| The instability of open pit slope is a complicated nonlinear changing process,in process of operation and excavation,both security and stability are critical which is related to the safety of people's life and property,as well as the environmental protection and evaluation.There are important theoretical value and practical significance to study deeply on stability of geotechnical engineering and risk assessment from various angles and aspects.Based on the engineering background of Chengmenshan open-pit mine excavation slope in Jiujiang city Jiangxi province,in view of the existing research methods of slope stability,using the synthesis methods of field measurement,theoretical analysis,experiment research,numerical simulation and monitor survey,and basing on geophysical prospecting,rock mesoscopic test,energy principle and the strength reduction FEM,catastrophe theory and entropy theory to study deeply on the failure mode of slope engineering,mechanics,energy law,dynamic stability problems.Build several comprehensive evaluation method models which are effective to reveal the evolution characteristics and instability mechanism of deformation and failure.Research mainly in the following:(1)Based on understanding geological environment and EH-4 geophysical prospecting deeply and the basic rock mechanics experiment,a complex three-dimensional geological model including fault zones and multiple stratums is established through finite element and finite difference program.Adopted multi regional unique points,the layout and tracking of monitor unit to analyze the spatio-temporal evolution characteristics of displacement,velocity and plastic yield.Demonstrated dynamically and predicted instability risk section of mining slope in disaster processing,meanwhile,combined with the displacement vector angle index to illustrate the variation characteristics of both balance stability and sliding instability of slope system.(2)Deduced various kinds of energy criterion of slope system based on energy principle,carried through secondary development of user subroutine in finite difference program,adopted the language "Fish" to compile source code of energy program,and made full use of computer visualization to show the time-space evolution characteristics and their transformation rule in detail among gravitational potential energy,elastic strain energy,kinetic energy,and dissipated energy.Analyzed the "disorder","orderly","self-organization" evolution characteristics of slope and the internal complexity changing reaction from angle of energy,as well as the energy dissipation with "dissipative structure",conversion efficiency and trend characteristics.And the local energy release rate was put forward to reflect directly complex dynamic energy variation characteristics of energy absorption,release and transfer in different characteristic regions.(3)The cusp catastrophic model of displacement and energy were deduced based on catastrophe theory,the catastrophe criterion of displacement and energy as well as the identifying and implementation process which were established to analyze the stability state and mutation law of slope system.It was proved to be uniform and consistent well after comparing with the conventional instability criterion.(4)According to the excavation scheme,analyzed unloading deformation and stress release characteristics in the third period of the whole slope excavation engineering process,and the dynamic characteristics,trends of stability and the plastic zone were also analyzed as well as the spatiotemporal dynamics of all kinds of energy.And combining the energy release rate with rock failure process to illustrate the inner transformation rule and dissipation mechanism of energy.The risk and catastrophic collapse area during slope excavation were simulated and predicted,and combining with the existing intelligent monitoring scheduling system,it will be advantageous to supervise safely,scheduling and guide roundly slope stability in the third phase of excavation.(5)Based on entropy theory,this paper puts forward several new slope stability evaluation method:fuzzy relative membership model,the entropy weight-fuzzy set pair analysis,situation jump and connection entropy method,the total landslide entropy criterion.Comparing comprehensively and authenticate mutually with the finite difference numerical model based on mutation and evolution of energy,they were proved to be consistent well and logical stongly,and they had a high utilization rate of information as well as intuitive and accurate results which offered new multiple ways for slope stability evaluation. |
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