Textbook in PDF format This book covers the mechanical problems of tunnels in traffic, hydraulic and mining engineering. By extending the complex variable method in mechanical analysis, it proposes accurate analytical solutions for tunnels. The solutions are further applied to the back analysis of tunnels, hole shape optimization, support design and estimation of tunnel stability. The considered rock characteristics involve elasticity, elastoplasticity, viscoelasticity and anisotropy, and various geometric conditions are included, such as circular/noncircular single/multiple tunnels with/without support at deep/shallow depths. Some original achievements are provided, including new mapping functions for complex regions, precise determination of the noncircular plastic zone around single/twin tunnels and related elastoplastic solutions and quantitative analysis of the interaction between rock and the support, which are new developments of theory and method in rock mechanics