常截面滚刀贯入试验中岩石破坏行为分析

Analysis on fragmentation behavior of rocks in indentation tests by disc cutter

为研究滚刀贯入过程中不同强度岩石的破坏行为,采用泥岩、花岗岩、砂岩和水泥砂浆制作立方体试样,结合岩石贯入试验加载系统和声发射监测系统,进行无侧向约束条件和有侧向约束条件下TBM常截面盘形滚刀贯入试验,获得完整荷载–贯入度曲线和声发射参数信息,分析不同岩石试样的破坏过程、破坏类型和破坏模式。结果表明:(1)软岩试样荷载–贯入度曲线跌落现象不明显,呈现延性破坏特征,而硬岩试样荷载–贯入度曲线跌落现象显著,具有脆性断裂特征。(2)无侧向约束条件下试样破坏类型属于劈裂破坏模式,有侧向约束条件下试样破坏过程由中间劈裂裂纹和侧向裂纹共同控制。(3)声发射参数曲线和荷载–贯入度曲线之间具有良好的对应关系,可以反映贯入过程中岩石试样内部损伤劣化和宏观裂纹形成过程。(4)类岩石材料滚刀贯入试验在一定程度上有助于更好地理解岩石贯入破坏过程和破坏模式,但类岩石材料与自然岩石材料在强度和变形性质上并不能完全吻合,因此相似材料模拟试验的结果需要进一步的验证。

The rock loading system and acoustic emission monitoring system were employed to conduct the indentation tests on four rocks with different strengths,namely mudstone,granite,sandstone and cement mortar specimens with cubic dimensions,with or without lateral confinement. The complete load-penetration curves and acoustic emission parameters were analysed together,and the process,form and mode of the rock fragmentation by TBM constant cross section（CCS） disc cutter were studied. The load drop of the load-penetration curve for soft rock is not obvious and the rock fragmentation presents the failure characteristic of elastoplasticity,while the load drop is remarkable in accordance with the brittle rupture for hard rock indentation test. The rock fragmentation without lateral confinement can be regarded as obvious splitting fracture mode and the failure process of the confined specimen is controlled by the combined effect of both splitting fractures and lateral fractures. The curves of acoustic emission parameters are in good agreement with the load-penetration curves and can generally reflect the damage,degradation and fracture formation of the indented rock specimens. The indentation tests conducted on the rock-like material can reproduce the fragmentation process and failure mode of the natural rock at some extent,but due to the discordances of the strength and deformation properties between rock-like material and natural rock,the results obtained from similar material simulations should be further investigated.