Research On The Design Of Annulus Open Hole Packer For Soil-Drilling And Injection Equipment

In recent years,with the increasing attention to ecological environmental protection in China,the in-situ remediation method of soil and groundwater has gradually become the mainstream of contaminated site treatment.The research on the isolation mechanism and the design of the packer in the soil layer is of great significance to improve the repair efficiency of the in-situ injection repair process.In this paper,theoretical analysis,design and numerical simulation methods are used to study the soil model and the structure of the packer.Firstly,the theoretical analysis mainly includes the mechanical analysis of the packer and the stress,displacement and permeability changes of the borehole soil.According to classical mechanics and soil expansion theory,the contact stress formula between packer and soil is deduced.The strength,shear strength,displacement change and permeability change of shaft wall soil are respectively obtained in parameter analysis,and the influence range of the strength,displacement and permeability in the soil is about 1.5-2m.The structure design is mainly based on the general structure of the expansion packer,and its main innovation points are as follows: 1.The central pipe and the rubber cylinder are non-linkage structure,and the central pipe can rotate,but the rubber cylinder does not rotate.2.the lower part of the rubber cylinder is provided with a sliding structure,the lower end of the rubber cylinder can slide upward;3.The packer rubber cylinder has an automatic reset mechanism.In the part of numerical simulation,a soil mass model was established by FLAC 3D software,and the isolation range was simulated and analyzed.According to the calculation,the given contact pressure was 0.47 MPa,0.71 MPa and 0.94 MPa,and the stress variation value in the soil was 0.15-0.45 MPa after simulation.The displacement and deformation range around the borehole is2.1～21.2mm.By comparison with the mathematical model,the comprehensive analysis shows that the influence range of the packer in the cohesive soil is about 1.5m.By studying the soil model and designing the packer,an open-hole packer structure acting on the soil and the packer isolation range in the cohesive soil were obtained.The research has greatly improved the repair efficiency of the in-situ remediation technology for contaminated sites and promoted the on-site application.