The Application And Study Of Rock Bolt In Anti-floating Design Of Multi-storey Underground Structure

With the continuous expansion of urban scale,the development of underground space and the continuous increase of the number of floors of underground buildings,the anti floating problem of basement of high-rise buildings built in sites rich in groundwater is almost often encountered.Due to the requirements of foundation buried depth of high-rise buildings,single-layer or multi-layer basement is often buried deep underground.When the site is rich in groundwater,The safety of basement structure under anti floating condition can not be ignored.Common anti floating measures include: counterweight method(such as backfilling high-density materials such as concrete),lowering interception and drainage method,uplift pile,uplift anchor rod,etc.In engineering practice,it is necessary to select more reasonable anti floating measures after technical and economic comparison in combination with the geological conditions,construction level and anti floating head of the proposed site.On the rock foundation,the use of anchor rod anti floating has the advantages of remarkable anti floating effect,simple construction operation,reliable construction quality and low cost.Guizhou is located in the mountainous area of Southwest China,and the construction site is full of rocks.Among them,karst geology is the most widely distributed.Groundwater is distributed in the pores of karst rocks,which can be said to be all pervasive,which brings great difficulties to such geotechnical engineering investigation and anti floating design of basement structure.Combined with a practical engineering project in Guizhou,this paper studies the design of anti floating anchor in Karst strongly developed strata.The main research work and results are as follows:(1)This paper summarizes the research and application status of pull-out anchor bolts at home and abroad,lists several typical engineering accident cases caused by anti floating,analyzes their causes,and summarizes and analyzes the geotechnical geological characteristics and underground hydrological characteristics of Guizhou combined with the practical application of anti floating anchor bolts in Guizhou Province.(2)Summarize and summarize the current specifications,technical measures and other relevant data on the design methods of anti floating anchor bolts,make comparative analysis,deeply analyze the working mechanism and failure mode of anti floating anchor bolts,and obtain the more suitable design methods and corresponding precautions in the design process for the areas with strong karst development in Guizhou.(3)The anti floating anchor bolt of the supporting project in the strongly developed karst stratum is designed.Through the test and detection of the on-site anti floating anchor bolt,the stress characteristics of the anti floating anchor bolt are analyzed,and the matters needing attention in the selection of the calculation parameters of the anti floating anchor bolt in the strongly developed karst stratum are put forward;Combined with the engineering construction experience,the quality assurance measures for the construction of anti floating anchor bolts in Karst strongly developed strata are put forward.(4)Using yjk software and ANSYS finite element software,the stress-strain distribution law and failure mode of anti floating anchor are numerically simulated.Compared with the test data,the precautions in the design and construction of anti floating anchor are further analyzed and summarized,so as to provide some reference basis for the design and construction of anti floating anchor in karst strongly developed strata.