Case study on the mechanics of NPR anchor cable compensation for large deformation tunnel in soft rock in the Transverse Mountain area,China

A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.

Compensation excavation method control for large deformation disaster of mountain soft rock tunnel

In recent years,the mine tunneling method and the new Austrian tunneling method have been considered the main theories of tunneling approaches in China.It is difficult for the traditional technique to overcome the large deformation problems imposed by complex geological conditions of mountain soft rock tunneling.Hence,the compensation excavation method has been proposed to solve this issue under the consideration that all damage in tunneling originates from the excavation.It uses supportive strategies to counteract the excavation effects successfully.This paper provides an overview of the fundamental ideas of the compensation excavation method,methodologies,and field applications.The scientific validity and feasibility of the compensation excavation method were investigated through the practical engineering study of the Muzhailing and Changning tunnels.

Excavation compensation theory and supplementary technology system for large deformation disasters

Given the challenges in managing large deformation disasters in energy engineering,traffic tunnel engineering,and slope engineering,the excavation compensation theory has been proposed for large deformation disasters and the supplementary technology system is developed accordingly.This theory is based on the concept that“all destructive behaviors in tunnel engineering originate from excavation.”This paper summarizes the development of the excavation compensation theory in five aspects:the“theory,”“equipment,”“technology,”the design method with large deformation mechanics,and engineering applications.First,the calculation method for compensation force has been developed based on this theory,and a comprehensive large deformation disaster control theory system is formed.Second,a negative Poisson's ratio anchor cable with high preload,large deformation,and super energy absorption characteristics has been independently developed and applied to large deformation disaster control.An intelligent tunnel monitoring and early warning cloud platform system are established for remote monitoring and early warning system of Newton force in landslide geological hazards.Third,the double gradient advance grouting technology,the two-dimensional blasting technology,and the integrated Newton force monitoring--early warning--control technology are developed for different engineering environments.Finally,some applications of this theory in China's energy,traffic tunnels,landslide,and other field projects have been analyzed,which successfully demonstrates the capability of this theory in large deformation disaster control.

Continuous Deformation Monitoring by Polymermatrix Carbon Fiber Sensitive Layer

Composite made of short-cut carbon fiber mat and vinyl ester resin was observed to be an effective sensor for tensile strain up to 6 000με. Based on its strain sensitivity, a skin-like sensitive layer which can continuously cover the structural surface to sense strain in large area was developed. The sensitive layer was applied to continuously monitor the deformation of a simply supported beam. The result indicates that the fractional change in electrical resistance of the sensitive layer reversibly reflects the beam deformation in each section and describes the distribution of the average strain of the beam. The effect of temperature change on the monitoring was studied by monitoring tests conducted at different temperatures ranging from 20 to 80 ℃, which reveals temperature sensitivity in the sensitive layer and the temperature dependence of the piezoresistive behavior when the temperature exceeds 50 ℃. By the application of differential conaection principle, a method for temperature compensation was established and the gauge factor for the monitoring was dramatically increased. This method was verified experimentally.

Iterative reverse deformation optimization design of castings based on numerical simulation of solidification thermal stress

In the casting process,in order to compensate for the solidification shrinkage to obtain higher dimensional accuracy of the casting,it is often necessary to modify the original design of castings,and a suitable compensation method has a decisive impact on the dimensional accuracy of the actual casting.In this study,based on solidification simulation,a design method of reverse deformation is proposed,and two compensation methods,empirical compensation and direct reverse deformation,are implemented.The simulation results show that the empirical compensation method has problems such as difficulty in determining the parameters and satisfaction of both the overall and local accuracy at the same time;while based on the simulation results for each node of the casting,the direct reverse deformation design achieves the design with shape.In addition,the casting model can be optimized through iterative revisions,so that higher dimensional accuracy can be continuously obtained in the subsequent design process.Therefore,the direct reverse deformation design is more accurate and reasonable compared to empirical compensation method.

Compressional Deformation in Indentation Process for Microlens Array Mold

The structure of a microlens array（ MLA） can be formed on copper by an indentation process which is a new manufacture approach we applied here instead of a traditional method to test the material property,thereby work time can be saved. Single-indentation and multi-indentation are both conducted to generate a single dimple and dimples array,namely micro lens and MLA. Based on finite element simulation method,factors affecting the form accuracy,such as springback at the compressed area of one single dimple and compressional deformation at the adjacent area of dimples arrays,are determined,and the results are verified by experiments under the same conditions. Meanwhile,indenter compensation method is proposed to improve form accuracy of single dimple,and the relationship between pitch and compressional deformation is investigated by modelling seven sets of multi-indentations at different pitches to identify the critical pitch for the MLA＇s indentation processing. Loads and cross-sectional profiles are measured and analyzed to reveal the compressional deformation mechanism. Finally,it is found that MLA at pitches higher than 1. 47 times of its diameter can be manufactured precisely by indentation using a compensated indenter.

Time-varying baseline error correction method for ground-based micro-deformation monitoring radar

In recent years, ground-based micro-deformation monitoring radar has attracted much attention due to its excellent monitoring capability. By controlling the repeated campaigns of the radar antenna on a fixed track, ground-based micro-deformation monitoring radar can accomplish repeat-pass interferometry without a space baseline and thus obtain highprecision deformation data of a large scene at one time. However, it is difficult to guarantee absolute stable installation position in every campaign. If the installation position is unstable, the stability of the radar track will be affected randomly, resulting in time-varying baseline error. In this study, a correction method for this error is developed by analyzing the error distribution law while the spatial baseline is unknown. In practice, the error data are first identified by frequency components, then the data of each one-dimensional array(in azimuth direction or range direction) are grouped based on numerical distribution period, and finally the error is corrected by the nonlinear model established with each group.This method is verified with measured data from a slope in southern China, and the results show that the method can effectively correct the time-varying baseline error caused by rail instability and effectively improve the monitoring data accuracy of groundbased micro-deformation radar in short term and long term.

Trajectory compensation for multi-robot coordinated lifting system considering elastic catenary of the rope

The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the kinematic and dynamic analysis of the lifting system,the elastic catenary mod-el considering the elasticity and mass of the flexible rope is established,and the effect of the deform-ation of the flexible rope on the position and posture of the suspended object is analyzed.According to the deformation of flexible rope,a real-time trajectory compensation method is proposed based on the compensation principle of position and posture.Under the lifting task of the low-speed move-ment,this is compared with that of the system which neglects the deformation of the flexible rope.The trajectoy of the lifting system considering the deformation of flexible rope.The results show that the mass and elasticity of the flexible rope can not be neglected.Meanwhile,the proposed trajectory compensation method can improve the movement accuracy of the lifting system,which verifies the ef-fectiveness of this compensation method.The research results provide the basis for trajectory plan-ning and coordinated control of the lifting system。

Compensation modification of plastic gear tooth profile considering meshing deformation

The plastic gear is widely used in agricultural equipment,electronic products,aircraft,and other fields because of its light weight,corrosion resistance,and self-lubrication ability.However,it has a limited range of working conditions due to the low modulus and thermal deformation of the material,especially in high-speed and heavy-duty situations.A compensation modification method(CMM)is proposed in this paper to restrain the heat production of the plastic gear tooth surface by considering the meshing deformation,and the corresponding modification formulas are derived.Improving the position of the maximum contact pressure(CP)and the relative sliding velocity(RSV)of the tooth surface resulted in a 30%lower steady-state temperature rise of the modified plastic gear tooth surface than that of the unmodified plastic gear.Meanwhile,the temperature rise of plastic gear with CMM is reduced by 19%compared with the traditional modification of removal material.Then,the influences of modification index and the segment number of modification on the meshing characteristics of plastic gear with CMM are discussed,such as maximum CP and steadystate temperature rise,RSV,transmission error,meshing angle,and contact ratio.A smaller segment number and modification index are beneficial to reduce the temperature rise of plastic gear with CMM.Finally,an experiment is carried out to verify the theoretical analysis model.

Performance of an Adaptive Optics System with Dual Deformable Mirrors

One deformable mirror （DM） in conventional adaptive optics system can not meet the needs of large scale and high order aberration compensation. In this paper, a dual DMs way is presented, which needs the decoupling of dual DMs. In dual DMs adaptive optics （AO） system, the decoupling algorithm of dual DMs is deduced. Stroke of one of DMs is large, spatial frequency of the other is high. According to the algorithm, the large stroke DM （LSDM） corrects low order aberration only, and the high spatial frequency DM （HSFDM） corrects other aberration. The experimental result for two 61-DM AO system is presented. The result indicates that the experimental performance of dual DMs AO system is almost the same with that of the conventional AO system using single DM with ideal stroke and equivalent spatial frequency.

聚合物三腔微管挤出口模结构对胀大变形的影响

聚合物熔体的模内流动状态与模外胀大变形直接影响微挤出制品的成型质量。文中基于Carreau模型,采用数值模拟方法,研究了聚合物三腔微管挤出过程中口模壁厚差与空心度结构特征对胀大变形行为的影响。结果表明,影响挤出胀大变形程度的关键因素是口模出口附近的轴向速度分布;内外壁厚差会导致较大壁厚位置处对应的型坯厚度增大,而较小壁厚位置处的型坯厚度减小,壁厚差变化对薄壁区域壁厚变形影响较大,达到91.4%;空心度减小能提升口模出口附近轴向速度分布均匀性,减小了70.1%的变形程度;基于胀大变形规律逆向补偿设计了口模形状与尺寸,明显改善了制品成型质量。研究结果对聚合物多腔微管的口模结构优化设计具有理论意义与工程应用价值。

基于预补偿的缸孔型线优化设计及其密封特性研究

以某非道路高压共轨柴油机为研究对象,建立了螺栓–缸盖–缸垫–缸套–机体装配耦合模型,采用仿真分析与测试相结合的方式研究了工作状态下的缸套热机耦合失圆变形。基于缸套变形结果设计了锥形、瓶颈形、纺锤形、椭圆形、椭圆纺锤复合形5种具有不同型线特征的异形缸套预补偿方案,研究了不同异形缸套的热机耦合变形量、傅里叶变形幅值及其密封与摩擦性能。研究结果表明,在第三缸的101.8 mm截面处,椭圆形方案的最大径向变形量比原机缸套减小了15.42%;椭圆形缸套的窜气量与原机缸套相比减小了1.34%,其他方案的窜气量均比原机缸套大;与原机缸套相比,纺锤形缸套和椭圆纺锤复合形缸套的机油消耗量减小了21.36%。

基于光纤传感技术的工程监测应用研究

光纤传感技术作为当前热门技术之一,在工程监测领域有着许多重要应用。通过探讨光纤传感技术在工程形变监测中的应用案例,展示了其在工程监测领域的重要性。光纤传感技术利用光纤作为传感元件,可以实现对形变的连续、实时监测,并提供高精度的监测数据。通过布设应变光缆和温度补偿光缆,在合璧津高速公路K134段高架桥上进行了监测实验。结果表明,光纤传感技术能够准确评估结构的变形情况,并通过温度补偿算法消除了温度变化对数据的影响。通过几何方法计算沉降位移,可以实现对沉降位移的估算。

基于全型面补偿的叶片弯曲回弹控制研究

为了研究高强度钢板在弯曲成形后的回弹变形,以某搅拌机叶片为研究对象,采用全型面迭代补偿法对叶片弯曲回弹进行数值模拟与实验研究。首先利用CAE软件对叶片弯曲成形进行数值模拟,并得到其型面关键点的回弹量;然后通过弯曲实验测其型面上对应关键点的实际回弹量;再将模拟回弹量与实测回弹量进行对比,来验证数值模拟的可靠性;最后将模拟回弹量对叶片模具型面先后进行两次全型面迭代补偿,最终将其弯曲后的回弹量控制在所允许的公差范围内。研究结果表明:模拟结果与试验结果在型面关键点的回弹量基本一致,全型面迭代补偿法能有效地控制制件的最终回弹量。

穿断层破碎带隧道围岩大变形控制双梯度注浆机制

近些年,中国西部大量深埋隧道工程因关键线路控制无法避让一些活动性断裂,常常在跨越断裂带范围内出现围岩大变形破坏现象,例如侵限、偏压、塌方、底鼓等灾害,严重影响隧道工程施工和运营的安全可持续发展。为了控制断层破碎带隧道围岩大变形,隧道工程设计者和建设者采用了多种控制方案,例如超前注浆、多层钢拱架被动支护、锚杆索主动支护等,但是都因断层破碎带围岩强度过低而出现超前注浆诱发围岩拉裂破碎、主动支护锚杆锚固力不足等现象。为解决上述难题,首先,提出一种增强穿断层破碎带隧道围岩强度的双梯度注浆技术,建立双梯度注浆概念模型,构建3种双梯度注浆模式;然后,确定特定工况下注浆材料粒径梯度与注浆压力梯度的适配条件;最后,通过理论分析、物理模型试验和现场试验,探索双梯度注浆机制及其控制效果。研究结果表明:1)随着开挖步序的增加,穿断层破碎带隧道拱肩变形最大,构造应力对围岩稳定性影响较大。2)在双梯度注浆作用下,浆液扩散效果良好,围岩未出现大面积脱落破坏,隧道周围岩体应力分布均匀。3)双梯度注浆形成了坚硬交叉浆脉骨架,达到了应力补偿效果,将围岩变形量从原来的3 100 mm控制到278 mm以内,实现了“零换拱、零侵限、零突涌”的目标。

高海拔低纬度灌区GNSS控制网投影变形问题研究

针对高海拔低纬度地区,GNSS控制网存在投影变形的问题,如何选取合理的投影面和投影带建立坐标系,从而控制投影变形小于2.5 cm/km是问题的关键。文章从理论上分析长度变形的影响规律,提出合理的解决方法,通过工程案例验证该方法在实际工程中应用的可行性。

电主轴热补偿及轴承故障检测在热辐射测温方面的研究

针对电主轴轴体的热变形以及重要零部件轴承在加工中心上的常见故障,提出基于收集电主轴温度变化的热误差实时补偿计算方法与轴承常见故障的诊断方法。热误差补偿方法可以通过对轴体上测温点数据的处理对电主轴单元进行实时的热误差补偿提高加工精度。故障诊断方法是对不同的温度节点设置不同的阈值,阈值对应着电主轴单元内部某些重要零件的故障特征,当节点温度变化超出阈值即进行报警以诊断具体零件的故障。促进了电主轴的智能化进程,为接下来的研究打下基础。

基于C#的最佳抵偿高程面选取软件设计与应用

规范规定建立或选择平面坐标系统的前提条件是测区内投影所引起的长度变形不大于25 mm/km。某测区公路工程施工控制网采用国家坐标系不能满足这一要求,为减小高斯投影长度变形所带来的影响,本研究选用膨胀椭球与重心坐标不变法建立工程抵偿坐标系,并基于C#语言进行抵偿坐标系最佳抵偿面选取软件设计。研究结果表明,该计算方法严密、可靠,软件计算结果快速准确,可以实现抵偿坐标计算的自动化处理,能够满足规范要求,可直接应用于工程生产。

考虑弹性变形的机械臂末端位姿误差补偿技术研究

常规的机械臂末端位姿误差补偿技术主要采用求解位置参数实现位姿误差补偿,忽略了机械臂自身弹性变形对误差补偿的影响,导致补偿结果精度较低.因此,提出考虑弹性变形的机械臂末端位姿误差补偿技术研究.构建以四参数定义为基础的机械臂末端运动学建模,在此基础上,基于抗拉强度等参数分析机械臂连杆、关节以及末端三个部位的弹性变形误差量,建立机械臂原点坐标系对位姿参数进行辨识,综合弹性变形情况计算位姿误差补偿值.实验结果表明:所提技术应用后得出的误差补偿结果表现出的标定轨迹重复度较高,补偿结果精度较高,满足了机械臂的实际应用精度需求.

龙门铣床横梁的工艺补偿研究

龙门铣床的横梁由于承载自身和主轴等关键零部件的质量,会产生严重变形,影响其几何精度,进而影响工件加工精度。因此,文章通过对横梁进行加工工艺补偿,来提高横梁的直线度。利用ANSYS Workbench对龙门铣床横梁进行静态特性研究,分析主轴在不同位置时横梁的最大变形区域和最大变形量,并以此为基础进行工艺补偿。借助激光干涉仪测量工艺补偿前后横梁的直线度,测量结果显示工艺补偿后横梁的直线度误差降低了90%,证实了工艺补偿对提高横梁几何精度的有效性与可行性。