Composite linings are often adopted in highway tunnels. The new Austrian tunneling method is used in tunnel’s designing and construction. For weak wall rock section

steel arch(or grid arch) + grouting + shortcrete network of united initial support form are adopted. The key to achieve dynamic design is to find a good method to evaluate initial support safety evaluation about shape steel reinforced shotcrete. This paper gives a systemic study on initial support safety evaluation and established a numerical calculation method. Firstly

according to the monitoring data

this paper analyzes the final settlement value and horizontal constringency of wall rock and makes it as a basis for parameter inversion. Secondly

adopting the mechanical parameters from inversion

the initial support internal force about shape steel reinforced shotcrete is calculated by stratum-structure numerical method. Finally

initial support safety is calculated and evaluated by safety factor calculation method of shape steel reinforced shotcrete. From the study of this paper

we find that the initial support of shape steel reinforced shotcrete can exert the strong support effect of shape steel. And that

when the shotcrete is upgraded

concrete plays a major supporting role. The space between shape steels is not prominence in increasing the initial support safety factor.