The retrieval of two-dimensional distribution of the earth''''s surface aerodynamic roughness using SAR image and TM thermal infrared image

The research for the land surface fluxes has madea quiet great progress for its breakthroughs in the fieldof regional or global interactions between land surfaceand atmosphere. However, many remote sensing mod-els for estimating the land surface fluxes need the pa-rameters of surface momentum, heat, resistance ofwater vapor at a referenced height, which are the func-tion of aerodynamic surface roughness zad. It hasbeen validated that the retrieval of the land surfacefluxes is very sensitive to…     

Some aspects of cast blasting techniques for dam construction

Summary A proposal is under consideration to construct a dam on an experimental basis by a cast (or directional) blasting technique, DBT. The dam site is located at Bharari Khad, a tributary of the Sutlaz river in Himachal Pradesh. Site investigations have been completed and a large scale blast has been designed for construction of the experimental dam.The paper describes the basic design concept of DBT and application of throw and caving methods for construction of dams. The preliminary tests required to design the blasting pattern are detailed. The technique has a great potential because it reduces construction cost and time particularly in inaccessible mountain regions.     

大型化综放开采煤层注水方案及参数确定

强调在大型化综放开采煤层中开设抬高中间巷进行煤层注水，其注水效率高，可一巷多用，防灾效果全面。结合算例，用有限元数值模拟方法模拟了在厚煤层中注水的过程，得到最小湿润范围准则为煤层厚度的1．5倍。分析了综放开采煤层注水工艺参数中注水压力、时间和钻孔间距与湿润范围的动态变化关系，给出了选取合理的注水工艺参数的方法。指出在大型化综放开采进行煤层注水，湿润时间充裕，同时，考虑到压裂并软化煤体，应采用较高的压力注水，此时，钻孔间距可扩大至35m。     

黑龙江、乌苏里江塌岸地质灾害及防治措施

黑龙江、乌苏里江沿岸地区受地理、地质地貌因素的影响,沿岸正遭受江水的侵蚀,塌岸严重,已造成大面积的国土流失.河流侵蚀、冻融作用、人为植被等使沿岸地质环境脆弱化,影响了沿岸地区经济可持续发展,直接威胁人民生命财产安全.治理塌岸,保护国土刻不容缓.本文全面论述了黑龙江、乌苏里江沿岸塌岸的现状、类型、成因及未来发展态势,提出了保护天然植被、护岸工程建设、退耕还林草等防治塌岸的具体措施和对策.     

绿洲-沙漠复合地表条件下的局地和有效粗糙度

地表空气动力学粗糙度是研究水平非均匀条件下陆面过程的基础,文中对黑河试验区各不同下垫面上地表空气动力学粗糙度进行了估算和分析,分别得到了地表空气动力学粗糙度ｚ０ｍ的有效值和局地值,发现各不同典型下垫面的局地ｚ０ｍ值明显不同,尤其在有作物存在时,绿洲的局地ｚ０ｍ值比沙漠、戈壁的值明显要大;而对同一测站,有效空气动力学粗糙度比局地空气动力学粗糙度值明显要大,运用应力分解理论对这种差异进行了解释,认为有效空气动力学粗糙度与复合表面的总应力有关,其代表了较大水平尺度内的表面和较高障碍物的综合作用,当涉及对陆表通量参数化问题时,必须首先确定水平尺度及相应的地表粗糙度参数     

Investigation into the Behaviour of a Support System and Roof Strata During Sublevel Caving of a Thick Coal Seam

Monitoring of strata control parameters and behaviour of a powered support was carried out during an experimental trial of a mechanized longwall sublevel caving face for exploitation of a 7.5m thick coal seam. Field observations indicated that the requirement of support density for underwinning of top coal by sublevel caving under intact strata is different from that for underwinning under broken and fractured rock mass. Analysis of the leg closure observations and support resistance variations during different mining cycles showed rapid increase of the setting load density of the support in relation to the yield load density. This resulted in a large amount of leg closure during mining cycles of the sub level caving face under broken rock strata. Due to operational constraints, the field observations could not provide enough information to visualize the behaviour of the overlying rock strata. Simulation of the field conditions was therefore performed on a physical model to bridge this gap of information. Results of laboratory investigations on the physical model are combined with those of the field to explain the critical behaviour of the support system during sublevel caving under broken rock strata.     

Controls on the aerodynamic roughness length and the grain‐size dependence of aeolian sediment transport

Estimates of the wind shear stress exerted on Earth's surface using the fully rough form of the law‐of‐the‐wall are a function of the aerodynamic roughness length, z₀. Accurate prediction of aeolian sediment transport rates, therefore, often requires accurate estimates of z₀. The value of z₀ is determined by the surface roughness and the saltation intensity, both of which can be highly dynamic. Here we report field measurements of z₀ values derived from velocity profiles measured over an evolving topography (i.e. sand ripples). The topography was measured by terrestrial laser scanning and the saltation intensity was measured using a disdrometer. By measuring the topographic evolution and saltation intensity simultaneously and using available formulae to estimate the topographic contribution to z₀, we isolated the contribution of saltation intensity to z₀ and document that this component dominates over the topographic component for all but the lowest shear velocities. Our measurements indicate that the increase in z₀ during periods of saltation is approximately one to two orders of magnitude greater than the increase attributed to microtopography (i.e. evolving sand ripples). Our results also reveal differences in transport as a function of grain size. Each grain‐size fraction exhibited a different dependence on shear velocity, with the saltation intensity of fine particles (diameters ranging from 0.125 to 0.25 mm) saturating and eventually decreasing at high shear velocities, which we interpret to be the result of a limitation in the supply of fine particles from the bed at high shear velocities due to bed armoring. Our findings improve knowledge of the controls on the aerodynamic roughness length and the grain‐size dependence of aeolian sediment transport. The results should contribute to the development of improved sediment transport and dust emission models. © 2018 John Wiley & Sons, Ltd.     

基于非定常面元法的海上浮式风机气动性能研究

对于海上浮式风机而言,由于受到剪切风、塔影效应、浮式基础运动等因素的共同影响,其气动载荷会更加复杂,因此如何准确快速地对海上风力机的气动性能进行预估显得尤为重要。基于速度势的非定常面元法理论,研究海上浮式风机气动载荷特性,编制了相关的计算程序。以NREL 5 MW风机为例,建立了叶片和尾流的三维数值模型,计算得到了不同风速下风机的输出功率以及叶片表面的压力分布,对比数据结果分析了该方法的可靠性。针对非定常流动,模拟了剪切风和塔影效应的作用,并重点分析了浮式基础运动对风机气动载荷的影响。研究表明,浮式基础的纵荡和纵摇会增加输出功率的波动幅值,艏摇运动会导致单个叶片上的气动载荷产生较大的波动,为浮式风机叶片控制提供了参考。     

北疆铁路沿线风沙危害的研究

北疆铁路沿线存在着严重的风沙危害。在三个典型路段风沙危害有不同的表现形式, 北疆铁路沿线风沙危害发生与当地干旱多风的气候条件、铁路沿线下伏含沙地层、铁路施工对地表的破坏以及艾比湖周围沙漠化的发展有关。作者通过实验计算空气动力学粗糙度, 比较了三种典型的机械防沙措施的效果, 指出了其中存在的不足。并根据研究结果, 提出了一个优化的防沙体系方案。     

Study on detecting spatial distribution availability in mine goafs by ultra-high density electrical method

The purpose of this research is to explore the spatial distribution and influence range of the mined-out area of a coal mine in Hebei Province, the advantages of ultra-high density resistivity method, such as large data volume, high efficiency and high precision, are brought into full play, the abnormal patterns of dislocation and partial drainage area of shallow continuous aquifer caused by subsidence zone are detected, and then the spatial distribution patterns of subsidence and fractures caused by deep mining subsidence zone are deduced, this method not only extends the exploration range of high-density resistivity method in mining subsidence disaster assessment, but also improves the accuracy of measurement, the distribution and influence range of mined-out area are revealed accurately, and good exploration results have been obtained in this project. How to select reasonable geophysical prospecting methods and give full play to the role of geophysical prospecting methods according to the geological characteristics of the study area, this exploration work is not only a good combination of geophysical prospecting methods and actual geological conditions, it also provides a valuable reference version for the exploration work under the same geological conditions.