Stress characteristics and hazard analysis of rock-burst and large deformation of a deep-buried tunnel on the Sichuan-Tibet Railway
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摘要: 青藏高原区域地质构造作用强烈，高地应力问题是川藏铁路隧道建设中面临的重点问题之一。本文基于水压致裂法实测的钻孔地应力数据，结合区域地质资料、室内试验、初始地应力场反演分析等，对某隧道地应力特征及工程效应进行了研究分析。地应力测试结果显示，该工程区应力场类型可划分为逆断型(SH>Sh>Sv)和走滑型(SH>Sv>Sh)两种类型应力场，水平构造应力占据主导地位，最大水平主应力优势方向为NE～NEE向，与区域应力场分布和周边活动断裂反映的力学机制基本一致。工程区初始地应力场反演分析结果表明，隧道轴线最大水平主应力SH为7.36～49.87 MPa，最小水平主应力Sh为4.36～25.97 MPa，垂向主应力Sv为5.24～31.69 MPa，隧道沿线73.00%的区域处于高到极高地应力状态，具有发生岩爆和大变形的潜在高地应力条件，综合岩石弹性变形能指数认为二长花岗岩和花岗闪长岩均具有中等岩爆倾向的储能和释能条件。最后，对该隧道不同埋深处岩爆和大变形危险性进行了分析。Abstract: The Tibetan Plateau region has strong regional geological tectonics. The high crustal stress problem is one of the key problems in the construction of the Sichuan-Tibet Railway Tunnel. Based on the drilling ground stress data measured by hydraulic fracturing method, combined with regional geological data, indoor tests and initial ground stress field inversion analysis, the stress characteristics and engineering effects of a tunnel are studied and analyzed. The ground stress test results show that the stress field type of the engineering area can be divided into: reverse fracture type (SH>Sh>Sv) and slip type (SH>Sv>Sh). Horizontal tectonic stress is dominating, and the dominant direction of maximum horizontal principal stress is NE~NEE. The direction is essentially consistent with the mechanical mechanism of regional stress field distribution and peripheral activity fracture. The inversion analysis of the initial ground stress field shows that the maximum horizontal principal stress SH along the tunnel axis is 7.36-49.87 MPa, the minimum horizontal principal stress Sh is 4.36-25.97 MPa, the vertical principal stress Sv is 5.24-31.69 MPa. 73.0% of the areas along the tunnel line is in a high to extreme high altitude stress state, with potential high stress conditions for rock bursts and large deformations. The comprehensive rock elastic deformation energy index believes that both monzonitic granite and granodiorite have energy storage and release conditions with medium rock burst tendency. Finally, hazard analysis of rock-burst and large deformations at different burial depths of the tunnel are studied.
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图 1 川藏铁路某隧道进出口位置
Figure 1. The entrance and exit position of a tunnel on the Sichuan-Tibet Railway
图 2 川藏铁路某隧道地质剖面图
Figure 2. Geological profile of a tunnel on the Sichuan-Tibet Railway
图 3 最大、最小水平主应力与隧道埋深的关系
Figure 3. The relationship between the maximum and minimum horizontal principal stresses and the tunnel burial depth
图 4 实测最大水平主应力方向玫瑰花图
Figure 4. The rose chart of the direction of the actual measured maximum horizontal principal stress
图 5 侧压力系数与隧道埋深的关系
Figure 5. The relationship between the lateral pressure coefficient and the buried depth of the tunnel
图 6 隧道轴线三向主应力及埋深分布
Figure 6. Three - direction principal stress and buried depth distribution of tunnel axis
图 7 模拟最大水平主应力方向玫瑰花图
Figure 7. The rose chart of the direction of the maximum level of main stress was Simulated
图 8 04钻孔实测地应力值与模拟值对比
Figure 8. 04 comparison of measured in-situ stress values in boreholes and simulated values
表 1 工程区岩石弹性变形能指数值
Table 1. Elastic deformation energy index of rock in engineering areas
岩性 天然密度
ρ/（g/cm3）试验温
T/（°C）岩石弹性变形能
指数Wet判定结果 二长花岗岩 2.70 25 3.60 中等岩爆 花岗闪长岩 2.69 25 4.00 中等岩爆 
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表 2 隧道实测钻孔地应力数据
Table 2. Measured borehole ground stress data of tunnel
编号 测试深度/m 主应力值/MPa SH方位 SH Sh Sv 01 104～272 04.53～11.39 04.34～09.02 02.66～06.96 N38.1°～42.3°E 02 101～299 05.11～09.55 05.07～08.85 02.58～07.65 N40.7°～45.3°E 03 275～400 12.51～16.16 08.92～12.49 07.43～10.80 N39.8°～53.2°E 04 370～720 08.48～22.46 07.86～18.94 08.89～17.29 N50°～70°E 05 110～415 11.05～24.78 08.73～16.61 02.96～11.14 N48°～52°E 06 222～471 07.19～12.31 05.69～10.30 05.80～12.28 N59°～72°E 07 135～716 09.65～26.26 06.85～19.26 03.62～19.20 N32°～63°E 08 082～113 05.24～07.26 04.76～06.18 02.23～03.06 N47.2°E 09 218～420 08.06～11.57 06.00～08.18 05.61～10.78 N31.7°～40.3°E 10 421～666 11.81～20.46 08.07～13.61 10.95～17.34 N41°～76°E 11 460～530 12.45～14.56 08.16～09.14 11.05～12.73 N48°E 12 180～261 07.23～12.44 05.71～09.35 04.87～07.06 N50°E 13 127～199 06.81～09.06 04.23～05.59 03.43～05.35 N32°～46°E 14 125～562 04.81～19.45 04.70～15.51 03.24～14.62 N46°E 15 095～421 08.00～23.59 07.76～16.83 02.46～10.94 N47°～51°E 16 071～515 02.95～23.46 01.37～17.68 01.84～13.38 N43°～53°E
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表 3 隧址区岩体物理力学参数取值
Table 3. Values of physical and mechanical parameters of rock mass in the tunnel site area
岩性 时代 弹性模E/GPa 泊松比v 密度ρ/（kg/m3） 燕山期花岗闪长岩 γδ53 33 0.22 2650 燕山期二长花岗岩 ηγ53 26 0.24 2760 砂岩夹板岩夹页岩 K1dSs+Sh 16 0.28 2650 燕山期闪长玢岩 δμ53 32 0.21 2730 压碎岩 FTγ 6 0.31 2650 断层角砾 Fb 3 0.33 2600 糜棱岩 Ml 4 0.32 2630
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表 4 隧道岩爆评价指标及评价结果
Table 4. Evaluation index and evaluation results of tunnel rock explosion
里程编号 隧道埋深/m 岩性 评价指标 H=2（欧氏距离） 评价
结果σc/σmax σθ/σc σc/σt Kv Wet 无 轻微 中等 强烈 CK006+500～CK007+100 560～580 花岗闪长岩 5.91 0.36 25.33 0.62 3.90 2.21 0.71 0.81 1.90 轻微 CK007+900～CK008+700 750～900 花岗闪长岩 5.05 0.36 25.33 0.62 3.60 2.18 0.66 0.67 1.54 轻微 CK008+700～CK009+150 680～980 花岗闪长岩 4.62 0.35 27.00 0.62 3.60 2.15 0.63 0.62 1.39 轻微 CK009+150～CK009+350 980～1020 花岗闪长岩 3.36 0.58 19.57 0.71 4.30 3.36 1.96 0.35 0.67 中等 CK009+350～CK009+850 1000～1200 花岗闪长岩 3.07 0.51 19.57 0.71 4.30 3.08 1.63 0.19 0.56 中等 CK009+850～CK010+350 1100～1250 花岗闪长岩 2.83 0.59 21.75 0.71 3.90 3.33 1.99 0.37 0.52 中等 CK010+350～CK010+600 1120～1210 二长花岗岩 2.76 0.51 21.75 0.62 3.60 2.96 1.53 0.49 0.59 中等 CK010+600～CK010+900 1270～1320 二长花岗岩 2.75 0.62 21.75 0.81 3.90 3.53 2.37 0.72 0.51 强烈 CK010+900～CK011+300 1130～1270 二长花岗岩 3.08 0.58 21.75 0.62 3.60 3.24 1.88 0.56 0.69 中等
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表 5 隧道大变形评价指标及评价结果
Table 5. Evaluation index and evaluation results of tunnel large deformation
里程
编号隧道埋
深/m岩性 评价指标 H=2（欧氏距离） 评价
结果σmax/MPa σc/MPa σb/σmax E/GPa K S W 无 轻微 中等 强烈 CK011+500～CK011+700 850～940 砂岩夹板岩 44.65 35.00 0.26 2.52 5.5 5.5 1.5 1.393 1.046 1.241 2.796 轻微 CK011+700～CK012+000 760～870 砂岩夹板岩 43.76 30.00 0.23 2.52 5.5 6.5 5.5 2.864 1.950 1.041 2.234 中等 CK012+000～CK012+300 670～760 砂岩夹板岩 37.15 30.00 0.27 3.13 4.5 4.5 2.5 1.405 0.806 1.375 2.404 轻微
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