Ground pressure law of fully mechanized large cutting height face in extremely-soft thick seam and stability control in tip-to-face area

When stepped coal getting technology was applied to high seam mining working face, with field observations the following aspects of working face were analyzed based on the inherent conditions of extremely soft thick seam mined by Liangbei Mine, such as the brokenness and activity law of rock seam in the working face, the law of load-bearing of its supports, and the instability character of coal or rock in tip-to-face area. The following are the major laws. Pressure intensity of roof in high seam mining with extremely soft thick seam is stronger than one in slicing and sublevel-caving as a whole. But the greater crushing deformation of coal side makes pressure intensity of roof in the middle of working face be equivalent to one in sublevel-caving. In the middle of working face the roof brokenness has less dynamic load effect than roof brokenness in the two ends of working face. The brokenness instability of distinct pace of roof brings several load-bearings to supports. In condition of extremely soft thick seam, the ratio of resistance increment of supports in two ends of working face is obviously greater than that of supports in the middle. Most sloughing in coal side is triangular slop sloughing caused by shear slipping in high seam mining with extremely soft thick seam. Ultrahigh mining is the major reason for roof fall. Instability of coal or rock in tip-to-face area can be controlled effectively with the methods such as improving setting load of supports, mining along roof by reinforcing floor and protecting the immediate roof in time, and so on.

考虑采空区压实度的端面顶板稳定性数值模拟

为研究不同采空区压实度条件下端面顶板稳定性,通过PHASE 2D有限元软件建立高刚度和低刚度2个采空区数值模型,研究端面顶板下沉规律、支承压力分布特征及端面顶板塑性区演化。研究结果表明,当采空区刚度为250 MPa时,开采前后直接顶下沉量最大值分别为90 mm和109 mm;当采空区刚度为600 MPa时,开采前后直接顶下沉量最大值分别为43 mm和74 mm;当采空区刚度由250 MPa增大至600 MPa时,工作面支承压力峰值由7.3 MPa降低为6.8 MPa;增大采空区刚度后,工作面端面顶板塑性区范围降低了44.3%。因此,有效提高采空区刚度能提高端面顶板稳定性,从而降低端面冒顶发生的概率。

矿井巷道斜巷与正洞夹角对交叉段影响的有限元分析

随着煤炭开采的技术趋于成熟,人们对开采过程中的安全问题也愈发重视。由于矿井中巷道功能类型的不同,施工过程中会出现巷道交叉的情况,唐口煤矿7307工作面施工道与7307轨道顺槽、皮带顺槽均属于交叉巷道。根据现场施工地质条件,利用Midas GTS NX有限元软件建立斜井与正洞夹角角度分别为30°,60°,90°三种工况下的有限元模型,对斜井与正洞夹角在交叉段应力场及位移场中起到的作用进行了分析,发现斜井与正洞相交角度的不同,对交叉段岩体结构的力学行为产生的影响也将不同。

Influence of Local Weather Conditions on Ventilation ofa Pitched Wooden Roof

This paper investigates the influence of temperature and wind conditions on ventilation of the air cavity beneath the roofing in a full-scale pitched wooden roof construction.The potential for condensation in the air cavity is studied.The relevant roof construction is equipped with 81 thermocouples and four air velocity measurement devices.A weather station at the site records outdoor temperature and wind conditions.Five periods between 2016 and 2018 are investigated.The findings show distinct periods of below-ambient temperature and positive condensation potential in the ventilated air cavity of the roof.A relation between low wind speed and positive condensation potential is shown.Difference in size of periods with below-ambient temperature and periods with positive condensation potential implies that the materials in the roof regulate the humidity in the air cavity.Large negative peaks in the condensation potential indicate dry-out of the construction.

陕北瑶渠矿区开采后期套管变形成因浅析

通过盐井井身特征、溶腔成型过程、顶板垮塌计算、矿体内应力平衡等方面分析了锦界瑶渠矿区水溶开采后期盐井套管变形成因,为保证水溶开采的持续稳定提供意见和建议。

暗挖工程中管幕支护施工引起的地层位移

随着城市化进程的推进,地下空间的开发和利用越来越受到人们的重视。管幕法作为一种有效的暗挖支护方式,越来越多的用于城市地下工程开挖施工。管幕施工中常用的技术主要有顶管法和夯管法。管幕施工造成的地层位移会对周围环境产生影响。探讨了管幕施工对地层的挤土扰动对环境的影响。考虑土体的剪胀特性和塑性变形,推得了在管挤入过程中周围土体内的位移场和应力场表达式,利用叠加法推导了管幕夯进引起的土体位移的理论解,研究了地层竖向位移对土层参数、初始应力、埋深等参数的敏感性,并分析了管间距和管的布置形式对管幕引起土体位移的影响。

片状放大器泵浦腔屋脊形反射器性能分析

用蒙特卡洛光线追迹法模拟和比较屋脊形截面反射器与平板反射器的光传输性能，分析反射器构型对泵浦腔性能的影响。三维光线追迹结果显示：在本文设定的腔体构型条件下，屋脊形反射器腔的光传输效率可达６３％，优于平板反射器腔的传输效率（η≤５６％）。

铝合金汽车顶盖充液成形的数值模拟

目的研究铝合金汽车顶盖拉延工序的充液成形工艺。方法基于有限元分析软件Dynaform,利用带局部刚性凹模整形的被动式充液成形工艺,通过建立有限元分析模型,优化成形过程中的关键工艺参数,分析变形规律并进行质量控制。结果成形过程中的液室压力加载路径、压边力、拉延筋,以及坯料形状等工艺参数对成形影响较大。液室压力不宜过早加载。液室压力过大或压边力过小不利于顶部产生充分塑性变形。压边力过大极易造成顶盖圆角处的破裂。结论该成形工艺可行,且数值模拟的准确性及适用性较高,采用该成形工艺可得到表面质量良好,未出现起皱、破裂缺陷的合格零件。

岩溶区桥基下伏溶腔顶板安全厚度分析

研究目的:以某客运专线岩溶区大桥为例,结合溶腔实际空间分布形态,对桥基荷载作用下溶腔岩体应力特征进行三维有限元分析,确定溶腔顶板的安全厚度。研究结果可为岩溶地区高速铁路、客运专线桥梁基础设计提供参考。研究结论:溶腔顶板厚度为30m和25m时,桥基附近岩体安全系数均在1.2以上,溶腔顶板安全系数在1.3以上,溶腔顶板是安全的;溶腔顶板厚度20m时,溶腔洞周局部岩体安全系数约1.1,溶腔顶板基本是安全的,但岩体强度储备不足。本工程桥基荷载作用下溶腔顶板最小安全厚度约为20m,对应基础最大埋深为13m;基础设计埋深为8m,溶腔顶板是安全的。

二维地震勘探在盐矿塌陷预测中的应用

水溶开采诱发地表塌陷是盐矿开采中常见的地质灾害现象。为了有效地预防地面塌陷而引起的安全事故和环境灾害的发生,必须查明塌陷原因,对可能的塌陷范围进行提前预警。因此,在盐矿开采区开展了系统性的二维地震勘查,在圈定的异常区发生地面塌陷,直接证明了地震勘探成果的准确性。从2012年1月1日预测到塌陷隐患至2012年4月12日塌陷发生,地震勘探预报塌陷整整提前了102天。因此,二维地震勘探可以准确地预测采卤溶腔的安全性,这为盐矿矿山企业的开采设计提供了依据。

掘进巷道过断层漏顶区域的施工工艺研究

清水营煤矿岩体节理与裂隙发育,富水性较好,属于典型的"三软"煤层。工作面推进过程中顶板易碎、易冒;煤层开采中,软岩巷道稳定性控制与支护问题,严重制约了该矿井的安全生产。该矿在掘进巷道过断层时,发生突发性漏顶事故,致使巷道停掘。在分析了研究区岩性、构造、地球物理特征以及煤岩的物理力学参数的基础上,针对现场地质条件变化先后采取了两套施工方案对漏顶区进行加固。最终依靠方案二获得了成功,即采用对掘进迎头冒顶区采用水泥、水玻璃浆液加固冒顶区,并对冒空区采用马丽散泡沫充填。施工完成后从迎头退后36m起底,由冒顶区下部通过。现场实践证明,方案二具备安全性与经济性,可为"三软"条件下的巷道开采系统设计、岩层控制、安全回采提供地质保障与技术支持。

材料找坡倒置屋面自带可泄水且能止水倒流的新型水落口设计

材料找坡之倒置屋面渗漏率高于其他屋面,这与渗水积蓄有关。为将保温层及找坡层中渗积水及时排出,设计了带泄水空腔的新型水落口。该设计能与传统构造层类及其工艺高度契合,能在解决保温层及找坡层中的渗积水之同时,防止明水倒流。

天山新二号双线铁路隧道断层坍方处理设计计算

天山新二号双线铁路隧道施工中,由于地质情况不明发生了断层破碎带坍方。根据坍体形态,对空腔地段采用明洞通过,对堆碴地段采用固结注浆大管棚支护、侧壁导洞法开挖,顺利地通过了坍体。文章对管棚结构承受的荷载及受力进行了探讨和检算,对明洞结构的护拱及缓冲层进行了设计计算论证。

CFD simulation of wind and thermal-induced ventilation flow of a roof cavity

The hygrothermal performance of a ventilated roof cavity is greatly affected by the airflow passing through it.This ventilation flow is mainly driven by the wind pressure difference between openings and the thermal-induced buoyancy.However,the wind effect is not well understood as it is often neglected in previous studies.The present study investigates the properties of such airflows,including the flow pattern,flow regime,and flow rate,using a CFD method.The target building is a large-span commercial building with a low-pitched roof.To study the wind-induced airflows,the onset atmospheric boundary layer wind flow was modelled,and the results were compared with the site-measured data recorded in the literature.To study the thermal-induced buoyancy effects,a roof cavity model found in the literature with experimental data was adopted.The findings show that the flow pattern in the roof cavity varied with the airflow driven factors.The flow separation at the windward eave inlet of the thermally induced flows are more pronounced compared with those of the wind-induced flows.Furthermore,the wind-induced airflows can generate around two times more ventilation flow rate through the roof cavity compared to the thermal-induced airflow.The findings indicate that wind-induced ventilation flows are the dominant factor of the roof cavity ventilation in a large-span,low-pitched building.

椭圆形溶洞顶板挠度的简化分析方法

通过合理的假设和简化,将溶洞顶板与嵌岩灌注桩看成一个相互作用系统,只考虑桩基的竖向荷载对顶板的影响。同时根据溶洞顶板的特征和边界条件,将其简化为椭圆形和圆形顶板两种力学模型。通过计算分析,得出了椭圆形顶板的应力和最大挠度公式,以及圆形顶板的挠度表达式,为合理地验算顶板的安全厚度提供了一定的依据。

和草沟煤矿50104工作面回风巷预裂切顶卸压技术应用

禾草沟煤矿50104工作面回风巷经历了临近50102工作面和50104工作面二次回采动压影响,工作面超前支承压力影响区域内巷道变形严重,影响工作面机尾支架推移和上端头的通风行人。为降低工作面回采影响,在回风巷道顶板实体煤侧实施双向聚能拉张成型爆破,切断与50104工作面顶板的力学联系,降低巷道超前支承压力和底鼓程度。工程实践结果表明:实施超前聚能爆破后,超前工作面10m处巷道围岩顶底板移近量和两帮移近量分别减小35.80%和58.12%。

建筑模板“桥型”支撑架的设计与施工

以长沙某工程的大型自动扶梯空洞上方屋面结构施工为例,通过在屋面结构下层洞口上搁置工字钢主梁,并在主梁靠近洞口边两侧分别焊接2根斜向支撑,最终形成"桥型"支撑横跨洞口。之后再在工字钢主梁上方搭设屋面层结构支模体系,从而将支模体系搭设高度由几十米以上降至一层层高,有效减小了支模体系的高度,增强了模板架体的整体稳定性,同时也避免了高处作业的安全隐患。

花石板1号大桥跨越特大型溶洞的处理方案

山区高速公路桥梁、隧道施工遇到特大型溶洞时,必须进行加固处理。以沪溶国道某桥为例,提出顶板锚喷加立柱支撑的处理方案并进行稳定性评价。实践证明,处理方案合理、经济、安全。

水平补救井压裂连通在大溶腔报废老井中的尝试

矿区报废老井,采用水平对接补救井压裂连通,使其恢复生产,增加产能提高岩盐利用率,为类似矿山提供参考。

三软煤层综放工作面片帮漏顶原因分析及对策

神火煤电公司泉店煤矿主采的山西组二1煤层属典型的三软中厚煤层,在实际回采过程中,容易发生片帮漏顶事故。根据综采放顶煤工艺的特点,分析了综放开采中片帮漏顶事故发生的原因,提出了超前管理、降低采高、拉超前架、煤壁打玻璃钢锚杆、加快推进速度等防治措施。通过实施这些措施,有效控制了破碎顶板对工作面回采的影响,实现了矿井的安全生产。