Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures(滇中引水工程海东隧洞围岩“小变形”试验段前期研究——兼及采用普通预应力锚索的风险与对策)

doi:10.3973/j.issn.2096-4498.2022.08.001

隧道建设（中英文） ›› 2022, Vol. 42 ›› Issue (8): 1321-1330.DOI: 10.3973/j.issn.2096-4498.2022.08.001

Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures(滇中引水工程海东隧洞围岩“小变形”试验段前期研究——兼及采用普通预应力锚索的风险与对策)

孙钧1，江宇1，李宁2，汪波3，樊勇4

（1. 同济大学隧道及地下工程研究所，上海 200092； 2. 上海理工大学，上海 200093；
3. 西南交通大学交通隧道工程教育部重点实验室，四川成都 610031； 4. 云南省水利水电勘测设计研究院，云南昆明 650021）

出版日期:2022-08-20 发布日期:2022-09-09
作者简介:孙钧(1926—)，男，江苏苏州人，1949年毕业于上海国立交通大学土木工程系结构工程专业，国内外隧道与地下工程知名学者、专家，同济大学荣誉、终身、一级教授，中国科学院(技术科学部)资深院士，前国际岩石力学学会副主席暨中国国家小组主席，中国岩石力学与工程学会名誉理事长(前理事长)，中国土木工程学会顾问、名誉理事(前副理事长)，中国土木工程学会、中国公路学会、上海市土木工程学会等学会隧道与地下工程分会前副理事长、理事长，港珠澳大桥技术专家组专家。

Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures
for Using Ordinary Prestressed Anchor Cables

SUN Jun1, JIANG Yu1, LI Ning2, WANG Bo3, FAN Yong4

(1.Institute of Tunnel and Underground Engineering,Tongji University,Shanghai 200092,China;2.University of Shanghai for Science and Technology,Shanghai 200093, China;3.Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;4.Yunnan Institute of Water & Hydropower Engineering Investigation,Design and Research,Kunming 650021,Yunnan,China)

Online:2022-08-20 Published:2022-09-09

摘要/Abstract

摘要： 针对高地应力软岩隧洞大、小变形围岩支护难题，强调普通预应力锚索和大尺度预应力让压锚索2种支护方案不同的适用条件。对发生一定大变形的软岩隧洞采用普通预应力锚索支护的风险进行分析，提出具体应对措施。以滇中引水工程海东隧洞试验段为例，对围岩大变形中的相对“大变形”与“小变形”限界进行了计算和探讨。通过原理分析、理论计算，并结合试验研究，验证锚杆、锚索施加预应力的重要性。此处认为： 1）普通预应力锚索适用于隧洞相对“小变形”区段，而让压锚索则适用于隧洞相对“大变形”区段，两者各适用于不同场合，绝不能相互取代； 2）隧洞中采用普通预应力锚索支护，预应力值切不能过高，否则有束筋拉断崩出洞外的风险，建议只有在围岩变形整体趋稳后才能开始张拉和灌浆； 3）海东隧洞试验段初定相对“大变形”与“小变形”的限界值为30 cm，具体还需在现场试验实施中进一步验证和修正； 4）锚杆、锚索施加预应力，可改善施锚区围岩的岩性参数，提高其强度和刚度； 5）此处对海东隧洞围岩“小变形”试验段的前期研究，希望引起业内各方专家的关注，进而得出改进、完善的建议意见，并在后续试验段实施中体现和实施。

关键词: 软岩隧洞, 围岩支护, 大变形, 小变形, 预应力锚索, 让压锚索, 施工风险与对策

Abstract:

Aiming at solving problems regarding the support to cope with the large and small deformation of surrounding 〖HJ4.5mm〗rock of soft rock tunnels with high ground stress, different applicable conditions are emphasized for two support options, namely support by ordinary prestressed anchor cables and support by largescale prestressed yielding anchor cables. Analysis is made on the risks of adopting ordinary prestressed anchor cables support for soft rock tunnels with certain large deformation, and specific countermeasures are proposed. With the trial section of Haidong water conveyance tunnel of the Central Yunnan water diversion project taken as an example, calculation and discussion are made on the threshold between the relatively "large deformation" the relatively "small deformation" of the surrounding rock. The importance of applying prestress to anchor bolts and cables is verified by means of principle analysis, theoretical calculation, and experimental research. It is considered in this paper that: (1) Ordinary prestressed anchor cables are suitable for tunnel sections with relatively "small deformation", while yielding anchor cables are suitable for tunnel sections with relatively "large deformation", and the two types of anchor cables apply to different occasions and cannot replace each other. (2) When ordinary prestressed anchor cables are used in a tunnel, the applied prestress cannot be too high, otherwise there will be unexpected risk of tendons breaking and bouncing out of the tunnel. It is suggested that tensioning and grouting cannot be started until the overall deformation of the surrounding rock becomes stable. (3) The preliminarilydetermined threshold between the relatively "large deformation" and the relatively "small deformation" in the trial section of Haidong water conveyance tunnel is 30 cm, which needs to be further verified and corrected during the field test. (4) Prestressed anchor bolts and cables can improve the lithological parameters of the surrounding rock in the anchoring area and increase its strength and stiffness. (5) It is expected that the preliminary study on the trial section of Haidong water conveyance tunnel with "small deformation" surrounding rock could attract the attention of experts in the industry to get more comments and further improved and refined suggestions, which will be reflected and implemented in the subsequent trial sections.

Key words: soft rock tunnel, surrounding rock support, large deformation, small deformation, prestressed anchor cable, yielding anchor cable, construction risks and countermeasures

孙钧, 江宇, 李宁, 汪波, 樊勇.

Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures(滇中引水工程海东隧洞围岩“小变形”试验段前期研究——兼及采用普通预应力锚索的风险与对策) [J]. 隧道建设, 2022, 42(8): 1321-1330.

SUN Jun, JIANG Yu, LI Ning, WANG Bo, FAN Yong.

Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures

for Using Ordinary Prestressed Anchor Cables[J]. Tunnel Construction, 2022, 42(8): 1321-1330.

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Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures(滇中引水工程海东隧洞围岩“小变形”试验段前期研究——兼及采用普通预应力锚索的风险与对策)

Surrounding Rock of Haidong Water Conveyance Tunnel of Central Yunnan Water Diversion Project: Risks and Countermeasures
for Using Ordinary Prestressed Anchor Cables

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