相对突出方向,且逐步与主震方向一致。     

Dynamic analysis and numerical modeling of the 2015 catastrophic landslide of the construction waste landfill at Guangming,Shenzhen, China

Since lots of underground and slope excavation works were conducted during the urbanization process, an increasing number of sites in ravines around a city have been used to stockpile a large amount of excavated soils. This brings a huge challenge for researchers and managers in the risk evaluation and mitigation of potential dangers of these man-made construction waste landfills. This paper describes a recently large landslide of the construction waste landfill, which occurred at a site of Guangming new district in Shenzhen, China, on December 20, 2015. This catastrophic landslide caused the death of 69 persons and 8 persons are still missing. In this paper, this landslide was numerically simulated and analyzed. In spite of neither high-intensity rainfall nor antecedent rainfall, a slope of this landfill with a relative height of 111 m sided and caused about 2.34 million cubic meters of the soils to travel over a gentle terrain more than 1.2 km. This means that the landslide mobility index (H/L = 0.092) is much lower than a general designed value and the values in most other cases. A depth-integrated continuum method and a MacCormack-TVD finite difference algorithm are adopted, in this paper, to numerically simulate the dynamic process of this large landslide. It is found that a Coulomb friction model with consideration of the pore water pressure effects can well reproduce the main characteristics of the dynamic process of this landslide. Sensitivity analysis has demonstrated that the high pore water pressure in the soils plays a significant role in its mobility and is a key factor to the severity of this landslide.     

关于地震预警的几个问题

地震预警是建立在高密度地震台网基础上的新技术,本文就地震预警的一些基本概念、关键技术、预警效果、预警部署及其在防震减灾方面的作用等进行了讨论,指出了地震预警存在的问题,以及需要研究的方向,并首次提出了预警能力、预警无效区、预警受益区、预警反应时间的概念.地震预警能力受预警系统的制约,实际地震预警能力除与台网密度、预警模式、自动处理系统、数据传输模式、发布系统等因素有关外,还与地震破裂性质有关.同时强调地震预警部署是复杂的社会工程,需要全社会的共同参与.     

挤压作用下盐岩流动的三维物理模拟分析

盐岩的流动性在盐构造的研究中一直颇受关注.本文结合物理模拟实验及模型的三维重建技术分析了影响盐岩流动的区域构造挤压位移负载和沉积差异负载两种作用力因素.研究认为,盐岩在构造挤压作用下存在明显的流动变形.在高挤压构造应变背景下(动力应变率约10-13s-1数量级),盐岩的流动变形主要受区域构造挤压的位移负载制约,其次是同...     

Seismic stability analysis of soil nail reinforced slope using kinematic approach of limit analysis

Prediction of the critical seismic yield acceleration coefficient and the seismic permanent displacement of soil nail reinforced slope under seismic loading has been playing an important role in helping design in the earthquake-prone areas. In this paper, the seismic stability of soil nail reinforced slope is analyzed using the kinematic theorem of limit analysis. The log-spiral failure mechanism is considered and the corresponding analytical expressions are derived to calculate the critical seismic yield acceleration coefficient and the permanent displacement of slope subjected to earthquake loading. A series of calculations are carried out to illustrate the influence of inertial force on the stability of a nail-reinforced slope. Parametric studies indicate that the strength and geometry of slope as well as characteristic parameters of soil nail have a significant effect on the critical seismic yield acceleration coefficient and the permanent displacement of soil nail reinforced slope.     

贵州茂兰喀斯特地区土壤全钙含量空间估算模型与迁移分析

文章在世界自然遗产地贵州荔波茂兰保护区采集土壤全钙数据,分析采用地理加权回归（GWR）方法进行空间分析的有效性,筛选识别影响土壤全钙空间分布的主要因子,建立喀斯特地区土壤全钙含量空间分布计算模型,获取研究土壤全钙空间分布基础数据。通过土壤流失方程（USLE）计算土壤侵蚀状况,对比分析土壤全钙与土壤侵蚀空间关联,揭示土壤全钙的空间迁移规律。结果表明:（1）在岩性一致条件下,相对高差和坡度是影响土壤全钙空间分布的主导因子;（2）GWR模型的预测精度优于全局回归的（OLS）,相关系数分别是0.41和0.39;（3）通过土壤全钙含量空间估算模型,计算得到研究区土壤全钙空间分布特征,土壤全钙为0 ~37.68 gkg-1。研究结论说明,在湿润气候的喀斯特地区,尽管植被覆盖度大,但土壤全钙空间分布仍然深受成土母质影响,喀斯特峰林土壤侵蚀强度大,土壤全钙含量高,物质迁移以流失为主,峰丛洼地土壤侵蚀强度小,土壤全钙含量低,物质迁移以淋溶流失为主。      

降水偏差订正的频率(或面积)匹配方法介绍和分析

针对AREM模式降水预报的偏差特征,开展了基于频率(或面积)匹配方法的降水偏差订正试验,重点介绍了该方法的原理和实现过程,并对订正前后的结果进行了系统检验,深入分析了该方法的优缺点并指出了可能的改进方向。经过3个月降水集中期(2012年6—8月)的逐日试验分析结果表明:(1)该方法能显著改善模式降水预报中雨量和雨区范围的系统性偏差,订正后降水预报的范围和平均强度与实况更加接近;(2)偏差愈大订正效果愈好;(3)原理上此法不能订正降水的落区位置偏差,但通过改变雨区范围的大小,订正后降水预报的TS和ETS的评分也有一定程度提高,尤其是小雨量段,订正使数值预报的"有雨或无雨"的定性降水预报的质量得到明显改善。针对该方法"不能改进降水落区偏差"的局限性,提出了5种可以改进和尝试的方法,同时指出,该方法和原理可以用于单站降水预报、雾和水文的流域预报的偏差订正。