Delay time optimization in blasting operations for mitigating the vibration-effects on final pit walls' stability     

X.Z. Shi  SH.R Chen 《Soil Dynamics and Earthquake Engineering》2011

Blasting induced vibration is one of the fundamental problems in the open-pit mines and intense vibration can cause critical damage to structures and plants nearby the open-pit mines, especially to the final pit wall's stability. It is very important to study how to control vibration induced by blasting in the mitigation of negative effects of blasting in open-pit mines. This study aims to examine the propagation of blasting induced ground vibrations and find the feasible approaches to reduce the harmful effects of vibrations induced by blasting on the final pit wall's stability. For this purpose, a series of field experiments were conducted in XinQiao Mining Co. Ltd. Sixty-six events and the blasting parameters of these shots were carefully recorded. During the statistical analysis of the collected data, the predictor equation proposed by the United States Bureau of Mines (USBM) was used to establish a relationship between the Peak Particle Velocity (PPV) and the Scaled Distance (SD) factor. The relationship between PPV and SD was determined and proposed to be used in this open-pit mine. Control of maximum charge amount per delay and the selection optimum interval time to reduce the intensity of vibration by waveform interference were applied in practice. Based on the field experiments, we can determine the maximum charge amount per delay and 15 ms delay were proposed to be used in this site, and a decrease in vibration of 24.5% was obtained.  相似文献   

Sedimentary records of natural and artificial Huanghe (Yellow River) channel shifts during the Holocene in the southern Bohai Sea   总被引：4，自引：0，他引：4  

Shuqing QiaoXuefa Shi  Yoshiki SaitoXiaoyan Li  Yonggui YuYazhi Bai  Yanguang LiuKunshan Wang  Gang Yang 《Continental Shelf Research》2011,31(13):1336-1342

Two gravity cores collected off the modern Huanghe (Yellow River) delta in the southern Bohai Sea were analyzed for grain size, the total organic carbon (TOC)/total nitrogen (TN) ratio, color diffraction, magnetic susceptibility, ¹⁴C dating and ¹³⁷Cs and ²¹⁰Pb isotope contents to clarify changes in the sedimentary environment during the Holocene. In particular, the effect of natural and artificial river-course shifts of the Huanghe on the Bohai Sea sediment was investigated. A peat layer, scouring surface and sharp changes in the grain size, TOC/TN ratio, sediment color (L^?, a^?) and magnetic susceptibility were identified and are likely to be due to the early-Holocene sea-level rise resulting in environmental changes from coastal to shelf environments in the Bohai Sea. After the sea level reached its maximum at 6-7 ka BP, the lateral shifts in the river course of the Huanghe formed 10 superlobes, and superlobe 7 (11-1048 AD) and superlobe 10 (1855-present) of the Huanghe delta affected the core sites. The northern site of BH-239 has been more affected by the Huanghe since the middle Holocene. Notably, in the superlobe 10 period, the reshaping of the northern Huanghe delta due to an artificial river-course shift from northward to eastward in 1976 (e.g., a∼10 km shoreline retreat due to coastal erosion) was recorded in the core sediments, particularly in terms of the TOC/TN ratio, sediment color (L^? and a^?) and magnetic susceptibility, owing to the huge sediment supply from coastal erosion of the former river mouth area.  相似文献   

Study on the S-wave Splitting Characteristics in the Longtan Reservoir Area,Guangxi,China     

Shi Haixi  Zhao Cuiping 《中国地震研究》2011,25(2):213-226

In this paper,the shear wave splitting features of the Longtan reservoir area are studied by adopting the traditional cross-correlation coefficient method and polarization analysis,using the data recorded by the seismic network founded by a project under the National Science and Technology Pillar Program from April 2009 to April 2010.We found that most of polarization directions at seismic stations are consistent with the direction of the overall regional stress field,but local structures and faults may con...  相似文献   

Modelling hydrological processes influenced by soil,rock and vegetation in a small karst basin of southwest China   总被引：1，自引：0，他引：1  

Zhicai Zhang  Xi Chen  Anas Ghadouani  Peng Shi 《水文研究》2011,25(15):2456-2470

Hydrological processes in karst basins are controlled by permeable multimedia, consisting of soil pores, epikarst fractures, and underground conduits. Distributed modelling of hydrological dynamics in such heterogeneous hydrogeological conditions is a challenging task. Basing on the multilayer structure of the distributed hydrology‐soil‐vegetation model (DHSVM), a distributed hydrological model for a karst basin was developed by integrating mathematical routings of porous Darcy flow, fissure flow and underground channel flow. Specifically, infiltration and saturated flow movement within epikarst fractures are expressed by the ‘cubic law’ equation which is associated with fractural width, direction, and spacing. A small karst basin located in Guizhou province of southwest China was selected for this hydrological simulation. The model parameters were determined on the basis of field measurement and calibrated against the observed soil moisture contents, vegetation interception, surface runoff, and underground flow discharges from the basin outlet. The results show that due to high permeability of the epikarst zone, a significant amount of surface runoff is only generated after heavy rainfall events during the wet season. Rock exposure and the epikarst zone significantly increase flood discharge and decrease evapotranspiration (ET) loss; the peak flood discharge is directly proportional to the size of the aperture. Distribution of soil moisture content (SMC) primarily depends on topographic variations just after a heavy rainfall, while SMC and actual ET are dominated by land cover after a period of consecutive non‐rainfall days. The new model was able to capture the sharp increase and decrease of the underground streamflow hydrograph, and as such can be used to investigate hydrological effects in such rock features and land covers. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

不排水条件下裂隙流体压力对引潮高的振幅比和位相差的响应     

刘春平  石云  万飞 《中国地震》2011,27(3):300-308

本文基于裂隙潮汐应力分析,提出了不排水条件下,单裂隙和多裂隙流体压力-引潮高的振幅比和位相差响应模型.基于响应模型的分析计算,绘制了单裂隙流体压力振幅比和位相差与裂隙产状的关系曲线,分析了岩体弹性参数(λ、μ)和Skempton系数(B)对裂隙流体压力振幅比和位相差的影响.结果表明,M2和O1波裂隙流体压力-引潮高的振幅比随裂隙倾角(DIP)增加而增加,位相差都在±165°～±180°( DIP＜ 15°)和0°～±10°(DIP＞15°)之间,且两波位相差符号相反;流体压力振幅比线性地响应岩体弹性常数(λ、μ)和Skempton系数(B)的变化,但位相差几乎不受裂隙和岩体弹性参数的影响.  相似文献   

新疆且末地磁基准台场址勘选     

史勇军  吴琼  李晓东 《地震地磁观测与研究》2011,32(6):162-167

对拟建设的新疆且末地磁台进行场址勘选,采取十字剖面测量和密跨度测量方法进行地磁场总强度F测量,对测量结果进行初步分析.分析结果表明,且末地磁台的地质条件、磁场梯度分布和背景噪声环境等地磁观测环境条件,符合国家地磁台建设规范的要求,适宜地磁基准台站建设.  相似文献   

高强钢筋高强混凝土框架结构非线性地震反应分析     

阎石  陈鑫  季保建 《世界地震工程》2011,27(2)

研究配有高强钢筋的高强混凝土框架结构的抗震性能.采用OpenSees开放式软件对配有高强钢筋的高强混凝土框架结构进行了地震作用下的非线性有限元分析,并将计算结果与同等参数条件下的结构拟动力试验进行了对比.得到不同峰值加速度情况下的结构层间反应时程曲线,层间位移滞回曲线,以及破坏模式等,数值计算结果与试验吻合程度较好.研究结果表明利用基于OpenSees的有限元分析方法,能够有效地分析配有高强钢筋的高强混凝土框架结构的地震响应,可以辅助研究该结构的抗震性能.  相似文献   

振动台试验模型地震反应的HHT研究   总被引：1，自引：1，他引：0       下载免费PDF全文

石春香  李胡生  罗奇峰  施卫星 《地震学报》2011,33(1):114-119

Hilbert-Huang Transform(HHT)是一种新的适用于非线性、非平稳信号,且具有自适应性的数据处理方法．本文简要介绍了一座45层钢筋混凝土框架结构及其振动台试验模型概况. 利用HHT分析了模型结构在不同烈度地震中的反应记录,得到了Hilbert时频幅值三维分布和Hilbert边际谱．Hilbert谱得到记录能量集中分布的频段与时间范围,捕捉到信号变化的主要特征. Hilbert边际谱曲线形状和峰值频率值随着地震烈度的升级而发生了相应变化,而且所有的结果图形体现出相同的规律性,预示着Hilbert边际谱在土木工程结构安全评价中的应用前景．   相似文献   

Pseudo-dynamic test and numerical simulation of high-strength concrete frame structure reinforced with high-strength rebars     

Xin Chen  Shi Yan  Baojian Ji 《地震工程与工程振动(英文版)》2011,10(2):303-311

This paper describes an investigation of a high-strength concrete frame reinforced with high-strength rebars that was tested in the structure engineering laboratory at Shenyang Jianzhu University. The frame specimen was pseudo- dynamically loaded to indicate three earthquake ground motions of different hazard levels, after which the test specimen was subjected to a pseudo-static loading. This paper focuses on the design, construction and experiment of the test frame and validation of the simulation models. Research shows that a high-strength concrete frame reinforced with high-strength rebars is more eff icient and economical than a traditional reinforced concrete frame structure. In addition to the economies achieved by effective use of materials, research shows that the frame can provide enough strength to exceed conventional reinforced concrete frames and provide acceptable ductility. The test study provides evidence to validate the performance of a high- strength concrete frame designed according to current seismic code provisions. Based on previous test research, a nonlinear FEM analysis is completed by using OpenSees software. The dynamic responses of the frame structure are numerically analyzed. The results of the numerical simulation show that the model can calculate the seismic responses of the frame by OpenSees. At the same time, the test provides additional opportunities to validate the performance of the simulation models.  相似文献   

利用可见光与近红外大气窗区的组合通道探测陆面上空气溶胶     

孙源隆  石广玉 《大气科学》2011,35(2):350-360

本文提出了一种利用可见光与近红外大气窗区内的0.5μm和0.85μm双通道的组合,通过观测地气系统的反射辐射从卫星上遥感陆面上空气溶胶的方法.模拟试验发现,对于不同类型的气溶胶,随着气溶胶光学厚度的逐渐增大,0.5μm和0.85μm双通道的反射辐亮度的差值和比值呈现出明显不同的变化趋势,据此便可以识别出气溶胶的类型,并...  相似文献