重载预应力混凝土轨枕放张破坏及对策研究

Destruction of prestressed concrete sleeper for heavy haul railway during removing tensioning equipment and its countermeasures

采用传统的模具进行有挡肩预应力混凝土轨枕生产时,在放张脱模过程中出现挡肩掉块、轨枕开裂等现象。为了研究这种轨枕放张过程中轨枕的破坏机理及其对策,通过3D接触关系构建了轨枕—模具相互作用模型,分析了放张脱模过程中轨枕受力及其破坏形式。同时,提出了采用复合模具来降低放张脱模过程中承轨槽的应力,以减少轨枕破坏。计算结果显示:采用钢模,在放张预应力钢筋时会造成轨枕承轨槽位置的第一主应力超过了混凝土的抗拉极限,在实际生产中在承轨槽位置可能会出现开裂。采用复合模具,原危险位置的第一主应力降低至混凝土抗拉强度以下,可保证轨枕的正常脱模。

When using the traditional mold for production of prestressed concrete sleeper used in heavy haul railway,sleeper cracking,bed retaining falling off and other damage during removing tensioning equipment may occurs. In order to study the destruction mechanism and countermeasures for prestressed concrete sleeper used in heavy haul railway concrete,a finite element model of the prestressed sleeper and mold was set up with a 3D contact model simulating the interaction between sleeper and mold. The composite mold was used to reduce the stress of sleeper groove during demolding,and reduce the damage of the sleeper. The results show that the adoption of steel mold will cause the first principal stress of rail groove greater than the tensile limit of concrete during removing tensioning equipment,and it may result in cracking at the bearing rail groove. By comparison,the adoption of composite mold may reduce the first principal stress of sleeper to be less than the tensile strength of concrete,ensuring a normal demolding.