Based on similarity theory

sand is used to simulate surrounding rock and iron wire is used to simulate rock bolt. The paper conducts actual measurement on the change rules of stress distribution

stability and regionalization of surrounding rock under different supporting forces of surrounding rock

different lengths of rock bolt and combined action of rock bolt and tunnel around supporting force during the excavation process of tunnels. Finite element modeling is used to simulate the stress distribution laws of surrounding rocks with different bolt lengths

and the range of surrounding rock plastic zone is acquired based on Drucker-Prager (D-P) yield criterion. The study shows that the carrying capacity of surrounding rock can be brought into full play through combined support of rock bolt and supporting force of surrounding rock. The supporting length of rock bolt should be no less than the external radius size of loose zone without any support. Under the condition of loose surrounding rock

the rock bolt length should be no less than one fifth of the tunnel span; and during comprehensive support process

the supporting force of surrounding rock should be about 5% of the vertical stress of primary rocks. By comparing the simulated results of the experiment and finite element modeling

the latter result is more conservative than the former one.