The treatment methods for shield machines when encountering hard rock and soft soil during underground construction are different, because these two geological conditions have great differences in the working mode and equipment performance requirements of shield machines.

  I. Hard rock treatment:

  1. Adjust the cutterhead configuration: Use tools suitable for hard rock cutting, such as carbide or diamond tools, and optimize the cutterhead configuration according to the hardness and hardness distribution of hard rock.

  2. Strengthen the propulsion system: Hard rock has high requirements for the propulsion system of the shield machine, and it may be necessary to increase the thrust and torque to ensure that the shield machine can be smoothly advanced.

  3. Control the earth pressure balance: When constructing in hard rock formations, pay special attention to the control of earth pressure balance to avoid excessive suction of mud and prevent ground subsidence.

   4. Monitor the cutterhead speed and propulsion speed: According to the cutting conditions of hard rock, adjust the cutterhead speed and propulsion speed in time to maintain the best cutting effect and propulsion efficiency.

  II. Soft soil treatment:

   1. Use appropriate cutterheads and cutting tools: In soft soil layers, soft cutting tools such as soft soil knives or rotating brushes should be used to reduce wear on the cutterhead.

   2. Strengthen earth pressure balance control: It is necessary to strictly control earth pressure balance to prevent ground subsidence and tunnel collapse. Grouting technology may be needed to enhance the bearing capacity of the soil.

   3. Control the advancement speed and cutterhead speed: Too fast advancement speed may cause ground subsidence, and too slow advancement speed may cause cutterhead blockage. It needs to be adjusted according to actual conditions.

   4. Use auxiliary equipment: When necessary, auxiliary equipment such as mud pumps and mixers can be used to improve the construction environment and help the shield machine to advance smoothly.

   5. Strengthen the maintenance of the cutterhead: Soft soil causes less wear on the cutterhead, but the soil on the cutterhead and cutting tools needs to be cleaned regularly to keep them in good working condition.

   When dealing with these two geological conditions, the shield machine operation team needs to have rich experience and expertise to adjust the construction parameters and take corresponding measures in time to ensure the safety and efficiency of the construction. In addition, detailed construction plans and emergency plans need to be formulated based on the specific geological conditions.