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| The Characteristics and Formation Mechanism of Rock-burst for a Long and Deep Tunnel of Chengdu-Lanzhou Railway |
| SONG Zhang, YUAN Chuan-bao, DU Yu-ben, WANG Yan-dong |
| (China Railway Eryuan Engineering Group Co. Ltd, Chengdou, Sichuan 610031, China) |
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Abstract Abstract：Research purposes： For its geological background such as the complex geological structure conditions, high tectonic stress field characteristics, hard and intact surrounding rock conditions, which is under construction for the Ping′an tunnel of Chengdu-Lanzhou railway, the rock-burst disasters of surrounding rock generally produced in the process of tunnel construction. According to the phenomenon of rock-burst and it′s failure characteristics of supporting structure, this paper based on the geological survey, the data analysis of geo-stress test and physical mechanics test of rock mass, from several aspects of the engineering geological environment, geological structure, geo-stress field and formation lithology, the formation mechanisms of rock-burst of surrounding rock which is in the environment of complex geological structure and high geo-stress field were analyzed in perspective of engineering geology, and the rock burst level of the other section of tunnel under similar engineering geological conditions were evaluated. Research conclusions： (1)In regional structure the 3# inclined shaft working area of Ping′an tunnel located in the front arc position of Jiaochang mountain structural belt, new and old structures such as fold and fault were developed and superimposed, with complex construction condition. (2) In tunnel rock-burst was mainly expressed as the phenomenon of rock burst loose, spalling, and ejection, etc., and with the failure characteristics of primary support concrete spalling, fracture, steel distortion, crack and collapse for the engineering structure. (3) Rock-burst was mainly presented as the immediate rock-burst characteristics in time, and rock-burst level is moderate to strong. (4) In perspective of engineering geology, the formation mechanism of rock-burst of tunnel surrounding rock can be summarized as the comprehensive influence of main factors such as the inoculation conditions of strongly complex geological structure, mechanics condition of high geo- stress field and condition of hard and intact surrounding rock. (5) The 〖JP3〗analysis methods and conclusions of this paper have certain reference significance for the design and construction of rock-〖JP〗burst of surrounding rock of tunnel engineering under similar engineering geological conditions in mountainous area.
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Received: 15 September 2017
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2017, Vol. 34 
