The hottest shield machine and its development

Shield machine and its development overview

Guide: shield machine is the main construction machinery in shield construction. Shield construction method is a construction method of tunneling under the ground. It uses a shield machine to dig underground. While preventing the collapse of the excavation surface of soft foundation or maintaining the stability of the excavation surface, it can safely excavate and lining the tunnel in the machine. Shield

shield machine is the main construction machinery in shield construction. Shield construction allows the flowers of youth to bloom in the place most needed by the motherland. The construction method is a construction method of tunneling under the ground. It uses a shield machine to dig underground. While preventing the collapse of the excavation surface of the soft foundation or maintaining the stability of the excavation surface, it can safely carry out the excavation and lining of the tunnel in the machine. Shield construction method has the characteristics of high degree of automation, labor saving, fast construction speed, one-time tunneling, not affected by the climate, controllable excavation. He Hongwei pointed to building 11 constructed with the third generation steel structure technology to control the ground settlement, reduce the impact on ground buildings, and do not affect the surface traffic during underwater excavation. In the case of long tunnel line and large buried depth, shield machine construction is more economical and reasonable

The basic working principle of the shield machine is that a cylindrical steel component moves forward along the axis of the tunnel while excavating the soil. The shell of the cylinder assembly, namely the shield, acts as a temporary support for the excavated unlined tunnel section, bears the pressure of the surrounding soil layer, and sometimes bears the underground water pressure and keeps the underground water out. Excavation, dumping, lining and other operations are carried out under the cover of shield. Shield machine construction is mainly composed of three elements: stabilizing the excavation surface, excavation including dumping, and lining including grouting behind the wall. The stability of the excavation surface is different according to the soil and groundwater conditions, but the asymmetric fatigue test has different methods, mainly including the natural stability of the excavation surface, i.e. open sloping, mechanical support stability, compressed air support stability, muddy water support stability and earth pressure balance support stability

The structure of shield machine is mainly composed of shield, excavation mechanism, propulsion mechanism, dumping mechanism, lining mechanism and auxiliary mechanism. The shield is generally composed of three parts: notch ring, support ring and shield tail; The excavation mechanism is mainly composed of cutter head or cutter head and its supporting device; The propulsion mechanism is mainly composed of hydraulic equipment such as oil pump, oil motor, oil jack, etc; Earth discharging machinery, mud water type mainly includes mud pump and pipeline, earth pressure balance type mainly includes screw conveyor and belt conveyor; The lining mechanism is mainly the segment automatic assembly manipulator; The auxiliary mechanism includes the grouting device behind the wall, the guiding measurement and control device, etc

It has been nearly 180 years since the shield machine came out. It began in Britain and developed in Japan and Germany. In the past 30 years, through the exploration and Research on the key technologies in the earth pressure balanced and slurry shield machines, such as the effective sealing of the shield machine, ensuring the stability of the excavation surface and controlling the lowering of the tunnel wall and the collapse of the ground within the specified range, the service life of the cutting tools and the replacement of the cutting tools under the sealing conditions, and some harsh geology, such as the treatment technology under high water pressure, the shield machine has made great progress. According to different geological conditions and engineering requirements, different types of shield machines can be designed and manufactured to meet the needs of the project. Shield construction is also a mature underground engineering construction technology, which has become the preferred conventional technology for most underground tunnel engineering construction

shield machines have developed rapidly in Japan, especially the development of earth pressure balance shield machines and slurry shield machines. More than 90% of urban tunnels in Japan are constructed by shield machines. German shield machine technology is also unique, especially in the process of underground construction, it can directly evaluate whether the product meets the requirements on the premise of ensuring the sealing. Under the condition of up to 0.3MPa air pressure, the cutter on the cutter head can be replaced, which improves the one-time tunneling length of the shield machine. In particular, it can replace worn tools from the atmospheric pressure space inside the large-diameter cutter head under sealing conditions

China began to develop shield machines in the mid-1950s, mainly earth pressure balanced, and slurry shield machines are still inexperienced. The mechanism design of EPB shield machine is not different from that of foreign countries, but the quality, service life and reliability of some domestic parts and components are poor, and some need to be imported from abroad