为研究岩石颗粒在循环加卸载条件下的接触力学性质,采用直径60 mm的大理岩球砾开展系列压缩破碎试验、准静态循环加卸载试验和动态循环加卸载试验。试验结果表明:在压缩荷载作用下大理岩球砾的弹性变形阶段较短,弹塑性变形阶段处于主导地位;随准静态循环加卸载次数增加,大理岩球砾的累计塑性变形、接触刚度-位移曲线斜率以及等效恢复系数都逐步增大,但增幅逐渐减小,最后趋近于稳定值;动态循环加卸载试验中球砾的累积塑性变形随循环次数演化曲线可以划分成初始阶段、等速阶段和加速(破坏)阶段,上限荷载越大、荷载幅值越大,大理岩球砾在初始阶段产生的塑性变形越大,累计塑性变形曲线进入等速阶段所需循环次数也越多;动荷载作用下的阻尼比随循环次数增加而逐渐减小,最后渐趋于稳定,上限荷载越大、荷载幅值越大,大理岩球砾循环加卸载初期的阻尼比越大,随循环加卸载次数增加,上限荷载和荷载幅值对阻尼比的影响逐渐减弱。研究成果可为分析堆石料、铁路道砟等岩石颗粒材料受力变形特征提供理论依据。
Abstract
A series of compression crushing tests,quasi-static as well as dynamic loading and unloading tests were carried out to study the contact mechanical properties of marble spheres of 60 mm diameter.The elastic deformation of compressed marble spheres lasts shortly,while elastoplastic deformation dominates.With the increase of quasi-static loading and unloading cycles,the cumulative plastic deformation,the slope of contact stiffness-displacement curve,and the equivalent restitution coefficient of the marble spheres all increase gradually,and finally approach a stable value.The development of cumulative plastic deformation of marble spheres under dynamic cyclic loading can be divided into three stages:initial stage,constant velocity stage,and accelerated stage.The larger the upper limit load and load amplitude,the larger the plastic deformation in the initial stage,and the more cycles required for the cumulative plastic deformation curve to reach the constant velocity stage.The damping ratio at the beginning of dynamic loading increases apparently with the increasing of upper limit load and load amplitude;but such effect gradually weakens with the proceeding of the cyclic loading and unloading.The conclusion of this paper can be used as a reference for studying the stress and deformation characteristics of rock granular materials.
关键词
大理岩球砾 /
循环加卸载 /
塑性变形 /
等效恢复系数 /
阻尼比
Key words
marble sphere /
cyclic loading and unloading /
plastic deformation /
equivalent restitution coefficient /
damping ratio
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