Features:

- It has the advantages of earth pressure shield and mud shield. It is suitable for a wide range of soil layers such as clay, sand, soft and hard composite, high water-bearing stratum, etc. It has excellent geological adaptability and economical use.

- In the earth pressure mode, the slag is used to excavate the soil in the earth chamber to stabilize the face and the screw conveyor to slag. In the mud mode, the mud in the soil tank is used to balance the face and the mud pipe to slag. Both modes can be freely converted within the hole as needed.

Difficulties in engineering:

The bottom of the tunnel is mainly located in the slightly weathered layer of the rock. It is characterized by a soft upper and lower hard stratum. The impact on the shield construction is mainly reflected in the shield tunneling attitude control and prevention of tool damage. At the same time, the stratum is constantly disturbed, and the surface deformation is easy to occur. When the shield tunneling through the small radius curve section, due to the serious unevenness of the pushing jack thrust, it is easy to cause the phenomenon of cracking, misalignment, slitting, and difficulty in controlling the posture of the shield machine during the tunneling process. Karst and liquefied sand layers, this area exploration reveals dissolved and soil caves in limestone, which is a region with high risk of karst ground collapse. Under the Baiyun Lake diversion canal, the water channel is 32m wide and 2m deep. The tunnel crossing the stratum is mainly clay layer, sand layer and rock layer. The lower part of the shield of the crossing channel is the 9c-2 rock formation, and the shield tunneling is difficult. During shield construction, surface settlement is prone to occur, causing disturbance to the pier; shield tunneling is likely to cause disturbance to the base layer of the pier; the shield is in the lava development zone, and the shield may break the balance and lead to deformation of the pier. Eventually, it will cause rapid deformation, affect traffic, and even cause traffic accidents.

Equipment overview: ZTSE6250 mud water / earth pressure double mode balance shield machine, excavation diameter 6.28m, total length 101m, total weight 520t, maximum slope 35‰, total power 1560kW.

Innovation: The shield design fully considers the various situations that may occur during tunnel construction, and has all the functions required for the excavation, mud discharge, support, grouting, guiding, and control processes in the shield construction, including Excavation system, main drive system, propulsion system, segment mounting system, mud water circulation system, grouting system, grease system, hydraulic system, electrical control system, laser guiding system, ventilation, water supply, power supply system, etc. Because the load varies greatly during the construction of the shield, and it is often difficult to obtain accurate load values, the shield has selected a large safety factor in the structural design, and the strength and rigidity of each component are left with a large margin. To meet the special load requirements of shield construction. The shield components and hydraulic and electrical components are all internationally renowned brand products, which fully guarantee the quality of the components of the shield machine.