The collapse of slope in the tunnel entrance section is frequently the main reason to cause the struc- tures fracture destroy or even collapse of the portal,so the stability of the tunnel access slope is a question that must be seriously considered in the time of design and operation of the tunnel.

Using Dianhuiping Tunnel on Changji highway as an example in this paper, in - situ tests at side and face upward slope and tunnel are carried through.

Treatment of instability of entrance slope of tunnel;