深孔地应力测试在铁路隧道工程勘察中的应用
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摘要
为分析铁路隧道隧址区地应力分布、发育方向、变化规律,判断隧道洞身围岩岩爆、软岩变形特征,运用单回路水压致裂法,对隧道区内施工的4个深孔进行了地应力测试工作。结果表明,隧道洞身附近最大水平主应力为12~21MPa,最小水平主应力为9.6~14.2MPa,估算垂直应力为9.6~15.4MPa;地应力特征是以构造主应力为主,三向主应力具有随深度增加而增大的趋势;隧道洞身附近最大水平主应力优势方向为NNW14°~28°,表明隧道洞身附近地应力以NNW向挤压为主,主应力方向与拟设隧道轴线走向夹角在12°~26°,对洞室围岩稳定有利。由于隧道埋深大,地应力高,构造发育,岩性构成复杂,软硬相夹,存在硬质岩产生岩爆,软质岩遇水变形的可能。建议隧道在硬质岩段施工,采用"短进尺、多循环、强支护"的掘进方法,在软质岩段施工,采用"少扰动、快封闭"的掘进方法。该研究对隧道的设计施工具有重要的现实意义。
To analyze railway tunnel site area crustal stress distribution, development orientation, variation pattern, and estimate tunnel trunk wall rock burst, soft rock deformation characteristics, using single circuit hydraulic fracturing method, carried out crustal stress testing in four deep boreholes in site area. The result has shown that the trunk nearby maximum horizontal principal stress is 12~21MPa,minimum 9.6~14.2MPa, estimated vertical stress 9.6~15.5MPa. Crustal stress is characterized by tectonic principal stress; three dimen sional principal stresses have an increasing trend along with the increase of depth. The trunk nearby dominant direction maximum hori zontal principal stress is NNW14o~28o, indicated crustal stress near the trunk is mainly NNW compression, included angle between principal stress direction and strike of proposed tunnel axis is 12o~26o, thus in favor of trunk wall rock stable. Since the deep buried depth of tunnel, crustal stress is high, structures developed, rock composition is complex, and alternating with soft and hard, thus hard rock burst and soft rock water deformation are possible. It is suggested that during the construction in hard rock sector, using the driving method of"short footage, multi-circulation and strong support", in soft rock sector"less disturbance, quick sealing". The study has great operation significance in tunnel design and construction.
To analyze railway tunnel site area crustal stress distribution, development orientation, variation pattern, and estimate tunnel trunk wall rock burst, soft rock deformation characteristics, using single circuit hydraulic fracturing method, carried out crustal stress testing in four deep boreholes in site area. The result has shown that the trunk nearby maximum horizontal principal stress is 12~21MPa,minimum 9.6~14.2MPa, estimated vertical stress 9.6~15.5MPa. Crustal stress is characterized by tectonic principal stress; three dimen sional principal stresses have an increasing trend along with the increase of depth. The trunk nearby dominant direction maximum hori zontal principal stress is NNW14o~28o, indicated crustal stress near the trunk is mainly NNW compression, included angle between principal stress direction and strike of proposed tunnel axis is 12o~26o, thus in favor of trunk wall rock stable. Since the deep buried depth of tunnel, crustal stress is high, structures developed, rock composition is complex, and alternating with soft and hard, thus hard rock burst and soft rock water deformation are possible. It is suggested that during the construction in hard rock sector, using the driving method of"short footage, multi-circulation and strong support", in soft rock sector"less disturbance, quick sealing". The study has great operation significance in tunnel design and construction.
引文
[1]湖南省煤田地质局第三勘探队.某隧道深孔钻探地质报告[R].湖南永州:湖南省煤田地质局第三勘探队,2011.
[2]中国地震局地壳应力研究所.某隧道地应力测量中间报告[R].北京,2009.
[3]中铁二局集团有限公司.铁路隧道施工规范(TB10204-2002)[S]北京:中国铁道出版社,2002.
[2]中国地震局地壳应力研究所.某隧道地应力测量中间报告[R].北京,2009.
[3]中铁二局集团有限公司.铁路隧道施工规范(TB10204-2002)[S]北京:中国铁道出版社,2002.
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