1引言围岩变化量测传统上一般采用数显或其他式收敛计等接触方式进行净空位移变化量测,再结合水准仪观测测拱顶下沉变化。在全断面开挖后这些方法易受施工干扰,人为因素对测量精度影响较大,测量速度慢,而且测量难度较大,难以满足已做好初期支护落底的隧道全断面围岩监控量测。徕卡全站仪断面测量系统可以通过它的免棱镜测量模式配合其功能———测量隧道断面净空,可作为围岩变化量测一种新的工具和手段,其基本原理 1 Introduction Surrounding rock change measurement traditionally used digital display or other convergence of contact methods such as changes in headroom displacement measurement, combined with the level of observation vault sinking changes. These methods are susceptible to construction disturbance after full-face excavation. Human factors have a great influence on the measurement precision, the measurement speed is slow, and the measurement is difficult, so it is difficult to meet the tunnel full-face surrounding rock monitoring amount Measurement. Leica total station cross-section measurement system through its prism-free measurement mode with its function --- measuring tunnel clearance headroom, can be used as a measure of the surrounding rock changes a new tool and method, the basic principle