Study on the deformation and failure modes of filling slope in loess filling engineering: a case study at a loess mountain airport

Lvliang airport is a typical loess filling engineering located in 20.5 km north of Lvliang City in Shanxi Province, China. By the end of March 2012, 14 fissures extending more than 7.5 m were observed in a loess-filled slope, of which the longest fissure is up to 82 m. Field monitoring and laboratory tests have been performed to investigate the slope failure modes. The test program includes wetting tests on unsaturated compacted samples and stress path tests on saturated samples. Field monitoring and observations show that differential settlement caused by non-homogeneity in compacted loess density might lead to the formation of fissures in the loess-filled slope. It was founded that the wetting deformation contributed to the development of differential settlement. Fissures are the essential factor for the loess-filled slope failure. Four deformation stages exhibit in the loess-filled slope prior final failure including development of the fissures, softening of the compacted loess, creeping of the slope leading edge and fissuring of the trailing edge and formation of the through-sliding surface. Development of the sliding surface mainly includes upward and downward expansion of the fissures. Upward expansion is a wetting failure process in loading condition, while downward expansion is a load-off wetting process. In addition, development of the sliding surface is accelerated by softening of the compacted soils as a result of water infiltration. Therefore, the key for taking countermeasures against filling landslides is to monitor and control the development of differential settlement and fissures in the slope shoulders. Digging out and extra-filling the fissures are an effective way for preventing these landslides.     

Evaluating climate change adaptation efforts on the US 50 states’ hazard mitigation plans

Climate change brings uncertain risks of climate-related natural hazards. The US Federal Emergency Management Agency (FEMA in Climate change: long-term trends and their implications for emergency management, 2011. https://www.fema.gov/pdf/about/programs/oppa/climate_change_paper.pdf) has issued a policy directive to integrate climate change adaptation actions into hazard mitigation programs, policies, and plans. However, to date there has been no comprehensive empirical study to examine the extent to which climate change issues are integrated into state hazard mitigation plans (SHMPs). This study develops 18 indicators to examine the extent of climate change considerations in the 50 SHMPs. The results demonstrate that these SHMPs treat climate change issues in an uneven fashion, with large variations present among the 50 states. The overall plan quality for climate change considerations was sustained at an intermediate level with regard to climate change-related awareness, analysis, and actions. The findings confirm that climate change concepts and historic extreme events have been well recognized by the majority of SHMPs. Even though they are not specific to climate change, mitigation and adaptation strategies that can help reduce climate change risks have been adopted in these plans. However, the plans still lack a detailed assessment of climate change and more incentives for collaboration strategies beyond working with emergency management agencies.     

非均匀各向异性储层地震AVAZ响应模拟及分析

基于波动理论的各向异性反射率方法能够充分考虑地震波动力学特征。对单界面理论模型、实际非均匀各向异性模型分别进行正演模拟及分析,比较Ruger理论与反射率方法模拟结果的波动力学特征。结果表明,对于界面模型两种方法均能得到相同的计算结果,但对于实际非均匀各向异性介质,基于Ruger理论的算法受时间采样率的影响,而基于波动理论的反射率方法输入实际空间域模型,计算结果不受时间采样率的限制。     

Image-aided platform orientation determination with a GNSS/low-cost IMU system using robust-adaptive Kalman filter

The availability of miniaturized sensors with enhanced capabilities, new methods for image processing, and easy access to small and low-weight airborne platforms for data acquisition, including unmanned vehicles, opens new possibilities for geodetic navigation applications and developing new developments in sensor fusion. In this context, the development of efficient methods, based on low-cost sensors, to extract precise georeferenced information from digital cameras is of utmost interest. We present a method to improve the performance of the integration of GNSS/low-cost IMU by exploiting the orientation changes retrieved from digital images. In this work, a robust-adaptive Kalman filter is also introduced to further improve the performance of the method deployed. The adaptive factor and the robust factor accomplished are determined by innovation information and the threshold value of orientation changes between consecutive images. Results from airborne tests used to assess the performance of the method are presented. The results show that using a non-metric camera, the Euler angle estimation accuracy of the GNSS/low-cost IMU integration can be improved to be close to 0.5 degree and an additional improvement, which can reach 59%, can be achieved after using the robust-adaptive Kalman filter.     

漠河盆地西部二十二站组碎屑锆石U-Pb年龄、地球化学特征及其物源意义

大兴安岭北部漠河盆地内广泛发育二十二站组,其形成时代及物质来源一直以来备受争议.本文在野外地质调查及岩相学的基础上,利用碎屑锆石LA-ICP-MS U-Pb法测年,并结合岩石地球化学等方法,探讨了二十二站组形成时代、物源区大地构造环境及沉积物来源.测年结果显示132个测点年龄主要分布在4个群落,分别为508.3～492.3 Ma;486.9～435.5 Ma;278.3～254.2 Ma;209.5～178.1 Ma.本次获得二十二站组最小碎屑锆石年龄为178.1 Ma,并结合漠河盆地东西部碎屑锆石的年龄,综合认为二十二站组形成时代应为中晚侏罗世.地球化学分析结果显示,二十二站组砂岩的稀土元素与活动大陆边缘的稀土元素曲线吻合较好,且相对亏损高场强元素(Nb和Ta)和大离子亲石元素(Ba和Sr),相对富集高场强元素(La、Th、Zr、Hf),地球化学特征与活动大陆边缘相似.综合古流向、源区母岩分析、碎屑锆石测年分析、微量元素特征等诸多因素,本次研究认为本区二十二站组砂岩的母岩主要来源于盆地南缘广泛分布的前中生代沉积-变质基底(兴华渡口岩群、佳疙瘩组、额尔古纳河组等)及各期中酸性火成岩.     

Numerical investigation of the hydrodynamic response of an impermeable sea-wall subjected to artificial submarine landslide-induced tsunamis

Landslides - Landslide-induced tsunamis are common natural hazards that potentially affect the safety and stability of waterfront structures. A numerical tank was constructed using FLOW-3D to...     

Numerical simulation of direct shear test of rockfill based on particle breaking

Acta Geotechnica - In the traditional Mohr–Coulomb criterion, the shear strength is determined by cohesion and friction angle. However, the particle breakage that occurs on the shear failure...     

固体潮观测数据预处理中的常用方法及计算机实现

从地震台站产出的原始地形变前兆数据出发,提出实际操作性较强的预处理方法,从已编制好的软件中给出处理实例,从而提高地震台站观测人员的科研能力,填补资料预处理方面的某些空白,对于地震台站人员集观测、科研于一体有着十分重要的意义。从95-01-02项目厦门地震台前兆数据预处理的实践表明:这些方法取得了明显的实效,直到今天仍然具有很大的使用价值。     

逆断层地震近场地震动影响场和地表形变模拟

本文设计了一个MW7.0级地震的简单的逆断层有限移动源破裂模型,计算了断层周围64个观测点的加速度、速度和位移时程及峰值,简单讨论了近场地震动峰值、断层附近地表永久位移(或地表形变)的分布特点,并讨论了永久位移和地面运动速度大脉冲的关系。重点研究了断层附近三分量的永久位移(或地表形变)大小、方向和地震动作用特点。