TBM刀具三维破岩仿真

根据TBM现场施工的特点,探索在ANSYS LS／DYNA环境下建立TBM刀具三维破岩仿真模型的方法. 通过算例成功模拟了某型TBM常截面盘形滚刀滚压破碎混凝土的施工过程,获得了TBM盘形滚刀的三向力以及刀圈、混凝土的应力场、刀刃侧滑等信息,并对其进行了分析. 仿真结果表明:盘形滚刀破岩过程呈现明显的跃进式破碎的特点,刀圈侧滑以及应力集中等现象是造成刀具失效的主要原因.该结论为刀盘的结构设计和工程施工维护提供了基础数据.     

刀盘掘进过程动态仿真

刀盘是岩石隧道掘进机(TBM)开挖岩石的关键部件,通过试验或者现场施工数据得到其与围岩的相互作用规律极为困难。利用数值模拟方法,在ABAQUS/Explicit环境下建立了模拟刀盘掘进的三维分析模型。采用扩展的DruckerPrager非线性弹塑性模型作为岩体的本构模型;应用包含单元删除功能的损伤失效准则模拟切屑的形成及分离,并基于显式积分算法实现了TBM刀盘掘进全物理过程的直接数值模拟,得到了刀盘的动态掘进载荷以及掌子面岩体的损伤失效状态。仿真结果表明:对于所选定的岩石力学参数,当推进距离达到8.5 mm时,掌子面岩体全面损伤,刀盘进入稳定掘进阶段;在掘进过程中,刀盘载荷波动剧烈,其第1阶主频约为刀盘转动频率的2倍。上述模拟方法可以为TBM掘进过程的分析提供有效的工具。     

Multi-degree-of-freedom coupling dynamic characteristic of TBM disc cutter under shock excitation

When the tunneling boring machine(TBM) cutterhead tunnels, the excessive vibration and damage are a severe engineering problem, thereby the anti-vibration design is a key technology in the disc cutter system. The structure of disc cutter contains many joint interfaces among cutter ring, cutter body, bearings and cutter shaft. On account of the coupling for dynamic contact and the transfer path among joint interface, mechanical behavior of disc cutter becomes extremely complex under the impact of heavy-duty, which puts forward higher requirements for disc cutter design. A multi-degree-of-freedom coupling dynamic model, which contains a cutter ring, a cutter body, two bearings and cutter shaft, is established, considering the external stochastic excitations, bearing nonlinear contact force, multidirectional mutual coupling vibration, etc. Based on the parameters of an actual project and the strong impact external excitations, the modal properties and dynamic responses are analyzed, as well as the cutter shaft and bearings' loads and load transmission law are obtained. Numerical results indicate the maximum radial and axial cutter ring amplitudes of dynamic responses are 0.568 mm and 0.112 mm; the maximum radial and axial vibration velocities are 41.1 mm/s and 38.9 mm/s; the maximum radial and axial vibration accelerations are 94.7 m/s2 and 58.6 m/s2; the maximum swing angle and angular velocity of cutter ring are 0.007° and 0.0074 rad/s, respectively. Finally, the maximum load of bearing roller is 40.3 k N. The proposed research lays a foundation for structure optimization design of disc cutter and cutter base, as well as model selection, modification and fatigue life of the cutter bearing.     

基于时间冲击最优的TBM换刀机器人轨迹规划

为了提高隧道掘进机(TBM)换刀机器人的工作效率,减小换刀过程中的运动冲击,提出基于改进型粒子群优化(PSO)算法的轨迹优化方法.采用位姿分离法与关节变量最小策略,对冗余关节机器人进行运动学分析.利用所求的逆解,将目标轨迹由笛卡尔空间映射到关节空间.针对每个关节使用5次NURBS曲线构造冲击连续的关节轨迹,以时间冲击最优构造目标函数,采用改进型PSO算法求解出最优时间序列,完成对轨迹的优化.通过对特定的换刀任务进行轨迹规划,得到各关节的优化轨迹.优化结果表明,提出的轨迹规划方法可以为换刀机器人各关节提供理想的轨迹,具有较强的轨迹跟踪能力.利用5次NURBS插值法与改进型PSO优化算法,可以保证轨迹的时间最短与冲击最小,提高了运行的效率与平稳性.     

双节理岩体TBM滚刀破岩过程数值模拟

为了研究节理特征对全断面掘进机(tunnel boring machine, TBM)盘形滚刀破岩的影响,采用颗粒流方法建立盘形滚刀与含平行双节理岩体的二维数值模型,进行不同节理倾角和间距的30组数值试验,根据数值试验结果研究岩体破裂模式、滚刀竖向接触力峰值随节理倾角和间距的变化规律、滚刀破岩过程中细观裂纹扩展规律。研究结果表明:不同的节理特征下,滚刀破岩可以分为4种基本的破裂模式;滚刀竖向接触力峰值随节理倾角的增大呈现先减小后增大的趋势,在节理倾角为30°或45°时最小,在节理倾角为90°时最大;滚刀竖向接触力峰值随节理间距的增大总体上呈现增大趋势;随滚刀的贯入,滚刀竖向接触力与细观裂纹个数有3个关联的变化阶段。通过研究TBM滚刀与节理岩体相互作用机制,揭示不同节理特征对滚刀破岩的影响规律,对TBM滚刀的合理设计和施工有一定的指导意义。     

Differentiation and analysis on rock breaking characteristics of TBM disc cutter at different rock temperatures

In order to study rock breaking characteristics of tunnel boring machine(TBM) disc cutter at different rock temperatures,thermodynamic rock breaking mathematical model of TBM disc cutter was established on the basis of rock temperature change by using particle flow code theory and the influence law of interaction mechanism between disc cutter and rock was also numerically simulated.Furthermore,by using the linear cutting experiment platform,rock breaking process of TBM disc cutter at different rock temperatures was well verified by the experiments.Finally,rock breaking characteristics of TBM disc cutter were differentiated and analyzed from microscale perspective.The results indicate the follows.1) When rock temperature increases,the mechanical properties of rock such as hardness,and strength,were greatly reduced,simultaneously the microcracks rapidly grow with the cracks number increasing,which leads to rock breaking load decreasing and improves rock breaking efficiency for TBM disc cutter.2) The higher the rock temperature,the lower the rock internal stress.The stress distribution rules coincide with the Buzin Neske stress circle rules: the maximum stress value is below the cutting edge region and then gradually decreases radiant around; stress distribution is symmetrical and the total stress of rock becomes smaller.3) The higher the rock temperature is,the more the numbers of micro,tensile and shear cracks produced are by rock as well as the easier the rock intrusion,along with shear failure mode mainly showing.4) With rock temperature increasing,the resistance intrusive coefficients of rock and intrusion power decrease obviously,so the specific energy consumption that TBM disc cutter achieves leaping broken also decreases subsequently.5) The acoustic emission frequency remarkably increases along with the temperature increasing,which improves the rock breaking efficiency.     

不同模式下 TBM 刀群三维回转切削仿真与优化设计

针对TBM刀群回转切削问题,建立了17寸盘形滚刀刀群切削岩石的数值仿真模型,使用有限元仿真分析软件ANSYS LS-DYNA对不同工作模式下的盘形滚刀回转切削岩石工作过程进行仿真。仿真结果表明,通过对盘形滚刀刀间距进行优化设计,分析不同刀间距下滚刀的力学参数,得到在该地质条件下,中心滚刀最优刀间距为75 mm、正滚刀最优刀间距为80 mm;通过对边滚刀安装角度进行优化,分析不同安装角度下滚刀的力学参数,得到边滚刀最优安装角度为6．5°;通过对滚刀切削岩石的顺次切削角度进行优化,分析不同顺次切削角度下滚刀的力学参数,得到正滚刀最优顺次切削角度为30°、边滚刀为20°。     

DS426卧式加工中心刀库随机换刀的控制方法及实现

介绍了DS426卧式加工中心的特点、组成、用途，阐述了刀库控制在此机床中的重要作用及刀库的硬件构成，采用法国NUM公司的数控系统，分析介绍了刀库随机换刀方式的控制方法，并给出了相应的控制程序．     

盾构切刀切削混凝土过程中的动态响应试验

为探究盾构切刀与混凝土的相互作用规律,开展室内切削试验,验证切削的实质是刀具与试件反复碰撞、挤压、切削和剥落的循环过程.通过切削力测试系统得到刀具前后角、刀具形状、切削深度和试件强度等因素对刀具法向切削力Fn与切向切削力Ft的影响规律,并分析得到各影响因素作用下Fn、Ft及切削合力Fc的波动范围.结果表明:刀具切削混凝...     

TBM钢拱架拼接机械手抓取对接机构

为了提高钢拱架拼接效率,降低人工作业对施工的影响,提出隧道掘进机(TBM)钢拱架拼接机械手的抓取对接机构. 利用图谱法对抓取对接机构进行构型设计,根据机构功能实现方式,将机构分解成2个支链,确定其自由度(DOF)空间和约束空间;根据线图的功能等效性,得到各支链自由度空间的若干同维子空间,配置合理的支链运动副,通过叠加组合,得到机构整体构型;建立机构的运动学模型,推导出机构各滑块位置与转动角的逆解;给出机构性能指标,利用螺旋理论,分析机构抓取模块的传递性能,结果表明,抓取对接机构的全局传递指标达到至少0.75,具有较好的传递性能,且其工作空间最大取值应小于π/2. 制作抓取对接机构的样机,对钢拱架拼接过程进行实验,验证机构的可行性.     

端曲面齿轮副复合运动规律及受力分析

根据微分几何和齿轮啮合原理的相关理论,分析了端曲面齿轮副复合运动的两种不同的传动形式,并采用仿真分析验证了其运动规律。计算并分析了端曲面齿轮副复合运动时的受力状况以及该齿轮副啮合过程中压力角的变化情况。搭建了验证其运动规律的试验平台,使用激光位移传感器测量该齿轮副的位移,将试验结果与理论值和仿真结果进行对比,验证了计算结果的正确性。     

TiN涂层刀具高速车铣切削性能及磨损机理

实验研究了高速车铣D60钢时TiN涂层刀具的切削性能和磨损机理.结果表明,在水溶性冷却液浇注冷却条件下,高频交变热应力较大,涂层剥落较快,TiN涂层刀具的耐磨性较差,不能适应切削加工的要求.与此相反,干式切削时,高频交变热应力较小,虽在涂层表面有微裂纹产生,但涂层不易剥落,刀具耐磨性较好,可进行长时间稳定切削.干式切削过程中,由于机械冲击,在刀刃处产生的微小凹缺陷,是造成刀具磨损的主要原因.不论湿式切削还是干式切削,涂层剥落后,切削区产生的瞬时热量聚集将使基体粘结相软化,进而导致硬质相颗粒脱落和基体的剧烈磨损.     

大豆生态需水的变化规律研究

以黑龙江省水利科学研究院自行研制的称重式蒸渗仪为测试手段,在国家“863”计划项目核心试验区甘南县,测试了半干旱区主要旱作物大豆的蒸发蒸腾量,结合大豆的生理指标,分析和研究了大豆生态需水的基本规律和特点,并进一步提出了大豆叶面蒸腾量和土壤表面蒸发量（即通常所说的棵间蒸发量）,可为半干旱地区发展节水灌溉提供基本参数。     

TBM挤压大变形隧洞管片错台及加固机理研究

软岩是重大交通、水电、矿山等工程建设中经常遇到的复杂介质,高地应力作用下软岩地下工程很容易产生围岩大变形,不仅对施工安全造成影响,而且还会造成建设工期和成本的迅速增加。软岩大变形已成为我国交通、水利、深部资源开发等工程领域亟待解决的重大课题。本研究以引大济湟隧道掘进机(tunnel boring machine, TBM)挤压大变形导致的管片错台为例,通过对现场监测成果的反演分析,系统研究挤压大变形不同错台的修复与控制方法,本研究成果对其他膨胀泥岩卡机事故脱困以及管片错台的工程具有指导意义。     

金相技术在农机刀片磨损机理研究中的应用

应用光学和电子金相技术,对不同刀片的刀刃进行分析,揭示了农机刀片的失效方式,磨损原因及磨损机理;查明了钢中在碳化物在磨损听行为,研究表明：农机刀片主要受夹杂于作物中的砂粒和地植物细胞中的非晶质硅酸体的磨粒磨损而失效,金相分析结果为寻求提高刀片寿命的途径指明了方向。     

侧向受荷桩基变形和受力规律的研究

在侧向受荷桩计算方法的基础上,提出了地面超载下邻桩侧向变形的共同作用分析方法,推导了关于侧向受荷桩内力和变形的微分方程,并编制了计算程序,对被动桩的内力和变形规律进行了研究。结果表明:(1)桩的变形随桩长增加而减小,但桩长超过合理桩长后,桩顶变形就趋于定值;(2)桩顶或桩端的约束条件仅对其附近小范围内的桩的变形和内力影响较大,对其他部位几乎没有影响;(3)桩的变形和内力受地面堆载的影响较大,与其大小呈线性比例关系,而与其距离呈非线性关系。因此在被动桩设计时,应选择合理的桩长并严格限制地面堆载的大小。     

Establishmen and vertification of an improved similitude law for dynamic ice force model test

To study the similitude laws for dynamic ice force model test which is a hot problem in ice mechanics.In this paper,a new modified similitude law for dynamic ice force model test is proposed based on ice-induced virbration theory and two reasonable assumptions.And the new law is vertified with an ice-induced pier virbration example.The numerical calculation results show that,firstly,the error of frequency factor between test value and theory value is small as well as that of displacement and velocity;Secondly,the time scale completely meet the similitude relation,the waveforms anastomotic well,and the phenomenon of offset and omit do not occur;Thirdly,as the damping ratio between prototype and model is nearly equal,the improved similitude law will still be applied.Therefore,the new modified similitude law is feasible to study dynamic ice force model test and can provide reference for the ice mechanics.     

好氧颗粒污泥的性质及形成机理的探讨

实验在SBR反应器中成功培养出好氧颗粒污泥,对其各项理化性质进行了描述,同时对其形成机理进行了初步的探讨. 研究结果表明：好氧颗粒污泥具有优良的沉降性能,其它各项理化性质也均优于普通活性污泥;其形成是各影响因素共同选择作用的结果.     

好氧颗粒污泥的性质及形成机理的探讨

实验在SBR反应器中成功培养出好氧颗粒污泥，对其各项理化性质进行了描述，同时对其形成机理进行了初步的探讨．研究结果表明：好氧颗粒污泥具有优良的沉降性能，其它各项理化性质也均优于普通活性污泥；其形成是各影响因素共同选择作用的结果。