Convergence$-$Confinement Method $($CCM$)$ is one of the theoretical foundations for the NATM.For example, Figure $1$ is often used in the ground$-$support interaction analysis of tunnel designing or construction planning, in terms of the application of the CCM$.$

Question $4$: Please present the meaning of the Figure $1,$ such as in terms of the components,or meaning of the axes, lines, points, etc. in the figure; write your comments on the figure,

such as in terms of significance or implication in both tunnel design and construction, your

understanding on the figure, and so on$.)$ points$)$

Figure $1.$ Sketch showing the ground$-$support interaction model in the CCM