As the core equipment of tunnel engineering, shield tunneling machines rely entirely on special cables for power transmission and signal control.The cable joint of shield tunneling machine is a key node that connects various sections of cables or cables with equipment, and its installation quality directly affects the reliability of the entire excavation system.In damp, vibrating, and high-pressure underground environments, the waterproof, wear-resistant, and conductive stability of joints are crucial and must follow strict process standards.

　　1、 Preparation work before installation

Safety and compliance are the primary principles:

1. Power off operation: It is necessary to confirm that the entire power supply system is completely powered off, and lock and tag the distribution cabinet (LOTO). Use a voltage tester to verify that there is no power.

2. Environmental assessment: Check the installation environment to ensure that the operating area is dry, free of standing water, with a temperature between 5-40 ℃ and a relative humidity below 80%.

3. Preparation of tools and materials:

① Specialized hydraulic crimping pliers, wire strippers, cable cutters, torque wrenches;

② Alcohol, dust-free cloth, conductive paste, insulation tape;

③ Shielded joint components of corresponding specifications.

　　2、 Standard wiring operation process

Following the precise process of "wire stripping processing crimping assembly":

1. Cable pretreatment:

① Accurately peel off the outer sheath of the cable according to the required size of the joint to avoid damaging the internal shielding layer and insulation layer.

② Reverse fold the braided shielding layer to expose a sufficient length of core wire; After the semiconductor layer is peeled off, it needs to be polished flat.

2. Conductor processing and crimping:

① Peel off the insulation layer of the core wire, with a length consistent with the depth of the crimping tube, and clean the exposed copper conductor with alcohol.

② After evenly applying the conductive paste, insert the crimping tube and use hydraulic pliers to crimp under the specified pressure, ensuring that the contact resistance is less than 5 μ Ω.

3. Joint assembly and sealing:

① Insert heat shrink tubing, sealing rings, armor fasteners, and other components in sequence;

② Use a hot air gun to evenly heat the heat shrink tubing from the middle to both ends, ensuring complete shrinkage and no bubbles;

③ Symmetrically tighten the stainless steel shell bolts to the specified torque and achieve IP68 protection.

4. Shielding layer treatment: Evenly disperse the shielding braided layer and fix it inside the joint shielding shell with a special clamp ring to ensure complete 360 ° contact.

　　3、 Key Quality Control Points

1. Dimensional accuracy: All wire stripping dimensions must be strictly executed according to the technical documents, with an error controlled within ± 1mm.

2. Cleanliness: The conductor and insulation surfaces must be free of oxidation and oil stains to ensure insulation strength.

3. Sealing reliability: The sealing ring should be fully seated, the heat shrink tubing should shrink sufficiently, and the torque of the shell bolts should meet the standard.

4. Grounding continuity: The shielding layer is connected to the joint housing with low resistance (<0.1 Ω).

　　4、 Testing and verification after installation

1. Insulation test: Use a 2500V megohmmeter to test the insulation resistance of the core wire to ground, with a requirement of>100M Ω.

2. Circuit testing: Confirm the correctness of wiring, without short circuits or open circuits.

3. Voltage withstand test: Conduct AC voltage withstand test according to the standard.

4. Dynamic monitoring: After the initial power transmission, use an infrared thermal imager to detect the temperature rise of the connector. If there is an abnormal temperature rise, it needs to be reinstalled.

The installation of cable joints in shield tunneling machines is a precision operation that integrates electrical technology, material mechanics, and environmental adaptability. Every detail is related to the continuity and safety of tunnel excavation. Only by strictly implementing standard processes can we ensure the stable operation of this' underground artery 'in complex environments tens of meters underground, providing inexhaustible power for national engineering projects.