共查询到19条相似文献,搜索用时 281 毫秒
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文中对岩金矿山地下开采应用的钢筋混凝土人工底柱代替矿石底柱作一介绍,并对人工底柱的应用条件,施工方法等有关问题作初步的探讨。 相似文献
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节约木材的底柱施工经验 总被引:1,自引:0,他引:1
本文介绍撰山子金矿利用锚杆吊挂半圆木人工钢筋混凝土底柱的施工方法,并用铁漏斗代替木漏斗,是一项节约木材、降低成本、加快进度的技术革新,可在有关岩金矿山推广应用。 相似文献
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河台金矿矿柱回采方法的改进 总被引:3,自引:0,他引:3
针对河台金矿浅孔留矿采矿柱回采存在的问题进行分析研究,通过用钢筋混凝土置换底柱,结合采用少量的上向以干式充填法置换间柱等办法来缩小采空区的规模,立足于对现有浅孔留矿采矿法进行改造,从而降低矿柱回采贫化率、损失率。上述措施已付诸实施,并取得了明显效果。 相似文献
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针对倾斜-急倾斜的薄矿体采用浅孔留矿法,在当前所使当中,顶底柱的可采矿量占矿块可采矿量的15%~20%,通过人工钢筋混凝土假底置换矿石底柱来提高矿石资源的回收率,保证回采过程中的安全性。 相似文献
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本文阐述经模拟试验,确定在深部开采中,用低弹性模量的混凝土构筑人工底柱代替矿石底柱,可减少底柱的应力集中,并可避免冲击地压的发生。 相似文献
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电石炉本体上部钢筋混凝土平台因承受的荷载大、工艺要求的跨度大,采用了劲性混凝土三叉梁的方案,文章针对这一新型结构形式的施工,从方案选择、钢筋接头设置、钢结构制作、灌浆和安装,以及钢纤维混凝土等主要方面进行了介绍。 相似文献
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详细介绍了淘锡坑钨矿采用人工假底替换传统采场底柱技术的工程试验,结果证明:当采场底柱品位较高采用人工假底技术时,具有施工简单、安全可靠和降低采矿损失率的优势,不仅可多回收资源,其经济效益也十分明显。 相似文献
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李剑飞 《有色冶金设计与研究》2007,28(6):30-32
介绍层布式钢纤维混凝土的路用性能,结合井冈山市城区路网改造工程的设计、施工情况,阐述了层布式钢纤维混凝土在旧路面改造中的应用。 相似文献
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Sherif El-Tawil Cahit Ogunc Ayman Okeil Mohsen Shahawy 《Canadian Metallurgical Quarterly》2001,5(4):258-267
Extensive testing has shown that externally bonded carbon fiber reinforced polymer (CFRP) laminates are particularly suited for improving the short-term behavior of deficient reinforced concrete beams. Accelerated fatigue tests conducted to date confirm that fatigue response is also improved. This paper describes an analytical model for simulating the static response and accelerated fatigue behavior of reinforced concrete beams strengthened with CFRP laminates. Static and fatigue calculations are carried out using a fiber section model that accounts for the nonlinear time-dependent behavior of concrete, steel yielding, and rupture of CFRP laminates. Analysis results are compared with experimental data from two sets of accelerated fatigue tests on CFRP strengthened beams and show good agreement. Cyclic fatigue causes a time-dependent redistribution of stresses, which leads to a mild increase in steel and CFRP laminate stresses as fatigue life is exhausted. Based on the findings, design considerations are suggested for the repair and∕or strengthening of reinforced concrete beams using CFRP laminates. 相似文献
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A set of 30 concrete beams reinforced with carbon/epoxy FRP (fiber-reinforced plastic) and four reinforced with comparable size steel rebars were subjected to static bending tests. Adequate bond between the FRP and the concrete was obtained, due to the use of carbon fiber overwrap on the smooth pultruded FRP rods. With adequate bond, the large strain to failure (>2%) of the FRP determines the ductility and failure mode of the FRP reinforced beams. An analytical evaluation of the fracture energy in these experiments shows that there is ductility due to the large fraction of the total strain energy that is absorbed in the concrete, because of the formation of distributed cracking. Variations in overwrap configuration, addition of steel stirrups, addition of polypropylene fibers, and comparison with four beams reinforced with equivalent steel reinforcement were also analyzed. 相似文献
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本文结合钢纤维混凝土的性能机理,对钢纤维混凝土多项性能进行分析,并根据钢纤维混凝土独特的性能,展望钢纤维混凝土应用前景。 相似文献
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This research studies the interaction of concrete, steel stirrups, and external fiber reinforced polymer (FRP) sheets in carrying shear loads in reinforced concrete beams. A total of eight tests were conducted on four laboratory-controlled concrete T-beams. The beams were subjected to a four-point loading. Each end of each beam was tested separately. Three types of FRP, uniaxial glass fiber, uniaxial carbon fiber, and triaxial glass fiber, were applied externally to strengthen the web of the T-beams, while some ends were left without FRP. The test results show that FRP reinforcement increases the maximum shear strengths between 15.4 and 42.2% over beams with no FRP. The magnitude of the increased shear capacity is dependent not only on the type of FRP but also on the amount of internal shear reinforcement. The triaxial glass fiber reinforced beam exhibited more ductile failure than the other FRP reinforced beams. This paper also presents a test model that is based on a rational mechanism and can predict the experimental results with excellent accuracy. 相似文献
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Their resistance to electro-chemical corrosion, high strength-to-weight ratio, larger creep strain, fatigue resistance, and nonmagnetic and nonmetallic properties make carbon fiber reinforced polymer (CFRP) composites a viable alternative to bonding of steel plates in repair and rehabilitation of reinforced concrete structures. The objective of this investigation is to study the effectiveness of externally bonded CFRP sheets or carbon fiber fabric in increasing the flexural strength of concrete beams. Four-point bending flexural tests were conducted up to failure on nine concrete beams strengthened with different layouts of CFRP sheets and carbon fiber fabric and on three beams with different layouts of anchored CFRP sheets. An analytical procedure, based on compatibility of deformations and equilibrium of forces, was presented to predict the flexural behavior of beams strengthened with CFRP sheets and carbon fiber fabric. Comparisons were made between the test results and the analytical calculations. The flexural strength was increased up to 58% on concrete beams strengthened with anchored CFRP sheets. 相似文献
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Christos G. Papakonstantinou Michael F. Petrou Kent A. Harries 《Canadian Metallurgical Quarterly》2001,5(4):246-253
The objective of the presented study is to examine the effects of glass fiber reinforced polymer (GFRP) composite rehabilitation systems on the fatigue performance of reinforced concrete beams. Experiments were conducted on beams with and without GFRP composite sheets on their tensile surfaces. The specimens were 152 × 152 × 1,321 mm reinforced concrete beams with enough transverse reinforcement to avoid shear failure. The results of this study indicate that the fatigue life of reinforced concrete beams with the given geometry, subjected to the same cycling load, can be significantly extended through the use of externally bonded GFRP composite sheets. An interesting finding is that, although the fiber strengthening system increases the fatigue life of the beams, the failure mechanism, fatigue of the steel reinforcement, remains the same in both strengthened and nonstrengthened beams. Thus, it is possible to predict the fatigue life of a cyclically loaded beam using existing fatigue models. 相似文献
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Kypros Pilakoutas Kyriacos Neocleous Maurizio Guadagnini 《Canadian Metallurgical Quarterly》2002,6(3):154-161
The conventional design philosophy for reinforced concrete (RC) relies heavily on the ductile properties of steel. These ductile properties are used as a “fuse” and conceal the large uncertainty in the determination of modes of failure caused directly by concrete. Current design guidelines for fiber reinforced polymer (FRP) RC structures have inappropriately adopted the same design philosophy used for steel RC, leading either to the adoption of conservative safety factors or reduced structural reliability. A reliability-based analysis of FRP RC beams shows that the current, very conservative partial safety factors for FRP reinforcement on their own do not influence the structural safety of overreinforced concrete elements. Proposals are made for the modification of the material partial safety factors to achieve target safety levels. 相似文献
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Patrick X. W. Zou 《Canadian Metallurgical Quarterly》2003,7(4):275-284
After a brief review of the ductility and deformability indices currently used in the design of concrete beams reinforced or prestressed with steel or fiber reinforced polymer (FRP) tendons, a new definition of a deformability index (factor) for prestressed concrete beams is proposed. The new factor is defined in terms of both a deflection factor and a strength factor. The deflection factor is the ratio of the deflection at failure to the deflection at first cracking, while the strength factor is the ratio of the ultimate moment (or load) to the cracking moment (or load). The proposed deformability factor is verified not only by test results obtained by the writer, but also by other test results available in the literature and it appears to be a suitable measurement of the deformability of concrete beams prestressed with either FRP tendons or steel tendons. 相似文献