石膏试样分级加载流变力学特性试验及应用

Experimental Investigation on Rheological Mechanical Properties of the Gypsum Sample under Step Loading and its Application

采用SAW-2000微机控制电液伺服岩石力学试验机,对自然和水饱和石膏试样开展了分级加载流变力学试验.根据流变力学试验结果,采用FLAC3D(fast lagrangian analysis of continua 3 dimension)模拟了水饱和石膏矿采空区顶板和地表沉降的蠕变规律.研究结果表明:自然和水饱和石膏试样的轴向应变和横向应变的大小取决于分级加载应力水平,且随分级加载应力水平的提高而逐渐增大;水饱和石膏试样的长期强度为其自然的长期强度的55%;自然和水饱和石膏试样的横向应变增量与轴向应变增量的比值随加载应力水平的提高而增加;石膏试样的流变力学特性曲线符合粘弹性流变特征,属于蠕变韧性破坏;石膏矿在淹井或闭坑后的半年至一年期间,是矿柱加速蠕变阶段且伴随矿柱的损伤演化直至破坏,是引发地表沉降的活跃期.

The rheologieal mechanical properties of the gypsum sample in a natural state and in a saturated state under step loading were measured by using SAW-2000 microcom- puter controlled electro-hydraulic serw rock mechanics testing machine. Based on rheologi- eal mechanical test results, FLAC3D was used to simulate the creep of goat＇ roof and surface subsidence in a saturated gypsum mine.The results show that the axial strain and the lateral strain of the gypsum sample in a natural state and in a saturated state depends on the steploading stress level, and that increases with the increase of the step loading stress level, and that the axial strain is more than the lateral strain, especially that the saturated gypsum is obvious.The long tern1 strength of the gypsum sample in a saturated state is 55% of it in a natural state, the axial strain increment and the lateral strain increment of the gypsum sam- ple in a natural state and in a saturated state increases with the increase of the step loading stress level.The rheologieal mechanical properties cuve of the gypsum sample in a natural state and in a saturated state is in good agreement with the viscoelastic rheologieal mechan- ical characteristics, which belongs to the creep ductile failure. During the period of six months to one year of the gypsum mine closed or flooded is the accelerating strain stage with the damage evolution and development, and the failure of the gypsum mine pillar, which is easy to happen in mining subsidence incident.