柱状节理玄武岩松弛圈尺寸效应及地应力影响
Influences of size effect and in-situ stress of columnar jointed basalt relaxation zone
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摘要: 为研究柱状节理玄武岩松弛圈尺寸效应及地应力对其产生的影响,选取了8种不同尺寸典型洞室,利用单孔声波法测试松弛深度,对161组测试成果进行数据统计及曲线拟合,建立了松弛深度经验计算公式。研究结果表明,断面尺寸及地应力是影响洞室松弛深度的2个主要因素;洞室边墙中上部松弛深度最大,尺寸效应明显,与洞室高度表现出明显的线型相关性,高地应力会加剧这种尺寸效应,在低地应力条件下,松弛深度一般是洞室高度的1/6,高地应力条件下,松弛深度一般是洞室高度的1/3,极端情况下24 m高洞室边墙中部松弛深度会达到10.2 m。Abstract: To investigate the influences of size effect and in-situ stress of columnar jointed basalt relaxation zone, 8 typical tunnels with different sizes are selected, and an empirical formula for relaxation depth is established based on the data statistics and curve fitting of 161 groups of test results by using the single-hole acoustic wave tests. The test results show that the excavation section size and high in-situ stress are the two main influencing factors of the relaxation depth. The maximum relaxation depth appears in the middle-upper part of side wall of cavern, the size effect is obvious and linearly correlates with the height of cavern, and high in-situ stress will increase the size effect. Under the low in-situ stress, the relaxation depth is generally 1/6 of the height of cavern. Under the high in-situ stress, the relaxation depth is generally 1/3 of the height of cavern, and in the middle of 24 m-high cavern wall, the extreme relaxation depth will reach 10.2 m.