3-D modeling of rock burst in pillar No. 19 of Fetr6 chromite mine

Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 19 failed and other pillars failed progressively as a domino effect and 4000 m2 of mine collapsed within a few minutes, consequently. For detail investigation, two 3-D numerical models were developed by 3Dec. The first, a base model, was used for estimation of stress on pillars just before failure and the other for investigation of rock burst in pillar No. 19. The results show that discontinuity parameters such as friction angle and shear stiffness is critical parameters in this pillar failure. In addition, it indicates that W/H ratio equal 0.3, the lack of ore extraction strategy and inadequate roof support are the major reasons for this failure. In this paper, the procedure of study was described.

Numerical modeling of coupled thermo-mechanical response of a rock pillar

Understanding the rock mass response to excavation and thermal loading and improving the capability of the numerical models for simulating the progressive failure process of brittle rocks are important for safety assessment and optimization design of nuclear waste repositories.The international cooperative DECOVALEX-2011 project provides a platform for development,validation and comparison of numerical models,in which the sp pillar stability experiment（APSE） was selected as the modeling target for Task B.This paper presents the modeling results of Wuhan University（WHU） team for stages 1 and 2 of Task B by using a coupled thermo-mechanical model within the framework of continuum mechanics.The rock mass response to excavation is modeled with linear elastic,elastoplastic and brittle-plastic models,while the response to heating is modeled with a coupled thermo-elastic model.The capabilities and limitations of the model for representation of the thermo-mechanical responses of the rock pillar are discussed by comparing the modeling results with experimental observations.The results may provide a helpful reference for the stability and safety assessment of the hard granite host rock in China＇s Beishan preselected area for high-level radioactive waste disposal.

大巷煤柱工作面过空巷矿压规律及控制技术

【目的】由于矿井工作面布置方式的调整,煤柱工作面经常会面临通过废弃巷道时覆岩顶板难以控制的情况。【方法】为解决这一问题,以河南赵固二矿二盘区外侧煤柱工作面过空巷为工程背景,采用理论分析、数值模拟和现场试验等方法,研究工作面与空巷覆岩破断组合结构,模拟不同支护强度下顶板应力-位移全周期演化规律,分析工作面矿压显现特征,提出相应的控制技术。【结果和结论】结果表明,基本顶不同破断形式对矿压显现特征影响显著,关键块断裂位置可分为煤柱上方、空巷上方和实体煤上方3种类型。通过建立工作面过空巷力学模型,研究基本顶超前破断力学机理,基本顶受到空巷-煤柱-工作面支护系统支撑作用,形成“砌体梁”稳定承载结构,判定基本顶滑落失稳时空巷支护强度的临界值为4.6MPa。数值模拟显示,工作面超前支承压力与空巷应力集中产生的叠加效应对煤柱影响显著,当工作面推进至距空巷5m时,煤柱失稳破坏,基本顶易发生超前破断。在工作面过空巷过程中,煤柱超前支承压力分布特征由“双峰型”转变为“孤峰型”。不同支护强度下的顶板应力分布特征存在明显差异,确定空巷支护强度为4.5MPa能够防止基本顶超前破断。最后,在研究区二盘区外侧煤柱工作面采用“锚网索”支护方式对空巷顶板进行补强支护,过空巷期间液压支架工作阻力在研究区域处于安全范围内,未发生顶板垮落和压架等事故,解决了二盘区外侧煤柱工作面过空巷技术难题,可为类似工作面提供参考依据。

Analysis of sp Pillar Stability Experiment: Continuous thermo-mechanical model development and calibration

The paper describes an analysis of thermo-mechanical （TM） processes appearing during the Aspo Pillar Stability Experiment （APSE）. This analysis is based on finite elements with elasticity, plasticity and dam- age mechanics models of rock behaviour and some least squares calibration techniques. The main aim is to examine the capability of continuous mechanics models to predict brittle damage behaviour of gran- ite rocks. The performed simulations use an in-house finite element software GEM and self-developed experimental continuum damage MATLAB code. The main contributions are twofold. First, it is an inverse analysis, which is used for （1） verification of an initial stress measurement by back analysis of conver- gence measurement during construction of the access tunnel and （2） identification of heat transfer rock mass properties by an inverse method based on the known heat sources and temperature measurements. Second, three different hierarchically built models are used to estimate the pillar damage zones, i.e. elas- tic model with Drucker-Prager strength criterion, elasto-plastic model with the same yield limit and a combination of elasto-plasticity with continuum damage mechanics. The damage mechanics model is also used to simulate uniaxial and triaxial compressive strength tests on the ,Aspo granite.

平台生态系统视角下零工工作者“三支柱” 人力资源管理模式的构建与实现路径

蓬勃发展的平台经济与零工经济打破了传统二元劳动关系,形成了由零工工作者、中介平台和服务请求者三方主体相互协同,对立统一而构建的零工平台生态系统。如何协调生态系统内所有参与者的人力资源管理活动,以促进系统要素的多边交流,是当前零工人力资源管理面临的主要挑战。为此,本文首先提出一种新型人力资源管理模式———零工工作者“三支柱”人力资源管理模式,并阐述其内涵与特点;其次,探讨零工工作者“三支柱”人力资源管理模式的要素组成与作用机理,即以算法为决策工具,以数据平台为信息支撑,以“人人皆是HRBP(人力资源业务伙伴)”为设计理念,赋能人力资源管理职能化、专业化和数字化,实现所有生态系统参与者的多边协同与价值共创;再次,对零工工作者“三支柱”人力资源管理模式中平台生态系统三方主体的价值共创进行演化博弈分析;最后,从强化零工工作者“三支柱”中HRBP的主体地位、协同共建零工数据生态体系、促进平台算法智能化与人性化的深度融合、构建零工工作者“三支柱”人力资源管理内外部联合监管机制等方面提出推动零工工作者“三支柱”人力资源管理模式的应用与实施路径。

基于《汽车正面碰撞的乘员保护》的某轻卡碰撞CAE模型对标探索与实践

文章旨在探讨基于《汽车正面碰撞的乘员保护》的某轻卡碰撞CAE模型的建立与修正。通过对该标准的详细解读和分析,结合实际案例,本研究建立了一套适用于某轻卡碰撞仿真的整车CAE模型及分析方法。经整车实物碰撞验证和比对,B柱加速度曲线相似度高达96.5%,加速度曲线峰值时刻基本吻合、试验峰值优于CAE峰值20g,驾驶室门框变形量差异小于20mm,证明该CAE模型在预测碰撞情况和评估车辆安全性能方面具有较高的准确性和可靠性。本研究的成果为轻卡碰撞仿真提供了一种新的方法和视角,对于提升轻卡碰撞安全性能具有重要指导意义和实践价值。

煤柱失稳条件下浅埋房柱式采空区上覆地层变形特征

在煤柱失稳引起房柱式采空区顶板变形但未塌落的情况下,地表产生较大变形,威胁地面建筑物的安全.采用物理模拟和理论分析研究该条件下房柱式采空区上覆地层变形的发育机制,结果表明,房柱式采空区煤柱失稳后地表最大变形点与初期失稳煤柱位置、采空区顶板裂缝处三者在竖直方向上相对应;在采空区顶板变形但未塌落的情况下覆岩变形可划分为“条带状”、“梯形状”和“漏斗型”变形区域.松散层变形为“漏斗型”发育;采空区顶板发生断裂前可视为均布荷载作用下的固支梁模型.在煤柱失稳条件下,岩梁跨中下表面拉应力区产生竖向裂缝,并垂直向上扩展,煤柱的持续失稳会导致岩梁沿原裂缝薄弱面发生破坏,最终导致岩梁发生拉破断.基岩变形发展至交界面时,松散层逐渐发生滑移-拉裂-剪切破坏,最终形成“漏斗型”破坏形态.

“双支柱”政策调控与企业金融资产配置时变关系研究:基于TVP-SV-VAR模型的实证检验

金融科技发展和市场制度变革给传统金融体系带来的巨大冲击,使得“双支柱”政策调控的有效性面临严峻考验。借助TVP-SV-VAR模型,实证检验“双支柱”政策调控对企业金融资产配置的动态脉冲效应。研究表明,货币政策和宏观审慎政策的调控效果呈现出阶段性的演化特征,二者的协同效应能够有效抑制企业金融资产的过度配置。相比制度环境冲击,“双支柱”政策调控在面对金融环境冲击时表现出更强的作用效果和力度。进一步研究发现,“双支柱”政策通过资本流动管理、资产价格稳定和金融风险缓释途径影响企业金融资产配置,且对流动性与非流动性金融资产配置的作用效果存在显著差异。研究结论为理解实体企业金融化和完善金融市场制度提供了新的理论视角,也为政府相关部门依据金融环境和制度环境进行“双支柱”政策调控的动态调整提供决策依据。

近距离煤层区段煤柱集中应力传递特征试验研究

探究煤柱应力向底板传递特征对确定近距离煤层巷道围岩控制方法具有指导作用。以山西杜儿坪矿近距离煤层为原型,开展上煤层开挖相似模型试验,利用DIC技术采集底板深度不同水平层位应变数据,分析垂直、水平、及剪切三种应变的分布特征和应变峰值距煤柱边界水平距离的变化规律,探究上煤层开采后区段煤柱集中应力向底板的传递特征。结果表明:煤柱底板区,三种应变均以煤柱中心为轴呈非对称双峰分布特征,垂直、剪切两种应变峰值为先开挖面煤柱侧小于后开挖面煤柱侧,而水平应变峰值则恰好相反,三种应变峰值均随底板深度增加而减小;采空区底板,垂直、剪切两种应变远离煤柱边界逐渐趋于0,而水平应变则显现出反复增减多变特征。三种应变峰值距煤柱边界的水平距离表现为垂直应变为先开挖面煤柱侧大于后开挖面煤柱侧,但剪切应变则刚好相反,而水平应变则先后开挖面煤柱侧均相等,且三种应变距煤柱边界水平距离均随底板深度增加而增大。垂直、水平应力分别为压、拉应力,而先后采面煤柱侧剪切应力则不同分别为拉、压应力;垂直、剪切两种应力均显现为高应力水平,但水平应力甚小;垂直、水平两类应力峰值均位于煤柱底板区,而剪切应力峰值却位于采空区底板;垂直、剪切两种应力随远离煤柱边界均趋于0,水平应力则显现反复转化增减特征。选择近距离煤层巷道围岩控制方法既应重视垂直应力的作用,也应关注剪切应力对其失稳破坏的影响。

紧邻大型空区的两阶段矿柱回采爆破参数优化与应用

采用爆破方法对紧邻大型空区的矿柱回采时,需要综合考虑采空区、运营巷道、硐室、设备以及地面建筑物的安全,同时也需确保爆破效果。为保证紧邻大型空区矿柱回采,以白音诺尔铅锌矿3-6#矿体为例,确定铅锌矿RHT模型参数,优化爆破参数并应用于现场。通过静力学试验确定RHT部分主定参数和从属参数,采用SHPB冲击试验和数值模拟对破碎模型参数进一步拟合,确定铅锌矿RHT模型参数。基于该模型,通过数值模拟确定最佳炸药单耗和排间延时,优化爆破设计。工程实施后,分析现场监测数据,验证了优化后的爆破参数合理性和可靠性;爆破后的大块率由原8%降至4%左右,同时地面和井下被保护的对象均未受影响;爆破对采空区顶板、底板及围岩损伤均较小,采空区处于稳定状态。

某乘用车正面碰撞仿真分析

为准确评价整车正面碰撞过程中的碰撞安全性能,采用CATIA软件建立整车几何模型,导入HyperMesh软件搭建整车有限元模型,结合LS-DYNA软件模拟汽车正面碰撞,并采用HyperMesh软件分析模型可靠性及碰撞过程中整车变形、B柱加速度、各部件变形等。仿真结果表明:整车碰撞期间,增加质量与总质量的比为2.16%,沙漏能与总能量的比为1.02%,整车模型可靠性满足要求;左右两侧B柱最大加速度分别约为42.5 g(g为自由落体加速度)、45.4 g,满足中国新车评价规程中两侧B柱最大加速度不得超过72 g的要求;该车前防撞梁最大变形为178.1 mm,前吸能盒最大变形为315.9 mm,前纵梁最大变形为618.9 mm,该车前部吸能部件具有良好的吸能效果;前围板最大变形为137.8 mm,满足碰撞试验前围板最大变形不超过150 mm的限值要求,可以保护驾驶员及乘客的安全。

煤田房柱式采空区地震响应特征物理模拟研究

在总结了蒙陕地区地震地质条件、煤田房柱式采煤时采空区特征的基础上构建了蒙陕地区房柱式采空区地质模型,并在水槽实验室对其进行物理模拟地震数据采集,使用针对性的处理流程对采集的数据进行处理,最后对成像结果中目的层进行属性分析,总结了蒙陕地区房柱式采空区的成像特征,其结果可以用于提升煤田采空区探测的效率和质量。

新车型调试B柱发花问题探讨

2010V工艺涂装车间中,面漆线Durr喷漆机器人在新车型调试中B柱发花是一个比较普遍的问题,给出了发花问题产生的原因和解决办法。

某微型电动车侧碰条件下的B柱轻量化研究

B柱加强板作为B柱最主要的支撑结构,在侧碰中起到关键的作用,在满足侧碰安全性能的前提下进行轻量化研究具有重要意义。根据GB 20071—2006《汽车侧面碰撞的乘员保护》试验要求,利用HyperWorks建立有限元模型,基于Crachfem失效模式进行仿真分析,依托成形性分析,对焊缝位置进行优化,对比B柱轻量化前后侵入量和侵入速度的变化情况,并通过试验验证。结果表明:侧碰过程中,侵入量最大的位置位于B柱的R+400 mm的位置,此处为人体的胸部肋骨区域。通过激光拼焊的方式把B柱加强板的材料由DP780改为DP780+B1500HS,不仅侧碰安全性能得到提高,而且实现轻量化减重13.2%。

分段空场嗣后充填法人工矿柱多源信息融合稳定性评价模型

针对分段空场嗣后充填法人工矿柱(充填体)稳定性评价指标因素概率分配过程和权重分配中存在的问题,综合考虑工程地质环境、岩体质量、力学响应指标、声发射参数特征和几何形态5类信息源的影响,建立了涵盖17项稳定性影响因素的人工矿柱(充填体)稳定性多源信息评价指标体系,并基于此确立了人工矿柱(充填体)稳定性D-S证据理论的识别框架及评价指标分级标准。通过引入正态隶属度函数及改进的K-L距离对指标因素概率分配和权重分配进行优化,构建了基于改进D-S证据理论多源信息融合的人工矿柱(充填体)稳定性评价模型。选取某分段空场嗣后充填开采矿山5个典型人工矿柱(充填体)对模型的适用性进行验证,结果表明:多源信息融合稳定性评价等级分别为AP-2、AP-3和AP-5(Ⅱ级)>AP-4(Ⅲ级)>AP-1(Ⅳ级),稳定性评价结果与前期位移、声发射现场监测分析评价和数值模拟分析评价结果基本吻合,验证了评价模型在实际应用中的科学有效性。该模型为人工矿柱(充填体)稳定性分析提供了一种更全面的综合评价方法。

Numerical and analytical investigations for the SOI LDMOS with alternated high-k dielectric and step doped silicon pillars

This paper presents a new silicon-on-insulator(SOI) lateral-double-diffused metal-oxide-semiconductor transistor(LDMOST) device with alternated high-k dielectric and step doped silicon pillars(HKSD device). Due to the modulation of step doping technology and high-k dielectric on the electric field and doped profile of each zone, the HKSD device shows a greater performance. The analytical models of the potential, electric field, optimal breakdown voltage, and optimal doped profile are derived. The analytical results and the simulated results are basically consistent, which confirms the proposed model suitable for the HKSD device. The potential and electric field modulation mechanism are investigated based on the simulation and analytical models. Furthermore, the influence of the parameters on the breakdown voltage(BV) and specific on-resistance(R_(on,sp)) are obtained. The results indicate that the HKSD device has a higher BV and lower R_(on,sp) compared to the SD device and HK device.

Numerical investigation into the effect of backfilling on coal pillar strength in highwall mining

This paper attempts to quantify the effect of backfilling on pillar strength in highwall mining using numerical modelling. Calibration against the new empirical strength formula for highwall mining was conducted to obtain the material parameters used in the numerical modelling. With the obtained coal strength parameters, three sets of backfill properties were investigated. The results reveal that the behavior of pillars varies with the type and amount of backfill as well as the pillar width to mining height ratio(w/h). In case of cohesive backfill, generally 75% backfill shows a significant increase in peak strength, and the increase in peak strength is more pronounced for the pillars having lower w/h ratios. In case of noncohesive backfill, the changes in both the peak and residual strengths with up to 92% backfill are negligible while the residual strength constantly increases after reaching the peak strength only when 100%backfill is placed. Based on the modelling results, different backfilling strategies should be considered on a case by case basis depending on the type of backfill available and desired pillar dimension.

Performance of inclined pillars with a major discontinuity

Discontinuities are an inherent part of the rock mass and majorly affect the stability of the excavation skin and pillars.The dip of the discontinuities and their properties also have a significant effect on the strength of the pillars.Empirical approaches are commonly used to determine the pillar strength but can overestimate the strength and don’t consider the inclination of the pillars and the strength reduction caused by discontinuities.Numerical modeling is a powerful tool and if calibrated can be used to evaluate the strength of the pillars with discontinuities having a range of properties.The effect of a discontinuity on inclined pillars was conducted which has been seldom considered in evaluating the pillar strength.Three-dimensional vertical pillars were simulated,and the pillar strength was calibrated to accepted theoretical results and then the discontinuities were introduced in different pillar inclinations with distinct width to height ratios to gain an insight into the effective pillar strength reduction.Based upon the results,it was found that the discontinuities have a significant effect with the increase in the inclination of the pillars even at a higher width to height ratios.

Design of crown pillar thickness using finite element method and multivariate regression analysis

Minerals are now being extracted from deep mines due to drying up of resource in shallow ground. The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology. In addition, high horizontal stress may cause collapse of hanging wall and footwall rocks, hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes. This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m. Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition. Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated. Then, a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed. The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine.

旭龙电站尾水调压室洞间岩柱围岩宏细观特性分析

为了将连续和非连续分析方法耦合用于地下厂房围岩稳定性分析,提出了一种基于软硬混合平行黏结模型的细观参数快速标定法,可根据给定岩石的宏观力学参数快速给出其颗粒流模型细观接触参数;在此基础上,构建了基于颗粒离散元PFC 3D与有限差分FLAC 3D耦合的旭龙地下电站尾水调压室三维离散-连续耦合分析模型,研究了开挖期尾水调压室洞间岩柱围岩变形与破坏宏细观特性,以及检修期间侧向水压力对洞间岩柱稳定性的影响。结果表明:检修期间尾水调压室水压力引起的围岩变形与应力增量变化是极小的,但洞间岩柱上半段22.7 m的高度存在塑形贯通区,局部稳定性较差,有必要在工程建设期开展尾水调压室及尾水支洞岩墩塑性贯通区专项支护方案研究,以确保旭龙地下电站工程的安全建设与运行。