Study On Stability And Designing Of Consequent Bedding Rock Cut Slope

With the development of construction of infrastructure, the problem of the stability of the consequent rock slope is met in the railway construction and the highway construction in mountain. The past engineering practice shows that the consequent rock slope is most likely to failure in the rock slopes, and it causes enormous loss of the engineering project and the life and belongs of the people. Now, the system research of the stability of the consequent rock slope, the relevant engineering measures and design methods are not developed. So, how to analyze the stability of the consequent rock slope and raise the reasonable design scheme to prevent the failure of the consequent rock slope become difficult problems to roadbed design engineers.Based on the project of the consequent bedding rock slope in the railway from Chongqing to Huaihua, the deformation and failure mechanism, stability analysis and support measures of consequent bedding rock slope are studied in detail by multiple methods. The main results and conclusions can be expressed as follows.1. On the basis of investigation of lots of typical sites of consequent bedding rock slope, the results of field investigation, the feature of the design, engineering measures of the consequent rock slope are summarized, and the consequent bedding rock slope is classified into three primary types and six secondary types by the angle of inclination and the combination of lithology. The engineering geology character and stability of each types are described as well.2. The major influence factors including the geology factor and engineering factor of stability and the deformation and failure modes of consequent bedding rock slope are summarized. The deformation and failure modes consists of nine types which are sliding and fracturing, sliding and compression cracking, bending and fracturing, plastic flowing and fracturing, sliding and bending, sliding and splitting and bedding sliding.3. For the consequent rock slope with multiple weak interlayer, the kinetic displacement formula including the energy coefficient used to calculate the stability of the slope is presented. Three failure modes about the sliding and fracturing were developed. The formula used to calculate the bedding slip rangeof the consequent bedding rock slope with failure mode of sliding and fracturing due to road cutting is presented considering the reduction of shear strength of the bedding plane due to unloading and weathering. Also, the formula used to estimate the stability of the consequent bedding rock slope with slip-bending mode is established by the application of elastic plane theory which can consider the influence of both slope length and the plasticity of rock mass.4. Four geological conditions types of the dip formation slope and its stability are described. The relation between the deformation discipline of layered rock slope due to excavation and the intersection angle of the strata and the slope strike direction are studied by theoretic analysis. The results show that when the intersection angle increase, the stability of the consequent rock slope increase as well.5. Based on series of model tests, the deformation mechanism of the consequent rock slope resulting from road excavation is studied. The results show that the primary failure modes of the slope are sliding and fracturing and bedding sliding. The deformation of the slope is mainly induced by the excavation, and reducing the disturbing of the construction is favorable to the slope stability. So, the slope reinforcement measures such as anchors, cables and anti-slide piles should be installed in advance to ensure the slope stability. The model test results show that the construction method of reinforcement in advance is effective measure to ensure the slope stability. The results show that the disturbing range of slope excavation decreases when the intersection angle increase, and when the intersection angle exceeds 35 degrees, there seems to be little probability of bedding slip of the slope, and the slope may not defined as consequent bedding rock slope.6. The sensitivity analyses on the stability parameters of the consequent rock slope is developed. The parameters include hydrostatic pressure, internal friction angle, cohesion and excavation angle of slope. The principles for determining internal friction angle and cohesion in different stages of engineering design have been purposed by using analogical design, regional investigation, in situ and laboratory test.7. According to the research results in this thesis as well as the domestic and foreign engineering experience in harnessing and design Consequent rock slope,ten engineering design principles have been developed. The good results have been obtained by applying the principles in the project of the consequent bedding rock slope in the railway from Chongqing to Huaihua.