Behaviour of an outward inclined-vertical framed retaining wall of an excavation

Acta Geotechnica - A new excavation retaining structure, referred to as an outward inclined-vertical framed retaining wall (OIVFRW), has been developed and adopted in practice. This retaining...     

A mechanism for the origin and development of the large-scale dunefield on the right flank of the lower reach of Laoha River, Northeast China

By viewing satellite imagery, a striking large-scale dunefield can be clearly perceived, with a size of nearly 63 km long and 11 km wide, and trending NE–SW, on the right flank of the lower Laoha River, Northeast China. By means of remote sensing imagery analysis and field observation as well as a comparison with a small-scale dunefield on the right flank of the lower Xiangshui River, analogous to the case of the lower Laoha River, this paper presents a new mechanism for its origin and development. The results show that:(1) the large-scale dunefield bears a tile-style framework overwhelmingly composed of transverse barchanoid ridges perpendicular to the predominant winds, and inlaid diverse blowouts.(2) The small-scale dunefield, referred to as a primary structural unit of the large one, is typical of an incipient dunefield, following the same rules of evolution as the larger.(3) A succession of barchanoid ridge chains can steadily migrate downwind in much the same manner as surface wave propagation in air or water stimulated by an incised valley, and ultimately tend to bear roughly the same wavelength and amplitude under stable climate and hydrologic regimes.(4) The first ridge chain acquires its sand source substantially from the downwind escarpments exposing the loose Quaternary sandy sediments to the air, while the ensuing ridges derive their sands dominantly from in situ deflation of the underlain Quaternary loose sandy sediments in blowouts, partly from the upwind ridges through northern elongated horns. Theoretically, the sands from riparian escarpments can be transported by wind to the downwind distal end of a dunefield after sufficient long duration.(5) The lower Laohahe region experienced probably three significant climatic changes in the past, corresponding to the three active dune belts, suggesting that once a large-scale dunefield occurs, it is nearly impossible to be completely stabilized, at least in its central portions. At present, seasonal shrinkage and stagnation of the lower Laoha River, widespread farming and afforestation in the valley, and establishing windbreaks downwind of the valley as well as surrounding the dunefield, appear to have significantly modified local flow fields and sand sources, engendering significant degradation of the dunefield.     

东亚夏季风石笋记录中缺失格陵兰间冰段25?

东亚季风是全球气候系统的重要组成部分[16]。了解北大西洋地区温度变化和东亚夏季风之间的关系对了解东亚季风的控制机制具有重要意义。葫芦洞和董哥洞石笋δ18O记录显示距今7510ka北大西洋地区千年尺度温度变化对东亚夏季风变化具有重要影响:较强的东亚夏季风与北大西洋地区较高气温对应,反之亦然[7,8]。但是,在此之前东亚夏季风变化与北大西洋地区温度变化之间是否具有类似的联系?到目前为止对这一问题尚没有明确的探讨。     

Dating of multi-period earthquake-triggered rockfalls: a method for revealing paleo-seismic events that occurred along the Yushu fault in the eastern Tibetan Plateau

Landslides - The quantitative study of earthquake-triggered rockfall debris along seismogenic fault zones has proven to be a valid approach for use in identifying paleo-earthquakes and faulting...     

浅层工程地震层析成像技术的应用研究

本文由射线理论出发,简要地阐述了浅层折射地震层析成像方法的原理,并给出了应用实例     

The Mathematic Models of the Kalman Filtering for Across-Fault Measurement

This paper makes a probe into the application of the Kalman filtering method to the data processing of across-fault measurements.On the basis of statistical regression,the mathematic and stochastic models of filtration are established by combining the regression method with Kalman filtering.In the filtering computation,not only the randomness of fault movements but also the time-dependent variation of environmental effects have been taken into consideration.By use of the adaptive filtering method,an estimation of the dynamic noise variance matrix is obtained through iteration.Models for one measuring line(leveling line or baseline),two measuring lines(both leveling lines or both baselines)and four measuring lines(two leveling lines and two baselines)are derived and established systematically.By means of these models,the data of across-fault measurements can be processed dynamically in real-time to provide the filtered values of height difference between benchmarks or baseline length at different time in     

密1井水位在日本北海道7.8级地震震前的异常反映

黑龙江省密山市密１井水位于１９９３年７月１２日２１时１７分日本北海道西南海域Ｍｓ７．８级强震前４天开始出现的水位异常现象，这可能是地下水位的远场前兆效应，对强震孕育过程的理解提供了新的科学线索。     

山东数字地震台网定位子台网 选取对定位结果的影响

选取山东及邻区4个不同区域的地震,分析“定位子台网”分布对地震定位精度的影响,研究“定位子台网”的选取规则.探讨两种台站分布情况下定位偏差、水平误差、拟合残差随空隙角、近台距离、远台距离的变化;定位偏差及水平误差与拟合残差的关系.结果显示,速报时选择4-9个分布相对合理的“定位子台网”参加定位,结果较好,使用水平误差估...