Abstract:

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.

Key words: threedimensional laser scanning technology, soft rock tunnel, deformation monitoring, experimental study