Study On Mechanical Properties And Optimization Control Of The Large Diameter Rig Drilling In Tunnel Collapse

In the construction process,the tunnel collapse is often occurred,and it is the first task of the rescue workers to carry out the rapid rescue of people trapped in tunnel.The large diameter rig rescue method is an advanced mechanical method in the current tunnel collapse rescue,which is favored by rescue workers with its safety and high efficiency.But the situation of the large diameter rig using less experienced and drill tools drilling force research of different types of tunnel collapse insufficient lead to encountered insufficient drilling power problems frequently,which often cause"drill tools stuck".For the FS-120 CZ large diameter introduced by China Railway two Bureau Kun Ming rescue team of tunnel collapse,this paper researches the influence of buried depth（drilling position）,drilling speed,the rock proportion and the boulder in the collapse accumulation body on the force of drill tools,and optimize control of the force of drill tools.The research contents and results are as follows:（1）According to the field test of large diameter drill,the position condition and operation flow of the drilling are summarized,and the force monitoring curve of drill tools is analyzed.The content analyzes the relationship between the force of each part of the drill tools and the drilling displacement;the influence of different types of tunnel collapse accumulation body and drilling speed on the force of drill tools.And the reason of"drill tools stuck"in the drilling process is analyzed emphatically.（2）A numerical simulation method for the drilling process of large diameter rig is proposed based on the Particle Flow Code in 3Dimensions(PFC^3D).A free falling body method for tunnel collapse model is established.The drilling process was simulated by using CAD modeling and importing PFC^3D to generate rigid drilling tools model.The dynamic numerical simulation of the drilling process of the FS-120cz large diameter rig is realized.（3）The PFC^3D numerical simulation of the influence of buried depth（drilling position）and drilling speed on the force of drill tools is carried out by the control variable method.In the process of analysis,it was found that the larger the burial depth,the greater the force of the drill tools,and the greater the curve jitter,but the impact of burial depth is tending to a certain threshold with the increase of burial depth,the impact on the force of the drill tools is less and less.Drilling speed has a significant influence on the force of the drill tools,the larger the drilling speed,the greater the force of the drill tools,and the greater the curve jitter.（4）Considering the complexity of the tunnel collapse accumulation body in the drilling process,this paper analysis the influence of the rock proportion and the boulder in the collapse accumulation body on the force of drill tools.The increase of rock proportion,the increase of the drilling tool,but the maximum range is 40%to60%.When the drill tools contact with the boulder,the force of the drill tools will increase obviously,about 2-3 times.When drilling into the boulder,the boulder should be broken as soon as possible in case the force of drill tools too large,if the drilling displacement is small,it can be considered to reselect the drilling position.（5）The influence of various factors（buried depth,drilling speed,the rock proportion and the boulder in the collapse accumulation body）on the force of drilling tools are summarized,the basic principle of force optimization control of the drilling tools is formed.The five problems that the drill tools may encounter and the corresponding force curve characteristics are analyzed.According to the force curve characteristics of the drill tools in drilling process which is monitored by MWD data acquisition system,the rescuers make real-time adjustment to avoid the"drill tools stuck".