共查询到20条相似文献，搜索用时 31 毫秒
1.
Essaïeb Hamdi Najla Bouden Romdhane Jean du Mouza Jean Michel Le Cleac’h 《Geotechnical and Geological Engineering》2008,26(2):133-146
The theoretical explosive energy used in blasting is a common issue in many recent research works (Spathis 1999; Sanchidrian 2003). It is currently admitted that the theoretical available energy of the explosives is split into several parts during a blast:
seismic, kinetic, backbreaks, heave, heat and fragmentation energies. Concerning this last one, the energy devoted to the
breakage and to the creation of blocks within the muckpile can be separated from the microcracking energy which is devoted
to developing new and/or extending existing micro cracks within the blocks (Hamdi et al. 2001; López et al. 2002). In order to investigate these two types of energy, a first and important task is to precisely study the main parameters
characterising the two constitutive elements of the rock mass (rock matrix and discontinuity system). This should provide
useful guidelines for the choice of the blasting parameters (type of explosive, blasting pattern, etc.), in order to finally
control the comminution process. Within the frame of the EU LESS FINES research project, devoted to the control of fines production,
the methodology was developed in order to: (1) characterize the in situ rock mass, by evaluating the density, anisotropy,
interconnectivity and fractal dimension of the discontinuity system and (2) evaluate fragmentation (both micro and macro)
energy spent during the blasting operation. The methodology was applied to three production blasts performed in the Klinthagen
quarry (Sweden) allowing to estimate the part of the fragmentation energy devoted to the formation of muck pile blocks on
one side and to the muckpile blocks microcracking on the other side. 相似文献
2.
Shijie Qu Shuhua Hao Guangping Chen Baohui Li Guangzeng Bian 《Fragblast: International Journal for Blasting and Fragmentation》2002,6(1):85-103
Blast design is a critical factor dominating fragmentation and cost of actual bench blasts. However, due to the varying nature of rock properties and geology as well as free surface conditions, reliable theoretic formulae are still unavailable at present and in most cases blast design is carried out by personal experience. As an effort to find a more scientific and reliable tool for blast design, a computer-aided bench blast design and simulation system, the BLAST-CODE model, is developed for Shuichang surface mine, Mining Industry Company of the Capital Iron and Steel Corporation Beijing. The BLAST-CODE model consists of a database representing geological and topographical conditions of the mine and the modules Frag + and Disp + for blast design and prediction of resultant fragmentation and displacement of rock mass. The two modules are established in accordance with cratering theory qualitatively and modified quantitatively by regression of the data collected from 85 bench blasting practices conducted in 3 mines of the Shuichang surface mine. Blasting parameters are selected based upon quantitative and comprehensive evaluation on the effect of the factors such as rock properties, geology, free surface conditions and detonation characteristics of the explosive products in use. In order to ensure practicality and reliability of the system, the BLAST-CODE model allows automatic adjustment to the selected parameters such as burden B and spacing S as well as explosive charge amount Q of any blasthole under irregular topographic and/or varying blastability conditions of the rock mass to be blasted. Simulation of the BLAST-CODE model includes prediction of fragmentation and displacement that are demonstrated in terms of swell factor, characteristic rock size x c and size distribution coefficient n by Rossin-Ramler's equation, and 3-dimentional muck pile profile. The BLAST-CODE model also permits interactive parameter selection based on comparison of the predicted fragmentation and displacement as well as the cost for drilling, explosives, and accessories until the most effective option can be selected. 相似文献
3.
基于某大面积深厚淤泥软基加固处理工程试验,从淤泥地基承载特征考虑,为定量确定软土之上覆盖层（包括原覆盖层及人工填土层）并反映静动力排水固结法中静力、动力荷载和排水体系的相互适应关系,建立了冲击荷载下淤泥地基上覆土层合理厚度 的定量模型。对该模型参数地基压力扩散角 、地基承载力特征值 、冲击荷载允许应力比R进行分析讨论。模型中变化的允许应力比R直观和定量地反映了冲击荷载大小与软土层排水体系布置方式、软土覆盖层厚度的相互适应关系,也可作为评判软基加固效果的参数。相关试验结果还表明,对于淤泥地基,实际夯击作用下 大于《建筑地基基础设计规范》中的23°～30°。工程应用表明,建立的模型与实际情况有较好的一致性,其定量的表达式也为工程人员设计应用提供了便利,对类似的软土地基处理工程有借鉴或指导意义。 相似文献
4.
基于Hoek-Brown强度准则,推导了在微小转动下嵌岩段桩侧法向应力及水平摩阻力计算模型,采用静力平衡原理建立了水平荷载作用下公路桥梁桩基嵌岩深度的计算公式,提出了嵌岩深度计算的新方法。参数敏感性及影响因素分析表明： （1）水平荷载引起的力矩 、桩径d、岩层上覆压力 、岩石单轴抗压强度 、岩体类别参数 、岩体地质力学分类指标RMR均对嵌岩深度有一定影响,在 、d不变的情况下,岩体质量和岩石单轴抗压强度对嵌岩深度的确定最为敏感; （2）岩体质量越差,所需嵌岩深度越大;岩体质量越好,岩层上覆压力对嵌岩深度影响越小,反之越大。（3）嵌岩深度随岩石单轴抗压强度的提高呈非线性缓慢地减小,在相同的单轴抗压强度下,岩体质量越好,嵌岩深度越小,反之越大。 相似文献
5.
Rock mass failure is a particularly complex process that involves the opening and sliding of existing discontinuities and the fracturing of the intact rock. This paper adopts an advanced discretisation approach to simulate rock failure problems within the discontinuous deformation analysis (DDA) framework. The accuracy of this approach in continuum analysis is verified first. Then, the advanced discretisation approach for fracturing modelling is presented, and the discretisation strategy is discussed. Sample rock static failures are simulated and the results are compared with experimental results. Thereafter, with a generalised definition of the artificial joints, this approach is further extended and applied in the simulation of blast-induced rock mass failures in which the instant explosion gas pressure obtained by the detonation pressure equation of state is loaded on the main blast chamber walls and the induced surrounding connected fracture surfaces. In the simulation instance of rock mass cast blasting, the whole process, including the blast chamber expansion, explosion gas penetration, rock mass failure and cast, and the formation of the final blasting pile, is wholly reproduced. 相似文献
6.
7.
In this paper, a great quantity of computation on the pile bearing capacity are made by using the wave equation computer program with successively varying input parameters. The effect of each parameter on the pile bearing is analysed. It is shown that all the parameters can be classified into two groups: the intrinsic parameters held by the pile-soil system and the auxiliary parameters held by the pile-hammer system. The intrinsic parameters, including the quake of soil, the visco damping coefficient, the elastic moduli of pile material, the cross section area and the length of the pile, play the dominant role in the determination of the pile bearing capacity. The auxiliary parameters, including the hammer weight, the hammer fall, the spring constant of the cap-block, the coefficient of restitution of cap-block and pile-cushion, and the efficiency of the hammer, etc., only influence the curves Ru = ｆ(S) or Ru =ｆ(N) but not change the value of the actual bearing capacity of the pile. From the analysis it is also indicated in the paper that the quake value of the soil, besides the intrinsic parameters held by the pile itself, is the mast influential factor on the pile bearing capacity. 相似文献
8.
本文应用波动方程计算程序,逐个改变输入参数,对单桩的承载力进行了大量的计算,分析了各个参数对桩承载力的影响。分析表明,所有输入参数可分为两大类:桩-土系统的固有参数和桩-锤系统的辅助参数。固有参数包括土的Q值、粘性阻尼系数J。和J,桩的弹模、截面积和桩长等等,它们的值决定桩的承载力;辅助参数包括锤重、落高、帽垫、桩垫和桩帽的弹簧常数、锤击效率等,它们的值的改变将表观上影响R-S曲线或R,-N曲线,但不改变桩的实际承载能力。 相似文献
9.
Drilling and blasting is a major technology in mining since it is necessary for the initial breakage of rock masses in mining. Only a fraction of the explosive energy is efficiently consumed in the actual breakage and displacement of the rock mass, and the rest of the energy is spent in undesirable effects, such as ground vibrations. The prediction of induced ground vibrations across a fractured rock mass is of great concern to rock engineers in assessing the stability of rock slopes in open pit mines. The waveform superposition method was used in the Gol-E-Gohar iron mine to simulate the production blast seismograms based upon the single-hole shot vibration measurements carried out at a distance of 39 m from the blast. The simulated production blast seismograms were then used as input to predict particle velocity time histories of blast vibrations in the mine wall using the universal distinct element code (UDEC). Simulated time histories of particle velocity showed a good agreement with the measured production blast time histories. Displacements and peak particle velocities were determined at various points of the engineered slope. The maximum displacement at the crest of the nearest bench in the X and Y directions was 26 mm, which is acceptable in regard to open pit slope stability. 相似文献
10.
J. Kemeny E. Mofya R. Kaunda P. Lever 《Fragblast: International Journal for Blasting and Fragmentation》2002,6(3):311-320
One of the fundamental requirements for being able to optimise blasting is the ability to predict fragmentation. An accurate blast fragmentation model allows a mine to adjust the fragmentation size for different downstream processes (mill processing versus leach, for instance), and to make real time adjustments in blasting parameters to account for changes in rock mass characteristics (hardness, fracture density, fracture orientation, etc). A number of blast fragmentation models have been developed in the past 40 years such as the Kuz-Ram model [1]. Fragmentation models have a limited usefulness at the present time because: 1. The input parameters are not the most useful for the engineer to determine and data for these parameters are not available throughout the rock mass. 2. Even if the input parameters are known, the models still do not consistently predict the correct fragmentation. This is because the models capture some but not all of the important rock and blast phenomena. 3. The models do not allow for 'tuning' at a specific mine site. This paper describes studies that are being conducted to improve blast fragmentation models. The Split image processing software is used for these studies [2, 3]. 相似文献
11.
损伤条件下深部岩体巷道光面爆破参数研究 总被引：3，自引：0，他引：3
岩体条件复杂多变,为了提高光面爆破的适应性、改善光面爆破效果,对损伤条件下深部岩体巷道光面爆破参数进行研究。通过对深部岩体巷道光爆层原岩应力场、光面爆破机制和振动损伤特征进行分析,基于爆炸应力波和爆生气体综合作用理论,考虑高原岩应力和岩石损伤影响,提出了损伤条件下深部岩体巷道光面爆破参数确定的计算方法。研究表明, （1）高原岩应力相当于提高了岩石的抗拉强度,不利于炮孔初始裂纹的形成及贯通,宜减小周边眼间距;（2）岩石损伤后,其他条件不变,光面爆破的炮孔间距和抵抗线值可适当加大;（3）高原岩应力和损伤条件下,光面爆破的炮孔间距较小时,容易造成爆后围岩损伤,降低围岩的稳定性能,因此,提高爆破效果的同时应及时加强支护,以确保施工安全和围岩稳定;（4）本文提出的光面爆破参数计算公式,经现场爆破验证效果良好,适用于复杂多变的岩体环境。 相似文献
12.
M. Mirahmadi M. Tabaei M. Soleiman Dehkordi 《Geotechnical and Geological Engineering》2017,35(5):1991-2002
The specific energy (SE) is the most important parameter to estimate the energy consumption in tunnel boring machines (TBMs). It is defined as the amount of required energy to excavate a unit volume of rock mass which used to predict the performance of TBMs. Several models are used to estimate the SE based on different parameters such as the rock mass properties, disc cutter dimensions and cutting geometry. The aim of this work is to propose new relations between the SE and the strain energy of rock mass (W) using the geological mappings of rock mass and TBM operational parameters from Amir-Kabir Water Transferring Tunnel of Iran. W is an appropriate criterion to estimate SE because it is a function of different parameters such as rock mass behavior, pre and post failure properties and peak and residual strains. In this study, to increase the correlation coefficient of relation between the mentioned parameters, the rock mass is classified in two methods, in the first method according to the geological strength index (GSI) all data is classified in three classes such as weak, fair and good and in the second method using the drop to deformation modulus ratio (η) the classification of data is performed in three classes such as η < 0.05, 0.05 ≤ η < 10 and η ≥ 10. The results show that there are direct relations between both parameters. It is suggested to estimate SE in all rock mass classes using the proposed relations based on GSI classification. 相似文献
13.
M. G. Şenyur 《Rock Mechanics and Rock Engineering》1998,31(3):181-196
Summary The purpose of this study is to statistically correlate the fragmentation gradient () and average fragment size () with the blasting test parameters for rock masses having different characteristics. Blasting tests were conducted in limestone
exposed during the highway construction between Tarsus and Pozanti (Turkey). Three test sites were classified as poor rock,
good rock, and very good rock according to their RMR ratings. The selected blasting test parameters that affect the degree
of fragmentation were burden, bench height and ANFO charge. After each blast, the muckpiles were screened and fragment size
distribution graphs were plotted. Yates' method was applied for experimental design and analysis of variance. The single and
combined effects of blasting test parameters were analyzed through the Yates' tables and significant and non-significant treatment
combinations were determined for different rock masses. Some conclusions drawn from this research are: 1. The increase of
RMR ratings promotes fragmentation, hence, increases blasting efficiency. 2. In rock masses of low RMR ratings, the volume
of broken material is large, but fragmentation into small sizes is low. The opposite is true for rock masses of high RMR ratings.
3. The length of charge column is the significant factor affecting the average fragment size regardless the type of rock mass
and is more significant in very good quality rock mass. 相似文献
14.
主要为大口径基础灌注桩施工而设计的YCJF-25型全液压冲击反循环钻机具有碎岩能量大、破岩效率高、排渣速度快、能有效避免孔底岩屑的重复破碎的特点。介绍了YCJF-25型全液压冲击反循环钻机性能参数,阐明了钻机的结构特点,对比分析了钻机的施工效率。 相似文献
15.
P. Rai F. L. Imperial President 《Fragblast: International Journal for Blasting and Fragmentation》2005,9(4):219-232
The present research paper is a case study in a limestone quarry in the Philippines where major problems in terms of improper fragmentation (large boulder count and poor pay-loader performance), poor wall control, and poor heave characteristics of the muck pile were witnessed. The paper highlights the role of modifying the firing pattern and, also, the application of stemming plug without incorporating any change in the stemming column length due to which incremental expansion in the mesh area could be implemented to determine the optimum mesh area. The optimum mesh area, due to the said changes in the blast design, was considerably larger in comparison to the pre-existing mesh area. The study has also highlighted the importance of indirect methods for characterizing and precisely adjudging the blast performance. 相似文献
16.
本文针对静力荷载作用的情况,对比了4种黏土中水平受荷大直径单桩的设计方法,包括基于p-y弹簧模型的API规范方法,以及新近发展的基于p-y弹簧模型的Zhang et al.(2017b) 、基于双弹簧模型的Wang et al.(2020) 方法以及基于三弹簧模型的Fu et al.(2020) 方法。考虑两种大直径单桩常用的长径比(L/D=5和10),通过与三维有限元结果比较,对现有设计方法进行了对比,分析了不同参数对预测结果的影响。结果表明:(1)对于大直径单桩的水平位移和转角,现行API规范的预测值最大,而Wang et al.(2020) 方法预测值最小; (2)Fu et al.(2020) 方法不仅考虑了桩底剪力及桩身摩擦造成的分布力矩,还能够有效捕捉初始剪切模量与土体延性对水平响应的影响,还因此具备其余方法所不具备的优势; (3)采用Fu et al.(2020) 方法时,桩土界面粗糙系数α越大,桩身位移与转角越大,且长径比越小影响越显著,而与桩身分布力矩有关的缩放系数ξp2的影响则相对有限,当L/D≥10时其影响可以忽略。 相似文献
17.
以李家峡大坝工程为例，对高边坡岩体的各向异性和动力牧场生进行了较详细的测试研究。在对层状岩体的各向异性系数对比分析的基础上，确定了爆破对岩体的破坏影响深度，并采用不同的测试参数综合地反映了断层的动力特性，这些测试成果不仅为大坝岩体的动力稳定分析提供了充足的数据，同时对大坝的建设也有重要的参考价值。 相似文献
18.
准各向同性裂隙岩体中有效动弹性参数与弹性波速关系的研究 总被引：4，自引：0，他引：4
从弹性波在介质中传播的特点和弹性波法在岩体工程中的实际应用情况方面,分析了弹性波在含裂隙岩体介质中的传播特征。将岩体中裂隙呈随机分布的裂隙岩体似为准各向同性裂隙岩体,根据能量平衡原理、岩石断裂力学理论和卡氏最小功能定理(Castiglano’s theorem),确定了准各向同性裂隙岩体的有效动弹性参数( 、 、 )与裂隙密度参数(Xv)的数学关系。在此基础上,根据各向同性介质中传播的弹性波理论,建立了准各向同性裂隙岩体中弹性波速( 、 )和 / 与裂隙密度参数(Xv)之间的关系。理论研究表明,在此裂隙岩体中,有效动弹性参数和弹性波速与裂纹密度参数之间相互的关系均近似成倒数函数的非线性关系;裂隙密度参数增加,有效动弹性模量( )也减少,弹性波速( , )也减小;在裂隙密度参数较小时,此裂隙岩体的有效弹性模量和弹性波速随裂隙密度参数的变化较大,说明裂隙体的有效弹性参数和弹性波速对裂隙体非常敏感。 相似文献
19.
嵌岩桩入岩位置在岩溶场地具有很大的不确定性,成桩难度和桩基方案技术经济性论证缺乏可靠依据,这是目前岩溶场地桩基础、筏板基础和复合地基优选时的常见问题。本文将基桩入岩起始位置处的高程定义为基桩入岩高程,岩溶场地所有基桩入岩高程的平均值称为场地桩基平均入岩高程。场地桩基平均入岩高程决定了场地基桩入岩深度的变化范围,反映了场地桩基成桩难度及其技术经济性。以柳州市金盛广场4#楼桩基工程为背景,基于岩溶区已有的桩基入岩概率模型建立了场地桩基平均入岩高程预测模型,所需数据来源于岩溶场地丰富、廉价的勘察钻探资料,无需补充其他额外测试或勘测数据,合理考虑了岩溶地基溶蚀特征和桩径大小等两个影响因素。研究表明,岩溶场地桩基平均入岩高程预测值与实测值误差一般不大于0.5 m,满足岩溶地区嵌岩桩技术经济性论证的精度要求,可作为岩溶场地基础方案优选和成桩工艺选择的基本依据。 相似文献
20.
使用隧道掘进机（TBM）开挖隧道时刀盘和盾体阻碍了对岩石状态的观察,这时可使用岩渣对岩石条件进行预测和评价。从滚刀破碎掌子面产生的岩渣中选取块状岩石进行点荷载试验可以获得岩石强度,但是受过滚刀损伤作用的岩石强度值与未受损伤的岩石强度值之间的关系尚不明确。从吉林引松供水工程TBM破岩产生的岩渣中挑选块状试样进行点荷载试验,同时在产生岩渣的相应位置钻取岩芯获取点荷载强度,与单轴抗压强度进行了对比,记录了取样地点地质状态、试样的尺寸、破碎状态以及等效断裂面积。结果表明：岩渣中的岩块受到滚刀作用产生的损伤强度值有所下降,为完整取芯试样的63.25%,原岩越完整受损程度越大;灰岩点荷载强度换算岩石单轴抗压强度系数约为25.3,直接使用岩渣时建议系数约为42.1;峰值荷载与等效断裂面积成正比;尺寸过大的试块往往与岩体原有裂隙有关,强度极低,不适宜用作点荷载试验。研究结果为TBM隧道现场快速获取岩石强度参数提供了方法和依据。 相似文献