Study On Stability And Deformation Characteristics Of Goaf Under Highway Subgrade

In the construction of highway engineering,the existence of underground goafs in the road area will bring great engineering risks and construction difficulties.If the treatment is improper,serious road diseases may occur.At present,the evaluation methods for the stability and deformation of the gobs under the highway subgrade are mainly empirical methods,or specific analysis is carried out according to specific working conditions..In this paper,relying on the treatment project of the goaf under the Lanluo Expressway,the indoor scale model test and finite element numerical simulation method are used to analyze and evaluate the stability and deformation characteristics of the gob structure under the highway subgrade under different conditions.,and the reinforcement effect of controllable curtain grouting reinforcement technology is calculated and analyzed.The main contents and conclusions of this paper are as follows:1.According to the survey data of the goaf under the subgrade,the appropriate similarity ratio was established by the similarity theory method,and the physical property parameters of the similar materials were determined.The appropriate mixing ratio of gypsum mortar similar materials was selected through the orthogonal test,and the different mixing ratios were clarified.The range of physical parameters of similar materials at different times;changing the buried depth and horizontal position of the goaf roadway,carrying out the bearing capacity model test to obtain the loaddisplacement curve at the loading position,and exploring the effect of different gob positions on the bearing characteristics of the gob structure underlying the subgrade.The particle image velocimetry(PIV)technology was used to observe the particle displacement development without disturbance,and the structural failure mode and deformation characteristics were explored through the displacement vector diagram.The reliability of the numerical calculation model was verified by comparing the model test and numerical calculation results.2.For the case where the underlying goaf is parallel or orthogonal to the subgrade,based on the assumption of plane strain,change the shape of the goaf,the burial depth ratio of the goaf,the surrounding soil parameters,the size of the overlying load,the relative position of the goaf and the subgrade,Based on key indicators such as the relative height of the overlying rock layer and the overlying soil layer in the goaf,the finite element limit analysis and finite element elastic-plastic analysis are carried out on the stability and deformation characteristics of the stratum in the gob under the road,and the quantitative analysis of the influence of different factors on the structure is carried out.Influence law of stability and deformation characteristics.3.Considering the inclined intersection of roadway and roadbed in goaf,Optum G3 software is used to establish a three-dimensional numerical model for finite element limit analysis,and key parameters such as soil cohesion c,internal friction angle φ,and burial depth ratio of goaf roadway are changed.,to explore the influence of the change of the load intersection angle between the gob roadway and the subgrade load on the structural stability and failure mode under the conditions of different burial depth ratios and different soil parameters.4.Relying on the treatment project of the goaf under the Lanluo Expressway,the controllable reinforcement treatment technology of the goaf based on the mold bag method and curtain grouting is designed and explained.Based on the verified numerical model,the engineering survey data is used to calculate and analyze the typical mining area.The influence of the stability before and after the reinforcement of the empty road section and the reinforcement range on the reinforcement effect.