Deformation Prediction and Support Countermeasure in the Intersection of Mountain Tunnel

• Main Authors: Fu-YuanHsiao, 蕭富元
• Other Authors: Chein-Lee Wang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/05567927413591570210

博士 === 國立成功大學 === 資源工程學系碩博士班 === 98 === Passenger and vehicle adits and ventilation shafts are commonly used for emergency access and ventilation in long tunnels. Increasing support load and additional tunnel deformation are occurred during the construction of tunnel intersection. It may endanger tunnel safety in the extreme condition. Most of the previous investigations for tunnel intersection were only limited to case study. Degrading the rock mass rating and support system in the intersection area are used in practice. Nevertheless, unexpected tunnel closure and support failure have been observed in several cases in Taiwan. A more rigorous design method is, therefore, needed. Controlling the movement of rock mass due to tunneling is the primary goal in supporting design for tunnel engineering. To understand the mechanical behavior in the tunnel intersection area, 80 cases of 3-D numerical analysis were performed by Flac3D program in the research. These analyses were conducted under various tunneling conditions, including rock strength, rock mass rating, overburden depth, and intersection angle. Results show that strength/stress ratio of rock mass and intersection angle play the significant roles in the deformation behavior of tunnel intersection. A criterion for assessing the effect of intersection angles on tunnel behavior has been established, and three categories of support design suggestions for different geological conditions have also been proposed. In addition, artificial neural network technique utilizing the database derived from the results of numerical analysis was further employed to establish a system for predicting the tunnel deformation and extent of plastic zone surrounding tunnels. The adequency of the deformation prediction system was examined by actual tunnel cases in Taiwan.