Research On Impact Of Perilous Rock Falling

The perilous rock mass refers to the steep slope of the hilly area,The rock mass with poor stability is composed of several groups of rock mass structures,perilous instability rock mass movement is the collapse,The collapse produced rockfall is extremely vulnerable to disaster.The collapse of perilous rocks is sudden,and the scale is not big,but the frequency is high,the randomness is strong,which seriously threatens the safety of the people's life and property and related infrastructure in the area,The impact stage of perilous rock falling will be directly decided the degree of damage.In this paper,theoretical analysis is carried out on the impact of rock falling and impact load vibration effect,The model experiment was carried out based on the example of the collapse in Jinfo mountain of Chongqing Nanchuan,Some main research results are as follows:(1)In the process of rocks falling,the lower air will be compressed by the rockfall,The influence of air compressive effect on the impact velocity of rockfall falling is considered.Set up the air compressed theory model,divided the falling process into n sections,using the theory of aerodynamics,energy conservation to carry on trace analysis.For piecewise,the calculation method of impact velocity is derived.(2)According to the Hertz collision theory,considered the impact of rockfall as an incomplete elastic collision,the completely elastic collision can be divided into"the compression stage"and"rebound stage"two parts,qualitatively calculate the time of each stage,based on the classical soil mechanics linear strain rebound curve and recompression curve to analyze the energy consumption of compress soil,combined the energy conservation theorem with the impact calculation formula,the time function of the rockfall impact is derived.(3)The moment when the rockfall falls to the ground will produce a powerful impact,while the dangerous rock body will be subjected to a powerful shock load,The shock load act as a stress wave action on rockfall.In this paper,combined with the wave mechanics and related fracture mechanics,reveals the law of the impact stress wave spreading between the internal joint surface of the rockfall and the secondly disintegrate form of tension stress in the rockfall body.(4)The model experiment was carried out based on the example of the collapse in Jinfo mountain of Chongqing Nanchuan,small scale model reduction was performed.The test instrument adopts DH311E piezoelectric acceleration sensor and the supporting DH5922 universal dynamic signal test and analysis system,to collection and output the vibration signal generated during the rockfall impact on the ground.At the same time,the leica hd camera.recorded the disintegration characteristics under the Stress wave excitation effect during the rockfall impact on the ground.(5)The model experiment was carried out based on the example of the collapse in Jinfo mountain of Chongqing Nanchuan,Small scale model reduction was performed.The test instrument adopts DH311E piezoelectric acceleration sensor and the supporting DH5922 universal dynamic signal test and analysis system,to collection and output the vibration signal generated during the rockfall impact on the ground.At the same time,the HD camera.recorded the disintegration characteristics under the stress wave excitation effect during the rockfall impact on the ground.(6)Aiming at the acceleration vibration signal obtained by indoor test model,the article has done the time-frequency analysis and acquired the result that acceleration hitting the ground excitation frequency rate is roughly about 150Hz,at the same time,the result of elimination noise particles on the surface of the whole process produced about 65.77ms^-2acceleration and maximum about 0.11184mm vertical deformation.At the same time,the author confirms the dangerous rock mass in the hit the ground in the process with continuous bottom-up impact disintegration characteristics.