The whole project is buried underground, so engineering geology and hydrogeology conditions play an important and even decisive role in the success or failure of the tunnel construction.
Should not only be detailed geological survey and exploration in exploration stage, as accurately as possible to grasp the tunnel project within the scope of the rock properties, the strength of rock mass, complete degree, ground stress field, the stable ability, the condition of groundwater state, the harmful gas and geothermal data, and according to these raw materials, preliminary selected appropriate construction methods, determine the corresponding construction measures and form a complete set of construction machinery.
Moreover, due to the complexity of geological conditions and the limitations of exploration methods, it is still inevitable that unexpected conditions occur during construction.
Therefore, in the construction of the long tunnel, it is necessary to take some technical measures such as test guide pit (such as qinghan tunnel in Japan), horizontal advance drilling, acoustic detection and lead guide pit, so as to further investigate the geological conditions in front of the excavation and timely grasp the changes.
In order to modify the construction method and technical measures as soon as possible.
The highway tunnel is a building with a flat shape. Under normal circumstances, there are only two working faces, namely, the inlet and the outlet, compared with the bridge and line engineering.
The construction speed of the tunnel is slow and the construction period is long.
Therefore, it is necessary to excavate additional auxiliary works such as vertical shaft, inclined shaft and horizontal hole to increase working face and speed up tunnel construction.
In addition, the tunnel section is small, the worksite is long and narrow, some construction procedures can only work in sequence, and some procedures can be along with the tunnel longitudinal development, parallel operation.
Therefore, the construction requirements to strengthen management, reasonable organization, avoid mutual interference.
The equipment inside the hole and the pipeline layout should be carefully considered and properly arranged.
Tunnel construction machinery shall be compact and durable.
The underground construction environment is poor, and may even worsen it during the construction, such as the harmful gas generated by blasting.
Effective measures must be taken to improve, such as artificial ventilation, lighting, dustproof, muffling sound, sound insulation, drainage, so that the construction site in accordance with health conditions, and have enough illumination, in order to ensure the health of construction personnel, improve labor productivity.
Most highway tunnels pass through mountains, so construction sites are generally located in remote mountains and narrow valleys, often far away from existing traffic lines, inconvenient transportation, and difficult supply. These are also one of the issues that should be considered when planning tunnel projects.
Highway tunnel is buried in the ground, once built, it is difficult to change, so in addition to careful planning and design in advance, the construction should be done without any future problems.
Of course, the tunnel project also has many advantages. For example, the construction can not be affected by the change of day and night, the change of seasons, the change of climate and other natural conditions.