| The construction of Yuhuai railway from Chongqing to Huaihua is faced with a great lot of cutting blasting engineering in layered rock masses. The seismic action in blasting results in the part or whole lamination breakage of slop rock mass in all probability, which will reduce the slope stability, even induce the cutting sliding or collapsing by any possibility. These not only affect the construct, but also add to the difficulties of protection construction. Thus, the engineering cost increases, even the safety accidents easily occur.In order to solve this problem, the field experiments for seismic effect and lamination effect of layered slope rock mass at Yuhuai railway DK375-DK377 were carried out. The attenuation laws of seismic waves for different blasting methods were obtained. The lamination ranges of rock masses caused by deep-hole and short-hole blasts were measured and the corresponding distribution laws of particle vibration velocities were also gotten. The control standard of vibration in the layered rock slope blasting was determined and moreover, the technical measures of blasting for reducing vibration were put forward.For a deep-hole blasting, the attenuation parameters of seismic waves along the cutting cross-sectional direction are K= 240.40, 1.54 and along the longitudinal direction K= 298.48 1.63. For a short-hole bench blasting, the corresponding attenuation parameters are K=42.96, a= 1.58 and K=58.92 1.52, respectively. For a short-hole smooth blasting, the attenuation parameters are K=35.03 1.21 and K= 72.24 1.67,respectively.Through the comparing analyses between the particle vibration velocity and the lamination range of rock mass, the critical vibration velocity of rock particles while rock masses occur lamination cracks in the region have been determined, which is 25.3 cm/s. The lamination range resulting from a deep-hole blasting is greatest. When the charge of a blast hole is 5 ~ 40 kg, the lamination range reaches 7.36-14.73 m.The lamination range induced by a short-hole bench blasting is much smaller than that of a deep-hole blasting, which does not exceed 2.5 m.The subsection construction scheme of which remains a protected layer and combines the deep-hole blasting with the cushion blasting is presented in this thesis. Some technical measures of reducing vibration, such that the single-hole charges of the deep-hole blasting and cushion blasting are controlled within 15kg and 5kg respectively and that the interval charging construction in a blast hole and the sequence micro-second ignition technique between blast holes as well as their internals are applied, can effectively control the particle vibration velocity of layered slope rock mass and the lamination range of rock mass. These can also reduce even avoid the lamination effect of rock blasting.The research results mentioned above were used in a few of some projects in Yuhuai railway construction. According to the concrete conditions of these construction sites, the corresponding technical measures for reducing seismic effect of blasting were taken and therefore, no quality safety accident resulting from excavating blasting occurred. The slope surface formed by blasting is stable and smooth, which accords with the demands of design and the acceptance criterion. The construction achieved better economic and social benefits.
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