露天台阶深孔爆破合理超深数值模拟分析

为了研究露天台阶深孔爆破超深对矿岩破碎效果的影响,基于ANSYS/LS-DYNA有限元数值模拟的方法对不同底盘抵抗线条件下超深对岩石破碎的影响进行了初步研究。结果表明,台阶深孔爆破存在临界超深,当超过该值后,作用在台阶坡底处应力值的增幅变小,爆破能量利用率显著降低。通过对应力变化规律的分析得到了临界超深值的范围,可为工程实践提供设计参考。     

超深孔控制爆破在宝泉电站路堑开挖中的应用与探讨

宝泉电站路堑超深孔爆破,处于复杂环境中,对环保要求严格,对爆破震速、飞石、爆堆坍塌距离等控制严格,爆破设计与施工难度较大,成功地探索了超深孔爆破控制技术,突破了小孔径、小台阶控制爆破的常规.     

中深孔与浅孔联合布孔在煤层底板爆破中的数值模拟研究

针对露天台阶爆破煤层底板与其毗邻的岩层力学性质差异较大,爆破时大块率高的问题,介绍一种改善煤层底板破碎效果的中深孔与浅孔联合布孔爆破方法。使用有限元分析软件LS-DYNA分析了联合布孔装药结构爆破过程中的应力分布规律,分析表明:联合布孔爆破方法相比传统中深孔爆破,增大了拉应力峰值,延长了拉应力对煤层底板有效作用时间;在宁夏大峰矿羊齿采区的应用实践表明,联合布孔爆破方法不仅改善了煤层底板的破碎效果,并大量节约了爆破生产成本。     

深孔爆破技术在不规则台阶中的应用

为了解决废弃矿区垦造水田工程,存在采矿遗留高度3～10 m不规则台阶的问题。且因为工期紧,对这些不规则台阶不能采取浅孔台阶爆破和深孔爆破相结合的方式施工。同时,低台阶开挖采取大于50 mm孔径爆破施工缺少理论依据,工程案例也较少。为此,根据以往经验和参考多边界石方爆破药量计算原理并结合现有钻孔设备,对不规则台阶采取梅花形布孔,用φ90 mm钻机钻孔,其中钻机无法打孔的局部位置在其后侧加密倾斜孔。采取多排深孔延时爆破技术,累计14 h一次性施工。因已购非电雷管段别有限,则利用现有雷管组网,采取分区接力的起爆网路,一次性成功爆破了高低不平的不规则台阶,除了爆堆表层2 m左右范围内有大石块,其余位置岩石破碎块度较小,爆破后无根底,达到预期效果,为后续工作创造了有利条件。     

利用浅孔改善深孔台阶爆破孔口块度技术研究

新疆别斯库都克露天煤矿由于岩体节理裂隙发育,深孔台阶爆破中孔口部分容易产生大块.为了改善该露天矿岩石爆破效果,采用了深孔之间布设浅孔的方式对孔口的爆破破碎效果进行改善.为了确定合理的爆破参数,采用了数值模拟方法对参数进行模拟验证.在露天矿现场取样制作试件测试了现场砂岩的岩石力学性质,基于实测岩石力学性质与现场爆破参数建立了数值模拟模型.对不同浅孔深度的五种模拟条件进行了模拟,分析了不同条件下孔口1～4m范围内的爆破应力波应力峰值,确定了4m浅孔深度下对于孔口部分爆破效果的改善效果最佳.在别斯库都克露天矿1216台阶尝试采用了增加4 m深度1.5 m装药长度的浅孔,明显改善了现场爆破效果.该研究结果可以对利用浅孔改善深孔露天台阶爆破孔口部分爆破效果,减少孔口大块提供技术参考.     

甘冲矿中深孔爆破影响因素分析

本文针对露天台阶中深孔爆破存在的几个主要问题，结合本矿的生产实际，对影响中深孔爆破的因素作了初步分析，提出了改进措施。     

深孔爆破中不同起爆方式对爆生裂纹的数值模拟

为了分清齐发爆破和逐孔起爆的方式对岩体裂纹的影响,运用LS-DYNA动力有限元分析软件,分别对深孔三孔齐发起爆和深孔三孔逐孔起爆的爆生裂纹扩展机理进行了数值模拟,并描述了深孔爆破时的应力分布云图和裂纹扩展以及损伤演化情况,得到岩体的破碎区和裂隙区的范围。模拟分析结果表明:采用逐孔起爆法使岩石的自由面发生改变,炮孔破坏更为严重,对爆破效果产生很大的影响。并对计算结果进行了分析,对指导工程实践有一定的参考价值。     

深孔爆破中不同起爆方式对爆生裂纹的数值模拟

为了分清齐发爆破和逐孔起爆的方式对岩体裂纹的影响,运用LS-DYNA动力有限元分析软件,分别对深孔三孔齐发起爆和深孔三孔逐孔起爆的爆生裂纹扩展机理进行了数值模拟,并描述了深孔爆破时的应力分布云图和裂纹扩展以及损伤演化情况,得到岩体的破碎区和裂隙区的范围。模拟分析结果表明:采用逐孔起爆法使岩石的自由面发生改变,炮孔破坏更为严重,对爆破效果产生很大的影响。并对计算结果进行了分析,对指导工程实践有一定的参考价值。     

义乌市采石场普遍推广中深孔爆破技术

义乌市各采石场在石料开采中,积极推广中深孔控制爆破技术,提高了石料产量,保证了采石爆破安全。本文阐述了使用小型潜孔钻机在采石场分台阶进行作业,同时采用毫秒延时起爆方法,有效地解决了爆破振动对采石场周边居民住房的影响。若在我国中小型采石场和矿山地区推广这种中深孔爆破技术将是一件利国利民的事。     

切割拉槽中深孔孔内分段爆破数值模拟

针对大冶铁矿切割井上部难以施工至设计高度从而影响立槽高度问题,考虑在切割巷的拉槽中深孔采用孔内分段爆破方案,以使得切割立槽高度达到设计高度,并解决悬顶的安全问题。为分析切割拉槽中深孔孔内分段爆破效果,基于ANSYS/LS-DYNA有限元数值模拟软件,对孔内分段装药和不分段装药两种不同装药结构下中深孔爆破切割立槽处应力变化、损伤区域进行模拟计算研究。结果表明：越靠近模型中部,应力波的叠加作用越强,其有效应力更加集中,所产生的损伤破碎面积更大。在矽卡岩区域内,两种不同装药结构的爆破方式在切割立槽处产生的有效应力大小高于矽卡岩的破坏强度,均能在切割立槽处造成较大面积的损伤破碎。在磁铁矿区域内,分段装药爆破后产生的爆破高度更高,在切割立槽处所产生的有效应力更大,产生的破碎面积更广。结合大冶铁矿现场实际爆破试验,孔内分段爆破后可顺利将悬顶安全处理,使得切割立槽达到设计高度,解决了后期施工生产的难题。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.