The Nonlinear Response Characteristics Of Transmission System In Mountain Disaster Chain

China is a mountainous country where mountain areas account for 66%of the total territory. Landslides, avalanches, debris flows and other slope disasters under gravity take place frequently. In particular, the mountain disaster chain causes larger scale damages than normal mountain disasters. In recent years, with the irregular changes of global climate and the increase of human social and economic activities, extreme weathers and geological events occur more often. The increasing trend of mountain disaster chain turns out to be a serious threat to people’s lives and properties as well as some major projects. The study of mountain disaster chain’s formation mechanism, dissemination process, and disaster modeand mitigation measures become issues of great scientific significance and practical value.Given the present study on mountain disaster chain is still in its infancy, the response characteristics of disaster transmission system is deserved our main concern since they are regarded as a crucial issue in mountain disaster chain. Three typical mountain disaster chains, namely, landslide triggered by earthquake、debris flows and the burst of the barrier lake are selected as research questions. Based on the nonlinear characteristics of disaster transmission system, we apply some theories and methods of nonlinear science, such as self-organized criticality (SOC), cellular automata, detrended cross-correlation analysis. Moreover, interpreting of remote sensing datas, exploration of field site, the shaking table experiment of sand pile and water tank, computer simulations are also used to reveal the nonlinear response characteristics of disastertransmission system under the intervention of primary system. The main work and conclusions are listed as follows:(1) Considering characteristics of landslides triggered by earthquake and debris flows, we designed a cellular automata model in which disturbance intensity increases, and another cellular automata model in which the intensities are random variables. Through a series of sand pile model experiments with vary perturbations, we have access to a number of response characteristics of SOC system under varied disturbance conditions. Expanding the application of SOC in catastrophe theory and promoting the development of experimental techniques with acellular automata sand pile model.(2) We propose that only when valleys are in late childhood or mountains are in middle adulthood, the slopes be always maintained at the critical gradient, and the system has evolved into a critical state. Furthermore, the common feature of such surface gravity process as collapses、landslides、debris flows is that the energy dissipation is realized though the glissade caused by lack of stability. Therefore, the sand pile model becomes a simple ideal model of real slope systems, which defines the application scope of SOC in mountain science.(3) The field data show that there exists a power-law relationship between the size and number of landslides in IX seismic intensity zone in the Wenchuan earthquake, and the same is true in X seismic intensity zone. However, the relationship changes to the lognormal distribution in XI seismic intensity zone. The field data show that there exists a power-law relationship between the size and number of landslides in Ⅸ、Ⅷ、Ⅶ seismic intensity zones in the Lushan earthquake. But with the decline of the seismic intensity, the density of landslides decreases monotonically. The cellular automaton simulation reveals that the dynamical mechanism of sand pile model is subject to two different properties, with 1-Fmax of disturbance value as a boundary. In the section of the disturbance value less than 1-Fmax, with the decline of the disturbance intensity, the dynamical mechanism of system can also be described by a power law distribution, but the density of avalanche decreases. Therefore, it must be increased in order to constitute an avalanche density index system complete description of the statistical properties of the SOC in this range. In the section of the disturbance value greater than 1-Fmax, with the increase of the disturbance intensity, the dynamical mechanism of sand pile model is from a strong power-law to a weak power law, then to a lognormal distribution. It is proved that the distribution model of landslides in different with seismic intensity zones. A complete characterization of the general characteristics of landslides in different seismic intensity zones from Ⅶ degree to XI degree is initially established.(4) Debris flow is close to sand pile model, the self-organization effects can not be ignored. The study on Jiangjia jully debris flow shows that there exists a power-law relationship between the size and number of debris flow, or it is close to the distribution of regional rainfall.(5) Cross-correlations between the seismic wave at Mexicali firehouse station and the water wave in a swimming pool and shaking table of water tank are analyzed by DCCA method. The results reveal that there is a significant positive correlation between the seismic wave at Mexicali firehouse station and corresponding water wave in the swimming pool and experimental shaking tank within 4 seconds, which proved that the design of shaking tank table experiment is feasible. Similar shaking water tank table experiments were carried out using three different earthquake waves, the results reveal that the main frequency of earthquake wave is the decisive factor of cross-correlation’s time scale.(6) We define the primary system and the disaster transmission system as the SOC-SOC Disaster Chain if they are all SOC systems. The typical SOC-SOC Disaster Chain, such as debris flows triggered by rainfalls is to be selected as research question. We have access to a number of response characteristics of SOC-SOC Disaster Chain. When the average intensity of disturbance is small, the complexity of disaster will be enlarged. With the increase of the disturbance average intensity, the enlargement will be gradually declined, until disappears. This is the first exploration about transfer characteristic of the SOC-SOC Disaster Chain transfer.In a summary, through the research on three typical mountain disaster chains, we succeed in gaining basic understanding of the nonlinear response characteristics of transmission system. The process from phenomenological to exact science is expected to be promoted by our exemplary explorations.