旧堡隧道地处区域性构造交汇部位，地层为古老的太古界变质岩，岩石因受多期地质构造运动作用，断裂构造极为发育。隧道地下水发育且部分地段存在承压水，在施工过程中，针对掌子面突水涌碴、开挖面坍塌，采取架设临时仰拱和临时挡墙措施，加固绕避； 针对初期支护大变形、二次衬砌开裂等情况，采取超前注浆、超前大管棚和双层初期支护等措施，确保隧道衬砌结构安全； 针对隧道地下水发育情况，采用排水型防水板、边墙增设碎石盲沟并增加泄水洞等措施，确保隧道运营安全。

Jiubao tunnel is located in the junction of regional tectonic whose main strata is old archaeozoic metamorphic rocks. The fault structure is developed well due to the geological structural movement. The groundwater is rich; and there is confined water in partial sections. Technologies, such as the temporary inverted arch, the temporary retaining wall, strengthening and avoidance are used so as to solve the water inrush and collapse of tunnel face. In order to guarantee the safety of tunnel lining structure, advance grouting, advance pipe roof and double primary support layers are adopted. In light of the rich groundwater, the drainagetype waterproofing plate, additional macadam blind drains and increasing drainage holes are adopted to guarantee the running safety of the tunnel.