基于蠕变试验的浅埋空区群结构时变力学特性研究

Study on Time-Variant Mechanics Properties of Shallow Goaf Group Based on Creep Experiment

空区结构力学特性随时间发生劣化是导致地表塌陷和空区坍塌的重要因素之一。以古马岭金矿浅埋空区群为研究对象,结合矿岩的压缩蠕变试验获取了围岩蠕变模型,利用数值模拟方法研究了该空区群结构时变力学特性。结果显示:矿岩的蠕变力学特性可用Cvisc模型加以描述;空区群形成后,地表岩体和围岩内部的应力和位移均随时间推移而发生变化,表现出显著的时变力学特性;空区群顶板下沉位移随时间加速增长,且中部采空区顶板位移最大,第5年时已达0.24 m,表明采空区顶板会随着时间发展而逐渐坍塌;矿柱两侧均出现随时间增大的横向变形,表面围岩逐渐片落,导致矿柱不断变窄,可能引起空区群发生大规模破坏;地表围岩形成以空区群中部为中心的塌陷区域,且塌陷深度和范围均随时间加速增长,在第5年时达到0.21 m,需要采取措施进行空区治理。

One of important factors that lead to ground and goaf collapse is the mechanical properties deterioration of shallow goaf group through time.Taking the shallow goaf group in Gumaling gold mine as an example,the creep model of the surrounding rock was obtained from rock creep test,and the time-variant mechanics properties of the shallow goaf group was analyzed by using numerical simulation method.The results show that the creep mechanical properties of the rock can be described by Cvisc model.After the goaf group is formed,the stress and displacement of ground rock mass and surrounding rock will change over time,showing significant time-variant mechanical characteristics.The roof displacement of the goaf group increases over time.The largest displacement is in the central goaf group,and the displacement is 0.24 m at the fifth year,indicating that the roof of goaf group will gradually collapse.The lateral deformation at two sides of pillar increases with time.Due to the surface failure of surrounding rock,the pillar continually narrows down,leading to the largescale destruction of the goaf group.The ground forms a subsidence area centered on the central part of goaf group.The depth and extent of subsidence area increase with time,reaching 0.21 m at the fifth year.Some measures should be taken to protect the goaf group.