高地应力软岩隧道围岩大变形NPR锚索控制方法研究

为解决高地应力软岩隧道建设过程中支护结构破坏、围岩大变形等问题,依托地处炭质板岩地层,具有地质构造复杂、断层发育、埋深大、地应力极高等特点的木寨岭特长公路隧道工程,对隧道围岩NPR锚索支护方案进行研究。首先,采用原位试验、现场勘察和室内试验方法,对其地质条件及破坏成因进行分析;然后,利用自主研发的高预紧力恒阻大变形锚索（NPR锚索）材料,设计出一种能够控制公路隧道围岩大变形的NPR锚索综合控制体系;最后,使用该控制体系在现场进行工业性试验,通过对NPR锚索加固区的围岩变形量、钢拱架应力和NPR锚索受力进行实时监测,分析NPR锚索支护方案的围岩控制效果。试验结果表明： 采用NPR锚索“非对称布设和长-短锚索组合搭配”的综合控制体系,能有效控制隧道围岩初期支护大变形难题,最大变形量从2936 mm控制到240 mm以内,消除了初期支护侵限、开裂等破坏隐患,控制效果显著。

Research on NPR Anchor Cable Support Scheme for LargeDeformation of Surrounding Rock in High GroundStress Soft Rock Tunnel

It is urgent to solve the problems, i.e. damage ofsupport structure, large deformation of surrounding rock etc.〖ＫＧ－３〗, in the construction of high ground stresssoft rock tunnels. Relying on Muzhailing extra longhighway tunnel project which is located in carbonaceous slate stratum with thecharacteristics of complex geological structure, fault developed, large burialdepth, and extremely high ground stress,a support scheme for large deformationof surrounding rock is studied. Firstly, the failure mechanism is analyzed byin situ test, site survey and indoor test. Then, theself developed high prestressedNPR anchor cable material is used, and a new comprehensive control system forlarge scale deformation disasters in the surroundingrock of highway tunnels is proposed. Finally, the control system is used toconduct industrial tests on site, and through real timemonitoring of the deformation of surrounding rock, steel arch stress and NPRanchor cable stress, the control mechanism of the NPR anchor cable is revealed.The results show that the large deformation problem can be effectivelycontrolled by the comprehensive control system of asymmetricalarrangement and combination of long and short anchor cables with NPRanchor cable. The maximum deformation decreases from 2 936 to less than 240 mmand damages of primary support, i.e. invasion, cracking, etc,. are eliminated.