Study On The Excitation-chain Effect Of Perilous Rock Avalanche

Group-occurring avalanche is a serious global geological disaster in rockymountain region, and the unstable rock masses in the source of landslip become themain factor of group-occurring avalanche. Therefore, the interaction of perilous rockmass should be taken into account in the avalanche mechanism study. Taken falling-typeperilous rock as research object and multi-disciplines (such as rock mechanics, fractureand damage mechanics, wave theory, elastodynamics) as theoretical basis, thesisanalyzes the mechanical mechanism of the perilous rock masses breakout from thecollapse and the chain-excitation effect affect on the other perilous rock caused by theavalanched. The main results studied are as follows:Focus on falling type perilous rock, an mechanical model of the excitation actionduring the collapse of perilous rock is established,According to the thesis analyzes themechanics characteristics at dominant fissure under the vertically incidence ofexcitation waves, and establishes the combined stress intensity factor calculationmethod on the tip of dominant fissure, and analyzes the fractured amplification effect onperilous rock’s dominant fissure caused by excitation action.Thesis generalizes the falling type perilous rock to cantilever beam, and studies thedeparture rate of landslide body at momentary avalanche as well as the chainedexcitation effect through the energy point. Meanwhile, thesis analyzes the formation ofexcitation wave and its propagation mechanism in perilous rock, and builds thecalculation method of peak particle vibration velocity and excitation intensity ofperilous rock under excitation action. All of those effective describe the excitationaction of avalanche’s intensive effect on the damage and avalanche of perilous rock.Based on the peak particle vibration velocity, thesis brings forward the damagevariable’s expression adopting damage mechanics, and analyzes the distributingcharacteristic of peak particle vibration velocity caused by excitation wave in fracturedrock mass combine with the microscopic damage model of rock and the excitationwave’s energy attenuation law in jointed rock mass.Then, according to the damagecriterion of peak particle vibration velocity, the lesion dimension’s calculation methodto other perilous rock induced by excitation wave can be established.According to the experimental model of the excitation action during the collapse ofperilous rock, six groups of test data in three test points at x and y directions are gained by piezoelectric acceleration sensor and dynamic spectrum instrument. To analyze thetest data, it can be gained that the excitation wave at y direction is bigger than one at xdirection.De-noising the excitation signals adopting db wavelet and threshold de-noisingmethod, the de-noising signal can be disassembled by db8wavelet, and energydistribution in9frequency bands can be gained. The characteristic parameters ofexcitation signal such as frequency distribution and the main vibration frequency can beobtained by wavelet time-frequency analysis. The time domain characteristics ofexcitation signal such as mean value, virtual value, standard deviation and probabilitydensity can be obtained by statistical analysis, meanwhile, the frequency domaincharacteristics of excitation signal such as spectrum, power spectrum and coherencefunction can be analyzed by the same way.Based on the model test of perilous rock avalanche excitation effect and take theYangchahe in Chongqing city as example, thesis quantizes the departure rate formula oflandslide body at momentary avalanche, the intensity of excitation wave, the influenceof excitation wave affects the stability of perilous rock, the peak particle vibrationvelocity induced by excitation wave and the lesion dimension of perilous underexcitation action. The results provide some scientific basis for the further research ofperilous rock damage and evolutionary mechanism...