Controlling entry in soft rock with natural support strength,strikesill,etc.

Presented the concept of the natural support strength.The natural support strength,the strike sill,the multifunction retractors (developed by the author) and etc.were used with the technical measures to change the passive support to the initiative support, and the soft rock entry was supported.And its process is simple and less equipment is needed,and the cost is low and the advance rate is high,which can meet the require- ments of actual mining.It solves many support difficult problems.

Failure mechanism of bolting support and high-strength bolt-grouting technology for deep and soft surrounding rock with high stress

In deep underground mining, the surrounding rocks are very soft with high stress. Their deformation and destruction are serious, and frequent failures occur on the bolt support. The failure mechanism of bolt support is proposed to solve these problems. A calculation theory is established on the bond strength of the interface between the anchoring agent and surrounding rocks. An analysis is made on the influence law of different mechanical parameters of surrounding rocks on the interfacial bond strength. Based on the research, a new high-strength bolt-grouting technology is developed and applied on site. Besides, some helpful engineering suggestions and measures are proposed. The research shows that the serious deformation and failure, and the lower bond strength are the major factors causing frequent failures of bolt support. So, the bolt could not give full play to its supporting potential. It is also shown that as the integrity, strength, interface dilatancy and stress of surrounding rocks are improved, the bond strength will increase. So, the anchoring force on surrounding rocks can be effectively improved by employing an anchoring agent with high sand content, mechanical anchoring means, or grouting reinforcement. The new technology has advantages in a high strength, imposing pre-tightening force, and giving full play to the bolt supporting potential. Hence, it can improve the control effect on surrounding rocks. All these could be helpful references for the design of bolt support in deep underground mines.

Strength failure of spatial reticulated structures under multi-support excitation

Under strong earthquakes, long-span spatial latticed structures may collapse due to dynamic instability or strength failure. The elasto-plastic dynamic behaviors of three spatial latticed structures, including two double-layer cylindrical shells and one spherical shell constructed for the 2008 Olympic Games in Beijing, were quantitatively examined under multi-support excitation （MSE） and uniform support excitation （USE）. In the numerical analyses, several important parameters were investigated such as the peak acceleration and displacement responses at key joints, the number and distribution of plastic members, and the deformation of the shell at the moment of collapse. Analysis results reveal the features and the failure mechanism of the spatial latticed structures under MSE and USE. In both scenarios, the double-layer reticulated shell collapses in the ＂overflow＂ mode, and the collapse is governed by the number of invalid plastic members rather than the total number of plastic members, beginning with damage to some of the local regions near the supports. By comparing the numbers and distributions of the plastic members under MSE to those under USE, it was observed that the plastic members spread more sufficiently and the internal forces are more uniform under MSE, especially in cases of lower apparent velocities in soils. Due to the effects of pseudo-static displacement, the stresses in the members near the supports under MSE are higher than those under USE.

Research on Bolt Support Technology in Soft Coal Seam Roadway

In order to solve the problem of surrounding rock control in soft coal seam roadway, taking the centralized return airway of No. 2 coal seam in Liangdu Coal Industry as the research background, the mechanical conditions of roadway surrounding rock were analyzed by means of field investigation, rock mechanics experiment and numerical simulation. The design principles of roadway support in soft coal seam were put forward: high strength anchor cable support, high preload support and high stiffness support. The bearing capacity of surrounding rock was strengthened by anchor cable support, and the deformation and failure of surrounding rock were effectively controlled. Through the numerical simulation method, the deformation and plastic failure range of roadwaysunder different support schemes are compared and analyzed. The support scheme of centralized transportation roadway is studied and determined, and the field test is carried out, which effectively controls the deformation of surrounding rock of roadway in weak coal seam.

某型舰船设备大负载复合材料支承冲击强度试验方法研究

舰船设备支承件的冲击特性研究受到各国海军的重视,然而超过常规冲击机能力范围的冲击载荷等要求,使得开展大负载支承件冲击强度试验成为难题。以某型动力设备的大负载复合材料支承为对象,采用水下非接触爆炸的方式,以标准浮动冲击平台冲击环境为输入参数设计其冲击强度试验方法:在低速冲击条件下,通过保证冲击载荷、降低试验负载质量、提高系统安装频率的途径来设计试验装置,依据冲击谱和冲击载荷计算对应的试验冲击因子来设计强度试验工况,并得出了实际试验与设计参数之间因试验系统多个结合面对冲击载荷传递影响的折减系数。试验结果表明,复合材料支承承受的冲击载荷与要求值之间的偏差在5%以内,为今后开展类似试验提供了参考。

极近距离煤层开采无煤柱自成巷控制方法研究

极近距离煤层传统长壁开采,受上层遗留煤柱和采空区垮落等因素的影响,下煤层开采过程中应力环境复杂、矿压显现剧烈,易诱发巷道围岩大变形。为解决上述问题,提出了极近距离条件下巷道定向切顶–约束高强支护无煤柱自成巷控制方法。通过顶板定向预裂切顶,主动改变顶板悬臂结构,切断采空区向巷道顶板的应力传递。充分利用矿山压力和岩体碎胀特性,取消煤柱留设,结合高强支护加强巷道顶板整体性,共同实现切顶自成巷。建立了极近距离煤层开采覆岩结构模型,计算了下煤层切顶自成巷巷旁支护阻力。以典型极近距离煤层为工程背景,开展了不同开采方法的数值试验对比研究,结果表明,提出的自成巷控制方法使巷道围岩应力降低59.8%,巷道顶板变形减少70.8%,并明确了极近距离煤层开采无煤柱自成巷控制机理。在此基础上,开展了典型极近距离煤层工程设计及现场应用研究,结果表明该方法有效降低了矿压显现程度,保证了自成巷的安全稳定控制。

悬臂式双级纵移钻锚机有限元强度分析与改进

悬臂式双级纵移钻锚机采用支撑臂与万向臂可快速灵活地打锚杆孔,由于悬臂长、臂端载荷大、结构复杂,存在强度不足的隐患。通过对其工况、所受载荷进行分析,采用SolidWorks和ANSYS软件对其进行了有限元强度分析。结果表明,最大应力发生在悬臂最长且外摆向上打顶部锚杆孔工况下,位于支撑座的大臂下支撑耳应力集中处,次大应力发生在悬臂最长且外摆向上打侧上部锚杆孔工况下,位于联接万向臂和推进器的直角连接板的肋板应力集中处。局部结构改进后进行有限元分析,其结构强度满足设计要求。

加快形成赋能农业科技创新的金融体系

论文主要探讨了农业科技创新对中国实现农业现代化和农业强国建设的重要性。通过分析国内外成功经验,提出加强金融支持农业科技创新的策略,旨在提升中国农业的质量和国际竞争力。农业科技创新是建立现代农业体系的关键,能显著提高生产力和推动农业可持续发展。文章借鉴了美国、德国、荷兰和日本等国在农业科技创新和金融支持方面的成功经验,指出政府主导、产学研紧密结合、法律制度完善及有效金融支持是农业科技创新成功的关键因素。这些国家通过建立强大的研发体系、推进政策支持、实施合作社模式和专业化经营等策略,有效促进了农业科技进步和农业产业的全面发展。科技创新和金融支持是推动中国农业产业转型和实现国家全面现代化的关键,需要政府、企业和金融机构等多方共同努力,营造有利于农业科技创新的环境和体系。中国需精准定位,借鉴国际经验,推进农业强国建设。强化金融对农业科技创新的支持,加快农村金融制度建设。建议通过优化政策、创新保险产品、改进金融服务和深化资本市场改革等措施,为农业科技创新提供金融支持。

海上移动平台直升机甲板圆管支撑结构安全评估

圆管支撑结构是海上移动式平台直升机甲板设计的重要部分,由于海上恶劣的风浪环境,使结构整体受风载荷的影响较大.现有直升机甲板圆管支撑结构的安全评估内容主要集中于圆管的静强度分析,缺乏风振响应分析,文中以海洋石油163平台直升机甲板为例,研究圆管支撑结构的静力和动力载荷输入,通过有限元强度分析和理论经验公式计算对比静力、风载荷作用下直升机甲板圆管支撑结构的受力情况,考虑风振涡激效应的准静态分析,在此基础上提出了直升机甲板圆管支撑结构的安全评估方法,探究了风载荷对结构整体安全的影响.

基于纸张纤维特征的纸页抗张强度智能模拟及预测研究

对纸页抗张强度进行智能模拟,有助于更好地对某种纸页的性能进行分析甚至预测。基于此,针对现有纸页抗张强度模拟方法的缺陷进行总结,认为现有典型Page分析模型存在客观性分析不足等问题,结合偏最小二乘法、支持向量机等构建了一种基于造纸纤维特性的纸页抗张强度智能模拟模型,借助该模型对某种典型纸页的性能进行模拟分析。测试结果表明:该模型能够高效、准确地对纸页抗张强度进行预测,与传统模型相比具有更强的实用性。

510L钢汽车大梁支架的失效分析

某微型卡车的大梁支架,材料为510L钢,在测试过程中开裂。为揭示其开裂的原因,对该支架进行了宏观检验、硬度检测、化学成分分析、金相检验和ANSYS workbench应力仿真。结果表明:支架中有在轧制过程中产生的纵向裂纹;开裂部位最大应力接近支架的屈服强度。上述两点是支架开裂的主要原因。

B型LNG燃料舱支座结构的强度分析

B型LNG燃料舱支座结构的受力机理较为复杂,其强度分析在设计中应给予重视。提出一套针对B型燃料舱支座结构强度分析的标准流程,能综合考虑层压木压力和摩擦力对支座结构强度的影响。给出一种B型燃料舱支座系统的设计方案,以典型的垂向支座和止横摇支座为例,应用子模型技术对其结构强度进行分析。支座结构的强度分析方法和应力分布特性可为实际工程中B型燃料舱支座的设计与分析提供参考。

基于Mohr-Coulomb准则隧道围岩-支护体系协同作用下支护强度分析

确定围岩-支护结构体系动态协同变形关系是地下工程支护需要解决的关键问题之一。运用Mohr-Coulomb准则推导隧道开挖支护后围岩径向变形与支护结构径向变形的协同方程,探讨Ⅳ级围岩塑性半径、围岩位移及支护刚度随支护强度的变化关系;并运用FLAC3D数值模拟验证协同变形方程的合理性和有效性。结果表明,围岩-支护结构体系协同变形方程能很好地反映围岩位移和塑性区半径随支护强度变化的关系,且相互关系是非线性的。支护强度为0.75 MPa时,理论计算拱顶沉降为18.9 mm,数值模拟拱顶沉降为21.6 mm;支护强度为1.5 MPa时,理论计算拱顶沉降为11.2 mm,数值模拟拱顶沉降为11.1 mm,表明围岩-支护结构动态协同变形方程的有效性。针对Ⅳ级围岩在采用超前支护和交叉中隔壁法(cross diaphragm,CRD)施工时,建议支护强度设计为0.75~1.5 MPa,支护刚度设计为59.8~375.0 kN/mm。

飞行保护头盔用TC4护目镜支架的热处理研究

为解决头盔用TC4合金护目镜支架强度低的问题,对其进行真空热处理,用金相显微镜、扫描电子显微镜等研究真空热处理工艺对护目镜支架显微组织及性能的影响。结果表明:在真空度为1×10^(-3)Pa下,1000℃保温20 min后淬火,合金发生相变,平均尺寸为2.6μm的等轴α相转变为宽度约为870 nm的细小片层α相,并弥散分布于β基体中,β晶粒平均尺寸约为260μm。相对原始组织,经真空热处理后,合金屈服强度和抗弯强度分别从1596、1942 MPa提高到1806、2170 MPa,分别提升13%、12%,这是因为纳米片层α相弥散分布的强化效应,显著提升了合金的强度等力学性能。

煤矿巷道快速掘进临时支架结构应用实践研究

对当前市场上已公布的超前支架进行研究分析,可以发现这些支架的设计、选型和生产主要是为了应对围岩的剧烈变化、高矿压和较低的保护力。因此,这类支架通常具有较重的质量、较大的体积、较高的保护力和较小的灵活性,应用局限于良好的巷道环境,而对于地质状况相对复杂的巷道,其应用范围会受到限制。因此,提出了一种全新的弱支护和强防护的支架设计方案,创新设计一种新型机载式的预先临时支架。

深厚软土区域水泥土强度影响因素与变形特征试验研究

针对深厚软土地区影响重力式水泥土墙强度的敏感因素如水泥标号、水灰质量比、水泥掺量、养护龄期等,通过室内试验得到了多因素耦合的强度变化规律,并结合水泥土墙变形分析提出了重力式水泥土墙变形控制的有效方法,为进一步研究深厚软土地区此类支护结构的适用性和优化设计提供参考。

矿用液压支架底座强度分析与优化分析

基于充填采煤液压支架底座基本结构,介绍了一种底座结构优化方案。通过Pro/E和ANSYS软件构建仿真模型,获取强度仿真分析结果,并由此对充填采煤液压支架底座结构进行优化调整,进而获取底座结构优化方案。将底座结构优化方案应用于工程实践,检验底座结果优化方案可行性和应用价值。最终确认该底座结果优化方案具有较强可行性。

偏心状态皮带廊道支架实例分析

通过对皮带廊道支架偏心状态与对称状态的比较,可发现偏心状态对支架截面强度的不同要求。结合现行国家规范与设计手册,辅助配以PKPM建模,计算得出偏心廊道支架主要数据。

樽海鞘算法优化支持向量机的RC柱抗侧移承载力预测

现有钢筋混凝土(RC)柱抗侧移承载力预测模型缺乏泛化性能,延性柱抗弯承载力的预测模型不能用于非延性柱的抗剪承载力,反之亦然。机器学习(ML)方法能够解决这一问题,但由于无法自动剔除冗余和不相关特征,使得ML模型复杂度高且容易过拟合。为此,提出一种樽海鞘算法优化支持向量机(SSALS-SVM)方法,基于给定的数据集,SSALS-SVM能利用樽海鞘优化算法(SSA)自动剔除冗余和不相关的特征,筛选最具代表性且各特征之间相关性弱的特征子集形成最优特征组合,同时对控制模型非线性拟合能力的超参数进行优化。优化后的模型既能识别出影响延性和非延性RC柱抗侧移承载力的设计变量,又能反映最优特征组合与抗侧移承载力间的非线性映射关系。为了验证SSALS-SVM方法的泛化性能,基于248个RC柱抗侧移承载力试验数据,分别与现有的RC柱抗侧移承载力预测模型进行对比,结果表明,SSALS-SVM比现有预测模型的泛化性能最高提升了83%。

高贝利特硫铝酸盐水泥在免拆钢筋桁架楼承板中的应用

装配式叠合楼板是由预制混凝土底板和现浇钢筋混凝土层叠合而成的装配整体式楼板。对比分析了装配式叠合楼板、钢质楼承板、纤维水泥板楼承板、细石混凝土免拆钢筋桁架楼承板的生产工艺与性能特点。重点分析了采用高贝利特硫铝酸盐水泥制作的细石混凝土免拆钢筋桁架楼承板的工艺特点及性能。高贝利特硫铝酸盐水泥细石混凝土底板吊装速度快、脱模时间短、低温免蒸养、免拆模;底板密度较小、收缩变形量小、抗压强度高、吸水率小、跨度大。