Micro-Pressure Wave Mitigation Regularity Analysis And Parameter Design Of The Opeing Buffer Structure At High-Speed Railway Tunnel Entrance

Aiming at the noise problems caused by high-speed rail tunnel operator, In this paper,engineering measures to reduce sonic boom of the tunnel entrance buffer structure were studied(train speed is 350km/h),determine the recommended scheme to direct the design and construction.The main conclusions are as follows:1、Optimal prameter analysis of top single-opening buffer structure(1)Top single-opening buffer structure with increasing distance from the opening to the entrance of the buffer structure, the first wave peak pressure gradient of decreasing the secondary peak value is incremented. After more than 15m from the entrance, the peak pressure gradient curve unchanged, indicating that compression wave formed entirely at around 15m, and is independent of the length and width of the opening.(2)When the opening width is 2m,3m,4m, with the distance from opening to the entrance of the buffer structure increase, best opening length showed a decreasing trend, when the distance between the opening and the opening width is increased,but the reduce rate decreases. Therefore, when the opening width is 2m, the opening distance is lm, and the length of the opening is 20m (opening ratio is 40%), the rate of decrease of buffer structure is maximum, the value is 45.31%.(3)Reduction rate per meter increases with the opening width increases and when the distance from opening to the entrance of the buffer structure decrease,the reduction rate per meter increases. So when the opening distance is lm, opening width is 4m, the length is 13m (opening ratio is 52%), the reduction rate per meter is maximum, the value is 3.08%/m.2、Optimal prameter analysis of top w-opening buffer structure(1)Fixed distance from the first opening to the entrance, with the second opening distance increases, the first opening of the optimal length increments, total length and total reduction rate of the buffer structure are increasing, but reduction rate per meter is reducing.Fixed distance from the second opening to the fisrt opening, whit the first opening distance increases, the length of the first opening is decreasing, total length and total reduction rate of the buffer structure increase at first and then decreases.(2) When the first and second opening’s distances is lm and 8m,also the first and second opening’s length is 12m and 3m,the total reduction rate of the buffer structure is the largest, reaching 53.10%. When the first and second opening’s distances is lm and 6m,the first and second opening’s length is 10m and 4m,the total reduction rate per meter of the buffer structure is the largest, which is 53.10%.