Study On Optimizing Blasting Parameters Of Yingpanshan Single-track Railway Tunnel

Drill and blast method is most commonly used in the construction of traffic tunnel method is drill and blast method of tunnel blasting most important links.However,there are few studies on the process and effect of the rock mass under the action of explosives.The traditional design of tunnel blasting based on engineering experience and engineering analogy is subjective.According to tunnel blasting hole made a systematic study of different type,achieved the following results:(1)Under control at home and abroad of rock blasting theory and numerical simulation software(LS-DYNA)based on the principle of,rock failure criteria are selected.Yingpanshan single-track railway tunnel engineering based on the project,implemented by means of failure criteria defined in the software unit of rock fragmentation process visualization.(2)A single-hole column charge blasting numerical model was established to analyze the crushing process and effect of rock mass under different uncorrelated coefficients of holes.The results showed that the radius of crushed area and the crack area decreased with the increase of the uncorrelated coefficient.When the uncorrelated coefficient was 1.5,the utilization rate of the explosive was maximum.(3)First of all,the characteristics of the blasting of the cutting hole were analyzed theoretically.Then,the cutting hole blasting numerical model was established according to the design parameters of the engineering cutting holes.The blasting effect of different angles of cutting holes was analyzed,and the parameters were found to be unreasonable.After that,we reduced the distances of the bottom of the cutting holes and increased the charging coefficients.And then,the blasting effect of different angles of cutting holes was analyzed again.The results showed that the larger the angle of the cutting hole was,the higher degree of the rock crushing was.It is suggested that the angle of the cutting hole should be 55°?65°,the charging coefficient should be about 0.85,and the distance of the bottom of the cutting hole should be within 70cm.(4)First of all,the characteristics of the blasting of auxiliary hole were analyzed theoretically.Then,the auxiliary hole blasting numerical model was established according to the design parameters of the engineering auxiliary holes.Six working conditions were set according to the different spaces and pitch of the holes.According to the breakdown of the rock mass of each working condition,it is suggested that the space of the auxiliary holes should be 100cm and the pitch of auxiliary holes should set to be 70cm.The space of the inner holes should be 80cm and the pitch of inner holes should be 60cm?70cm.(5)Based on the analysis of the characteristics of the smooth blasting,the smooth blasting numerical model was established according to the engineering parameters.After the calculation,it was found that the over-excavation occurred,and the average linear over-excavation was about 22cm.The model was re-established by adjusting the minimum resistance line(light burst layer thickness)and the distance between the peripheral hole and the contour line for calculation and analysis.The increase of the thickness of the blasting layer could not reduce the overturning,but it would make the bursting degree of the blasting layer rock mass decrease rapidly.Increasing the distance from the blasting hole to the design excavation contour can effectively control the overturning.It is recommended that the hole rely on smooth blasting project moved 20cm to the contour line and the minimum resistance line changed to be 70cm.