Research On Methods Of Control Survey Inside The Long-And-Large Tunnel

At present, High-speed railway is in the rapid construction phase in our country. The transport infrastructure is also gradually improved. As an important part of the transportation infrastructure, a lot of tunnels are going to be constructed. Tunnel engineering is mostly in the complex topography of the mountain areas. The influence of plumb line deflection on lateral through error should be taken into account when designing the outside tunnel control network. At the same time, the control survey inside the tunnel is the core part of tunnel survey. The form of traverse network inside the tunnel is the key of tunnel survey. The complex construction environment in tunnel cut down the accuracy of the control survey. Especially when the excavation length is too long or the traverse inside tunnel have short sides, the accuracy of the breakthrough point is difficult to be guaranteed. To solve the above problems, this thesis mainly researches on methods of control survey inside the long-and-large tunnel. The paper mainly contains the following:1. Analysis of the lateral break-through error of tunnel caused by surveying errors of the horizontal control network. And the safety of the estimation formula is illustrated with a practical engineering example.2. This thesis focuses on analyzing the effect of alignment error and error of focusing on the accuracy of azimuth which is transferred with short sides. The methods of improving the accuracy of azimuth which is transferred with short sides are proposed.3. The impact of plumb line deflection on distance and angle measurement is analyzed in detail. And through controlling the altitude angel of the entrance side and decreasing the height difference of adjacent traverse point in auxiliary tunnel, the influence of plump line deflection on tunnel lateral error could be diminished.4. According to adjustment with conditions, a formula for estimating the lateral error of traverse inside tunnel which a varying quantity gyroscope azimuth angles has been deduced. The optimal position of the gyro azimuth is determined by using the method of multivariate function for conditional extremum. Then the number of the azimuth angle of the gyroscope is calculated by the calculation of the length of 6 kilometer and 9 kilometer tunnel through case studies.