Study On Stability Analysis Method Of Flexural Toppling Rock Slope

With the continuous construction of mine,railway and highway engineering in our country,frequent engineering disturbance makes slope frequently"toppling"deformation and failure.The further development of toppling deformation and failure will lead to landslide or collapse,which will cause irreparable damage to the slope and have an adverse effect on the project construction.In this paper,the flexural toppling failure mechanism of anti-dip rock slope is studied,and the regional characteristics of toppling failure are analyzed by discrete element software UDEC.Combined with the mechanical failure characteristics of anti-dip rock strata,the calculation model of potential fracture depth of superposed tipping area based on the limit equilibrium analysis method is established,which realizes the quantitative evaluation of stability of anti-dip rock slope.The main work and achievements of this paper are as follows:（1）In view of the lack of systematic research on the flexural toppling failure mechanism of anti-dip rock slope,the failure mechanism was systematically analyzed,and the failure mechanism was simulated and verified by the numerical simulation software UDEC.In this paper,the geological causes of the inverted dip of rock strata are summarized into four types:original tilting rock strata,a wing of fold structure,a plate of fault structure,and uneven settlement of strata.The factors leading to slope the flexural toppling summarized,and the slope areas of the flexural toppling are divided into four categories according to the difference of the development stage of the flexural toppling and the failure modes of rock strata.The systematic analysis of slope the flexural toppling failure mechanism is realized.The research on the failure mechanism of the flexural toppling has important guiding significance for the excavation and treatment of anti-dip rock slope.（2）In order to solve the problems of complex force condition and difficult determination of failure depth of anti-dip rock slope,a calculation model of potential fracture depth of superimposed tipping zone based on limit equilibrium analysis method was proposed.According to the failure mechanism of the strata in the superposed tipping area,the fracture depth models under three different conditions were established for the possible slope positions of the N_t-1 block in the area,and the calculation expressions of the potential fracture depth in the superposed tipping area were determined comprehensively.The calculation model can quickly judge whether the slope is at risk of the flexural toppling failure,and predict the toppling scale when the risk slope occurs,which is of great significance for predicting the overall failure scale of the anti-dip rock slope.（3）In view of the lack of quantitative evaluation of the flexural toppling failure mode of the anti-dip rock slope,a quantitative evaluation method of the flexural toppling rock slope stability based on the calculation of the breaking depth is proposed.Based on the difference of deformation characteristics of rock strata in each failure area when the slope is flexural toppled,the instability area of the slope is determined as shear slip area,superimposed tipping area and cantilever tipping area respectively.The force analysis of each area is carried out,and the stability coefficient of the slope is defined by the stability coefficient of rock strata at the top of shear slip area.The proposed method makes the stability evaluation results of the flexural toppling slope more objective and has practical significance for engineering construction.（4）In order to verify the engineering applicability of the fracture depth method,taking the central slope of the north side of the northeast stope of Changshanhao Mine as an example,the fracture depth method and G-B method were used to calculate the stability of the reverse dip rock slope,and the calculation results of the two methods were compared and analyzed.Both fracture depth method and G-B method show that the slope is in an unstable state,which accords with the engineering practice.The fracture depth method not only focuses on the deformation characteristics of each region of the slope,but also takes into account the overall deformation of the slope.Compared with G-B method,the fracture depth method is more reasonable in calculating and analyzing the flexural toppling failure of the slope.