摘要
针对600～800 m特厚表土层中冻结井筒的支护难题,根据约束混凝土原理,提出合理的解决途径是采用内层钢板高强钢筋混凝土复合冻结井壁结构。通过模型试验,对该种井壁结构的应力、变形和强度特性进行深入研究,结果表明:由于内层钢板筒的约束作用,井壁结构中混凝土处于三轴受压应力状态下,其变形能力和抗压强度都得到较大程度的提高,井壁破坏时,内缘混凝土的环向应变可达-4 000με,表现出较好的延性特性,改善了高强混凝土的脆性缺陷。如将目前现场使用的现浇高强钢筋混凝土冻结井壁改为内层钢板高强钢筋混凝土复合结构形式,则井壁承载能力可大大提高,可合理地解决特厚表土层中冻结井筒的支护难题。影响该种井壁极限承载力大小的因素依次为混凝土抗压强度、厚径比、内层钢板厚度和配筋率,其中提高混凝土强度对井壁承载力影响非常显著,如将混凝土强度提高10 MPa,则井壁承载力将提高约13.8%。而增大配筋率对井壁承载力影响甚微,所以,在实际工程应用中,为经济合理设计井壁,只需配置单外排钢筋。最后,根据理论分析和试验结果推导出该种井壁承载力的计算公式,从而为该种井壁结构的工程应用提供设计依据。
Based on the theory of confined concrete,the composite shaft linings of inner steel plate cylinder and high strength reinforced concrete have been adopted to solve the difficult problem of supporting coal frozen shafts penetrating through thick soil cover of 600–800 m.Through model experiments,the mechanical characteristics of such shaft linings are studied.The test results indicate that the concrete′s deformational capacity and compressive strength increase greatly in triaxial compression stress state in inner steel plate cylinder;and the shaft lining is fairly plastic when it fails,and the brittleness defect of high strength concrete is improved.If the shaft linings of high strength reinforced concrete,which are used in site now,have been changed to the composite shaft linings of inner steel plate cylinder and high strength reinforced concrete,and the load bearing capacity of shaft lining will be increased greatly,and the supporting problem of the frozen shaft in the special deep alluvium will be reasonably solved.The main factors affecting load bearing capacity of this shaft lining are the concrete compression strength,the ratio of lining thickness to inner radius,the thickness of inner steel state and the reinforcement ratio.Increasing concrete compressive strength has a remarkable effect on the load bearing capacity of shaft lining.If concrete compression strength increases 10 MPa,the load bearing capacity of shaft lining will increase about 13.8 percent.Moreoveri,ncreasing reinforcement ratio has small effect on the load bearing capacity of shaft lining.Therefore,single outer row steel bar is used in practical engineering to economically and reasonably design shaft lining.Finally,a formula to calculate the load bearing capacity of the composite shaft linings of inner steel plate cylinder and high strength reinforced concrete was obtained according to the theory and experimental results.These results have provided a basis for similar engineering practice when designing this kind of shaft lining structure.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第1期153-160,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
安徽省自然科学基金资助项目(050440502)
安徽省"十五"二期科技攻关计划项目(040120493)
关键词
采矿工程
特厚表土层
冻结井壁
内层钢板筒
高强钢筋混凝土
模型试验
mining engineering
super-deep alluvium
frozen shaft lining
inner steel plate cylinder
high strength reinforced concrete
model experiment
