A Research On The Stability Of The Old Goaf In A Quarry In Shenzhen

With the development of economy and the expansion of city scale,the demand for construction land has increased,especially in the first-tier cities.How to develop and utilize the land resources of many old goaf outside the city has gradually become a new research hotspot in the engineering field.However,not all old goaf are suitable for engineering construction.Engineering construction above the old goaf must be studied for its stability under load conditions.The study of the stability of old goafs is a comprehensive and complex subject.In the actual project,the theory can not fully reflect the problems existing in the actual project,in other words,there is a phenomenon that theory lags behind reality.With the rapid development of computer technology,a lot of simulation software came into being,what is more,there are many applications of the numerical simulation of old goaf,which play a very well guilding role in the construction above the old golfs.Based on detailed investigation project of the original Shenmao Cement Plant Quarry in Dakang Community,Yuanshan Community,Longgang District,Shenzhen City.In this paper,through the comprehensive analysis of existing literature at home and abroad,the influencing factors of the stability of the old goaf,the analysis method of the stability of the old goaf and the feasibility of the numerical simulation software FLAC 3d in the study of the stability of the old goaf are analyzed and studied.First,the actual situation of the proposed site is introduced in detail,and the site monitoring is carried out in this area.According to the settlement monitoring and geological survey data,select the most likely to occur instability deformation of key areas for research.The stability of goaf roof under the dangerous area load is calculated,judged and even checked of the applicability of the formula by using thickness-span ratio,beam-slab stress theory and stability mechanics balance calculation method provided in geotechnical engineering manual.the stability of goaf roof is judged and the applicability of the formula is verified.Then the influence factors of goaf stability in this dangerous area are simulated by FLAC3 D.By adjusting the material property parameters of soil and rock mass,the displacement and stress changes of foundation under load are simulated and the relevant displacement and stress nephogram and change curve are obtained by adjusting the material property parameters of soil and rock mass and then the law is summarized.Finally,the conclusions of these methods are analyzed comprehensively,make suggestions on the layout of the buildings in the old goaf.Numerical simulation has been rapidly developed and applied in engineering field and solved many practical problems.Different simulation softwares have its own advantages and disadvantages,therefore,in view of the complexity of the study area,the model is built using the auxiliary software CAD,Surfer and ANSYS,mainly using the ANSYS software powerful modeling,grid division function and good compatibility,generate model information and into FLAC3 D software corresponding program in FLAC 3Dmodel which overcomes the FLAC3 D software in the establishment of complex geological model workload,long cycle,error-prone defects,greatly improve the efficiency and accuracy of modeling.Through this research,the rationality of numerical simulation is also verified,which provides a reference for similar goaf research in the future.