| In recent years,with the implementation of geotechnical engineering such as mining and tunnel tunneling,engineering disturbance will destroy the natural stability of fractured rock mass and lead to rock collapse.Therefore,monitoring and early warning of the failure process of fractured rock mass is of great significance to the safety implementation of geotechnical engineering.In this paper,the strain field,infrared radiation temperature field and acoustic emission ringing times of single prefabricated fissure rock specimen in the process of uniaxial compression are monitored.Based on principal component analysis,the multiple monitoring information is fused and analyzed,and the probability warning of specimen failure stage is proposed from the perspective of energy accumulation.Based on the digital image correlation technology,the strength characteristics and crack development of the specimens with complex fractures under different filling conditions are compared,and a method to identify the abnormal precursors before the failure of complex fractured rock mass is proposed.The main research results are as follows:(1)The standard deviation curves of horizontal,vertical and shear strain fields under uniaxial compression of single prefabricated fissure rock specimens can be roughly divided into three stages: stable stage,low speed differentiation stage and fast differentiation stage.(2)The infrared radiation standard deviation curve basically maintains a linear growth before the peak stress,and rises sharply when the peak stress is reached,with an increase rate of 34.76%.High temperature bands are formed on the surface of the test block.The ae ringing times curve is stable before the peak stress,and the ae ringing times reach the peak when the test block is on the verge of failure.(3)According to the principal component analysis function,the order from strong to weak is the standard deviation of horizontal strain field,the standard deviation of shear strain field,the standard deviation of vertical strain field,the standard deviation of temperature field,and the number of acoustic emission ringing.(4)Based on the fusion function of multiple information,the failure process of single prefabricated fissure rock specimen was quantitatively analyzed from the perspective of energy accumulation,and the cumulative probability of specimen failure at any time was determined.(5)In the uniaxial compression test of rock samples with complex fractures,HIPS filling and low strength gypsum filling increase the peak strength by 56.34% and29.11%,and increase the elastic modulus by 119.59% and 25.77%,compared with those without filling.(6)The weaker the strength of complex fracture specimens under different filling conditions,the more intensive the germination of new cracks in the failure process,and the more complex the expansion situation.The order of standard deviation of the length of prefabricated cracks responding to the failure process is HIPS filling & GT;Low strength gypsum filling & GT;No filling,consistent with the magnitude of peak stress;The order of deviation of inclination Angle of prefabricated cracks is HIPS filling & GT;Without filling & gt;Low strength gypsum filling,consistent with the size of the peak strain.(7)The macroscopic crack expansion of the specimen with complex cracks is accompanied by the generation of stress drop,and the corresponding gray standard deviation-time curve changes suddenly.At the precursory point A2,the precursory/peak stress ratio is 0.91,and the precursory/failure time ratio is 0.84,which can be used to identify the failure precursors of complex fractured rock mass and realize the instability warning of rock.Figure 32 Table 16 Reference 80... |
PDF Full Text Request