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针对软板岩内部特殊的构造及其遇水膨胀的特点,以湖南省怀化芷江地区的板岩为例,选取14组岩样分别进行矿物成分、微观结构测试和侧向约束膨胀试验,研究软质板岩的膨胀特性及其微观机制。结果表明:软质板岩侧向约束膨胀率与吸水时间之间呈指数函数关系,在试验早期,侧向约束膨胀率随吸水时间的延长而增大,且增长速率较快,侧向约束膨胀率-吸水时间关系曲线较陡;在试验后期,侧向约束膨胀率趋于稳定,侧向约束膨胀率-吸水时间关系曲线由陡变缓。侧向约束膨胀率随着吸水率的增长呈乘幂函数关系增长,在试验早期增长较快,而后增长速率变小,直至最后趋于稳定。轴向膨胀率随轴向荷载的增加呈负对数函数减小,初期减小幅度较大,后期逐渐变低。结构面方向和试样轴向的夹角α在区间[0°,90°]之间变化时,极限侧向约束膨胀率随着夹角α的增大而减小。
In view of the special structure inside the soft slate and the characteristics of its swelling with water, taking the slate in Zhijiang area of Huaihua, Hunan Province as an example, 14 groups of rock samples were selected for mineral composition, microstructure test and lateral restraint expansion test respectively. Expansive properties of soft slate and its microscopic mechanism. The results show that there is an exponential relationship between the lateral restraint expansion rate and the water absorption time of the soft slate. In the early stage of the experiment, the lateral restraint expansion rate increases with the increase of the water absorption time, and the growth rate is faster and lateral restraint expansion The relationship between rate and water absorption time is steeper. Late in the experiment, the rate of lateral restraint expansion tends to be stable, and the curve of lateral restraint expansion rate-water absorption ratio slows down from steepness. The lateral restraint expansion rate increases exponentially with the increase of water absorption, increases rapidly in the early stage of the experiment, and then increases at a slower rate until finally stabilizes. The axial expansion rate decreases negative logarithm with the increase of axial load, the initial decrease is larger and the later is gradually lower. When the angle α between the direction of the structural plane and the axial direction of the specimen changes between the interval [0 °, 90 °], the ultimate lateral restraint expansion rate decreases with the increase of the included angle α.