破碎软岩注浆结石体的动力冲击试验及动态损伤模型辨识

Dynamic properties of grouting-reinforced rock mass and its damage mechanics model

岩体注浆结石后的动力特性直接影响到岩体加固工程的动力稳定性,目前对破碎软岩注浆结石体的动力特性并不明确,因此开展结石体动力特性的定性与定量研究具有较大意义。选取典型的软岩碎块,假定注浆裂隙的均匀性并忽略浆液扩散的随机性,通过简化控制注浆模仿过程制备注浆结石体试样,借助SHPB装置进行了动态冲击压缩试验。研究结果表明,注浆结石体的破坏大部分发生在浆-岩胶结面,细观上表现出显著的脆性损伤开裂特征,宏观全应力-应变曲线初始阶段无显著的压密过程,较小应变时便达到峰值强度,但峰值强度后阶段表现出显著的应变软化特征,破坏后阶段存在一定的残余强度;软岩碎块与水泥的质量比对结石体的动力特性具有显著影响,成分最优配比条件下结石体的峰值强度可达到极大值;相同材料含量比条件下含水率越高其动峰值强度及弹性模量普遍越小,表明含水率对结石体动力特性具有显著影响。此外,基于连续损伤及统计强度理论,辨识得到了软岩注浆结石体的动态损伤力学模型及其参数,对比表明理论计算结果与实测曲线具有较好的一致性。研究成果可为开展破碎软岩注浆体的特性研究提供借鉴与参考。

It is very significant to carry out the qualitative and quantitative research on the dynamic properties of grouting-reinforced rock mass,which directly reflects the grouting reinforcement effect of broken rock mass and its dynamic stability in engineering.By selecting typical fragments and simplifying the simulation of grouting process,the grouting-reinforced rock mass was prepared using a core machine.In the process,the uniformity of rock crack was promised and randomness of the grout diffusion was neglected.Dynamic shock tests of the grouting-reinforced rock mass was carried out by using the Split Hopkinson Pressure Bar.The results show that,the quality ratio between the rock mass and cement plays an important role on the dynamic properties of grouting-reinforced rock mass,and the peak strength can reach the maximum under an optimal ratio.In addition,based on the continuum damage theory and statistical strength theory,a dynamic damage mechanics model for grouting-reinforced rock mass was presented,and the model parameters were fitted,which have a great association with the sample components.There is a good coherence between stress-strain curves calculated by the proposed model and those obtained directly from the experimental data.The research results may extend the theoretical study fields with respect to the properties of grouting-reinforced rock mass.