不同初始应力下卸荷煤体氧化特性
发布时间：2018-10-24 12:55
【摘要】：为探讨不同初始应力下卸荷煤体氧化特性,采用程序升温实验、煤岩三轴蠕变实验、压汞实验对易自燃原煤样及其不同初始应力下卸荷煤样进行微观氧化特性对比研究。结果表明:宏观方面,不同初始应力下卸荷煤体比原始煤样更容易氧化,特征温度点下各实验煤样的CO产生量-应变曲线与轴应力-应变曲线具有相似的规律,且煤样氧化能力随初始应力大小变化曲线呈"驼峰状",当初始应力达到15 MPa,煤岩处于塑性变形裂隙扩展阶段,煤样卸荷后与氧气接触能力显著增强;初始应力达到25 MPa,煤岩处于应变软化阶段,煤样卸荷后与氧气接触能力最强,间接增强了煤样的氧化能力。不同初始应力下卸荷煤体的特征温度点均提前于原始煤样,使得发生氧化自燃的时间提前。微观方面,煤体总孔容和孔径分布共同制约着氧化反应进程,初始应力使煤体的孔容积、孔径增大,小孔和微孔是O_2与煤基质氧化反应区域的主要贡献者,小孔、微孔孔容值和比表面积随初始应力的变化趋势与实验煤样氧化能力随初始应力变化趋势相同。根据实验结果,随着煤层埋深增大,地应力增高,采动卸荷后煤体氧化危险程度增大;当煤层赋存地应力随埋深达到临界值后,采动卸荷后煤体氧化危险性程度将会降低;对于同一开采水平,应力相对集中区卸荷后煤体将更易发生氧化自燃,其氧化难易程度与煤体强度、赋存应力存在一定关联。
[Abstract]:In order to study the oxidation characteristics of unloaded coal under different initial stresses, the micro-oxidation characteristics of unloaded coal samples under different initial stresses were studied by temperature programmed test, triaxial creep test and mercury injection test. The results show that unloading coal under different initial stress is easier to be oxidized than the original coal sample under different initial stress. The CO yield and strain curves of experimental coal samples at characteristic temperature have similar laws to those of axial stress-strain curves. When the initial stress reaches 15 MPa, the oxidation capacity of coal sample is in the stage of plastic deformation and crack extension, and the contact ability of coal sample with oxygen is obviously enhanced after unloading. The initial stress of 25 MPa, is in the strain softening stage, and the contact ability of coal sample with oxygen is the strongest after unloading, which indirectly enhances the oxidation ability of coal sample. The characteristic temperature point of unloading coal under different initial stress is earlier than that of the original coal sample, which makes the time of spontaneous combustion of oxidation ahead of time. Microscopically, the total pore volume and pore size distribution of coal body jointly restrict the oxidation reaction process. The initial stress makes the pore volume and pore diameter of coal body increase, and the pore and micropore are the main contributors of oxidizing reaction region between O _ 2 and coal matrix. The change trend of pore volume and specific surface area with initial stress is the same as that of experimental coal sample. According to the experimental results, with the increase of coal seam depth and the increase of in-situ stress, the degree of oxidation hazard of coal body increases after mining and unloading, and the degree of oxidation hazard of coal body will be reduced after mining and unloading when the buried stress of coal seam reaches the critical value. For the same mining level, the oxidation spontaneous combustion of coal will occur more easily after unloading in the stress relative concentration area, and the degree of oxidation difficulty is related to the strength of coal body and the existing stress.
【作者单位】： 河南理工大学安全科学与工程学院;煤炭安全生产河南省协同创新中心;重庆大学煤矿灾害动力学与控制国家重点试验室;河南理工大学机械与动力工程学院;
【基金】：国家自然科学基金资助项目(51304070,51674103,U1361205)
【分类号】：TD752.2
本文编号：2291477
[Abstract]:In order to study the oxidation characteristics of unloaded coal under different initial stresses, the micro-oxidation characteristics of unloaded coal samples under different initial stresses were studied by temperature programmed test, triaxial creep test and mercury injection test. The results show that unloading coal under different initial stress is easier to be oxidized than the original coal sample under different initial stress. The CO yield and strain curves of experimental coal samples at characteristic temperature have similar laws to those of axial stress-strain curves. When the initial stress reaches 15 MPa, the oxidation capacity of coal sample is in the stage of plastic deformation and crack extension, and the contact ability of coal sample with oxygen is obviously enhanced after unloading. The initial stress of 25 MPa, is in the strain softening stage, and the contact ability of coal sample with oxygen is the strongest after unloading, which indirectly enhances the oxidation ability of coal sample. The characteristic temperature point of unloading coal under different initial stress is earlier than that of the original coal sample, which makes the time of spontaneous combustion of oxidation ahead of time. Microscopically, the total pore volume and pore size distribution of coal body jointly restrict the oxidation reaction process. The initial stress makes the pore volume and pore diameter of coal body increase, and the pore and micropore are the main contributors of oxidizing reaction region between O _ 2 and coal matrix. The change trend of pore volume and specific surface area with initial stress is the same as that of experimental coal sample. According to the experimental results, with the increase of coal seam depth and the increase of in-situ stress, the degree of oxidation hazard of coal body increases after mining and unloading, and the degree of oxidation hazard of coal body will be reduced after mining and unloading when the buried stress of coal seam reaches the critical value. For the same mining level, the oxidation spontaneous combustion of coal will occur more easily after unloading in the stress relative concentration area, and the degree of oxidation difficulty is related to the strength of coal body and the existing stress.
【作者单位】： 河南理工大学安全科学与工程学院;煤炭安全生产河南省协同创新中心;重庆大学煤矿灾害动力学与控制国家重点试验室;河南理工大学机械与动力工程学院;
【基金】：国家自然科学基金资助项目(51304070,51674103,U1361205)
【分类号】：TD752.2
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1 刘殿书,王万富,杨吕俊,谢夫海;初始应力条件下爆破机理的动光弹实验研究[J];煤炭学报;1999年06期
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