喷层混凝土-围岩组合体波动特性及动力特性研究

A study on the stress wave characteristics and dynamic mechanical property of the sprayed concrete-surrounding rock combined body

针对早龄期喷层混凝土与围岩黏结面近区介质的动态冲击问题,利用Φ75 mm SHPB试验装置,分别对龄期为3 d,7 d,10 d喷层混凝土-围岩组合体试件进行SHPB试验,对其应力波传播规律及其动态力学特性进行了研究。试验结果表明:透射系数与冲击速度和混凝土龄期密切相关,随冲击速度的增大,不同龄期试件透射数均呈减小的变化趋势,相同冲击速度下,透射系数随试件龄期的增大而增大;随着应变率的增大,试件混凝土破坏模式由张应变破坏向压剪破坏转变,岩石呈现出张拉破坏特征;组合体动态抗压强度及动态强度增长因子随应变率的增大而增大;应变率大于80 s^(-1)时,3 d龄期试件表现出塑性特性,7 d和10 d龄期试件则表现出脆性特性。

In order to investigate the dynamic response problem of the medium around the adhesive surface made by the adherence of early age sprayed concrete on rock,a split Hopkinson pressure bar(SHPB)of75mm in diameter were adopted to study the stress wave propagation rules and dynamic mechanical properties of the sprayed concrete-surrounding rock combined bodies at the age of3d,7d and10d.The experimental results show that the transmission coefficient is closely related to the impact velocity and the age of concrete.It will decrease as with impact velocity for the specimens of3d,7d and10d.The transmission coefficient increases with concrete age under the same experimental velocity.The damage degree will increases gradually as the growth of the strain rate.The failure pattern of the concrete changes from tearing strain damage to crushing damage,and the rock presents the tensile failure mode.The dynamic compressive strength and the dynamic strength increasing factor increase with the growth of strain rate.When the strain rate is beyond 80s^-1,it shows the plastic property for specimens at the age of3d and brittle property for specimens at the age of7d and 10d.