Research On The Deep-seated Fracture Development Features And Evaluation On The Facture Rock Mass Quality Of The Slope At The Ye Ba Hydropower Station

The Deep-seated fracture weaken rock mass structure and reduce rock mass quality,even make rock mass' s strength parameters deteriorative.so it is very important to assess deep-seated fracture's development features and rock mass quality for genetic mechanism,slope stability,rock mass availability and so on.Take Ye Ba Hydropower Station 's deep-seated fracture as an example,with site investigation,sonic test,seismic wave CT to reveal deep-seated fracture's Spatial development and failure characteristics.Distribution based on the spatial characteristics of deep-seated fracture,deformation and failure characteristics,occurrence situ stress environment and its relationship with the structure of space,made of deep-seated fracture and deformation pattern classification.Based on the deep-seated fracture characteristics,introducing structural plane spacing,longitudinal wave velocity values,structural plane characters,the establishment of a new fracture in deep rock mass structural plane and classification scheme.With RMR rock mass quality classification method,introducing fracture of rock mass "The number of unit volume fracture K",to establish suitable for rock mass' s deep-seated fracture classification method of RMR.According to the rock mass' s deep-seated fracture field trials,laboratory experiments,and vertical velocity correction RMR value is based on the use Hawk Brown failure criterion of rock strength parameters obtained include the type of deep-seated fracture.The main results are as follows.(1)According to the basic characteristics of deep-seated fracture,the definition of Ye Ba Hydropower Station's Deep-seated fracture as "Distributed in conventional weathering unloading belt,the controlled faults,fissures grow or slow dip fault zone,the local development of a single open space larger width or length of intensive development was slightly open state tensional empty joints,or the performance of filled with sugar-like debris of broken,weathered general,local groundwater by late action".(2)Deep-seated fractures had been uncovered on the left and right slope of Yebatan hydropower station at low,middle and high elevation.The horizontal depth,which represented the location of deep-seated fracture,was between 80 m and 150 m from the surface of slope.With elevation decreasing,the horizontal depth decreased.(3)According to width,density,P-wave velocity,weathering grade,geostress and the relationship of tectonic structure and deep-seated fracture,three relaxation types of deep-seated fracture including slight relaxation(SR),medium relaxation(MR)and intense relaxation(IR)had been divided.In addition,three failure types of deep-seated fracture including tensile-shear fracture,shear fracture and tensile fracture had been proposed.(4)Obvious differences with respect to geological characteristics of SR,MR and IR had been revealed by field survey.The width of fracture had been extended from millimeter level to centimeter level with relaxation grade increasing.On the contrary,weathering grade,P-wave velocity and rock quality designation(RQD)had been decreased.Specially,P-wave velocity and RQD of SR were larger than 4500m/s and 70% respectively,and weathering grade was weak.In addition,P-wave velocity and RQD of IR were less than 3000m/s and 50% respectively,and weathering grade was intense.(5)According to deep-seated fracture expose in adit and using the imaging technology of seismic wave CT propose comprehensive identification method with seismic velocity(less than 4500m/s),faultage as termination border.(6)Based on the structure plane(deep-seated fracture)density,longitudinal wave velocity structure plane(deep-seated fracture)traits and other indicators,propose new rock structure type deep-seated contain fracture: "deep-seated fracture massive structure","close second block structure" and "close mosaic structure." "Deep broken block structure" and "close second block structure" structural differences smaller spacing,spacing greater than 30 cm,"tight mosaic structure" structural spacing is 10 ~ 30cm;"a close second block structure" and "close mosaic structure " rock longitudinal wave velocity values were greater than 4450m/s," the deep-seated fracture block structure " rock longitudinal wave velocity value is less than 4450 m /s.(7)The introduction of deep-seated fracture rock of " The number of unit volume fracture K ",on RMR classification method be amended to establish suitable for deep-seated fracture rock mass classification method.Deep-seated fracture may consider opening width,density,and other fillings on rock quality deteriorates.Classification showed good discrimination,and with macroscopic geological characteristics and field test results agree better,slight of loose rock is ?1(RMR= 51~60),moderate relaxed type of deep rock is ? 1~ ? 2(RMR=41to52),intense relaxation type of rock to ?2~?(RMR=30~44)based.(8)In field tests,triaxial tests and corrected RMR score is based on the use of Hawk Brown failure criterion to obtain three types of deep fracture rock mass deformation modulus and strength parameters.Slight relaxation type deformation modulus average of the maximum,about 17 Gpa,relaxation-type medium,intense relaxation type with an average of slightly relaxed type,respectively 65% and 40%.Slight of loose rock strength parameters f of 0.95~1.15,c is 1.15~1.50MPa;moderate relaxed type of rock strength parameters f of 0.75~1.00,c is 0.90~1.15MPa;intense relaxation type of rock strength parameters f 0.55~0.80,c is 0.70~0.95 MPa.