Experimental Study On The Technique Of Smooth Blasting And Its Damage In Railway Cutting Excavation

With the development of our national economy, our railway construction has gotten into an unprecedented high-speed development period. Great deals of railways have been constructed, are constructing or will be constructed, and many railways already existing will be rebuild or extended. As all of the new railway construction is faced with a lot of blasting cutting engineering, the stability of the slope must be involved. With the development of the blasting technology, and in order to improve the quality of the excavation slope, the best approach is adopting the weak disturbance technique, such as pre-splitting blasting and smooth blasting in excavation, which can avoid or reduce the destroy to the surrounding rock and make the slope smooth, beauty and stability.Smooth blasting in slope excavation has been experimented successfully in hydroelectricity, highway and railway department in our country, and has widly applied in hydroelectricity and highway constructions, especially. However, because of the particularity of the railway environment and some objective and subjective restrictions, this technique has not been entirely generalized in railway construction up to now. So based on the examinations of cutting blasting, in the Zhegan electrified railway DIK119+150～DIK119+350 in order to make the electrified railway straight for improving the speed, the smooth blasting tests were done, the approaches of selecting the reasonable smooth blasting parameters and their construction craft procedure were performed or summarized in order to satisfied in high standard with the require of the slope excavation with high quality, reduce the problem of the roadbed substantially.The smooth blasting excavation tests were done in the Zhegan railway DIK119+150～DIK119+350. Many engineering examples all over the world and the data relating to the test were analyzed, the approaches of selecting the reasonable blasting parameters, the blasting equipments and charge configuration and their construction craft procedure for the smooth blasting fitting for the railway construction were performed or summarized. According to analyzing the sonic wave velocity detecting in the rock slope by the weak disturbance excavation blasting, the damnification of the remaining rock of slope was studied, and finding that the smooth blasting with decoupling charge can reduce the damnification range of the remaining rock of slope enormously, and the range was decreased to the 10～15 times of the diameter of the charge hole and the effect on the remaining rock was small, too, so it had a remarkable effect on the excavation quality. In addition, the excavation quality evaluation criterion of integrity horniness rock slope by the weak disturbance blasting was presented.The experiment results showed that it was the smooth blasting excavation that could make the slope surface stability, smooth and beauty, and the half cast factor was 95% or so, which was good for improving the quality of excavation quality, lowering construction costs, getting a better economic efficiency. At the same time, the approach of selecting the reasonable blasting parameters, the blasting equipments and their construction craft procedure was beneficial to extending its scope of application so that it has reference value to similar engineering.