The Relaxation Characteristics And Effects Of Rock Excavation On The Right Bank Of A Hydropower Station On The Jinsha River

On the right bank of a hydropower station on the Jinsha River,the excavation Slope is high and steep,which excavation depth near to 100m.There are many lithology layers,intraformational faulted zones and bedding fault zone are developed,and rock media type is complex.The relaxation of the rock mass is obvious,the quality and mechanical parameters of the rock mass are affected by the unloading relaxation.Based on the extensive collection of data,this paper analyzes the loosening phenomenon,relaxation depth and relaxation time of foundation rock,and evaluates the mass and mechanics parameters of the loosening zone and compares it with the rock mass below the slack zone.Simulate the thrust load of arch dam and analyze the stress-strain characteristics of arch dam.Specific results are as follows:?1?A variety of unloading and relaxation phenomena appeared including:easy to see in the aplanatic basalts in the"onion skin","plate crack"phenomenon,the structural plane dense development,and the burst hole cracks and so on.Analyzing the borehole image,the slack fissure is easy to develop in the vicinity of the orifice of the aplanatic basalt.The depth of the hole is gradually changed to the fracture or structural plane of the shear.?2?The depth of unloading relaxation is 0.8¹.8m,the maximum attenuation rate is 15.62%,which general is 7¹0%,and the decay rate increases from 3 to 6 months after excavation.Slow down.Rock mass relaxation factors in addition to the time,but also includes fracture structure,elevation,lithology,etc.?3??₂ and?are the main mass quality of foundation plane.Respectively,compared with the relaxation zone the descending rate of acoustic wave in the lower rock mass is 20%⁴0%,and the mass of rock mass is reduced about 2 grades.?4?Based on the field deformation test,and the mechanical parameters of the foundation rock are taken.Compared with rocks below relaxation zone,the deformation modulus of the slack zone decreased about 57⁶5%,rock mass strength parameters decreased about 25⁵9%.?5?Through the comparative analysis of similar engineering experience,the right bank of the shoulder canopy zone can meet the engineering requirements.The model is used to simulate the recovery of the rock mass after the laying of the dam,and the availability of the loose rock mass is verified.At the same time,the relaxation rock mass treatment measures suggestions are put forward.