[Objective] Deep tunnels exhibit characteristics such as high ground stress and strong excavation disturbance. Especially in an intact hard rock environment, the original elastic strain energy stored in surrounding rocks is suddenly released due to the unloading effect during excavation, which can easily trigger rockburst disasters. Severe rockbursts pose a great threat to construction personnel and equipment such as tunnel boring machine (TBM), delaying the construction period and causing huge economic losses. Rockburst hazard is one of the key factors that affect the safety and efficiency of TBM excavation in deep tunnels. Active prevention is the most important technical method for controlling rockburst risk and ensuring personnel and equipment safety during construction. [Methods] With the deeply buried TBM section of the Xianglushan Tunnel in the Dianzhong Water Diversion Project as the engineering background, numerical simulations were performed to analyze the mechanisms and effects of two active rockburst control methods: destress blasting and pilot tunnel. A creep damage model with internal variables was employed to simulate the TBM continuous excavation process. Factors influencing the effectiveness of active rockburst control, such as the external insertion angle, number of advance blasting holes, and diameter and length of the pilot tunnel, were considered. The mechanisms of two active rockburst control methods were elucidated, and the release effects and spatiotemporal evolution processes of stress and energy of surrounding rocks under different construction parameters were studied. [Results] The results demonstrated that active control had achieved the stress “peak-shaving” effect during TBM excavation by preconcentrating rock stress, thereby preventing sudden energy accumulation and reducing rockburst risk. Briefly, it had transferred rockburst risk during the secondary excavation to the construction process of destress blasting and pilot tunnel. The active control method and specific excavation parameters could be determined based on the actual rockburst risk level and on-site conditions. Destress blasting was suitable for local targeted stress release, ensuring that high stresses within the length of advanced boreholes are effectively released in a controlled manner. Increasing the number of advance blasting holes was more important for reducing rockburst risk than increasing the external insertion angle. Compared with destress blasting, pilot tunnel could better transfer and reduce the high stress of surrounding rocks and fully release energy from high-energy-storing rock masses. Furthermore, the overall stress and energy release effects demonstrated by pilot tunnel were better, and the technique’s impact range was wider than those of destress blasting. Increasing the diameter and length of pilot tunnel could further reduce the risk of rockbursts. In conclusion, the construction of a pilot tunnel was more complex than that of destress blasting, but its stress release effect was generally better. In cases where a tunnel may have faced strong rockburst risk or other ineffective measures, pilot tunnels could be considered for realizing proactive prevention and rockburst control. [Conclusions] These research results can increase our understanding of the mechanism of rockburst prevention and offer a theoretical basis and a reference for rockburst active control and parameter optimization in practical engineering.
[1] 李邵军,郑民总,邱士利,等.中国锦屏地下实验室开挖隧洞灾变特征与长期原位力学响应分析[J].清华大学学报(自然科学版), 2021, 61(8):842-852. LI S J, ZHENG M Z, QIU S L, et al. Characteristics of excavation disasters and long-term in-situ mechanical behavior of the tunnels in the China Jinping Underground Laboratory[J]. Journal of Tsinghua University (Science&Technology), 2021, 61(8):842-852.(in Chinese)
[2] 张镜剑,傅冰骏.岩爆及其判据和防治[J].岩石力学与工程学报, 2008, 27(10):2034-2042. ZHANG J J, FU B J. Rockburst and its criteria and control[J]. Chinese Journal of Rock Mechanics and Engineering, 2008, 27(10):2034-2042.(in Chinese)
[3] 汪珂.深埋隧道岩爆预测及防治技术现状综述[J].隧道建设(中英文), 2021, 41(2):212-224. WANG K. Overview of state-of-art of rockburst prediction and prevention techniques for deep-buried tunnels[J]. Tunnel Construction, 2021, 41(2):212-224.(in Chinese)
[4] 欧阳林,张如九,刘耀儒,等.深埋隧洞岩爆防控技术及典型工程应用现状综述[J].长江科学院院报, 2022, 39(12):161-170. OUYANG L, ZHANG R J, LIU Y R, et al. Review on rockburst prevention techniques and typical applications in deep tunnels[J]. Journal of Yangtze River Scientific Research Institute, 2022, 39(12):161-170.(in Chinese)
[5] 肖亚勋,冯夏庭,陈炳瑞,等.深埋隧洞极强岩爆段隧道掘进机半导洞掘进岩爆风险研究[J].岩土力学, 2011, 32(10):3111-3118. XIAO Y X, FENG X T, CHEN B R, et al. Rockburst risk of tunnel boring machine part-pilot excavation in very strong rockburst section of deep hard tunnel[J]. Rock and Soil Mechanics, 2011, 32(10):3111-3118.(in Chinese)
[6] 汪洋,王继敏,尹健民,等.基于快速应力释放的深埋隧洞岩爆防治对策研究[J].岩土力学, 2012, 33(2):547-553. WANG Y, WANG J M, YIN J M, et al. Research on prevention measures of rock burst based on rapid stress release in deep tunnel[J]. Rock and Soil Mechanics, 2012, 33(2):547-553.(in Chinese)
[7] ZHANG C Q, FENG X T, ZHOU H, et al. A top pilot tunnel preconditioning method for the prevention of extremely intense rockbursts in deep tunnels excavated by TBMs[J]. Rock Mechanics and Rock Engineering, 2012, 45(3):289-309.
[8] 房敦敏,刘宁,张传庆,等.高地应力区大直径TBM掘进岩爆风险控制[J].岩石力学与工程学报, 2013, 32(10):2100-2107. FANG D M, LIU N, ZHANG C Q, et al. Rockburst risk control for large diameter TBM boring in high geostress region[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(10):2100-2107.(in Chinese)
[9] 吴世勇,周济芳,杜成波.基于爆破卸压地应力快速释放的强岩爆防治方法与效果评价研究[J].工程科学与技术, 2018, 50(4):22-29. WU S Y, ZHOU J F, DU C B. Study on prevention and control effect of strong rock burst based on rapid stress release of blasting relieving pressure technology[J]. Advanced Engineering Sciences, 2018, 50(4):22-29.(in Chinese)
[10] HE S Y, LAI J X, ZHONG Y J, et al. Damage behaviors, prediction methods and prevention methods of rockburst in 13 deep traffic tunnels in China[J]. Engineering Failure Analysis, 2021, 121:105178.
[11] 赵毅. TBM强岩爆掘进段小导洞超前应力释放施工技术[J].隧道与地下工程灾害防治, 2022, 4(1):78-85. ZHAO Y. Advance stress release construction technology of small pilot tunnel in TBM strong rock burst tunneling section[J]. Hazard Control in Tunnelling and Underground Engineering, 2022, 4(1):78-85.(in Chinese)
[12] HAN X B, LIANG X M, YE F, et al. Statistics and construction methods for deep TBM tunnels with high geostress:A case study of Qinling Tunnel in Hanjiang-Weihe River Diversion Project[J]. Engineering Failure Analysis, 2022, 138:106301.
[13] 王旺盛,陈长生,王家祥,等.滇中引水工程香炉山深埋长隧洞主要工程地质问题[J].长江科学院院报, 2020, 37(9):154-159. WANG W S, CHEN C S, WANG J X, et al. Major engineering geological problems of Xianglushan deep-buried long tunnel in central Yunnan water diversion project[J]. Journal of Yangtze River Scientific Research Institute, 2020, 37(9):154-159.(in Chinese)
[14] ZHANG L, LIU Y R, YANG Q. A creep model with damage based on internal variable theory and its fundamental properties[J]. Mechanics of Materials, 2014, 78:44-55.
[15] ZHANG L, LIU Y R, YANG Q. Study on time-dependent behavior and stability assessment of deep-buried tunnels based on internal state variable theory[J]. Tunnelling and Underground Space Technology, 2016, 51:164-174.
[16] 张泷.基于内变量热力学的流变模型及岩体结构长期稳定性研究[D].北京:清华大学, 2015. ZHANG L. Research on rheological model based on thermodynamics with internal state variables and long-term stability of rock mass structures[D]. Beijing:Tsinghua University, 2015.(in Chinese)
[17] VLACHOPOULOS N, DIEDERICHS M S. Improved longitudinal displacement profiles for convergence confinement analysis of deep tunnels[J]. Rock Mechanics and Rock Engineering, 2009, 42(2):131-146.
[18] 侯少康,刘耀儒.双护盾TBM掘进数值仿真及护盾卡机控制因素影响分析[J].清华大学学报(自然科学版), 2021, 61(8):809-817. HOU S K, LIU Y R. Numerical simulations of double-shield TBM tunneling for analyzing shield jamming control factors[J]. Journal of Tsinghua University (Science&Technology), 2021, 61(8):809-817.(in Chinese)
[19] 中华人民共和国住房和城乡建设部,中华人民共和国国家质量监督检验检疫总局.水力发电工程地质勘察规范:GB 50287-2016[S].北京:中国计划出版社, 2017. Ministry of Housing and Urban-Rural Development of the People's Republic of China, General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China. Code for hydropower engineering geological investigation:GB 50287-2016[S]. Beijing:China Planning Press, 2017.(in Chinese)
[20] CHEN B, GU C S, BAO T F, et al. Failure analysis method of concrete arch dam based on elastic strain energy criterion[J]. Engineering Failure Analysis, 2016, 60:363-373.
[21] TANG B Y. Rockburst control using destress blasting[D]. Montreal:McGill University, 2000.
[22] ZHANG R J, LIU Y R, HOU S K. Evaluation of rockburst risk in deep tunnels considering structural planes based on energy dissipation rate criterion and numerical simulation[J]. Tunnelling and Underground Space Technology, 2023, 137:105128.
[23] LI C Y, HOU S K, LIU Y R, et al. Analysis on the crown convergence deformation of surrounding rock for double-shield TBM tunnel based on advance borehole monitoring and inversion analysis[J]. Tunnelling and Underground Space Technology, 2020, 103:103513.
[24] 张照太,陈竹,陈炳瑞,等.大直径TBM通过深埋强岩爆洞段的岩爆防治方法[J].煤炭学报, 2011, 36(S2):431-435. ZHANG Z T, CHEN Z, CHEN B R, et al. TBM construction method in the large overburden and intensive rock burst zone[J]. Journal of China Coal Society, 2011, 36(S2):431-435.(in Chinese)
[25] YAN P, ZHAO Z G, LU W B, et al. Mitigation of rock burst events by blasting techniques during deep-tunnel excavation[J]. Engineering Geology, 2015, 188:126-136.
