Geo-Engineering Study On High Slope Stability And Dynamic Design Of Expressway In Mountain Area

The slope stability is the key technical problems which affect construction safety, progress and cost of expressway engineering, not only because the route is long so that there are many slopes along it, but also the slope failure models are complex. There are many slope stability evaluation methods and design methods for highway slope, but they do not connect the geological conditions of slopes perfectly. As a result, there are many problems during application, such as, the models are complex so that the design periods are long, and it is difficult to realize dynamic design and informational construction. So the author constructed engineering geological classification of slopes for support schemes design based on generalization of support measures and their scope of application through study on rock mass structure and failure models of many slopes along Expressway from Tangkou Town to Tunxi City in south of Anhui Province, China. Then obtained slope stability evaluation methods and design schemes about different types of slopes by optimization through design result certification and slope deformation monitor. The research findings achieve anticipative aims and make some progresses both in slope classification and in dynamic design. The research findings are described as follows:(1) The dynamic slope design method for expressway in mountain area is established. Its base is the study on rock mass structure and failure model of slopes, its key content is engineering geological classification of slopes, its aim is slope stability evaluation method and support schemes design method. The author established the system of slope stability evaluation and support schemes design which can be described as follows: "engineering geological conditions investigation→description of rock mass structure→analysis of slope failure model→slope stability qualitative analysis and quantitative evaluation based on geological procedure→geological hazard control and support schemes design→slope deformation monitor".(2) The evaluation method of rock mass structure is studied systemly applicable to slope stability evaluation and support scheme design. The types of rock mass structure applicable to expressway slope in mountain area are divided into block structure, assistant-block structure, cloddy pulverescent structure, cataclastic structure, and scattered structure. And classification and description system of discontinuities are established according to characteristics of expressway slope, which describe discontinuities as controlled weak structural plane, normal weak structural plane, and joint. And then method of rock mass partition is studied for slope.(3) Based on analysis of slope support measurement generalization and their application scope, schemes design is studied including four common types of slopes: landslide, potential arc slide, deep block destroy, superficial block destroy. Then the the design scheme and support measures is studied, the result indicates that the slope design scheme classification is divided into cutting slope to reduce load, massive support scheme, weak support scheme, and slope surface protection. And the application scope of different design schemes is studied.(4) The slope classification for support is divided into block structure slope, tabular structure slope, cataclastic structure slope, and scattered structure slope according to rock mass structure and failure model. Based on study on geological conditions, influence factors of slope stability and main failure models, the slope support schemes and measurements are put forward, which make for rapid selection of slope support schemes of different type slope.(5) The slope stability evaluation and support schemes design method for block structure slope along Expressway from Tangkou Town to Tunxi City is studied. That is, to combine discrete element method to search key block of slope with block theory to evaluate the stability of key block quantitatively, which develops slope stability evaluation and support schemes design method for block structure slope.(6) The forming mechanism and slope failure model of ancient tabular structure rock mass are studied for the first time in mountain area of South of Anhui Province, in China. The tabular structure rock mass can be divided into bedding slope and counter inclined slope. According to characteristic of tip deformation rock mass in the study area, the tip deformation rock mass can be divided into plate-pile structure tip deformation rock mass, cataclastic structure tip deformation rock mass, and scattered structure tip deformation rock mass. Then the slope failure model, stability evaluation method and support measures of tabular rock mass slope are put generalized systemly.