Study On Ventilation Design Method For TBM Construction Of Long-distance Water Conveyance Tunnel

With the progress of technology,more and more long tunnels appear in water conservancy,highway,railway and other industries,and the application of TBM is also increasing.With the increase of tunnel length,the ventilation resistance and air leakage of duct increase.At the same time,with the increase of the power of TBM,the construction environment at the heading face is seriously deteriorated.The harsh construction environment endangers the physical and mental health of the constructors,reduces the working efficiency of the constructors and mechanical equipment,and increases the loss of construction machinery and equipment.Therefore,the study of ventilation design method for long-distance TBM tunnel construction is of great significance for the promotion of tunnel mechanization construction.In this dissertation,a variety of methods,including literature survey,theoretical analysis,and deduction,numerical simulation and analysis,field testing,etc.,are used to study the design method of single-head ventilation for long-distance TBM construction relying on the TBM construction area of Qinling Water Conveyance Tunnel of the water diversion from the Han to the Wei River.The main achievements are as follows:1.By means of data investigation,field test and theoretical analysis,the theoretical basis of ventilation calculation for long-distance tunnel construction is studied.The ventilation mode of water conveyance tunnel construction is selected,the ventilation environment control standard of TBM construction water conveyance tunnel is determined,and the calculation method of ventilation demand of TBM construction water conveyance tunnel construction is known.2.By using the method of theoretical analysis,the temperature law of long-distance TBM construction tunnel is studied.Using the laws of conservation of mass and energy,the temperature distribution law at different locations of long distance TBM construction water conveyance tunnel is found out.According to the temperature distribution law of TBM construction tunnel,artificial refrigeration cooling measures for TBM construction water conveyance tunnel are adopted.3.The calculation method of air leakage rate of air duct based on fan performance is studied by theoretical analysis and field test.The performance of series-parallel fan is defined.Based on the principle of orifice outflow and the existing cases,the formula for calculating the 100-meter air leakage rate of soft air duct and the method for calculating the air leakage rate of air duct are defined by using MATLAB to fit the data.4.By means of theoretical analysis and numerical simulation,the ventilation design method of single-head construction under the influence of natural wind pressure is studied.Based on the 5#-7# sections of the Qinling Water-Conveyance Tunnel of the water diversion from the Han to the Wei River,the non-linear equations considering the balance of wind pressure nodes and the conservation of mass are calculated by using the program compiled in C language.Combining with numerical simulation and field test,the ventilation design method of single-head construction considering the influence of natural wind pressure is defined through multi-inclined wells.The above results provide technical support for improving ventilation design of long and deep buried TBM diversion tunnel construction and key technologies of design and construction of long and deep buried TBM.