Research On Rational Driving Direction And Expansion Gap Of Double Shield TBM In Deep Mixed Rock Strata

Today,engineering construction is in rapid development period,large scale construction of water conservancy,highway,railway and mine engineering in china,deep buried long tunnel has become the main project or key control project of large,extra large water conservancy,transportation and mine construction.For TBM construction with long tunnel(Full Face Tunnel Boring Machine),it has obvious advantages in the stability of surrounding rock and tunneling rate.Based on the consideration of construction safety,cost,cycle,safety construction and stability control of surrounding rock,etc.,TBM construction will become the first choice and inevitable development trend of tunnel construction.In recent years,with the rapid development of tunnel engineering in our country,TBM construction technology is widely used in tunnel construction,but there are also many problems to be solved,numerous engineering practices have shown that:in the complex geological environment and high stress conditions,TBM tunneling process if you encounter uneven soft and hard rock,deep high stress deformation will cause the TBM shield is easy to be jammed.The accident of TBM jamming will cause serious threat to the construction safety of TBM excavation in deep composite stratum.The treatment of engineering disasters and accidents will not only delay the construction period,but also cause huge economic losses.Therefore,from the point of view of TBM jamming control,the three-dimensional discrete element software 3DEC is adopted in this paper,the reasonable excavation direction and the excavation clearance of TBM are studied by numerical simulation:(1)A numerical model of interaction between double shield TBM and composite rock mass is established,the influence of different combinations of dip angle,strike direction and tunnel excavation direction on the total pressure of the cutterhead and shield is studied;the influence of dip angle,strike and lithology on the distribution of plastic zone after tunnel excavation is analyzed,put forward reasonable layout in the deep strata in the proposed composite.(2)Based on the above research,the most favorable tunneling direction,explore the influence of the inclination of different strata and the clearance of excavation on the pressure of shield is studied when the strike angle between composite rock strike and tunnel axis is 90 °.when the dip angle of the rock varies from 0°to 90 °,the pressure acting on the cutter head,front shield and rear shield varies with the inclination angle;the pressure of cutterhead,front shield and rear shield is analyzed when the overcut is 5cm,10cm,15cm,20cm;the shape and size of shaping zone are compared with the dip angle and lithology of rock formation.