Research On Key Technology And Application Of Karst Foundation Treatment

The geological structure of karst regions is unique,characterized by irregular and complex underground spatial structures.At the same time,groundwater activity is frequent,with underground rivers,lakes,and other water systems widely distributed.These characteristics pose numerous challenges to engineering construction,such as poor bearing capacity of foundations,high risks of geological hazards,soil erosion,and other issues,which seriously threaten the safety and reliability of engineering projects.However,China lacks specialized equipment and methods for geotechnical exploration of karst areas,as well as calculation methods for bearing capacity and reinforcement of karst foundations.In this study,based on the analysis of typical hydrogeological conditions,soil characteristics,and their main physicochemical properties in karst areas,a research approach combining systematic investigation,theoretical research,technological development,and application demonstration was adopted.The research utilized a combination of field experiments and laboratory tests.Key technologies,including integrated exploration of building foundation in karst regions,calculation of bearing capacity,and foundation treatment,were developed.Furthermore,practical engineering applications were conducted.The specific research content is as follows:(1)To address the issue of cave detection in karst foundation exploration,a technology based on cave sonar detection system was proposed.Although traditional acoustic methods can detect shallow rock structures and caves,they are limited in depth and accuracy.This study integrated multiple detection methods,employed pile-bottom cave sonar detection method,utilized slurry in pile holes as the medium for sound propagation and coupling,combined JL-SONAR and PBCA devices with three-dimensional numerical simulation technology,and achieved accurate detection of cave structures at the bottom of karst foundation piles.The research found that the sonar detection system can effectively reveal the internal structure of cave bottoms and provide reliable data support.In addition,signal analysis methods and numerical simulation research were conducted to further explore the mechanism of acoustic detection and signal directional analysis techniques.This technology provides an engineering-adaptable and widely applicable method for detecting cave bottoms in karst foundation exploration,enabling the timely identification of potential geological hazards and ensuring the safety and stability of engineering projects.(2)The 3D-H model proposed in our study overcomes the limitations of the micro-scale directional model by introducing a hexagonal pattern,further improving the constitutive relationship of granular materials.Parameter calibration and model prediction were conducted through case analysis.The influence of different initial confining pressures and void ratios on the model,as well as the angular distribution of micro-variables under different strain states,were studied.Subsequently,the CFD-DEM coupling method was applied to analyze the stability of tunnel face in karst strata shield tunnels.The effects of different friction coefficients,tunnel burial depths,grouting volumes,and rolling friction coefficients of karst strata particles on the instability mechanism of pre-reinforced tunnel excavation face were investigated,enhancing the applicability of the CFD-DEM method in karst foundation calculations.Through this research,a deep understanding of the stability characteristics of karst foundation was obtained,providing reliable technical support for engineering practice.