湖北云应盐矿深部层状盐岩直剪试验研究

DIRECT SHEAR TESTS FOR LAYERED SALT ROCKS OF YUNYING SALT MINE IN HUBEI PROVINCE

为了解湖北云应盐矿深部层状盐岩,特别是盐岩和硬石膏夹层界面的抗剪性能,开展3类典型岩体的直剪试验。试验结果表明:层状盐岩界面和盐岩、硬石膏的剪切应力–位移曲线较为相似,加载初期曲线的斜率较小,剪应力增加缓慢而位移增加较快;当剪应力达到某一数值后,剪切位移增加变得缓慢,曲线斜率变大;快达到峰值强度时曲线斜率再逐渐由陡变缓;达到峰值强度后出现软化,剪应力随位移的增加逐渐达到残余强度,从峰值强度到残余强度过程中,相对而言,层状岩石交界面的剪应力下降得比较快。试验结果还表明:盐岩硬石膏交界层面处的抗剪强度参数c,?值分别为4.08 MPa和45.9°,和盐岩试样和硬石膏试样的强度参数相差并不大,甚至还略强。这说明湖北省云应盐矿深部层状盐岩中盐岩和硬石膏夹层的交界层面具有较强的粘结力,不是一个弱面,这将有利于盐岩溶腔的密闭性和稳定性。层状盐岩的这一特殊力学特性对于在深部层状盐岩构造中开展能源储备是非常有利的。

For investigation on the characteristics of shear deformation and strength of layered salt rocks in Yunying Salt Mine, Hubei Province, direct shear tests on three types of rocks are carded out. It is shown that the curves of shear stress vs. displacement of salt rock, anhydrite and layered salt rock are similar： during the beginning stage of shear loading, the slope coefficients are small, the shear displacement increasing fast while the shear stress increasing slowly; when the shear stresses reach a certain value, the increase of shear displacement slows down, and the slope coefficients get larger; the increase of shear displacement becomes fast again prior to shear stress reaching peak value; after peak point, strain softening appears, the shear stresses decreasing slowly and reaching residual strength finally. The test results also show that the shear strength of layered salt rocks is close to or even slightly higher than that of salt rock and anhydrite： cohesive strength c = 4.08 MPa, and frictional angle φ = 45.9°. This indicates that the interfaces between salt rock and anhydrite are not weak as expected. The strong interface property of layered salt rocks will guarantee the sealability and stability of salt caverns, and benefit the energy（oil and gas） storage in layered salt rocks formation in depth.