Experimental Research Of Dam Foundation Rock Damage Under Blasting Loading

After the hydraulic structures foundation rock blasting excavation, usually formed a certain depth damage layer near the rock mass contour line cause by blasting effect. Studying the damage degree of the damage layer, can provide useful references for evaluating the hydraulic structures' stability,the dam safety research impervious effect and strengthening result. Paper based on the dam foundation surface rock quality acceptance for the excavation blasting, using FLAC D numerical simulation process, analyzed the porous rock blasting cases damage rule and given some methods to reduce blasting damage. The main research contents as follows:1,According to developed process of rock blasting theoretical models and the computation research, analyed the characteristics of the current rock blasting theoretical model. Highlights the damage model and point out the advantages and disadvantages of these models.2,Combined with the dam foundation surface blasting excavation, take ultrasonic test on the excavation aera to evaluate the rock quality. With the test, insured the blasting damage affected range, evaluated the foundation surface rock excavation quality. In each test profiles with and the original rock and damage the boundary more specifically, but only by their respective wave speed boundary value the depth of the hole - wave to delimit the turning trend curve, the divide wave velocity can not apply mechanically point to differentiate other test profile.3,From the ultrasonic test data, the change regularity of waveform,amplitude,frequency,wave velocity variation is analyzed. The analysis shows that with the hole depth increases, the waveform becomes progressively from not law to law, amplitude and wave speed also increased and the frequency started to move from the low-frequency part to the high-frequency part. However, the existence of local fluctuations, primarily the situation where the rock has changed.4,Using numerical model to determine the scope of damage. Dynamic analysis of properties using FLAC3D conducted under the simulated blast porous analyzed the development of cumulative damage law. With the increase in the number of blasting the rock more and more serious damage by surrounding the hole blasting on the nearby area there are also affected. This effect increases with distance continuously decreased beyond a certain range can be ignored. Determine the impact of blasting and blasting damage the depth range.5,Finally, on how to reduce the damage degree, did some simulated and according to the similar engineering experience, combining with the actual situation on site, put forward some construction proposals..This paper closely combining the actual engineering, using theoretical analysis and field test and numerical tool in studying on rock mass eumulative damage effects under blasting loading. It founded a effective methods for studying on the stability of rock mass under the frequent blasting operations systemieally.