深埋老黄土隧道支护限阻器力学特性及其应用研究

为深入探究基于限阻器的隧道让压支护,即限阻支护的受力特征,基于室内试验结果,采用数值计算和数据拟合的方法,系统阐明了限阻器的力学性能和本构关系,提出限阻支护的数值模拟方法;并结合工程应用,分析不同参数下限阻支护的变形和受力特征。结果表明:限阻器的力学性能与竖板的高度和厚度相关,引入预制弯弧可使限阻器性能可控;限阻器采用应变软化/硬化实体单元和弹性正交异性膜单元模拟;限阻器较小的恒阻值降低了限阻支护的轴力但同时也增大了弯矩,有利于小偏心受压破坏防治但增加了大偏心受压破坏风险;限阻器的合理压缩量为7~12 cm,建议在工程应用中对限阻器做降高、增厚和弯弧优化,可进一步增效降本。

大变形巷道限阻耗能型支护结构研究

为了解决深部煤矿开采过程中所遇到的“高地应力、大变形、支护结构破坏”等问题,以朱集东矿东部辅助轨道大巷为工程背景,采用变形监测与数值模拟的方法研究深井软岩巷道围岩变形特征规律;依据围岩耗能支护理念,设计出控制巷道围岩能量释放与变形的“限制支护阻力阻尼器”(简称“限阻器”);通过数值分析与室内静压试验相结合的方式得到限阻器试件的性能指标与设计参数之间的关系,并验证限阻器的工作性能;最后通过数值模拟对比巷道常规支护与限阻耗能支护形式的变形与受力情况,验证巷道限阻耗能型支护方案的可行性。结果表明:限阻器的试验压缩量均达到了80%以上,具有较大的变形行程,在保证初期支护发生较大变形的前提下,达到降低围岩压力、耗散围岩能量的目的。限阻耗能支护较巷道常规支护最大主应力值分别降低51.2%、89.8%,提高了结构的安全性。

限阻耗能型支护在高速公路软岩大变形隧道中的应用——以玉楚高速公路齐云隧道为例

为解决玉楚高速公路齐云隧道大变形问题,引入限阻耗能型支护设计理念,采用限阻耗能型支护方案进行研究。通过静压试验进行限阻耗能型支护元件的方案比选,对比分析直板型、弧板型、斜板型限阻器的压力-变形情况。试验结果表明,弧板型限阻器工作性能更佳,其恒阻值约为3 MPa,初始峰值小于C25混凝土抗压强度,且压缩变形具有导向性和可控性,满足设计需求。因而选用弧板型限阻器进行设计,并将优化后的结构应用于齐云隧道。根据限阻耗能型支护在大变形隧道的应用效果,得到以下结论:1)支护结构受形变压力控制,除限阻器在设计行程内产生塑性变形以外,其余初期支护结构均在弹性范围内工作,增加了结构的安全性,围岩压力最大值仅为0.13 MPa,可以看出施作限阻器能够更有效地释放围岩压力;2)在齐云隧道施工中,相较于常规支护方法出现的初期支护结构混凝土剥落、钢架压溃现象,限阻耗能型支护段落的限阻器产生了显著的变形,但支护结构状态整体较好,达到了治理大变形的功效;3)限阻器不仅加工方式简单,且施工工艺与台阶法相适应,具有良好的可操作性和经济效益。

限阻耗能型支护结构在单线铁路隧道大变形中的应用研究

为解决单线铁路隧道施工过程中遭遇的高地应力软岩大变形进而导致的初期支护破坏问题,对原直板形限阻器进行优化,研究其在不同优化参数下的力学性能,并将其应用于中老铁路沙嫩山二号隧道单线段,开展限阻耗能型初期支护现场试验。通过限阻器性能参数试验研究和施工应用效果研究,得出以下结论:1)弧板限阻器受压变形时方向可控,有效行程得以提高,经历弹性变形、屈服下降变形、恒阻塑性变形和压实上升4个阶段。2)改变限阻器竖向钢板径高比可以改变限阻器的初始应力峰值,但对恒阻应力值的影响很小,实际应用限阻器时应选取对应初始应力峰值为8 MPa时的径高比较为合适。3)试验段采用限阻器后,围岩压力得到释放,避免了初期支护过载破坏,在未加强初期支护参数的前提下,既保证了支护结构的安全性,又提高了经济性。

强风化炭质板岩地层隧道限阻耗能大变形控制技术研究

为解决高地应力强风化炭质板岩地层隧道大变形技术难题,以某强风化炭质板岩地层隧道大变形处治为研究背景,采用室内试验及数值仿真方法对限阻耗能大变形控制技术进行研究。研究结果表明:反预折纹管结构型式限阻耗能装置承载力与吸能效果均优于其他结构型式装置;将反预折纹管限阻耗能装置施设于钢架后,钢架变形有所减小,隧道衬砌结构整体应力有所降低,安全系数有所增加,监测断面最小安全系数增加15.79%,表明反预折纹管限阻耗能装置可作为高地应力强风化炭质板岩地层隧道大变形环向处治措施。研究结果可为类似工程大变形处治设计提供参考。

一种新型限阻器在软弱围岩隧道中的试验研究

软弱围岩隧道在开挖过程中,围岩随着应力能量的释放往往会产生较大变形甚至坍塌。以吴华高速公路项目庙沟梁隧道为工程实例,通过室内试验和现场实测,针对穿越红黏土层的软弱围岩隧道设计了一种新型限阻器,并探究限阻器对隧道变形的影响。结果表明采用220 mm×600 mm×8 mm连接钢板和100 mm×220 mm×4 mm竖板的限阻器能够满足隧道变形要求;设置限阻器段的围岩未产生较大变形,整体处于安全状态;设置限阻器能够明显减小隧道中钢架围岩侧应力、钢架净空侧应力、轴力和弯矩。通过试验说明采用新型限阻耗能型装置,可以充分释放隧道围岩压力,有效解决隧道大变形问题,为此类地质隧道初期支护施工提供一种新的解决思路和技术经验。

深埋老黄土隧道限阻耗能型支护方法

为解决蒙华铁路阳山隧道深埋老黄土段的初期支护破坏问题,从合理处理围岩压力和变形关系的角度提出耗能支护理念;在分析依托工程初期支护受力机理的基础上,设计基于限阻器的限阻耗能型支护,在试验段进行施工,测试支护的受力与变形,分析限阻耗能型支护的工作性能。结果表明:深埋老黄土隧道在支护设计时不能忽略支护的变形能力,应从能量支护的角度统筹围岩压力与变形;围岩压力以形变压力为主,初期支护整体处于小偏心受压状态,故将以受压变形为主的竖板厚7.5 mm、高280.0 mm、间距100~150 mm的钢板型限阻器环向嵌入原支护的左右拱脚位置,通过限阻器形成限阻耗能型支护,实现围岩压力释放和支护内力降低;限阻器在距掌子面约1.5倍洞径时开始压缩变形,最终压缩量为100~150 mm,小于设计压缩量,且支护除特殊情况外无破损现象,支护内力有较高安全系数,围岩压力释放充分;相比加强型支护,限阻耗能型支护既能提高支护的安全性又能降低工程造价,节省直接成本1.4万元·m^(-1),优越性明显。

限阻器在高水平地应力隧道支护中的研究与应用

为解决蒙华铁路如意隧道高水平地应力岩层段初期支护因受力过大而破坏的问题,文章通过理论分析、数值模拟以及现场施工反馈等方法,并基于室内试验、地应力测试以及现场监控量测数据,对限阻耗能支护技术的工程应用方法及作用机理进行研究,结果表明:(1)针对高构造应力环境,在保证围岩自承能力不明显降低,且不明显增加松散压力的前提下,可控制地引导围岩变形、围岩能量释放分散转移的限阻高延性支护是合理可行的;(2)限阻器是一种合理有效的限阻高延性支护手段,成功解决了如意隧道高地应力水平岩层中初期支护破坏问题;(3)限阻器显著降低了结构内力,但也改变了结构的内力分布,在应用中还需进一步完善。

限阻器施工技术在中老铁路项目沙嫩山二号隧道中的应用

国内外在治理隧道大变形中积累了相当充足的经验。不同于传统的强调高强度、大刚度的支护理念,法国-意大利圣马丁隧道在治理大变形时,采用了将喷射混凝土支护与让压锚杆、可滑动钢架协同工作的屈服控制型支护。国内的蒙华铁路阳山隧道,利用了低碳钢良好的峰后承载能力和塑性变形能力,提出并研发了“直板式限阻器”,并结合喷射混凝土与钢架支护,成功控制了隧道变形,并保证了初支不破、不拆、不换。因为限阻耗能支护结构较好的经济型与有效性,故在中老铁路项目沙嫩山二号隧道中采用该种方式治理隧道大变形。

三维激光扫描辅助隧道大变形控制研究

为解决在高地应力软岩大变形隧道控制研究中,传统监测方法有限断面有限点、监测结果以点带面、难以发现最大最小平均变形,无法为隧道初支优化调整提供有效数据支撑等问题,以沙嫰山二号隧道为依托,采用三维激光扫描仪对隧道初期支护进行全息变形监测,获取隧道初期支护的变形全貌,并进行沉降收敛和断面轮廓变形分析。同时依据三维激光变形监测结果,设计适应隧道变形特征的限阻耗能支护结构,对软岩大变形隧道初期支护破坏问题进行控制。结果表明:(1)三维激光扫描仪与全站仪沉降监测方差为3.03 mm、收敛监测方差为3.42 mm,两种仪器监测精度相当;(2)三维激光扫描仪监测结果显示,初期支护左侧出现受围岩剪切滑移带影响的局部鼓出问题,鼓出影响范围为左拱脚至左拱腰,且沿里程方向呈现明显的时空效应,监测段初期支护变形包络结果显示,拱顶左侧变形平均值35.2 cm、右侧变形平均值16.4 cm;(3)依据三维激光扫描仪监测结果不对称的设计限阻耗能支护结构,与设计支护段相比,对初期支护破坏取得了较好的控制效果,同时通过变形加速度来判断隧道变形速率的发展,避免累计变形和变形速率预警中假型性预警现象。

单线铁路隧道大变形支护及施工技术

为解决单线铁路隧道穿越软弱围岩的大变形问题,结合某工程实例,基于“抗放结合”的支护理念,提出限阻耗能支护结构;制作限阻器构件进行性能验证,并采用有限元软件对比常规支护方案和限阻耗能支护方案的变形、最小主应力等指标。研究发现,限阻器构件能够在发生大行程变形的情况下,提供一定的支护阻力;限阻耗能支护结构承受的围岩压力显著小于常规支护结构,更能够适应大变形隧道的支护。

高原隧道建设中的大变形支护原理及施工研究

以高原隧道施工为例,针对高原隧道建设出现的变形问题,提出新的解决方案,结合项目具体情况,分析大变形支护原理并总结施工要点,通过前期准备、变形检测、设备安装等多项技术方法,实现对变形现象的合理检测,提升隧道项目施工建设水平,减少大变形支护问题的发生概率,保证项目顺利竣工。

神座隧道大变形治理措施应用研究

为解决神座隧道初支的大变形问题,根据“以放为主,限量抵抗,抗放结合,多挖少支”的原则,提出了采用限阻耗能支护结构作为大变形治理方案:1)增大预留变形量;2)在钢拱架拱腰处设置限阻器;3)在初支背后预留一定空间填充柔性材料。旨在通过限阻器和柔性材料的压缩变形对支护结构进行让压控制,以释放围岩能量。治理结果表明:1)应用限阻耗能支护实现了结构“支得住”的目标,但由于预留变形量不足及隧道左侧偏压,出现了单侧部分初支侵限的情况;2)在后续施工控制中,需根据隧道不对称变形的特征对预留变形量、柔性材料填充厚度和限阻器的可压缩量、位置等进行针对性调整,保证二衬净空。

一种适应隧道大变形的限阻耗能型支护结构研发与应用

为解决隧道大变形初期支护因受力过大而破裂问题,通过理论分析和试验验证,自主研发利用材料峰后性能实现能量释放的"限制支护阻力阻尼器",简称"限阻器"。通过室内试验和工程调研,确定限阻器设计参数,制定由限阻器组成的限阻耗能型支护的设计和施工方案,并应用于工程实践,得到以下结论:(1)在应对隧道大变形等高能问题时,支护理念应从传统的大刚度、强支护转变为允许围岩变形、控制围岩能量释放的限阻释能型支护;(2)限阻器环向嵌入到初期支护受力关键部位中,将传统刚性支护转化为"刚–柔–刚"型的限阻释能型支护,成功解决了深埋老黄土隧道和高地应力水平岩层隧道中初支开裂问题,是一种可行有效的隧道支护手段;(3)限阻耗能型支护整体性和安全性有保证,且限阻器取材容易,加工方便,施工简单易操作,故限阻器增加了结构安全性的同时又提高了经济性。

Mechanical properties of disc-spring vibration isolators based on boundary friction

To ascertain the influence of the boundary friction on mechanical properties of disc-spring vibration isolators a load-displacement hysteresis curve formula of disc-spring vibration isolators is derived on the basis of the energy conservation law as well as considering the effect of the boundary friction.The formula is validated through the finite element analysis and static load tests.On this basis the effect of the boundary friction on the bearing capacity is researched. Then the dynamic performance of disc-spring vibration isolators is studied by dynamic tests.The experimental results indicate that the boundary friction can promise a larger damping with a ratio of 0.23 for disc-spring vibration isolators.Compared with the loading frequency the loading amplitude has a greater impact on the energy consumption dynamic stiffness and damping of vibration isolators.This research can provide valuable information for the design of disc-spring vibration isolators.

Static Induction Devices with Planar Type Buried Gate

Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.

Three-dimensional tensor controlled-source electromagnetic modeling based on the vector finite-element method

Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method.

Finite element analysis of the free-damped beam-stiffened plate

A finite element model is presented for free-damped beam-stiffened plates. The nodes of the plate elements are treated as master-nodes, and the corresponding nodes of the beam elements are considered as slave-nodes. The stiffness and mass matrices of the elements are developed. Based on the analysis of the dynamic properties of the structures, modal loss factors are predicted by the modal strain energy method. Finally, an example is given to compare the results obtained from the proposed method with the results of the ANSYS software. The results show that the method in this paper is computationally efficient, simple and feasible with high precision and engineering practicability.

Contrast between 2D inversion and 3D inversion based on 2D high-density resistivity data

The 2D data processing adopted by the high-density resistivity method regards the geological structures as two degrees, which makes the results of the 2D data inversion only an approximate interpretation;the accuracy and effect can not meet the precise requirement of the inversion. Two typical models of the geological bodies were designed, and forward calculation was carried out using finite element method. The forward-modeled profiles were obtained. 1% Gaussian random error was added in the forward models and then 2D and 3D inversions using a high-density resistivity method were undertaken to realistically simulate field data and analyze the sensitivity of the 2D and 3D inversion algorithms to noise. Contrast between the 2D and 3D inversion results of least squares inversion shows that two inversion results of high-density resistivity method all can basically reflect the spatial position of an anomalous body. However, the 3D inversion can more effectively eliminate the influence of interference from Gaussian random error and better reflect the distribution of resistivity in the anomalous bodies. Overall, the 3D inversion was better than 2D inversion in terms of embodying anomalous body positions, morphology and resistivity properties.

Multi-field dynamic modeling and numerical simulation of aluminum alloy resistance spot welding

In order to explore the influence of welding parameters and to investigate the Al alloy (AA) nugget formation process, a comprehensive model involving electrical-thermal-mechanical and metallurgical analysis was established to numerically display the resistance spot welding (RSW) process within multiple fields and understand the AA-RSW physics. A multi-disciplinary finite element method (FEM) framework and a empirical sub-model were built to analyze the affecting factors on weld nugget and the underlying nature of welding physics with dynamic simulation procedure. Specifically, a counter-intuitive phenomenon of the resistance time-variation caused by the transient inverse virtual variation (TIVV) effect was highlighted and analyzed on the basis of welding current and temperature distribution simulation. The empirical model describing the TIVV phenomenon was used for modifying the dynamic resistance simulation during the AA spot welding process. The numerical and experimental results show that the proposed multi-field FEM model agrees with the measured AA welding feature, and the modified dynamic resistance model captures the physics of nugget growth and the electrical-thermal behavior under varying welding current and fluctuating heat input.