Stability Analysis Method Of Soil Slope Based On Real-time Monitoirng Displacement In Seasonal Frozen Area

In the construction of national economy infrastructure, just like highway, tunnel andsubway construction and excavation, etc, a variety of soil slopes were formed. Soil slopeespecially in seasonal frozen area, the role of rain and freeze-thaw cycles leads to shear strengthof soil damage and slide. If we can master the characteristic of slope deformation and stabilitythrough monitoring, the landslide can be prevented effectively by taking correspondingmeasures and landslide disaster lowered by early warning.Due to the generation of landslide disaster is a gradual process of development, if we canmaster the change rule of soil slope deformation and stability in time, there is enough time toreinforce soil slope or provide early warning measures, it can prevent occurrence of landslideand reduce the landslide hazards effectively.At present, safety monitoring of the slope contains monitoring of slope displacement,stress-strain and underground water level and other parameters, and analysis slope safety stateby setting the alarm value approach. If the monitoring value is less than the warning value, theslope is in a safe state. If the monitoring value exceeds the warning value, the slope is in adangerous state. It has great experience to set a threshold value to judge the slope stability state,usually making error judgment of slope stability due to alert value setting unreasonable.And for the analysis of slope stability, along with the development of slope stabilityanalysis method, current regular use of stability analysis method such as the slice method andstrength reduction method, can accurately calculate the slope stability safety factor. However,the acquisition of slope soil mechanic parameters is the current difficulties in slope stabilityanalysis. Because of the soil is not uniform, and the internal distribution is discrete andasymmetry. The soil mechanical parameters for calculation are generally obtained by laboratorysoil test, and the soil samples are coming from the field. The soil samples for laboratory test areoften disturbed, and the soil properties are quite different. If using in situ testing for soil slopemechanical parameters, the test results can not represent the entire slope soil mechanicalproperties due to in situ test, obtaining only a few points of soil sample test results, and the insitu test cost is often quite expensive. Due to the difficulty of obtaining the mechanicsparameters of soil slope, there are difficulties in slope stability calculating, so that we usuallycannot analysis slope stability in real-time. Parameter inversion method can obtain slope soil mechanical parameters according to theslope safety monitoring results, and analysis the slope stability. So, this method can combineslope safety monitoring and stability analysis effectively, which has overcome detects of slopemonitoring and stability independent development in the geotechnical engineering. Along withthe development of monitoring techniques, slope safety real time remote monitoring hasbecome possible, which can obtain slope deformation state in real-time. Slope soil mechanicalparameters can be obtained by parameter inversion calculation, which can be used to calculatethe slope stability. Therefore, the research of slope displacement monitoring, parameterinversion algorithm and slope stability analysis has great theoretical and practical significance.In this paper, combined with national high technology research and development plan (863project) named 'Research of large range road disaster parameter monitoring and identificationand early warning system in seasonal frozen region', several aspects of research work havebeen carried out as follows:1. The main method and basic principle of slope surface and deep displacement monitoringwas introduced, the suitable conditions, advantages and disadvantages of these monitoringmethods are summarized. The slope displacement remote monitoring system developed by thestudying team was introduced, this system was successfully applied in Changchun west railwaystation deep foundation pit displacement monitoring, and achieved good results, which canprovide reference for slope displacement monitoring.2. According to the calculation method of slope stability, limit equilibrium method andstrength reduction method, the effect of slope geometry factors (slope height, slope angle andslope morphology) and slope soil shear strength parameters (cohesion and friction angle) onslope stability have studied. The sensitivity of the influencing factors on the slope stabilitysafety factor has calculated through a numerical example. The method for determining theposition of slope sliding surface has adopted strength reduction method.3. Due to changes in the external environment such as rainfall and the effect of freeze-thawon soil slope effect, this paper argues that affects the stability of soil slope is affected mainly bychanging the soil shear strength parameters (cohesion and friction angle) value. The effect ofdifferent water content and freeze-thaw cycles on the slope soil shear strength parameters(cohesion and friction angle) has studied by laboratory test.4. Because we can not establish the relationship between the deformation and the stabilityof slope, according to the basic concept of strength reduction method, the function relationshipbetween slope displacement and strength reduction coefficient is obtained, combined with the finite element method to get the function relationship between slope displacement and strengthreduction coefficient. In order to get the safety coefficient of slope stability by monitoring, theneural network algorithm is used to simulate the function relationship between strengthreduction coefficient and slope displacement, through measuring the slope displacement valuescan get the reduction of slope stability, and also obtain the slope stability state.5. In order to better grasp the slope stability, this paper adopts the displacement parameterinversion method to calculate mechanic parameters of soil slope by intelligent inversion. Thegenetic algorithm has been used to optimize the initial weights and bias values of neuralnetwork, thus the optimal topology structure of neural network is established, which can satisfythe precision requirement of inversion calculation.6. In order to guarantee the safety foundation pit support structure, the finite elementmethod was used to calculate the deformation of supporting structure under loads, and the loadand internal force distribution of the top beam was obtained. When external loads reach thevalue, top beam reaches the ultimate bearing capacity. The CFRP is used to reinforce the topbeam. And ANSYS was used to calculate the bearing capacity and deformation characteristic oftop beam reinforced by CFRP.7. The safety monitoring method and the monitoring results of Changchun west railwaystation deep foundation pit have been introduced, and the method proposed in this paper areused to evaluate the stability of foundation pit, so that slop stability state can be obtainedaccording to the measured displacement data. So, the safety of foundation pit construction hasprotected, and can provide practical reference for foundation pit safety monitoring.