EFFECT OF UNEQUAL DEFORMATION IN DEVELOPMENT OF ADVANCED PLASTIC PROCESSING TECHNOLOGIES

An effect of unequal deformation in development of advanced plasticprocessing technologies is researched by studying an in-plane bending process of strip metal underunequal compressing. The research results show the following: If appropriately controlled, unequalplastic deformation can play an important role not only in the improvement of quality of partsobtained by plastic processing technologies, but also in the development of new processes foradvanced plastic working technologies. A coordinated growth of unequal plastic deformation candevelop the deformation potentiality of material to the fall. The degree of unequal plasticdeformation can be used as bases for optimization design of processes and dies of plastic forming.

Analysis of soft rock roadway deformation mechanism in Zhangshuanglou Mine

On basis of ground stress surveying and analysis of physical nature and mechanics character of rock, the deformation mechanism of west main roadway in Zhangshuanglou Mine is studied. It is put forward that engineering mechanics nature, infiltration of water and concentrated stress on pillar are the main factors to affect stability of the west main roadway. The overall thinking used to restore the roadway is raised.

Investigation into the deformation of a large span roadway in soft seams and its support technology

We investigated the deformation failure mechanism of surrounding rock from the aspect of engineering support for a roadway in seams with soft roofs and soft floors and observed the large displacement of the roadway in these soft seams.The result shows that the deformation area is quite large,and settlement of the roof is evident and displacement of the side walls is also obvious.We considered rock bolt-cable coupling for roadway support in seams with soft roofs and floors,in which the cable should be fixed at key positions.As well,we designed an optimal scheme to support a roadway in soft seams of the Shizuishan Second Mine in Ningxia,China.Field monitoring results show that bolt-cable coupling support has achieved the aims of roadway stability control and minimizes deformation.

Impact Strength Analysis of Plate Panels with Welding-Induced Residual Stress and Deformation

The paper describes the simulation of impact loads applied on plate panels with welding-induced residual stresses and deformation (WSD). Numerical simulations using FEM are carried out to study the influence of welding-induced residual stresses and deformation on the impact strength of plate panels. Welding is simulated using a three dimensional thermal mechanical coupled finite element method. The welding stress and deformation are taken as the initial imperfections in the impact strength analysis and their influence on the behavior of plate panels subjected to impact loadings. The impact loadings from the three directions, the lateral direction and two in-plane directions of the plate panels are studied. Results show a certain reduction in the impact strength due to the existence of welding stress and deformation in the plate panels. It is found that the reduction of impact force is strongly influenced by the welding deformation and the impact directions in the plate panels. This reduction is more significant when the impact force is in the lateral direction.

Floor heave characteristics and control technology of the roadway driven in deep inclined-strata

Based on in-mine instrumentation and theoretical analysis of the unsymmetrical large-deformation that occurred in the roadway after excavation,Differential Floor Heave(DFH)was found to be the main reason for roadway failure.It needs to be pointed out that the specific roadway was driven in inclined rock strata.In addition,the factors that contribute to the occurrence of DFH are discussed in detail.It is believed that DFH is triggered by the unsymmetrical stress distribution in the floor and the different rock types encountered near the two floor corners.Hence,DFH control should be focused on the left floor corner where shearing failure occurs initially and the left floor surface where tensile failure is more severe.The proposed DFH control strategies include unsymmetrical grouting for the whole roadway,re-design of the roof and ribs support,reinforcement of the weak zones,and release of the concentrated stress in the earlier stage.Meanwhile,it is recommended that in the later stage,both bolts and cable bolts with higher strength and the backfilling technique using the coal measure rocks and concrete should be employed in the reversed-arch floor.The field instrumentation results,after using the proposed control strategies,indicate that large deformation in a DFH roadway has been successfully controlled.

Measurement of in-plane deformations of microsystems by digital holography and speckle interferometry(Invited Paper)

The reliability of microsystems is an important issue and for their quality inspection, it is necessary to know the displacements or deformations due to the applied mechanical, thermal, or electrostatic loads. We show how interferometrical techniques like digital holography and speckle interferometry can be used for the measurement of in plane deformations of microsystems with nanometric accuracy and we give a description of the measurement uncertainties.

Simultaneous 2D in-plane deformation measurement using electronic speckle pattern interferometry with double phase modulations

Electronic speckle pattern interferometry（ESPI） and digital speckle pattern interferometry are wellestablished non-contact measurement methods. They have been widely used to carry out precise deformation mapping. However, the simultaneous two-dimensional（2D） or three-dimensional（3D） deformation measurements using ESPI with phase shifting usually involve complicated and slow equipment. In this Letter, we solve these issues by proposing a modified ESPI system based on double phase modulations with only one laser and one camera. In-plane normal and shear strains are obtained with good quality. This system can also be developed to measure 3D deformation, and it has the potential to carry out faster measurements with a highspeed camera.

Testing of a Full-Scale Composite Floor Plate

A full-scale composite floor plate was tested to investigate the flexural behavior and in-plane effects of the floor slab in a grillage of composite beams that reduces the tendency for longitudinal splitting of the concrete slab along the line of the primary beams. This is important in cases where the steel decking is discontinuous when it is orientated parallel to the beams. In this case, it is important to demonstrate that the amount of transverse reinforcement required to transfer local forces from the shear connectors can be reduced relative to the requirements of Eurocode 4. The mechanism under study involved in-plane compression forces being developed in the slab due to the restraining action of the floor plate, which was held in position by the peripheral composite beams;while the secondary beams acted as transverse ties to resist the forces in the floor plate that would otherwise lead to splitting of the slab along the line of the primary beams. The tendency for cracking along the center line of the primary beam and at the peripheral beams was closely monitored. This is the first large floor plate test that has been carried out under laboratory conditions since the Cardington tests in the early 1990s, although those tests were not carried out to failure. This floor plate test was designed so that the longitudinal force transferred by the primary beams was relatively high (i.e., it was designed for full shear connection), but the transverse reinforcement was taken as the minimum of 0.2% of the concrete area. The test confirmed that the primary beams reached their plastic bending resistance despite the discontinuous decking and transverse reinforcement at the minimum percentage given in Eurocode 4. Based on this test, a reduction factor due to shear connectors at edge beams without U-bars is proposed.

水平层状碳质页岩地层高速铁路大断面隧道基底变形机理研究

我国西部、西南部地区在建及建成的高速铁路隧道常发生仰拱隆起病害,严重威胁着隧道施工进度及运营安全。依托兴山东隧道典型的水平层状碳质页岩地层,开展仰拱基底隆起机理研究,对仰拱基底以下的围岩进行模型简化,应用构件试验定性分析、数值模拟定量计算的方法,揭示了不同层厚、层间黏聚力以及材料强度对层状岩体破坏模式的影响,分析导致水平层状围岩隧道底鼓的原因,并提出相应的底鼓控制处置技术。研究结果表明:(1)层厚的减小降低了层状复合岩体抵抗变形和破坏的能力,主要表现为弹性阶段的缩短和变形速率的加快;层间黏结强度的降低破坏了层状复合岩体的整体性,导致层状岩体加速进入单一岩层受力阶段,但对极限承载力劣化效应不明显;(2)岩体本身材料强度降低极大地降低了层状复合岩层的承载能力,使得破坏过程显著加快,影响程度和范围进一步加深,结合数值模拟结果进一步证明了岩体本身强度在层状岩体的变形和破坏当中占据主导位置;(3)列车振动的疲劳损伤、地下水聚集的弱化作用以及围岩的长期力学性能均将影响隧道仰拱的稳定性,变形控制效果排序为:加深仰拱>基底注浆>仰拱锚杆。

深埋矿井沿空留巷切顶卸压底板变形控制

目前有关巷道底鼓的研究与实践主要探讨巷道底板的变形机理及控制技术,对沿空留巷切顶卸压前后底板力学分析不全面。针对该问题,基于煤体分区破坏特征构建了切顶前后巷道围岩和底板力学模型,分析实体煤、巷旁支护及采空区对底板的作用,获得切顶前后巷道底鼓解析解,得出巷旁煤帮弹塑性区、巷道支护体及顶板下沉区底板所受载荷共同影响巷道底鼓量大小。采用数值模拟验证切顶卸压前后沿空留巷围岩破坏特征、应力分布及底鼓量变化,结果表明:切顶卸压技术可有效缩小巷道实体煤侧面及顶部的破坏区域,维持巷道围岩结构稳定;巷道底板最大应力、巷旁支护阻力、巷道底鼓量均下降,平均降幅分别为25.78%,56.14%,54.07%。现场应用结果表明,厚硬顶板沿空留巷底鼓量由709.3451 mm降至320.9658 mm,切顶卸压技术可以优化巷道围岩应力结构,抑制巷道底鼓,有效改善底板破坏情况。

浆液套管增强沿空掘进煤柱稳定性数值模拟研究

为解决采动作用下沿空掘进巷道一侧窄煤柱变形等问题,现场采取浆液充填套管加固煤柱底板以改善煤柱的稳定性。采用数值模拟分析浆液充填套管对底板岩体变形的控制作用机制。数值计算结果显示,在横断面方向煤柱两侧测点变形高、中间测点变形低,近采空侧的测点变形大于近巷道侧测点变形。煤柱基底变形不一致会导致煤柱受力不均,顶板荷载作用下煤柱变形形态更加复杂。施加浆液充填套管后,煤柱基底测点的变形量减小。巷道侧煤柱底板测点变形减少20.5%,大于采空区一侧的改善效果19.2%。采动作用下随着深度增加底板岩层变形逐渐减小,施加浆液充填套管后底板岩层变形减小。对类似矿井的沿空掘进巷道一侧煤柱变形研究有指导意义。

含正断层倾斜煤层底板变形特征及开采危险性研究

为研究含正断层倾斜煤层开采时受断层的影响,通过数值模拟对工作面推进过程中底板变形特征进行研究,同时监测断层面的应力和位移量变化对开采危险性进行分析。结果表明:工作面推进时,靠近断层面的底板破坏深度约为完整底板的2倍,上盘底板塑性破坏区比下盘范围更广,深度更大;对垂直应力变化分析,开采上盘煤层时对煤层和煤层底板影响较大,而开采下盘煤层时对煤层顶板和煤层影响较大;垂直位移量在煤层底板和煤层处具有明显变化,煤层底板变化较小;煤层开采易导致断层活化,尤其位于煤层顶板和煤层附近的断层带表现最活跃,冲击地压更容易发生在此区域内,而煤层底板处所受影响较小。

数控落地镗铣床滑枕变形及模态分析

数控落地镗铣床加工过程中由于滑枕水平伸出会产生变形,在加工过程中容易产生加工误差,影响加工精度。分析滑枕变形的原因,建立悬臂梁数学模型,描述滑枕结构的变形过程,并进行变形理论计算,以验证模型的可靠性。同时建立SolidWorks滑枕三维模型,借助有限元分析软件ANSYS Workbench分析滑枕在不同行程下的变形情况,并对滑枕进行模态分析,获取结构振动特性,为镗铣床滑枕优化设计提供重要的理论依据。

浅埋中厚煤层沿空留巷底板变形力学分析及底鼓控制技术

沿空留巷技术对提高煤炭采出率、改善巷道应力环境及保障矿井安全、高效有重要意义。为了解决浅埋煤层沿空留巷底鼓变形的问题,以乌兰木伦煤矿12407和12408综采工作面为工程背景,基于顶板载荷条带分割法引入等效载荷概念,建立沿空留巷底板等效载荷分布模型,进行沿空留巷底板力学分析并计算出巷道底板的最大底鼓量,采用FLAC~(3D)数值计算方法分析沿空留巷底鼓变形主控因素,数值模拟结果显示:巷旁充填体与隔离煤柱的强度差异性导致巷道底板非对称变形,同时在超前高应力和高强度支护的复合作用下,底板成为围岩承载系统中的薄弱环节最终发生破坏,基于上述理论分析、数值模拟及现场工程实践提出浅埋煤层沿空留巷底鼓控制技术。结果表明:沿空留巷严重底鼓主要是由于工作面推进后超前段煤帮塑性区煤体和巷旁支护体处于高应力作用下,致使底板岩层发生高应力剪切破坏和拉伸破坏;通过优化支护方案,防止工作面推进后顶板无法及时垮落造成悬顶,可有效减小留巷底鼓变形,并提出了巷旁充填体迎山角浇筑设计,优化巷旁充填体参数与底板岩层强度匹配等沿空留巷底鼓防治措施,从减小高应力区应力集中、缓解巷道底板卸压变形和提高底板岩层强度3方面控制沿空留巷底鼓量。现场工程实践表明,上述方法对沿空留巷底鼓作用有良好改善,保障了沿空留巷安全,实现矿山无煤柱的安全经济开采。

倾斜底板非对称底鼓灾变机理及灾变模式研究

深部高应力倾斜底板岩层易发生非对称底鼓灾害。采用有限元-离散元耦合数值方法(FDEM)研究倾斜底板非对称底鼓灾变机制、灾变模式,以及岩层倾角对底鼓模式的影响。结果表明:(1)应力驱动型底鼓灾变机制为碎胀性的渐进挤压大变形,环形切向集中应力是造成上述灾变的应力驱动源;(2)当倾角为15°~30°时,非对称底鼓特征明显;当倾角为45°~75°时,非对称特征减弱;当倾角为0或90°时,底板呈对称底鼓特性。

地下水作用致隧道底鼓和双块式无砟轨道变形规律研究

水压作用会导致隧道底鼓变形,变形传递至轨道会引起轨道几何状态不良。本文从轨道几何形位变化角度出发,对水压力作用导致隧道底鼓时引发的轨道几何状态劣化问题展开深入研究,提出了水压力的近似计算方法;基于荷载-结构法建立了隧道内双块式无砟轨道数值计算模型,分析了不同找平层水压作用下轨道的几何不平顺特征和变化规律。结果表明:隧道底鼓-无砟轨道几何不平顺现象是道床板与找平层接触状态变化、沿线路纵向与隧道横断面内的横向变形叠加作用的结果;水压作用除引起轨道高低几何状态劣化外,还可导致轨道轨向、水平变化及扭曲变形;受承压水头和水压分布长度影响,水压引起的内外轨的高低、轨向以及轨道水平变化曲线具有各自形态特征,而并非单一抛物线或正弦线。通过数值模拟,验证了隧底找平层底鼓变形的接触状态非线性力学行为,揭示了底鼓变形下轨道线路三角坑的形成机理。

乌兰木伦煤矿12煤沿空留巷底鼓机理及控制技术研究

当采矿地质条件适宜实施沿空留巷时,可取消工作面区段煤柱,一方面能够大幅度提高煤炭资源回收率,另一方面在掘进队伍紧张时可以更好地安排采掘接替活动。为此,乌兰木伦煤矿在12煤实施了柔模混凝土沿空留巷技术,为控制实施过程中出现的底鼓变形,在调研12407工作面沿空留巷底鼓破坏现象的基础上从机理层面开展了沿空留巷巷道底鼓变形的深层次分析。基于极限平衡理论和滑移场理论进行力学建模,计算得出了采动支承应力作用下沿空留巷巷道底板垂向压力值及最大底鼓压力位置,由此提出了柔模混凝土墙迎山角、临时加强支护优化和打设木点柱等相应的控制措施,控制后的巷道底板平整度良好,能够很好地满足巷道复用需求。

铝合金底架端部地板组装预置反变形工艺分析

针对铝合金底架端部区域焊接变形问题,文章分析了底架的结构组成,通过理论建模计算和试验验证并行的方法确定了预置反变形作用力的位置及大小,并对端部地板组焊工艺进行了优化。工艺优化后,枕梁端部区域的预置反变形作用力满足屈服强度要求,焊后地板平面度达到工艺预期效果,产品质量稳定。

软岩巷道围岩变形治理技术应用

针对软岩巷道围岩变形加剧问题,以山西侯村煤矿轨道大巷地质条件为背景,采用数值模拟、现场试验方法,对比分析了巷道在无支护条件与采用锚索支护+注浆改性条件下的围岩变形情况,设计了轨道大巷围岩支护加固与注浆技术方案,并进行了现场应用。根据施工后的巷道围岩变形情况,巷道半年内两帮最大变形量为38 mm,顶底板最大变形量为25 mm,表明该方案能够有效控制巷道围岩变形。

薄煤层沿空留巷支护方案优化与应用

针对金辛达煤矿“110”工法沿空留巷巷道围岩变形严重问题,以203工作面胶带顺槽为背景,采用钻孔窥视、取芯测试等方法,分析了薄煤层沿空留巷围岩变形机理,确定了薄煤层沿空留巷支护主要控制点为顶板浅部变形与底鼓变形;因此,设计了针对性巷道支护方案。实行新的支护方案后,掘进期间巷道围岩变形检测结果表明,顶底板移近量最大为95mm,两帮移近量最大为135mm,围岩变形均在可控范围内。