煤破坏过程中蠕变—渗流耦合试验研究

发布时间：2018-06-17 12:48

本文选题：煤破坏 + 蠕变　；参考：《辽宁工程技术大学》2015年硕士论文

【摘要】：流变特性是软岩的一项重要的力学性质,尤其在煤矿开采过程中,地表灾害显现具有滞后性,具有时间效应,表现为蠕变特性；而开采导致煤层覆岩产生裂隙,当雨天地表积蓄水之后,雨水便会渗透进煤层中,导致煤的力学性质发生改变,导致地表塌陷、巨洞或滑坡事故。故进行煤峰前峰后的蠕变-渗流耦合规律试验研究有着很重要的工程意义。论文应用试验研究和理论分析的方法,对煤峰前峰后的蠕变-渗流规律进行了研究,其内容为：1、自主研发三轴蠕变-渗流试验系统,包括：加载系统,稳压系统、监测系统、密封系统；其中加载系统采用手动水泵进行人工加压；稳压系统采用稳压罐来保证试验过程中压力的稳定；监测系统采用千分表和电阻应变仪两种方式对试件的变形进行观测,采用密闭式量筒对渗流量进行测量；密封系统采用直径80mm的热缩管和密封圈对试件进行密封；2、试验采用分级加载法,在峰前的试验当中,首先测量煤体的初始渗流量和逐级加载压力时的瞬时变形,之后测量煤在当前应力级别下12小时内的蠕变量和渗流量,最后拟合出试件的变形量、渗流量与时间的关系曲线图,分析出试件峰前的裂纹扩展情况及蠕变-渗流特性规律,得出在轴压和围压固定时,随着孔隙水压的增大,渗流量也不断的增大,并且随着孔隙水压的增大,试件的蠕变量也增大的规律；并对试验结果采用高斯拟合公式得出峰前蠕变-渗流耦合方程：3、在峰后的试验当中,将试件逐级加载至破坏,为了更好的观察峰后的围压、轴压的变化,在破坏之后将轴压加载至20MPa,进行24小时的试验,记录试验过程当中渗流量、轴向变形、轴压、围压的变化并拟合曲线,分析出试件峰后的裂纹扩展情况、应力松弛规律以及蠕变-渗流特性规律,得出试件破坏后随着轴压逐渐松弛,轴向蠕变速率逐渐减缓,渗流量逐渐降低,围压增大并逐渐趋于平缓的规律;并对试验结果采用高斯拟合公式得出峰后蠕变-渗流耦合方程。
[Abstract]:Rheological property is an important mechanical property of soft rock, especially in the process of coal mining, the surface disaster appears to have hysteresis and time effect, which is shown as creep property, while mining causes cracks in overburden rock of coal seam. When the surface water accumulates on rainy days, Rain Water will infiltrate into the coal seam, resulting in the change of the mechanical properties of the coal, resulting in the surface collapse, giant hole or landslide accident. Therefore, it is of great engineering significance to study the creep-seepage coupling law after the coal peak. In this paper, the creep-seepage law after the peak of coal is studied by means of experimental research and theoretical analysis. The creep-seepage test system is developed by ourselves, which includes loading system, steady pressure system and monitoring system. The sealing system, in which the loading system is manually pressurized by a manual pump, the pressure stabilizer is used to ensure the stability of the pressure during the test, and the deformation of the specimen is observed by the monitoring system in two ways, the meter and the resistance strain meter. The sealant flow is measured with a closed cylinder, and the sealing system uses a heat shrink tube with diameter 80mm and a sealing ring to seal the specimen. The test adopts the method of step loading, and in the test before the peak, First, the initial seepage flow of coal body and the instantaneous deformation of coal under step by step loading pressure are measured, then the creep amount and seepage flow rate of coal within 12 hours under the current stress level are measured. Finally, the curves of deformation, seepage flow and time of the specimen are fitted. The crack propagation and creep-seepage characteristics of the specimen before the peak are analyzed. It is concluded that when the axial pressure and confining pressure are fixed, the seepage volume increases with the increase of pore water pressure and increases with the increase of pore water pressure. The creep amount of the specimen also increases, and the creep seepage coupling equation: 3 is obtained by using the Gao Si fitting formula. In the post-peak test, the specimen is loaded to failure step by step, in order to better observe the confining pressure after the peak, The change of axial pressure, loading the axial pressure to 20MPa after failure, carries on the experiment for 24 hours, records the change of seepage flow, axial deformation, axial pressure, confining pressure and fitting curve, and analyzes the crack propagation after the peak of the specimen. The stress relaxation law and creep-seepage characteristic rule show that the axial creep rate decreases gradually and the confining pressure increases and tends to be gentle gradually with axial compression gradually loosening after failure. The Gao Si fitting formula is used to obtain the creep-seepage coupling equation after the peak.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD31

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