Research conclusions: ( 1) The rational support parameters should be chosen for construction of shallow double － arch tunnel with bias weak rock according to the field geological conditions． ( 2) The high － frequent monitoring measurement works must be done during construction of the tunnel under bad geological conditions to instruct the tunnel construction．( 3) The reasonable change of construction process can ensure the safety of the tunnel construction． ( 4) The anti － slide pile and back pressure refilling can effectively solve the bias problem of weak rock tunnel．