Analysis Of Lower Waves Velocity And Valuation Of Excavation-disturbance For The Foundation Rock Of Granite In Complicated Geology Environment

Engineering rock mass is formed by long-term geological effects with complex structure and characteristics of the geological body. In the actual rock engineering rockmass excavation, due to the occurrence condition changes, which change the mechanical properties of rock excavation, often appear slack rupture, cause danger occurs, affect the project smoothly, etc. Similarly, originally landscape in seemingly appropriate dam site topography condition often due to high geostress, rock properties such as weakening the excavation is delayed construction period, increase the project cost, and even have to give up the original design. Located in the middle of the canyon area in DaDu River DaGang Mountain power station also meet similar engineering problems, left the foundation surface (EL1135-1040m) acoustic detection already excavation single-drillhole acoustic wave abnormity is low. Accordingly, while commands a large field survey data and acoustic detection onthe basis of the achievement of DaGang Mountain complex geological environmental conditions for determining the center, the different geological conditions, and then single-drillhole acoustic curves characteristics in the dam site area of geological environment by various factors listed analysis, and comprehensive utilization rock quality inspection hole left the evaluation of the foundation excavation disturbance characteristics. The main research method, content and some research results are as follows:(1)Combined with landform, stratigraphic lithology, geological structure, geostress, neotectonic movement DaGang Mountain, comprehensive clarify existing unique complex geological environment characteristics, this is understanding the existing foundation rock sound waves of lower granite foundation;(2)Understanding the foundation surface already excavation on engineering rock mass characteristics, through the rock quality, weathering degree, altered characteristics, drilling axial and so on the different engineering geological conditions, analysis single acoustic curves features and differentiate to stress release region, stress adjustment region, stress stable region, and analogy with the Three Gorges Hydropower Plant and LaXiWa Hydropower Station, outstanding research area foundation rock detection acoustic abnormity; (3)In the dam site area granite with petrological characteristics (such as the formation environment, altered characteristics, hidden micro fracture characteristics, etc.), geostress characteristics, geological structure, fault activity and superficial aspects of life DaGang landscape transformation revealed low power station granite wave;(4)To discuss the foundation already excavation face typical artificially disturbance phenomenon, comprehensive utilization acoustic and variable mould and so on rock quality inspection hole, quantitative evaluation DaGang Mountain foundation surface left, and then analyzes the excavation disturbance characteristics of engineering rock mass of aging response.