胶结充填体与围岩复合体的力学特性

Mechanics characteristics of cemented filling and surrounding rock

为保证充填采场安全和矿石的连续高效开采,需要研究不同强度时期充填体与围岩相互作用规律及其对充填采场稳定性的影响。本文首先选用工业石蜡作为接触带材料模拟早期强度充填体,并考虑接触带区域应力环境的复杂性,模拟围岩与早强充填体接触区域的非均匀受力情况。为有效表征接触带区域破坏稳定情况,实现从定性分析到定量评价转变,在围岩和早强充填体的接触面放置PVC塑料薄片,结合显微成像、电镜扫描、声发射监测和应变值监测等手段,开展不同荷载作用下围岩与早强充填体相互作用室内试验研究,监测分析胶结充填体与围岩复合体的应变变化、裂纹扩展和变形演化及稳定破坏情况。试验结果表明:加载过程中,接触带区域的变形增长较快,应变值起伏变化较大,突变现象明显;加载之后,模拟接触带的石蜡存在3种不同情况的损伤特征:①螺旋式损伤破坏,②类平行式损伤破坏,③交叉损伤破坏,而接触带附近的表壁监测点应变值呈现稳定递增趋势。研究结果揭示了充填体与围岩复合体在荷载作用下的力学特性,有利于指导早强充填体下采场的稳定性,也实现了表壁裂纹扩展和内部损伤破坏之间的同步表征。这为进一步研究充填体与围岩复合体在二维和三维荷载作用下的力学特性研究提供了研究思路。

In order to ensure the safety of filling stope and ore mining efficiently,it is necessary to study the interaction between the filling and surrounding rock in different strength periods,which influences the stability of filling stope.The paraffin was selected as the contact material to simulate the early strength of the filling body,and also considering the complexity of the stress environment in the contact zone,the non-uniform stress in the contact zone between the wall rock and the early-strength backfill was simulated.In order to effectively characterize the regional instability in the contact zone and realize the transformation from qualitative analysis to quantitative evaluation,the PVC plastic foil was placed on the contact face between the surrounding rock and the early strength filling body.Combined with the microscopy imaging,electron microscope scanning,AE monitoring and strain monitoring,the laboratory experiment of the interaction between the surrounding rock and the early strength filling body under different load conditions was studied.The strain change,crack growth deformation evolution,stability failure of cemented backfill and surrounding rock complex were monitored and analyzed.The results show that the deformation of the contact zone increases rapidly,the strain value fluctuates greatly and the abrupt change is obvious.After loading,the paraffin in the contact zone shows three different damage characteristics: one is spiral damage,the second is the parallel type of damage,the third shows the characteristics of cross-damage,and the strain around the contact zone shows a steady increasing trend. The results also show the complex mechanical and deformation characteristics of filling body and surrounding rock,which has a certain guiding significance to ensure the stability of the stope with the early strength filling body.The synchronization between crack propagation and internal damage is realized.The study provides a research idea for further studying the mechanical properties of backfill and surrounding rock complex under two-dimensional and three-dimensional loads.