亚黏土地层隧道台阶七步开挖施工现场测试研究

湖南省衡炎高速公路云阳山隧道进口段为亚黏土地层，由于该地层含水量高、可塑性强、自稳能力差，承载力低，给隧道施工造成困难。根据云阳山隧道亚黏土地层台阶七步开挖法实际施工情况，选取典型断面，进行了拱顶位移、钢支撑受力的量测，研究台阶七步开挖法各施工步骤对隧道围岩和支护结构稳定性的影响，同时进行了地表沉降和位移的监测，特别是对沿隧道纵向地表沉降进行了监测，获得了亚黏土地层条件下采用台阶七步开挖法施工围岩变形以及结构受力的特征，对于台阶七步开挖法的推广应用具有参考作用。

The Study of Field Measurements of Short Step and Seven-step-excavation in a Tunnel of Mild Clay Stratum

The imports of Yunyangshan Tunnel of Hengyan Expressway in Hunan Province is the mild stratum, which is of high water content, strong plasticity, poor stability and low capacity, so there are difficulties in the construction of the tunnel. According to the actual situation of the short step and seven-step-excavation in mild clay stratum of Yunyangshan Tunnel, a typical cross-section is selected, in which the vault displacement and the force of the steel support were moni- tored. The stability of both the supporting structure and rock was analyzed during the short step and seven-step-excava- tion. The ground surface subsidence and horizontal displacement, especially the tunnel along the longitudinal surface subsidence and displacement were monitored. It is shown that the short step and seven-step-excavation is effective in the mild clay stratum.