The deformation characteristics of the rock mass in the intersection between the Muzhailing highway tunnel and the inclined shaft is a complicated three‐dimensional problem. Under the influence of high geostress, large deformation hazards may occur in the surrounding rock. Taking this as the research background, this paper analyzes the deformation mechanism of surrounding rock before and after prestressed anchor cable support through numerical simulation. Then, through theoretical analysis, a new tunnel support method using high prestressed constant resistance and large deformation anchor cable was proposed. The field monitoring results show that the constant resistance and large deformation anchor cable support can well control the deformation of surrounding rock, and the maximum deformation is within 300 mm. At the same time, the constant resistance anchor cable can always maintain a high prestress, which makes the stress of the surrounding rock uniform, and reduces the risk of damage to the steel arch due to local pressure. Moreover, the support method limits the expansion of the plastic zone and improves the overall stability of the surrounding rock.

The Muzhailing highway extra-long tunnel is affected by high geostress, and during the construction, large deformation of soft rock frequently occurred. Taking this as the research background, the high-prestressed constant resistance and large deformation anchor cable support scheme was proposed. In the field test, the indicators of three support schemes were compared, including the convergence deformation of surrounding rock, the deep displacement of surrounding rock, the axial force of anchor cable and bolt, and the stress between primary support and surrounding rock. The field test results show that: under the support of bolts, the cumulative deformation of surrounding rock exceeded 1500 mm, and the primary support damage was serious; In the second scheme, under the support of 4 m and 5 m long constant resistance anchor cables, although the large deformation of surrounding rock was controlled, the cumulative deformation was about 600 mm; In the third scheme, under the support of 5 m and 10 m long constant resistance anchor cables, the cumulative maximum deformation of surrounding rock was reduced to 216 mm, and all the data of the field test were within the controllable range. Therefore, high prestressed constant resistance and large deformation anchor cable support measures can effectively control the large deformation of surrounding rock.