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对成兰铁路龙门山北段隧道群4种典型千枚岩进行不同加载方位角的强度和变形特性对比试验研究,研究结果表明:加载方位角和岩石矿物成分严重影响千枚岩变形特性,并与围压水平有关。千枚岩单轴抗压强度随方位角变化呈“U”型的各向异性特征,所试验的4种千枚岩各向异性率由大至小对比关系为:HP>MP>QP>CP。试样一般在峰值应力前产生扩容现象,扩容起始应力和形式与加载方位角或层理发育程度相关。三轴压缩试验中,千枚岩垂直层理加载时的峰值强度、长期强度和残余强度比平行层理加载明显偏高,并随围压水平增加而增大。千枚岩不同加载方位角下单轴压缩试验破坏模式归纳为4种:层理面滑移剪切破坏、压拉剪切破坏、张拉破坏、复合破坏。
Comparative tests on strength and deformation characteristics of four types of typical phyllites in the northern segment of the Longmenshan tunnel in the Chenglan Railway show that loading azimuth and rock mineral composition seriously affect the deformation characteristics of phyllite And the confining pressure level. The anisotropy of uniaxial compressive strength of phyllite with “U” -type changes with azimuth angle shows that the correlations of anisotropy of four phyllites from high to low are: HP> MP> QP > CP. The sample generally dilates before peak stress, and the initial stress and form of expansion is related to the loading azimuth or the degree of bedding development. In the triaxial compression tests, the peak strength, long-term strength and residual strength of phyllite vertical bedding are obviously higher than those of parallel bedding bedding and increase with the increase of confining pressure. The failure modes of uniaxial compression tests under different loading azimuth angles of the phyllite can be divided into four types: slip shear failure of bedding plane, tensile shear failure, tensile failure and composite failure.