24 6 Vol.24 No.6 2005 8 Chinese Journal of Rok Mehanis and Engineering Aug. 2005 2 2 (. 30027 2. 30007) TU 457 A 000 695(2005)6 2982 07 COMPREHENSIVE STUDY ON PREDICTION OF ROCKBURST IN DEEP AND OVER-LENGTH HIGHWAY TUNNEL LU Qing SUN Hong-yue SHANG Yue-quan CHEN Kan-fu 2 XU Guo-feng 2 (. College of Civil Engineering and Arhiteture Zhejiang University Hangzhou 30027 China 2. Zhejiang Provinial Planning Design and Researh Institute of Communiations Hangzhou 30007 China) Abstrat Cangling tunnel in Taizhou Jinyun highway with a depth about 768 m and with a length about 7.6 km will be the deepest and longest tunnel in Zhejiang Provine after onstrution. Rokburst is a serious problem during the tunnel exavation. For the predition of rokburst physio-mehanial properties of the rok masses were tested in the laboratory and the in-situ stress state in the engineering area was measured and analyzed. Then the rok masses along the tunnel were lassified on the basis of loal geologial investigation. A mehanial model was developed to express the atual onditions of the engineering area aording to properties of the rok masses foal mehanism solutions and in-situ stress state. The in-situ stress field of the engineering area was regressed by 3D finite element method (FEM) by using in-situ measured stress. The alulated results were applied to numerial analysis of the stress distribution in rok masses around the tunnel. Finally the probability and intensity of rokburst along tunnel were predited aording to four different rokburst predition models developed by predeessors on the basis of alulated stress distribution around the tunnel and uniaxial ompressive strength of the rok masses. Key words tunneling engineering rokburst in-situ stress numerial simulation 2004 08 3 2004 2 08 (403728) (978 ) 200 E-mail lvqing@zju.edu.n
24 6. 2983 [ 8] 3. R 70%) Φ Φ Φ Kidybinski W = Φ () W 2 3 ( ET b ST ET SP /ΦST C SP 0 K94+760 K02+290 K94+760 K02+340 7.6 km 768 m Fig. Energy aumulation in rok speimen [2 9 ] W ET 90 077 m 239 370 m 50 768 m W ET 2.0 ( ) NE NEE 2.0 W ET 5.0 ( ) (2) WET 5.0 ( )
2984 2005 (2) 4 2 MTS85Teststar 0. mm/min R b 70% 9 3 4. 2 WET 4 WET 2.7 2.26 3.2 3 40 2 2 NEE NW EW NWW Tabe Uniaxial ompressive strengths of the two main speimens /MPa 69.3 5.3 80.4 65.6 3.3 (996 5 ) 2 Fig.2 Foal mehanism solutions in north areas to the engineering site Vp 3.2 4.2 km/s [2] G IV V 7.9 27.3 MPa IV V II III [9] 4.2
24 6. 2985 3 () H ) h ) (2) 2 (3) NW30 72 NW 2 3 Table 2 Fitting results of horizontal prinipal stresses inreased with depth based on in-situ data Fig.3 Finite element bak analysis model of in-situ stress field based on measured results H h H /m H = 0.098 8H+3.24 2 CS 40.30 3 () h = 0.054 4H+2.694 0 H = 0.067 0H 0.03 2 CS2 62.3 h = 0.035 0H+.80 0 (2) H = 0.55 H 0.56 8 CS3 393.60 h = 0.02 0H 0.548 () H h (2) H (m) (3) 4.3 3 km 8 km 0.000 m K98+300 K00+ 200 H ) 4.8 7.3 MPa y ) 3.0 7.3 MPa 3 K98+060 K00+440 NW69 3 Table 3 Physio-mehanial properties of rok masses 6 39 /MPa /(kn m 3 ) 4.4 5 000 0.22 26.5 8 000 0.26 24.0 0 x ) 50 m 40 m() 3 83 665 26 59 [3 4] x y
2986 2005 3 3 () Russenes Russenes 974 Kirsh R / R 0.20 ( ) ( 4 ) 0.20 / R 0.30 ( ) 59.5 MPa ) 48.9 (3) 0.30 / R 0.55 ( ) MPa 0.55 / R ( ) 32.825 30.376 27.928 25.480 23.03 20.583 8.34 5.686 3.237 (2) R / 4.5 R / = 4.5 R / = 5.5 2.5 R / 2.5 ( ) ( ) ( ) ( ) (4) (a) x = 4. MPa y = 7. MPa 5.604 47.608 43.63 39.68 35.623 3.627 27.632 23.637 9.642 (3) Rb / R R (b) x =5.0 MPa y = 6.7 MPa 69.3 MPa Rb 5.3 MPa 4 ( MPa) R 60 MPa Rb Fig.4 Distribution of under different initial stress states after 50 MPa exavation (positive for ompression stress MPa) 4 Russenes 5 III K98 637 4 K99+638 Rb / Russenes K97 702 K98 637 K99+638 K00+892 b / Rb / = 3 6 ( ) (5) Rb / 3 ( )
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