Reliability Analysis And Risk Assessment On Bedding Slope Of Red Sandstone In Western Hunan

Slope is the most common and extremely important geological environment in highway construction. The previous have studied a lot from theory to engineering practice, but some problems such as uncertainty are still hard to solve in practice. Lots of red sandstone with characteristic of easy weathering, easy disintegration, low long-term strength, slow tilt single interbeds, poor deformation and stability distribution along with Chang-Ji highway. It is easy to occur bedding slope. Based on the traditional safety factor, consider of the uncertainty of geotechnical parameter, a reliability analysis and risk evaluation system with the region characteristic of western Hunan is built to make the engineer design according to the results of risk assessment.The conflict between recently investment and long term benefits of the project can be more effectively coordinated.(1) The mineral composition, chemical composition, physical properties, water-physical properties, mechanical properties and expansion mechanism of the red sandstone are studied by experiments.(2) The crumbling property in soaking of the red sandstone is studied by three schemes. It points out that the crumbling stability of red sandstone is relative. A quantitative evaluation method of red sandstone crumbling is put forwarded.(3)The influence of triaxial stress state and tilt single of the structure plane in deformation and failure of layered rock mass is analysed by numerical simulation. Experimental results show that, with the increase of tilt single of the structure plane, the triaxial compression strength of layered rock-mass first decreases and then increases.The anisotropic strength of the rock is related to confining pressure. Interaction exists between soft interlayer and hard interlayer.(4)Through direct shear tests, the influence of moisture content on shear strength parameters of muddy intercalation was studied in detail. The influence of water-rock interaction is considered as one of the main influencing factors causing bedding slide.(5) The correction calculation method of ground stress in slope rock mass under the gravity stress and tectonic stress field was studied. The influence of ground stress to red sandstone bedding slope stability is revealed from the rock damage. According to the Mohr-Coulomb criterion, the concept of destruction approaching degree is introduced to promote the evaluation analysis for the rock mass damage based on the revised ground stress, and the proposed evaluation method is in accordance to the 5 levels of rock mass damage class, which in turn build the corresponding relationship of Q value with the rock mass damage.(6) The basic principles and analysis methods of reliability,as well as the statistics processing of geotechnical parameters of red sandstone bedding slope in western Hunan is studied.(7)The red sandstone bedding slide in werstern Hunan often occurs along the muddy intercalation. According to this characteristic, the corresponding geological model, mechanical model and reliability analysis model are established(8)The risk assessment system of red sandstone bedding slope in werstern Hunan is established from the four aspects:risk identification, risk analysis, risk evaluation and risk management.(9) In slope instability probability, one is based on the frequency of historical slide, the other is based on potential slide. we should select the maximum instability as slope design instability.