Resistance of grid steel-tube-confined concrete targets against projectile impact: Experimental investigation and analytical engineering model

Steel-tube-confined concrete(STCC) targets are provided with excellent anti-penetration performance over semi-infinite concrete(SIC) targets since the steel tube imposes passive restraint on the in-filled concrete during the penetration process. Grid STCC system with square steel tubes is a potential solution to protective structures. In this paper, experiments of 9-cell grid STCC targets penetrated by 12.7 mm Armor Piercing Projectile(APP) were performed. The influence of side length and thickness of steel tube,steel ratio and impact velocity on anti-penetration performance were taken into account. Additionally,single-cell square STCC targets were also designed and tested for comparison with the 9-cell grid STCC targets. Damage modes and parameters of the tested targets were measured and discussed. Moreover,the stiffness of radial confinement of grid STCC targets is achieved according to the elastic solution of infinite cylindrical shell in Winkler medium. Furthermore, the penetration resistance and depth of penetration(DOP) for grid STCC targets are obtained on the basis of the dynamic finite spherical cavityexpansion(FSCE) models including radial confinement effect. It is shown that the 9-cell grid STCC targets with optimal dimension match of thickness and side length of steel tube can reduce the DOP by about17 % and 23 % in comparison with the SIC targets and single-cell square STCC targets, respectively, due to both the confinement of square steel tube to concrete in the impacted cell and the additional confinement of the surrounding cells to the impacted cell;the penetration resistance and DOP of the grid and cellular STCC targets with similar steel ratio is close, and thus the grid STCC targets with simpler manufacturing process and excellent in-plane expandability are preferred in engineering practice;moreover, the predicted results of DOP model based on the FSCE models agree well with the tested results with the maximum disparity less than 12 % and the proposed model is more applicable to the grid and cellular STCC targets with high radial confinement.

大断面软岩斜井高强度钢管混凝土支架支护技术

查干淖尔矿主斜井泥岩段围岩变形量大,速度快,巷道支护困难,结合主斜井泥岩段膨胀性软岩的工程地质条件和围岩变形特征,并结合主斜井泥岩段的巷道围岩变形特点,设计了高强度钢管混凝土支架支护方案,其中,巷道断面采用马蹄形,钢管混凝土支架主体钢管选用194 mm×10 mm无缝钢管,充填C40钢纤维混凝土,辅助金属网支护和混凝土喷层支护。通过数值分析可知,主斜井泥岩段开挖后及时施加钢管混凝土支架支护方案,钢管混凝土支架承载能力大,能够提供强大的支护反力,限制巷道围岩向巷道空间的移动,保证巷道围岩稳定和支护结构可靠。通过巷道施工和现场监测分析可知,大断面软岩巷道高强度快速支护方案易于施工,能够维持主斜井泥岩段软岩巷道围岩的稳定。

环梁连接的RC梁-钢管混凝土柱框架试验研究

介绍了一个采用钢筋混凝土 (RC)环梁连接的 2层 2跨RC梁 -钢管混凝土 (STCC)柱框架的拟动力试验和静力试验。为了研究环梁在地震作用下的破坏形态 ,大部分节点设计成“弱环梁、强框架梁” ,即环梁屈服先于框架梁 ;少量节点设计成“强环梁、弱框架梁” ,即框架梁屈服先于环梁。试验表明 :小震时 ,框架的刚度降低很少 ;中震时 ,刚度降低约 3 0 % ;大震时 ,层间位移角小于 1 10 0 ;即使弱环梁已经破坏、层间位移角达 1 3 4,框架的承载力仍未下降 ;能够实现“强柱弱梁”和实现塑性铰形成于框架梁端的“强连接、弱构件”的抗震设计概念。RC环梁与STCC柱之间局部范围的缝隙不影响框架的整体抗震性能 ;环梁与柱之间几乎无相对竖向滑移。采用RC环梁连接的RC梁 -STCC柱框架具有良好的抗震性能。

RC环梁连接的钢管混凝土柱-RC梁框架计算模型研究

RC环梁连接的钢管混凝土柱-RC梁框架在竖向荷载和水平荷载作用下,在环梁一定高度范围内,环梁与柱之间会有很窄的缝隙。通过有限元分析研究了环梁连接的转角刚度和环梁区域框架梁等效宽度以及它们的影响因素,结果表明环梁宽度和框架梁宽度对转角刚度和等效宽度影响较大。框架内力、位移计算以及两层两跨框架结构的静力试验和拟动力试验表明,环梁连接的钢管混凝土柱-RC梁框架可以采用梁柱直接刚性连接的模型进行弹性分析。

蜂窝钢管约束混凝土靶抗多发打击试验研究

混凝土广泛应用于防护结构,对混凝土施加约束可以有效改善其脆性,从而提高其抗弹性能。钢管约束混凝土抗侵彻性能优良,在防护结构中具有广阔的应用前景。为了研究蜂窝钢管约束混凝土的抗侵彻性能,推进钢管约束混凝土的工程应用,进行了蜂窝钢管约束混凝土靶(STCC)和半无限靶抗12.7 mm穿甲弹多发打击对比试验,得到了靶体损伤模式,测量了漏斗坑的体积与深度等损伤参数,计算了蜂窝钢管约束混凝土靶等效侵彻阻力,分析了先发打击对后发打击的影响。结果表明:蜂窝钢管可将弹丸侵彻产生的混凝土损伤限制在被打击单元内,其核心混凝土的损伤模式为“漏斗坑+侵彻隧道+侧面裂纹”;与半无限混凝土靶相比,蜂窝钢管约束混凝土靶抗4发打击的侵彻深度(DOP)可减小约18%,抗6发打击的漏斗坑体积与深度分别可减小约78%和55%,其抗多发打击性能明显优于半无限混凝土靶。

动压巷道钢管混凝土支架支护技术应用研究

针对清水煤矿动压巷道变形破坏严重的问题,在动压巷道南二06工作面材料上山巷道进行了钢管混凝土支架支护实验,采用准219×8型弧墙半圆拱钢管混凝土支架,经理论计算该支架承载能力为2113.02kN,可提供支护反力1.15MPa。现场施工后进行了为期60d的巷道顶底板移近量监测,两帮最大移近量约为4cm,顶底板最大移近量约为5cm,巷道稳定。