Research on Deformation of Surrounding Rock by Linear Monitoring Technology in Large Underground Cavity with High Geostress
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摘要: 基于工程地质调查及滑动测微计监测成果,从空间连续角度(围岩应变)讨论了圆筒形洞室穹顶、长廊型洞室群中隔墙岩柱在下挖阶段的围岩变形特征;分析圆筒形洞室顶板变形空间分异性和演化规律;揭示了洞室群中隔墙岩柱的松弛圈范围及演化特征。研究表明:(1)结构面对圆筒形洞室穹顶围岩变形量级影响很小(5 mm以内),穹顶结构面区段与Ⅲ级围岩变形规律类似,围岩变形主要发生在掌子面近接施工期,且影响范围局限于正穹顶;(2)滑动测微孔内空气与洞室大气联通,测值具有周期变化规律;(3)长廊型洞室中隔墙岩柱松弛圈范围与应力集中程度影响成正比,应力集中区松弛区深度约为开挖高度的1/3;松弛圈的发展主要发生在下挖阶段,洞室成型后,基本无扩展。研究成果可供高地应力深埋洞室的支护结构优化和稳定性评价参考。Abstract: Based on the monitoring data of INCREX Mobile Extensometer implemented on the dome and engineering geological investigation in large underground cavity, the deformation characteristics of surrounding rock of dome in the cylindrical cavern and the middle wall of the long corridor-shaped underground cavern are discussed, as well as the development of relaxation circle. The spatial differentiation and evolution law of deformation in the cylindrical cavern dome are analyzed. The range and evolution characteristics of relaxation zone of mid-partition in large underground caverns are clarified. The results show that: (1) The structural plane has little influence on the deformation magnitude of the surrounding rock of the cylindrical cavern dome (within 5 mm), and the deformation law of the joint rock in the dome is similar to that of the grade III surrounding rock. The deformation of the surrounding rock mainly occurs in the construction period near the excavation face, and the influence range is limited to the normal dome. (2) The air in the measuring micrometer borehole is connected with the air in the cavern, and the measured value has a periodic variation. (3) The range of relaxation zone is proportional to the degree of stress concentration, and the maximal depth of relaxation zone is about 1/3 of the excavation height. The development of relaxation zone is mainly concentrated in the excavation stage, and there is basically no expansion after the cavity is formed. The research results can provide reference for the optimization and stability evaluation of the supporting structure of deep buried caverns under high geostress.
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图 14 高应力洞室松弛圈范围与洞室高度关系曲线[10]
表 1 实际分层开挖信息
开挖层序 分层尺寸(宽×高)/m 开挖时间(年月) Ⅰ 34×12.6 201401—201412 Ⅱ 34×3.6 201411—201505 Ⅲ 34×8.5 201505—201512 Ⅳ 31×8.5 201602—201610 Ⅴ 31×8.5 201609—201612 Ⅵ 31×10 201611—201703 Ⅶ 31×8.5 201702—201709 Ⅷ 20×13 201708—201711 Ⅸ 20×9 201712—201805 Ⅹ 16×5 201801—201806 表 2 尾水调压室监测点埋设参数统计表
部位 仪器类型 测点编号 位置 1号尾调室 滑动测微孔 SCzwt-1-1 正穹顶 多点变位计 Mzwt-1-2 正穹顶 滑动测微孔 SCzwt-1-2 下游侧穹顶 多点变位计 Mzwt-1-5 下游侧穹顶 4号尾调室 滑动测微孔 SCzwt-4-1 下游侧穹顶 多点变位计 Mzwt-4-5 下游侧穹顶 表 3 主厂房-主变洞中隔墙监测点埋设参数统计表
仪器类型 测点编号 位置 埋设日期(年-月-日) 滑动测微孔 SCzc0-012-1 厂纵0-12 2017-01-07 滑动测微孔 SCzc0+229-1 厂纵0+229 2016-07-09 表 4 圆筒型洞室穹顶围岩变形特征值
部位 测点编号 位置 累计变形/mm 最大应变 量值
/(mm·m–1)距穹顶
/m1号尾
调室SCzwt-1-1 正穹顶 4.737 0.585 12.1 Mzwt-1-2 正穹顶 3.67 0.37 1.5~3.5 SCzwt-1-2 下游侧穹顶 6.818 0.393 23 Mzwt-1-5 下游侧穹顶 16.82 1.89 1.5~3.5 4号尾
调室SCzwt-4-1 下游侧穹顶 4.918 0.4 21 Mzwt-4-5 下游侧穹顶 21.73 4.72 1.5~3.5 表 5 左厂房–主变洞中隔墙围岩变形特征值
测点编号 位置 累计变形mm 最大应变 量值/(mm·m–1) 距厂房/m SCzc0-012-1 厂纵0—12 58.828 4.377 26 SCzc0+229-1 厂纵0+229 60.126 9.449 3 -
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