Study On The Stability Of Rock Slope Excavation Under High Altitude Stress Conditions

With the country's infrastructure construction and the development of mineral energy,the scale of human engineering construction is constantly expanding,and human activities in mineral energy development are faced with more and more complex difficulties.The influence of human activities on the excavation of large slope has caused a huge disturbance,and more and more major engineering accidents have occurred during the excavation of the slope,which has posed a serious threat to the national economy and the safety of people's lives and property.Therefore,researchers pay more attention to the stability of rock slope,and have made great progress,rock slope excavation has become an important research direction of geotechnical engineering.High in-situ stress slope mainly refers to that the horizontal tectonic stress is the main influencing factor in the calculation of the slope stress,while the normal in-situ stress state is mainly the self-weight stress.Based on the excavation of the medora copper mine in Ecuador as the research background,this paper selects the excavation of the rock mass slope,carries out the exploration and investigation on the site,and looks up various local data to obtain the geographical and geological conditions of the medora copper mine.After studying the stability analysis methods of rock slope at home and abroad,the reasonable numerical analysis methods and mathematical tools are selected.The slope of medora copper mine belongs to the rock mass slope,so it is excavated by the open pit mining method commonly used in the engineering field.At the same time,the selection of mechanical parameters of rock slope and the establishment of a reasonable model are of great significance in the evaluation of slope stability.Using FLAC3 D numerical analysis software,a mathematic model of the copper mine rock stratum slope excavation,the meshing model is reasonable and gives reasonable physical and mechanical parameters,choose the appropriate yield failure criterion,the mining slope in in-situ stress and simulate excavation under high in-situ stress calculation,the slope when the simulation is in a state of instability,security and stability,in order to ensure the continued excavation of slope for the need of mining slope reinforcement of support,mining slope stability is obtained by the numerical simulation of the related data,for the slope excavation process has the reference value of the mine area,this paper concluded the following results:(1)displacement obtained by simulation calculation under two excavation states of slope in mining area.When the slope is excavated to the second,third,sixth and seventh levels,the calculation of the maximum equilibrium rate is no longer convergent with the numerical calculation.The slope in the mining area is faced with different degrees of instability,resulting in different displacement.After the slope is supported,the displacement decreases and the slope is in a safe state again.By comparing the displacement of the two excavation methods,the excavation process of high in-situ stress state is more in line with the actual situation when simulating the excavation of high slope in the mining area,and it also meets the economic and safety requirements of the slope support process.(2)stress analysis of mining slope under two excavation conditions.The maximum principal stress and minimum principal stress of the mine slope increase with the increase of the slope depth,and the value of the maximum principal stress changes from tensile stress to compressive stress at a certain depth of the excavation face.In addition,the maximum values of the two are located at the lower right corner of the model.With the increasing of the excavation depth,the maximum and minimum principal stresses of the excavation face are decreasing.The maximum value of the principal stress will be greatly reduced after the support and reinforcement of the unstable slope.(3)according to the data access and technical specification requirements,the allowable safety coefficient of the slope in the mining area is 1.15.When the result of numerical simulation is less than the allowable value,it means that the slope in the mining area is in a state of instability.At this point,it can be seen from the displacement cloud diagram that the displacement is too large and the calculation of equilibrium rate no longer converges.For excavation depth is larger,the obvious horizontal tectonic stress influence factors in the high slope of deep excavation,high ground stress simulation calculation of slope safety factor is more security,ensure the construction safety,to reduce the loss of state property and people's life.(4)the change of the vertical displacement and vertical stress in the key nodes per level excavation,the choice of excavation slope vertices for key nodes,on the slope monitoring data of key nodes,you can better understand the changing process of the mining slope stability The displacement change of key nodes is more detailed.The simulation calculation under the two states is compared.Through the eight nodes selected in this paper,the simulated excavation under the state of high in-situ stress is more in line with the general law of slope excavation in the mining area.(5)Poisson ratio,as one of the important physical mechanical parameters in slope stability calculation,plays an important role in the calculation of high slope excavation,and poison ratio has an important influence on slope stability by affecting the size of the least major stress.