Nowadays, as the acceleration of urban construction, the district range and population density become larger and larger, if we don’t enlarge the degree of the drainage construction, the old pipeline has not adapted with our society, so the drainage tunnel in construction is necessary.
There are various pipelines underground, including the communicant, electrical, fuel gas, industrial and so on, they may connect with many apartments, so the construction is difficult and the financial affair is big.
By the analysis of the disadvantages of drainage, building a tunnel is quite suitable. While because the various pipelines are underground 8 meters and the subway is underground 8-40 meters, the digging of drainage should be underground 45 meters.And here introduce the application of self drilling anchor bolt in urban construction
Analysis of different geological model of anchoring effect of self drilling rock bolt
1 Hard rock
Surrounding rock strength than the big, tunnel surrounding rock without plasticization, don't need internal pressure effect.At the same time, the strength of the hard rock of the rock itself is good, the stability of the tunnel is usually controlled by discontinuity on the fracture mechanics, therefore, to maintain and control the rock anchor block, make the surrounding rock, mainly inhibitory and the relative displacement of the fracture surface parallel or orthogonal direction so as to facilitate the formation of balance arch.
2 Soft rock
In the surrounding rock strength than the soft rock tunnel surrounding rock in plasticizing, need to pressure balance effect and formed within the arch effect is given priority to, mainly control the radial displacement of tunnel wall and internal relative displacement of surrounding rock.Surrounding rock using elastic-plastic body completely assume parsing, because of the existence of internal pressure and reduce the plastic area and the surface displacement.But if you want to make the plastic zone does not occur, then at the beginning of the excavation takes a lot of supporting capacity.So we must with other means of support, such as shotcrete.
3 Sand soil surrounding rock
In small depth of sand soil surrounding rock, shotcrete is effective, according to the measurement results of the past, vault near the anchor is almost not affected by strain and stress of only.On this occasion, therefore, the use of bolt, main is to prevent the collapse of the constraints and enhance the arch foot near to give priority to.