黑山铁矿露天采场边坡稳定性研究与治理实践

黑山露天采场西边坡由于断层节理发育，造成大面积滑坡，给采场安全生产造成极大威胁。采取现场编录和工程钻等手段，详细摸清了西边坡岩体断层节理情况。通过对边坡进行稳定性分析研究，制定出具体治理方案。采用地表截洪沟阻水、770 m水平预留宽台阶并在宽台阶外缘砌筑干砌石挡墙、对宽台阶实施喷锚支护加固等措施，消除了770 m水平以上边坡对下部各台阶生产作业的威胁，保证了露天采场深部的安全生产。     

近距离煤层煤柱高应力下巷道支护技术研究

文章通过研究煤柱下高应力巷道顶板及两帮的变形机理和破坏情况,确定高应力作用下巷道的支护方式为强力锚杆锚索组合支护。该技术成功地应用于潞安集团某矿的巷道支护中,取得了良好的技术效果和经济效益,可以在类似条件下的煤柱高应力巷道中推广应用。     

锚杆退锚机锈死螺母破切器破切力分析

对螺母锈死的锚杆回收可采用螺母破切器对锈死螺母进行切除,破切刀的力学特性对破切器的性能影响很大。通过对螺母破切过程的力学分析,得到了破切力的计算公式和不同参数情况下破切力P随破切深度h的关系曲线图,进而得出破切刀刀刃宽度、楔形角、摩擦系数对破切力都有较大影响,在刀具设计中应尽可能减小破切刀刀刃宽度及楔形角,在使用中应尽可能减小摩擦系数。     

箱形截面柱剪力键式全螺栓连接受力性能研究

为了解决传统箱形截面柱法兰连接节点对结构空间占用的问题，提出了一种箱形截面柱剪力键式全螺栓连接节点，并对2个全螺栓连接箱形截面柱和1个整体式箱形截面柱进行拟静力试验研究。观察了全螺栓连接箱形截面柱的破坏现象，分析了全螺栓连接箱形柱的滞回性能、承载力、刚度退化、延性以及耗能能力等受力特性。结果表明：整体式箱形截面柱和剪力键式全螺栓连接箱形截面柱均发生塑性铰破坏；滞回曲线饱满，具有良好耗能能力；剪力键和水平单向螺栓的设置可使全螺栓连接箱形截面柱承载力提高24.64%,竖向高强螺栓拉力降低29.44%;节点处钢连接件的设置约束了箱形截面柱的屈曲变形，与整体式箱形截面柱相比，全螺栓连接箱形截面柱的位移延性系数提高了26.47%;钢连接件间无滑移，剪力键式全螺栓连接节点连接可靠。通过剪力键式全螺栓连接节点与刚接节点有限元分析结果对比，表明在工程应用中箱形截面柱剪力键式全螺栓连接节点可等效刚接。采用GB 50011—2010《建筑抗震设计规范》对箱形截面柱剪力键式全螺栓连接节点进行承载力验算，计算结果与试验结果吻合。     

Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints

Abstract

The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.     

树脂全长锚固锚杆外形尺寸优化实验室研究

锚杆全长预应力锚固支护方式是解决复杂困难巷道支护的有效手段,但是由于施工困难,一直制约着它的应用与推广。通过优化锚杆外形的方法,在保证锚杆锚固性能的前提下,解决煤矿巷道全长锚固施工困难的问题。采用实验室试验的方法,对锚杆外形与锚杆锚固性能以及安装阻力之间的关系进行了研究,提出锚杆外形相关参数的合理值。优化后的锚杆横肋高度由原来的1.46 mm降低为1.00 mm,锚杆横肋间距由原来的11.05 mm增加到33.15 mm,横肋采用交错布置的方式。对锚杆横肋高度和间距优化后,锚固长度125 mm时锚杆的拉拔力比改进前反而提高了7.7%;锚杆安装过程中的平均扭矩比优化前降低约40%,安装锚杆所需要的推力仅为优化前的50%左右,最大值为0.73 kN。     

On analysis and redesign of bolted L‐flanged connections

In wind turbine towers, the preferred design is circular tubes that are connected by a bolted flange joint. The design is typically that of an L‐flange resulting in an eccentrically loaded bolted connection. The eccentricity results in a non‐linear relationship between external load on the tower and the tensile force in the bolt. In the literature and also in standards, different models are presented for this important non‐linear response. In the present paper, a simplified expression for the non‐linear force response is presented based on finite element calculations using contact analysis. The L‐flange connection is in essence a bad design because it leads to a non‐optimal ratio between external force and bolt force. Furthermore, bolt bending results in an even higher bolt stress resulting in a reduction of strength. The present paper presents simple modifications of the L‐flange design that considerably improves the connection strength. Copyright © 2017 John Wiley & Sons, Ltd.     

雅园立交桥盖梁加固技术

雅园立交桥在使用十多年后桥梁结构和隐形盖梁均出现了一些病害,文中着重介绍盖梁加固设计方案及其特点、难点,具体施工方法、相关注意事项及技术措施,对立交桥梁的加固技术也进行了探讨。     

Modeling the temperature-dependent mode I fracture behavior of adhesively bonded joints

An ethylene propylene diene monomer (EPDM) rubber film has been used as an inhibitor and insulation in solid rocket motors (SRMs) due to its excellent heat-insulating property. EPDM is wrapped on the surface of the grain layer-by-layer via an adhesive; thus, the adhesive property between EPDM films is one of the key factors that influence the structural integrity of an SRM. The adhesive properties are largely temperature dependent, therefore, it is essential to study the effect of temperature on the properties of the bonding interface between EPDM films. In this article, double cantilever sandwich beam (DCSB) and uniaxial tensile experiments were performed to study the temperature-dependent mode I fracture of the bonding interface, in the service temperature range of the SRMs. A comparison of experimental and numerical results obtained using experimental parameters indicates that the fracture parameters determined by the simple beam theory (SBT) and the compliance-based beam method (CBBM) are not accurate. Next, we obtained accurate parameters using an inverse analysis method. Moreover, we made an initial attempt to establish a temperature-dependent cohesive zone model to predict the temperature-dependent fracture behavior of adhesively bonded joints. Good agreement between experimental and numerical results demonstrates that this temperature-dependent model is applicable.     

锚杆支护技术在煤巷快速掘进中的应用分析

煤炭产业作为国家经济发展的支柱型产业,在社会建设中发挥着重要作用。当前阶段,为满足社会需要,煤炭工程在作业过程中开始不断探索新型的挖掘技术,其中锚杆支护技术由于劳动强度低、经济性强、支护效果好,在煤巷快速掘进工程中的应用日益广泛。为提升锚杆支护技术的应用效果,对其在煤巷快速掘进中的应用进行分析。