软岩隧道三维扫描变形监测技术的试验研究

为解决传统监测技术单点监测无法满足软岩隧道整体性变形监测的局限性，采用三维激光扫描技术进行软岩隧道整体性变形监测试验，从隧道结构的变形时间、变形空间分布及变形量进行整体分析。首先建立全站仪和三维激光扫描仪测量误差模型，分析三维扫描监测技术与传统隧道监测技术的特点，通过平面标靶和棱镜靶球精度试验得出平面标靶最佳入射角范围小于60°，棱镜靶球自动提取距离不大于45 m，作为测站设置和控制点布设的依据； 然后以渭武高速木寨岭隧道2号斜井工程为依托，开展软岩隧道三维扫描变形监测技术的试验研究。研究结果表明： 中台阶开挖支护前已发生较大变形，最大变形位置为左侧上台阶与中台阶交界处，空间分布呈左大右小，试验段最大累计变形达0.48 m，下台阶及时封闭成环及2层初期支护有利于变形控制。

Experimental Study on Deformation Monitoring Technology  of Three dimensional Scanning in Soft Rock Tunnel

In order to overcome the limitation that the traditional single point monitoring technology cannot meet the soft rock tunnel integral deformation monitoring, the 3D laser scanning technology is used to conduct the soft rock tunnel integral deformation monitoring test, and the deformation time, spatial distribution and amount of the deformation of the tunnel structure are analyzed. Firstly, the measurement error models of total station and 3D laser scanner are established, the characteristics of monitoring technology are analyzed, the optimal incidence angle range of plane target less than 60° and the automatic extraction distance of prism target ball less than 45 m are obtained by the accuracy tests of plane target and prism target ball, and which are taken as the basis for the setting of measuring station and the layout of control points. And then, the experimental study on the 3D scanning deformation monitoring technology of soft rock tunnel is carried out in No. 2 inclined shaft of Muzhailing Tunnel on Weiwu Expressway. The results show that large deformation has taken place before the excavation and support of the middle bench; the maximum deformation is located at the junction of the left upper bench and the middle bench, and the deformation form shows greater in left side than right side; the maximum cumulative deformation of the test section reaches 0.48 m; and the in time closure of lower step and double primary support are beneficial to deformation control.