Modelling the Impact of Rockmass and Blast Design Variation on Blast Fragmentation

Most blast fragmentation models assume the rock mass properties. explosive properties and blast design variables to be constants and uniformly distributed within a blast. However, in reality all these input variables vary within a blast resulting in variation in the resulting fragmentation size distribution. A stochastic modelling approach is introduced in this paper to quantify this variation. This technique takes the input variables as statistical distributions rather than constants and through several thousand iterations, generates a statistical representation of the expected fragmentation resulting from a poduction blast. A case study of three production blasts from a large open pit mine are presented and the modelled fragmentation 'envelope' shows good agreement with the fragmentation 'envelope' estimated from Split image analysis. The various blast-related parameters influence different parts of the fragmentation distribution, e.g., rock strength and explosive velocity of detonation have most impact on the fines. The technique is used to identify the parameters that have the greatest influence on various size fractions. Such an analysis will be useful to direct resources to efficiently minimise the variation.     

高速公路爆破中破碎块度控制的研究

从理论分析入手，结合工程实践，探讨了高速公路爆破中大块产生的原因，并提出了控制破碎块度的有效措施。     

Stability Assessment of a Pit Slope Under Blast Loading: A Case Study of Pasir Coal Mine

In Pasir mine, coal seams and host rocks of varying thickness have been uniquely deposited with an average dip angle of 85°. The host rocks are weak and mainly composed of mudstone and sandstone comprising of 90–95% of the total pit volume. The thickness of coal seams and host rocks ranges from sub-metric to few tenths of meter. The overall safe pit slope angle was evaluated to be 27° for mining depth of 50–150 m. Several slopes failure incidents have occurred in the mine causing considerable disruption in production and monetary loss. It is envisaged that slope failures may be triggered due to blasting conducted in steeply dipping stratified deposit. In order to investigate the causes of slope failures, peak particle velocity (PPV) and accelerations at various locations from the blast site have been measured. In addition, finite element models of pit slope have been analyzed by applying static or gravity loading as well as blasting or dynamic loading. This paper elaborates the results of in situ measurements of ground vibration and numerical investigation and suggests possible causes of slope failures in Pasir mine.     

涡动相关仪观测数据的处理与质量评价研究

涡动相关仪能够较准确地直接测量地表—大气间的湍流交换,在世界范围内得到了广泛的应用。但它的使用是有条件限制的,如果不进行必要的修正,得到的通量就可能有较大的误差。以密云观测站一年的涡动相关仪观测数据为例进行分析。结果表明：野点值剔除、坐标旋转以及超声温度订正对地表感热、潜热等通量的测量结果影响均在±1%之内,但坐标旋转对动量通量影响较大,必须对潜热和CO2通量进行空气密度效应订正;湍流谱在惯性副区基本满足-2/3次方定律,协谱基本满足-4/3次方定律。经过对观测数据的筛选和处理后,约75%的观测数据质量较好,2%的数据需要剔除。通量贡献源区分析表明,全天和白天均有超过70%的通量源区落在感兴趣区域内,超过90%的通量贡献最大点落在感兴趣区域内。     

包头市地下水质量评价

地下水质量评价为保护和开发地下水资源,防止和控制地下水污染,保障人民身体健康提供科学依据。结合相关地下水调查资料采用单指标评价、内梅罗指数和模糊综合评价三种方法,对包头市地下水水质分别进行评价,通过对评价结果综合分析认为:模糊综合评价结果更符合区域地下水总体特征,包头市潜水Ⅳ类、Ⅴ类占到取样点总数的36%,质量整体较差;承压水Ⅰ—Ⅲ类遍及包头市全区,质量整体较好。     

某污染场地周边地下水环境质量评价

在分析了某污染场地周边地区水文地质条件的基础上,对区内17个监测点进行了地下水取样测试,并选取17项环境质量评价因子,以《地下水质量标准》(GB/T14848-93)为评价标准,采用单因子评价法、综合指数评价法与模糊综合评价法对某污染场地下水水质予以评价。结果表明,研究区地下水中的N-NH3、SO24-、总硬度、pH、Cr、Mn和As等多项指标超标,地下水水质受到了较严重的污染,其南、北两区域的油库、垃圾场以及城市污水排放是可能的地下水污染源。     

Assessment of the leachate movement in a sealed landfill using geophysical methods

This paper describes a case study concerning the use of integrated geophysical methods applied to environmental assessment. The study is focused on an old municipal solid waste sealed landfill site, located in Gaeiras, Central Portugal. The problem is related with leachate overproduction in this domestic and industrial waste landfill that became an environmental problem with urgent assessment, so that a solution could be planned. Due to the lack of accurate information regarding the shape, history and development of the landfill, the use of a set of classical geophysical methods was the option, since they are non-invasive and non-destructive. The available area was small, almost restricted to the landfill area. To conduct this assessment, electromagnetic RF-EM and Geonics EM34, spontaneous potential (SP), vertical electrical soundings (VES) and magnetic prospecting surveys were planned to understand the various problems that could be related with the leachate overproduction. The joint use of these classical geophysical methods was targeted to investigate bedrock depth and structure (RF-EM, EM34 and VES), waste and leachate characteristics (EM34 and magnetics) and groundwater flow (SP) in the landfill. Geophysical results were correlated with hydrogeological information, integrated and interpreted, using geographic information system tools. The results obtained were important to understand the geological mechanisms that are responsible for leachate overproduction and to suggest remedial measures.     

Assessment of geomechanical characterization of a rock mass using a seismic geophysical technique

Summary In this article the use of the seismic properties of a rock mass to assess the geomechanical behaviour of the rock mass is examined and illustrated. The correlation between the values of seismic velocity and some basic parameters of rock mechanics, such as RQD and fracture frequency, have been established. Moreover, the relationships between the engineering rock-mass classification systems and seismic quality index (QI) have also been derived. The relationships have been derived from an investigation for a proposed dam in Wadi Mujib, Jordan. The ground conditions comprise colluvial and fluvial superficial deposits overlying limestones, mudstones, marls and shales. It is suggested that the relationships obtained in this study could be applied in areas that have similar lithological and structural characteristics.     

关于饮用地下水水质评价标准的探讨——以华北平原地下水水质调查结果为例

地下水水质评价方法应以人体健康为依据,同时满足原理简单、计算简便、物理意义明确三个特点.基于地下水水质标准GB/T14848-93,修订了其分级限值,使得评价结果的物理意义更为明确.本文根据华北平原地下水水质测试结果评价了水质状况,对水中主要有机和无机组分在区域上的分布特征及可能来源进行了分析.为了使地下水水质评价的结果更加适合我国的国情,提出了地下水饮用适宜性评价意见,并对评价结果进行了讨论.     

Assessment of identifiable defect size in a drilled shaft using sonic echo method: Numerical simulation

The purpose of this paper is to study the capabilities of the sonic echo method in assessing the location of defects and the minimum possible detectable defect size in a drilled shaft. Three-dimensional axisymmetric finite element models were performed to investigate the effects of the defect size, defect depth-to-shaft diameter ratio, and shaft-to-soil stiffness ratio on the response of the sonic echo test. According to the results from the numerical simulations, a useful formula for defect size assessment in a shaft based on the sonic echo method is proposed, considering these factors simultaneously. Furthermore, a formula for predicting the detectable length-to-diameter ratio of a shaft was also recommended which correlates with the shaft-to-soil stiffness ratio and it varies from 10 to 32.     

The Fragmentation in a Protoplanetary Disk and the Properties of the Resultant Self-Gravitating Clumps

We study the fragmentation properties in the protoplanetary disk and properties of the resultant self-gravitating clumps using our newly constructed disk model. Our disk model includes the mass inflall term from a molecular cloud core and the photoevaporation winds effect. We adopt the conventional fragmentation criterion to judge whether a protoplanetary disk can fragment. In this work, we follow our previous work to investigate the properties of the resultant self-gravitating clumps. In our calculation, the initial masses of the resultant self-gravitating clumps lie in the range of tens of M_J to more than one hundred of M_J, where M_J is the Jupiter mass. These initial masses can seemingly account for the masses of extrasolar planets in magnitude. We also calculate the subsequent gas accretion of clumps in 1.27 × 10⁴ yr after the formation of self-gravitating clumps. We find that the subsequent gas accretion of self-gravitating clumps is very efficient, and the clump masses grow to hundreds of M_J and the physical radii R_c of clumps increase to about 10 AU. Additionally, we also calculate the orbital migration of clumps. We find that most clumps have short migration timescale to be accreted onto the protostar, and only a small fraction of clumps have long migration timescale (>10⁶ yr) to successfully become gas giant planets. These results are consistent with previous studies.     

长江流域水质评价的几种方法

采用单因子指教和综合指数及模糊综合法对长江流域进行了评价,并对各种方法进行了比较分析.根据监测数据和水质报告,采用线形回归法预测了长江流域未来8年需要处理的废水量.预测结果表明,每年需处理的废水量逐年增加.     

山西城市生态环境质量评价

本文以城市生态位理论为依据，对山西省辖市以及行署所在城市的生产位、生活位、环境位三个评价体系参数进行选择和评价。     

Blast Damage and Blast Dilution Control: The Application of Bulk Emulsion Systems at the WMC St Ives Junction Mine

The application of modern bulk emulsion explosive systems at an underground gold mine resulted in a 57% improvement in gold dilution. While this improvement is impressive and could be expected to be achieved at other sites, the work required to assess and demonstrate the benefits is painstaking. Forty-eight rings involving a total of approximately 50 000 tonnes of ore were monitored using various modern surveying instruments over a 6-month period. The geometric data included blasthole locations and deviation, and the cavity monitoring of stopes. Implementation of a bulk emulsion system not only provided logistical benefits but it also has the desirable explosive properties associated with reducing the effects of blast damage and blast dilution.     

模糊综合评判在测绘产品质量评定中应用程序设计研究

应用模糊综合评判原理,建立适合测绘产品质量评定的数学模型,在软件的支持下,通过计算机运算,输出可量化的评定结果。