冻融循环下类岩石材料蠕变特性研究

RESEARCH ON CREEP CHARACTERISTICS OF ROCK-LIKE MATERIALS UNDER FREEZE-THAW CYCLES

以西部寒区隧道中的页岩为代表,建立描述冻融循环作用下类岩石材料的蠕变模型;采用水泥、河沙、粉煤灰制成类岩石材料,进行不同冻融循环次数的冻融循环试验和单轴蠕变试验;通过ABAQUS软件模拟寒区隧道围岩冻融下的蠕变特性,得到“拱顶-侧墙-拱底”三者之间的应力破坏规律。结果表明:1)选用西原模型+温度阻尼器+非线性流变参量模拟的蠕变模型能够描述冻融时岩石材料的蠕变特性;2)应变随着荷载及时间的增加而发生较大程度的递增,且随着冻融次数的增加,损伤程度加剧,抗变形能力减弱;3)寒区隧道围岩冻融下最大应力主要集中在拱顶与侧墙以及拱底与侧墙的交汇处。

The creep model described rock materials under freeze-thaw cycles was established in the light of shale in tunnels of the western cold region.And the rock-like material specimens made of cement,sand and fly ash were cast,and after different freezing-thawing cycle tests,uniaxial creep tests were carried out.Finally,the creep characteristics of tunnel surrounding rock in cold regions were simulated by ABAQUS and obtained the stress failure law of“tunnel vault-sidewall-arch bottom”.The results showed that:1)the creep model of Nishihara,temperature dampers and NVPB model could describe the creep characteristics of rock-like materials under freeze-thaw cycles;2)the strain increased greatly with the increase of loads and time.The extent of damage was gradually increased and the deformation resistance was weakened with the increase of freeze-thaw cycles;3)the maximum stress of tunnel surrounding rock in cold regions was mainly concentrated at the interface between the vault and sidewall,and between the bottom and sidewall.