大直径中空孔直眼掏槽爆破的空孔应力集中效应研究

为了探明大直径中空孔直眼掏槽爆破的力学机理，采用理论分析和数值模拟方法研究了大直径中空孔直眼掏槽爆破的空孔应力集中效应。建立了空孔应力集中效应的力学模型，基于弹性力学和波动力学理论阐明了空孔应力集中效应的力学机理；开展了典型工况下大直径中空孔直眼掏槽爆破的数值模拟，并基于应力波传播、岩体损伤和岩体第一主应力峰值等结果分析了空孔的应力集中效应。研究结果表明：空孔应力集中效应主要源自孔洞应力集中效应和应力波叠加效应；大直径中空孔直眼掏槽爆破过程中，应力波在空孔壁处发生反射并与入射波产生叠加，叠加多位于空孔邻近区域以及掏槽孔间区域；岩体损伤程度较高的区域主要为掏槽孔周边、空孔周边以及相邻掏槽孔与空孔形成的三角区域，掏槽孔周边以外的损伤区域与应力波叠加区域基本对应；空孔附近存在显著的应力集中效应，且距空孔壁越近的位置应力集中效应越明显。研究成果拟为隧道工程大直径中空孔直眼掏槽爆破设计提供理论基础。     

含空孔直眼掏槽爆破效果分析模型

直眼掏槽是隧道掘进深孔爆破中的关键技术 ,炮孔深度对掏槽爆破效果有重要影响。本研究通过建立槽腔内抛体运动的二相流力学模型 ,揭示了炮孔深度影响掏槽效果的物理本质 ,阐述了炮孔深度对掏槽效果的影响规律 ;为含空孔直眼掏槽爆破参数设计提供了依据。理论分析结果与工程实践相吻合。     

硬岩隧道全断面开挖掏槽爆破参数优化

硬岩隧道全断面掏槽开挖对控制掏槽腔体大小、掌子面平整度及拱底欠挖要求较高。依托寨山隧道洞身Ⅲ级硬岩全断面开挖,采用现场试验、问题分析和经验公式的方法,提出了掏槽眼爆破参数的优化方法。从扩展掏槽腔体积的角度,主掏槽面域内自上而下增设复式掏槽短眼4对,主掏槽眼深度扩展为3.8 m,主、复式掏槽短眼孔底间距减小为0.3 m;从岩石炸药单耗、爆破破岩负担体积的角度,确定了主掏槽眼最大单孔装药量为3.0 kg。结果表明：采用优化掏槽参数,爆后硬岩掌子面光滑、底面平整、岩堆块石尺寸合理。掏槽整体炸药单耗减小约4.5%。     

直眼掏槽药量计算的理论探讨

由于直眼掏槽一般采用一个或几个空孔作为自由面和岩石破碎补偿空间,因此,研究空孔附近沿长药包的爆破过程是合理确定直眼掏槽药量的根本依据。目前,国内外在直跟掏槽爆破中,药量主要根据经验确定。本文试图根据直眼掏槽机理,综合考虑各种因素,导出装药量计算公式。并对有关问题进行探讨。     

新大成二线隧道爆破掘进施工技术

新大成二线隧道紧临既有线隧道,为确保既有线隧道和行车安全,采取了导坑超前三步开挖,中空大直径直眼掏槽,炮眼水压爆破和实时爆破振动监测等技术措施,安全完成了工程,全段施工进度达每月59m。     

大石山隧道光面爆破开挖技术

在大石山隧道爆破开挖中,采用了光面爆破、非电毫秒雷管微差爆破、M形掏槽爆破和导爆索间隔装药等爆破技术,使光爆眼残留率达到了100%,确保了隧道断面成形质量.爆破效果表明,所确定的爆破方案及设计参数是有效的.     

基于灰色关联分析浅埋隧道爆破振动影响因素

为安全、科学地控制浅埋隧道爆破振动的危害,采用灰色关联分析方法对浅埋隧道爆破振动影响因素进行分析。选取总药量、最大单段药量、掏槽孔最大单段药量、爆心距和段数为研究的相关因素变量,确定振动速度和主振频率为系统特征变量,结合某隧道爆破实测数据,进行灰色关联计算,然后对其计算结果进行排序和优势分析,得出影响浅埋隧道爆破振动因素的主次顺序,其中总药量、掏槽孔最大单段药量、爆心距和段数起着主要作用;得出了影响浅埋隧道爆破振动的准优因素为总药量,掏槽孔最大单段药量对其也起着主要作用。灰色关联分析法的分析结果对确定浅埋隧道爆破振动影响因素可以提供科学的理论依据。     

立井深孔直眼分段掏槽破岩作用和参数设计

本文通过对深孔装药分段爆破作用特性的分析，探讨了立井深孔直眼分段掏槽爆破的破岩机理，并比此为基础在理论上提出直眼分段掏槽爆破参数的设计计算方法。     

地铁隧道小净距下穿地下洞室振速控制研究

为控制地铁隧道爆破在小净距下对人防洞室的有害振动效应,以武汉市地铁5号线隧道的爆破掘进工程为依托,基于ANSYS-Lsdyna平台,通过建立地铁隧道掏槽孔延时起爆的三维数值模型,研究掏槽炮孔的电子雷管最佳延时设置时间,结合对比分析数值模拟和隧道爆破振动监测数据,采用等效弹性边界的载荷加载的数值模拟方法,能够有效地模拟复杂环境下地铁隧道掏槽爆破振动,能较好地模拟隧道爆破对小净距下人防洞室的振动规律。对掏槽孔而言,隧道不同级掏槽起爆适宜合理时间为10 ms,同一级掏槽起爆合理延时时间为6 ms,合理最大单段药量为0.6 kg。     

地铁隧道小净距下穿地下洞室振速控制研究

为控制地铁隧道爆破在小净距下对人防洞室的有害振动效应,以武汉市地铁5号线隧道的爆破掘进工程为依托,基于ANSYS-Lsdyna平台,通过建立地铁隧道掏槽孔延时起爆的三维数值模型,研究掏槽炮孔的电子雷管最佳延时设置时间,结合对比分析数值模拟和隧道爆破振动监测数据,采用等效弹性边界的载荷加载的数值模拟方法,能够有效地模拟复杂环境下地铁隧道掏槽爆破振动,能较好地模拟隧道爆破对小净距下人防洞室的振动规律。对掏槽孔而言,隧道不同级掏槽起爆适宜合理时间为10 ms,同一级掏槽起爆合理延时时间为6 ms,合理最大单段药量为0.6 kg。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。