A three dimensional model of muckpile formation and grade boundary movement in open pit blasting     

R. L. Yang  A. Kavetsky 《Geotechnical and Geological Engineering》1990,8(1):13-34

Summary Formulation and case studies of a three dimensional kinematic model are presented. Thein situ overburden geometry can be simulated accurately and various initiation patterns of blasts can be modelled. The overburden geometry, hole patterns and explosive distribution are all explicit model inputs. Because the effect of explosive properties, rock mass condition and inter-row delay are very difficult to measure in terms of blast performance, these are represented in the model by control parameters which are left for calibration using field data. The output of the model is a three dimensional muckpile shape of any cross section and a contour map of grade distribution within the muckpile. Two case studies are presented which have shown that the model is a valuable tool for optimizing production blasting as well as for controlling grade dilution during blasting.  相似文献   

从水流挟沙力和河槽形态规律分析黄河调水调沙   总被引：3，自引：0，他引：3  

张遂业  涂启华 《水文》2005,25(6):33-36

在分析水流挟沙力和河槽水力形态规律的基础上，研究调节流量、含沙量和泥沙组成的优化组合，解决河道输沙减淤和河槽相对稳定问题，提出调水调沙方向。达到合理利用水资源和河道减淤与治理相结合的目的．  相似文献   

The geomorphological significance of airflow patterns in transverse dune interdunes   总被引：1，自引：0，他引：1  

M.C. Baddock  I. Livingstone  G.F.S. Wiggs   《Geomorphology》2007,87(4):322-336

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Shaking‐table tests on reinforced concrete frames with different isolation systems     

Mauro Dolce  Donatello Cardone  Felice C. Ponzo 《地震工程与结构动力学》2007,36(5):573-596

The effectiveness of seismic isolation in protecting structural and non‐structural elements from damage has been assessed in an extensive programme of shaking‐table tests, carried out on four identical 1/3.3‐scale, two‐dimensional, reinforced concrete (R/C) frames. Four different isolation systems were considered, namely: (i) rubber‐based, (ii) steel‐based, (iii) shape memory alloy (SMA)‐based and (iv) hybrid, i.e. based on both SMA and steel components, isolation systems. This paper presents a comprehensive overview of the main results of the experimental tests on base‐isolated models, whose structural response is described through: (i) maximum base displacements; (ii) maximum interstorey drifts; (iii) maximum storey accelerations and (iv) maximum storey shear forces. The evolution of the fundamental frequency of vibration of the R/C frame during the tests is also described. The beneficial effects of using base isolation resulted in no or slight damage, under strong earthquakes, to both structural and non‐structural members, as well as to the internal content of the building. The comparison with the experimental results obtained in shaking‐table tests on similar fixed‐base models emphasizes these positive aspects. Finally, advantages and drawbacks related to the use of each isolation system are discussed in the paper. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Effects of surface characteristics on infiltration patterns in an arid shrub desert   总被引：3，自引：0，他引：3  

Xin‐Ping Wang  Xin‐Rong Li  Hong‐Lang Xiao  Ronny Berndtsson  Yan‐Xia Pan 《水文研究》2007,21(1):72-79

Precipitation is often the sole source of water replenishment in arid and semi‐arid areas and, thus, plays a pertinent role in sustaining desert ecosystems. Revegetation over 40 years using mainly Artemisia ordosica and Caragana korshinskii at Shapotou Desert Experimental Research Station near Lanzhou, China, has established a dwarf‐shrub and microbiotic soil crust cover on the stabilized sand dunes. The redistribution of infiltrated moisture through percolation, root extraction, and evapotranspiration pathways was investigated. Three sets of time‐domain reflectometry (TDR) probes were inserted horizontally at 5, 10, 15, 20, 30 and 40 cm depths below the ground surface in a soil pit. The three sets of TDR probes were installed in dwarf‐shrub sites of A. ordosica and C. korshinskii community with and without a microbiotic soil crust cover, and an additional set was placed in a bare sand dune area that had neither vegetation nor a microbiotic soil crust present. Volumetric soil moisture content was recorded at hourly intervals and used in the assessment of infiltration for the different surface covers. Infiltration varied greatly, from 7·5 cm to more than 45 cm, depending upon rainfall quantity and soil surface conditions. In the shrub community area without microbiotic soil crust cover, infiltration increased due to preferential flow associated with root tunnels. The microbiotic soil crust cover had a significant negative influence on the infiltration for small rainfall events (～10 mm), restricting the infiltration depth to less than 20 cm and increasing soil moisture content just beneath the soil profile of 10 cm, whereas it was not as strong or clear for larger rainfall events (～60 mm). For small rainfall events, the wetting front depth for the three kinds of surface cover was as follows: shrub community without microbiotic soil crust > bare area > shrub community with microbiotic soil crust. In contrast, for large rainfall events, infiltration was similar in shrub communities with and without microbiotic soil crust cover, but significantly higher than measured in the bare area. Soil water extraction by roots associated with evapotranspiration restricted the wetting front penetration after 1 to 3 h of rainfall. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

某隔震结构动力特性的理论分析与脉动测试   总被引：1，自引：1，他引：1  

贾洪  徐茂义  闫维明  李振宝 《震灾防御技术》2007,2(4):384-390

本文针对国内最大单体隔震建筑建立了SAP2000三维分析模型,并进行了动力特性的理论分析;现场对实际建筑进行了平移振动、扭转振动、垂直振动和平面内弯曲4个方面的脉动测试。利用工程振动反演理论分析了该结构的固有频率、振型、阻尼等动力特性,将实测结构动力特性与理论分析结果进行比较,详细分析实测结果与理论结果差别的原因,并据此对理论模型进行修正,为今后类似结构的设计积累了资料。  相似文献   

Shape Similarity measures of Linear Entities     

ZhangQiaopin  LIDeren 《地球空间信息科学学报》2002,5(2):62-67

The essential of feature matching technology lies in how to measure the similarity of spatial entities.Among all the possible similarity measures,the shape similarity measure is one of the most important measures because it is easy to collect the necessary parameters and it is also well matched with the human intuition.In this paper a new shape similarity measure of linear entities based on the differences of direction change along each line is presented and its effectiveness is illustrated.  相似文献   

塔克拉玛干沙漠腹地复合沙垄的流场和上覆沙丘组合及动态特征   总被引：6，自引：4，他引：6  

李恒鹏  陈广庭  薛东前 《干旱区地理》2001,24(1):80-85

复合沙垄是最大的沙丘地貌类型之一，表现为简单沙丘类型的垂直叠加和水平连接，在沙垄的高大地形影响下，沙垄不同部位形成不同的风沙环境特征。以塔克拉玛干沙漠腹地/复合沙垄为例，通过野外实地观测研究其流场和上覆沙丘组合特征。研究结果表明，复合沙垄的流场可分为沙垄迎风坡气流加速区、沙垄背风坡气流转向减速区、垄间粗沙平地气流风速风向恢复区和气流风速稳定区。受沙垄流场和地形的控制，沙垄上覆新月形沙丘链，垄间地分有简单新月形沙丘、沙堆、沙片、侵蚀地、简单线形沙丘。上覆沙丘分布特征表现为：垄间地上覆新月形沙丘疏密度较小，沙垄迎风坡和沙垄背风坡上覆新月形沙丘疏密度较大，而且超过1，说明沙垄迎背风坡上覆沙丘有叠置现象。沙垄上覆沙丘高度自沙垄迎风坡底部到顶部增高，背风坡上覆沙丘高度自沙垄顶部到背风坡底部减小，上覆沙丘在自身形态、地形和流场的共同影响下，存在相对运动，表现为分布进一步集中，因此沙垄有增高的趋势。  相似文献   

Strain and competence contrast estimation from fold shape     

Stefan M. Schmalholz  Yuri Yu. Podladchikov 《Tectonophysics》2001,340(3-4):195-213

A new method to estimate strain and competence contrast from natural fold shapes is developed and verified by analogue and numerical experiments. Strain is estimated relative to the nucleation amplitude, A_N, which is the fold amplitude when the amplification velocities caused by kinematic layer thickening and dynamic folding are identical. A_N is defined as the initial amplitude corresponding to zero strain because folding at amplitudes smaller than A_N is dominantly by kinematic layer thickening. For amplitudes larger than A_N, estimates of strain and competence contrast are contoured in thickness-to-wavelength (H/λ) and amplitude-to-wavelength (A/λ) space. These quantities can be measured for any observed fold shape. Contour maps are constructed using existing linear theories of folding, a new nonlinear theory of folding and numerical simulations, all for single-layer folding. The method represents a significant improvement to the arc length method. The strain estimation method is applied to folds in viscous (Newtonian), power-law (non-Newtonian) and viscoelastic layers. Also, strain partitioning in fold trains is investigated. Strain partitioning refers to the difference in strain accommodated by individual folds in the fold train and by the whole fold train. Fold trains within layers exhibiting viscous and viscoelastic rheology show different characteristic strain partitioning patterns. Strain partitioning patterns of natural fold trains can be used to assess the rheological behaviour during fold initiation.  相似文献   

雨滴尺度谱谱参数和形状因子的分析     

周文贤  陈金荣  齐久成 《气象》1996,22(4):13-16

作者计算了３次降不过程的雨滴尺度谱参数，并进行Ｍ－Ｐ分布拟合和Г分布拟合。同时还计算了雨滴谱形状因子Ｓ（Ｚ，Ｒ），分析了形状因子与雨强之间的关系。  相似文献