| The layered rock slope (including bedding and counter-bedding rock slope) with weak intercalated layer is comman geologic body. However, before the 2008 Wenchuan eatrthquake event, the dynamic responses and seismic stability evaluation method of layered rock slope with weak intercalated layer don't attract much attention of engineering and academia field. In the 2008 Wenchuan earthquake event, many layered rock slopes with weak intercalated layer occurred in the earthquake stricken area, since then many researchers started to pay their attention to the dynamic responses and seismic stability evaluation method of layered rock slope with weak intercalated layer. As one of research means which can reveal the dynamic response of research object directely, shaking table test has been widely used in civil engineering seismic research. Based on similarity theory and large scale shaking table test, the response and reinforcement measure of layered rock slope with weak intercalated layer were studied in this work. Based on the Hilbert-Huang Transform (HHT) and the data collected in the shaking table test, the developing process of seismic damage inside model slope was studied, and then the dynamic failure mode of layered rock slope with weak intercalated layer was researched using energy-based method. Based on the elastic wave mechanics and Hilbert-Huang Transform, the time-frequency calculation method for instantaneous seismic safety coefficient of layered rock slope was derivated with considering the time-frequency-amplitude characteristics of seismic wave, and the collected data in the shaking table test was used as an example to show how this time-frequency calculation method was used to calculate the instantaneous seismic safety coefficient of layered rock slope. The research in this paper will guide identifying the dynamic failure modes, optimizing the reinforcement measure and evaluating the seismic safety of layered rock slope with weak intercalated layer. The main achievements and conclusions obtained in this work are as follows:(1) The large scale shaking table test of layered rock slope with weak intercalated layerAccording to the prototype of a bedding and a counter-bedding rock slopes with weak intercalated layer, two test models were designed and constructed, one of which simulates bedding rock slope and another one simulates counter-bedding rock slope. The compressed El Centro and Wenchuan qingping earthquale records according to the similarity relation were used to excite the test model. In the test, the acceleration, displacement and frequency response of the bedding and counter-bedding rock slope with weak intercalated layer were studied, and the influence of moisture condition of soft intercalated layer on the acceleration, displacement and frequency response was discussed.(2) The dynamic characteristics parameters calculation and analysis method in frequency domain of layered rock slope according to the transfer functionThe two kinds of transfer function (i.e. relative transfer function and absolute transfer function) of layered rock slope with weak intercalated layer were compared in this paper. The method using transfer function to calculate the dynamic charateristics (i.e. natural frequency, damping ratio and vibration mode) was introduced, and the dynamic characteristics of bedding rock slope and counter-bedding rock slope were compared. According to the transfer function, the frequency-domain response estimation method of layered rock slope with weak intercalated layer was developed.(3)The engery-based method for dynamic mode identification of layered rock slope with soft intercalated layer based on the HHT and marginal spectrumBased on the acceleration data collected in the shaking table test, Hilbert-Huang Transfer and the marginal spectrum, which denotes the energy of seismic wave, by analyzing the variation rule of marginal spectrum amplitude at different positions in the slope, the developing process of slope seismic damage under seismic wave excitation with various intensities can be identified. Based on the inferred seismic damage results inside the slope, and combined with the sloep face displacement and observed fissures, the seismic failure mode of layered rock slope with weak intercalated layer can be obtained. The dynamic modes of bedding rock slope and counter-bedding rock slope were compared in this paper.(4)The dynamic reinforcement measurement of layered rock slope with weak intercalated layerAccording to the post-earthquake investigation for anchoring structure and slide-resistant piles, the bedding and counter-bedding rock slopes were reinforced by slide-resistant pile at slope toe and pre-stressed anchor cable at slope surface and anchor rod comprehensively. The El Centro and Wenchuan qingping earthquake record were used to excite the test model, the acceleration, surface displacement and the axial rorce of pre-stressed anchor cable of reinforced slope were analyzed in this paper.(5) The time-frequency calculating method of instantaneous seismic safety coefficient for layered rock slope Based on the elastic wave mechanics and Hilbert-Huang Transform, the time-frequency-amplitude characteristic was separated in the time-frequency domain, and then the time-frequency calculating method of instantaneous seismic safety with considering the time-frequency-amplitude characteristic of seismic wave was established. The collected data in the shaking table test were taken as an example, the instantaneous seismic safety of bedding plane near the monitoring point under the excitation of first strong section of Wenchuan Qingping wave was obtained. |
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