Study On Crushing Rangeand Design Method Of Boulder Blasting In Shield Tunnel

With the development of our national economy and urbanizationprocessaccelerated,as a main construction method of urban subway tunnel construction,shield tunnelinghas faced more and more challenge from complex geological conditions.In coastal areas,the main problem is the boulder in the excavated section is difficult to break,in the engineering,how to effectively solve this problem has become a focue issue.In this paper takesthe subway shield boulder blasting pretreatment construction site in Xiamen as an engineering background.Andthrough the application of theoretical calculation,numerical simulation and field test,systematically study the broken zones of the blasting pretreatment construction and the charge structure design method in coastal areas,the blasting effect under conventional working conditions is analyzed and optimized,and the design method of new charge structure under special working conditions is established,which could provide experiences and references toassociated works going well.The main research work and results are as follow:1.Based on engineering practice and explosion dynamics mechanics,thedestory partition scope of the bould blasting in the coastal area was calculated.2.By means of finite element software ANSYS/DYNA three-dimensional numerical model to study the crack propagation process and blasting effect with single cylindrical emulsion explosive under different charge structures,and the reasonable results after compared were obtain,which were promoted to double boreholes and the range of reasonable blasting parameterswas acquired.3.Aim at the special situation in the construction process,put forward a new type of special charge structure which by means of shaped-charge effect,and the design method of the main blasting parameters was calculated.4.According to the main parameters of the special charge structure,the orthogonal test meet the requirements was designed,the influence of blasting effect under different parameters and the optimal parameter combination of this charge structure was obtained.5.The shield tunnel broken boulder blasting construction design technology under different work conditions was established,which could be well used in the shield tunnel boulder blasting pretreatment construction guide in coastal areas,it improved the construction efficiency and effectively guarantee the safety of the existing building.