含瓦斯砂岩卸围压变形特征与渗透规律试验研究

发布时间：2018-01-27 02:09

本文关键词： 采矿工程瓦斯砂岩卸围压渗透率模型　出处：《岩土力学》2017年12期 　论文类型：期刊论文

【摘要】：为研究含瓦斯砂岩卸荷破坏过程中的变形及渗流规律,采用自主研发的含瓦斯煤热-流-固耦合渗流伺服试验系统,开展了不同围压和相同瓦斯压力条件下的卸围压渗流试验,建立了基于应变指标的瓦斯渗流模型。得出的主要结论有:(1)含瓦斯砂岩破坏表现出明显的脆性特征,峰值应力点后瞬间,应力、应变及流量均出现突跳;(2)应力-应变及渗透率变化呈现明显的阶段性特征:孔隙、微裂隙压密及弹性变形阶段(Ⅰ、Ⅱ阶段),砂岩渗透性为0;卸荷屈服阶段(Ⅲ阶段),产生新的损伤,渗透性小幅增加;卸荷破坏应力跌落阶段(Ⅳ阶段),应力突降,应变陡增,裂隙贯通后渗透性陡增,是渗透性主导阶段;破坏后阶段(Ⅴ),应力、应变及流量变化均趋于稳定;(3)含瓦斯砂岩破坏阶段,受气体压力和泊松效应影响,使径向应变和体积应变远大于轴向应变;(4)含层理砂岩卸荷破坏形式以产生沿层理面方向的张剪混合裂缝为主。基于Kozeny-Carman方程和裂隙流理论,建立了应变相关渗透率模型,揭示了含瓦斯砂岩损伤破坏渗流机制,对研究瓦斯突出、及在破断岩体中的运移规律及抽采孔优化设计等具有借鉴意义。
[Abstract]:For the deformation and seepage law of gas bearing sandstone unloading failure in the process of coal containing gas thermal fluid solid coupling seepage servo test system with independent research and development, carried out in different confining confining pressure seepage test pressure relief gas pressure and the same conditions, the establishment of a gas flow model based on strain index. The main conclusions are as follows: (1) the gas sandstone exhibits brittle failure characteristics, the peak stress after the moment, stress, strain and flow were jumping; (2) stress - strain and permeability change showed obvious phase characteristics: pore and micro fracture compression and elastic deformation stage (I and II stage), the permeability of sandstone is 0; unloading yield stage (stage III), produce a new injury, a slight increase of permeability; unloading stress drop damage (stage IV stage), stress drop, the strain increased sharply, after the fissure permeability permeability is increased sharply, leading order After the destruction stage; (V), stress, strain and flow changes were stable; (3) the failure stage of gas bearing sandstone, affected by the gas pressure and the Poisson effect, the radial strain and volumetric strain is far greater than the axial strain; (4) containing bedding sandstone unloading failure form to produce along the bedding plane direction the tensile shear mixed fractures. Kozeny-Carman equation and fracture flow theory based on a strain dependent permeability model, reveals the failure mechanism of Seepage Damage of gas bearing sandstone, study of gas outburst, and is of great significance in breaking off the rock movement and drainage hole optimization design.

【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;重庆大学资源及环境科学学院;
【基金】：国家科技重大专项(No.2016ZX05045-004)~~
【分类号】：TU45
【正文快照】： 受长期地质构造作用的影响,煤岩体的受力状态和赋存环境相当复杂[1],在其形成过程中,伴随产生大量的瓦斯气体,受地质条件影响,产生的瓦斯气体赋存于覆岩及煤层中[2],一旦受到采动影响,煤、岩体的原有应力状态遭到破坏,应力重新分布,进而导致煤、岩体内的孔隙、裂隙结构发生变

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