破碎千枚岩隧道施工工法比选试验研究

 为探明破碎千枚岩隧道在不同工法下的变形及支护力学响应特征，寻求一套适宜该种地层的合理工法体系，以该地层的隧道开挖为依托，采取现场试验与数值模拟相结合的方法，研究隧道在7种不同工法下的洞周变形、锚杆轴力、围岩–初期支护和初期支护–二衬接触压力、拱架及二衬内力变化规律。研究表明：工法S1，S2因较易引发洞室大变形等病害而不适合隧道开挖；工法S3能满足开挖条件但需增强支护参数体系；工法S4～S7均能有效抑制变形、保障隧道稳定，其中，工法S5，S6以支护承受较大荷载为代价，且施工难度大、工期长、造价高，工法S7对围岩扰动次数最多且初期支护不能及时封闭成环，工法S4既可抑制围岩变形，减小作用至衬砌的形变压力，又可提供稳定的支护力，在特殊地层时该法能迅速转变成工法S6，S7，缩短工法转换时间，有利于破碎千枚岩等软岩隧道的长期稳定。

EXPERIMENTAL STUDY OF COMPARISON AND OPTIMIZATION OF TUNNELING SCHEMES IN CRUSHING PHYLLITE

In order to find a reasonable construction scheme system for tunneling in crushing phyllite，the field tests and numerical simulations are combined to present the variation laws of the deformations around the tunnel，axis forces of anchors，contact pressures between surrounding rocks and primary support as well as between primary support and secondary lining，and the internal forces in arch frames and the secondary lining under 7 tunneling schemes. The study indicates that the schemes S1 and S2 are both unsuitable for the tunnel excavation because of the large deformation and other hazards. The excavation conditions are satisfied in scheme S3，but the supporting system should be reinforced. For schemes S4–S7，the deformations will be controlled effectively to maintain the tunnel stability. However，in addition to the heavy loads applied on the supporting system，the schemes S5 and S6 will result in numerous construction difficulties，long construction period and high cost. For scheme S7，the surrounding rocks are most frequently disturbed and the primary lining cannot be enclosed in time. For scheme S4，the deformations of the surrounding rocks can be well controlled，whilst the loads can be reduced and the supporting pressure can be provided for tunnel stability. Besides，scheme S4 can be transformed rapidly to schemes S6 and S7. It is beneficial to maintain the long-period stability of tunnels excavated in crushing phyllite or other soft rock layers.