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。     

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。     

Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Directed self‐assembly (DSA) using soft materials is an important method for producing periodic nanostructures because it is a simple, cost‐effective process for fabricating high‐resolution patterns. Most of the previously reported DSA methods exploit the self‐assembly of block copolymers, which generates a wide range of nanostructures. In this study, cylinders obtained from supramolecular dendrimer films with a high resolution (<5 nm) exhibit planar ordering over a macroscopic area via guiding topographical templates with a high aspect ratio (>10) and high spatial resolution (≈20 nm) of guiding line patterns. Theoretical and experimental studies reveal that this property is related to geometrical anchoring on the meniscus region and physical surface anchoring on the sidewall. Furthermore, this DSA of dendrimer cylinders is demonstrated by the non‐regular geometry of the patterned template. The macroscopic planar alignment of the dendrimer nanostructure reveals an extremely small feature size (≈4.7 nm) on the wafer scale (>16 cm²). This study is expected to open avenues for the production of a large family of supramolecular dendrimers with different phases and feature dimensions oriented by the DSA approach.     

Feasible Preparation of a Thin‐Film Composite Nanofiltration (TFC NF) Membrane with Enhanced Skin–Substrate Adhesion and Compaction Resistance: In Situ Construction of Rigid–Flexible Polymer Composited Microspheres (CPs) in the Casting Solution

Novel microspheres (CPs) composited by rigid and flexible polymers are synthesized and embedded in the supporting membranes to enhance both the skin–substrate adhesion and compaction resistance of the thin‐film composite (TFC) nanofiltration membranes. The CPs are in situ formed in the casting solution after the rigid poly(p‐phenylene terephthamide) (PPTA) is produced in the flexible poly(m‐phenylene isophthalamide) (PMIA) solution. Then the PPTA/PMIA in situ blending membranes are prepared by using the NIPs method, and the TFC NF membranes are fabricated via interfacial polymerization on them. The CPs are characterized via polarizing microscopy and TEM. The surface morphology and chemical composition of the blended membranes are characterized by using FESEM, AFM, FTIR, and WCA, respectively. As the results show, the supporting membrane with higher PPTA content exhibits higher permeability, thermal stability, and compaction resistance. Moreover, the adhesion strength between the TFC functional layer and the supporting membrane is improved significantly. It is proposed that this improvement can be attributed to the CPs that are exposed on the top surface of the supporting membrane, which leads to a great enhancement because of the anchoring effect between the functional layer and the CPs.     

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。     

谈过陷落柱施工技术及措施

以国内某煤矿过陷落柱施工为例,根据地质资料,介绍了其施工方案及工艺流程,着重对巷道断面规格的支护形式及支护参数进行了分析,总结了施工质量控制要求,为其他矿山井下施工提供参考。     

承钢1780线精轧机的减速机螺栓断裂分析

介绍了对承钢1780生产线F1精轧机减速机输入轴固定螺栓和F3精轧机减速机地脚螺栓断裂的断口形貌.对其最大承受力和直径进行了计算,对其微观组织进行了分析,找到了这两起螺栓断裂失效的原因,给出了相应的解决措施.     

铸钢轮装制动盘螺栓孔裂纹产生原因分析

以存在螺栓孔裂纹的铸钢轮装制动盘为研究对象,通过裂纹断口宏微观形貌观察、显微组织分析、拉伸性能测试、冲击性能测试、布氏硬度测试等手段分析了制动盘摩擦面螺栓孔裂纹的性质和成因。结果表明:裂纹属于热疲劳裂纹,螺栓孔倒棱处及摩擦面附近存在缩孔、疏松等铸造缺陷是导致制动盘在制动过程中循环交变热应力驱动下产生裂纹的主要原因;粗大的沿枝晶状分布组织降低了制动盘的强度、韧性和热疲劳性能,加速了裂纹的扩展。     

D型复合材料管连接性能研究

格构式复合材料塔采用了通过钢制螺栓机械连接的D型复合材料管,其中复合材料管制孔和螺栓预紧力对杆件承载力影响还没有相关研究,其承载特性不太清楚。为准确掌握D型复合材料管的连接性能,通过D型复合材料管的塔节间模型节点试验,得到复合材料杆件连接孔端部以劈裂和剪切破坏为主;通过有限元模型分析了螺栓预紧力对D型复合材料管连接性能的影响,结果表明D型复合材料塔用抗剪螺栓的预紧扭矩宜控制为220 N?m。     

浅谈高边坡支护的施工方法

本文作者根据自己多年的施工实践经验,就高边坡支护的施工方法及技术要点控制等问题作以简单阐述,对于高边坡支护的施工方法、现场监测以及制定应急抢险措施等问题进行了探讨,以此保证能消除安全隐患和确保施工质量,供同行参考。