TBM, shield tunnel boring machine full name, is a special tunneling machinery, modern shield tunneling techniques integrates optical, mechanical, electrical, hydraulic, sensing, information technology in one, with excavation cutting Soil body, delivery earth ballast, assembled tunnel lining, measuring guide correction and other functions, involving geology, civil engineering, machinery, mechanical, hydraulic, electrical, control, measurement technology and other subjects, but also according to different geological conduct “tailored” type of design and manufacture of high reliability requirements. Shield tunneling machine has been widely used in subway, railway, highway, municipal, hydropower tunnel project.
Open
Hand digging and semi mechanical shield are semi-open excavation. This method is better adapted to the geological conditions, excavation surface can be maintained in Excavation stable or auxiliary measures to maintain stability cases, the excavation is generally dig down from the top layer by layer. If the soil is poor, but also borrowed jack braced excavation face plate for temporary support. Using open excavation, processing isolated obstacle, correction, over break are otherwise easy. In order to minimize disturbance of the ground, to properly control the amount of exposure time over break.
Mechanical cutting formula
Section refers to the whole rotating cutting disk excavation and shield of similar diameter. According to the quality of the geological conditions, the cutter head can be divided between the tool holders no seal plate and seal plate has two. No seal between the turret plates is suitable for the soil conditions better. Cutter head excavation, construction or correction in the corners is not as easy to open excavation over break. In addition, removal of obstructions not as open excavation. Use cutter head shield, mechanical structure is complicated, power consumption is large.
Mesh type
Another micro tunneling technique, using a grid-type excavation, the excavation by the grid beam and grating into many squares. The supporting role of the excavation face is from the soil cohesion resistance thickness range within the grid and generated. When the shield forward, the soil to be squeezed out from the grid. Depending on the nature of soil, adjusting the opening area of the grid. When using a grid-type excavation, after all the jack is retracted, it will have a greater shield back phenomenon, leading to surface subsidence, therefore, construction must take effective measures to prevent the shield back.
Extrusion
Full and partial squeeze excavation, since this micro tunneling technique is no or only partially unearthed a greater disturbance to the formation, in the construction axis, should try to avoid ground buildings. Topical squeeze-type construction, be careful to control the amount of excavated to reduce and control the surface deformation. When the full-squeeze-type construction, shield the soil within a certain range around the crowded dense.