Study Of Fractal Characteristics Of Grout Consolidation Process Of Soil-rock Mixture

The particle size distribution,pore structure,pore number and volume distribution,and pore surface area of geotechnical media all have fractal characteristics.Fractal theory can deeply reveal the hidden regularity,hierarchy and scalar invariance in complex strata.Fractal dimension is an effective means to accurately characterize the soil skeleton and quantitatively describe the spatial configuration of the soil.The fractal characteristics of the injected medium have an influence on the arrangement of grouting holes,the quality and cost of grouting projects.The fractal theory can be applied to the transport process of slurry in the geotechnical medium.The microstructure of the spatial distribution of geotechnical and grouted stone bodies can be described.This provides a scientific basis for the quantitative study of complex changes in the grout transport process.The research on grouting process of soil-rock mixture was carried out in this paper.The non-homogeneous soil-rock mixture stratum model was constructed,and the field equation considering the coupling of seepage and stress with the consideration of tortuosity was established.The numerical simulation of the diffusion process of slurry was conducted.The fractal characteristics of the grouting diffusion boundary were analyzed.Based on the fractal characteristics of pores and tortuosity,the relationship between fractal dimension,maximum diffusion radius,and mechanical parameters of grouting was studied,and the physical parameters of grouting medium,fractal characteristics of slurry diffusion process,and fractal characteristics of stratum strength after grouting consolidation were explored.The main research contents and conclusions of this paper are as follows:(1)A microscopic model of soil-rock mixture based on fractal characteristics was constructed.The fractal characteristics of pores and tortuosity were considered,and a nonhomogeneous physical parameter model of geological formations was constructed based on the correlation of physical properties such as permeability and density.The free curve surface deformation equation was used to introduce scaling factors to construct blocks of different shapes and sizes.The particle size distribution of the research area was reflected from the perspective of particle size fractals,and rock blocks were randomly placed in the distribution area to establish a two-dimensional geometric model of soil-rock mixture.The mechanical properties of the microscopic elements of the soil-rock mixture were described using the fractal interpolation algorithm based on the fractal characteristics of physical parameters,and its mechanical model was constructed.The mechanical properties of the microscopic elements were described using the fractal interpolation algorithm to achieve the construction of the soil-rock mixture mechanical model.The non-homogeneous geological formation model of the soil-rock mixture was used to simulate loading tests.The results showed that the larger strain area was mainly distributed in the sparsely distributed rock blocks at the interface between soil and rock,and the axial strain of the soil-rock mixture increased with the increase of rock content.(2)The diffusion process of soil-rock mixture grouting and its fractal characterization were studied.Based on the fractal characteristics of pores and tortuosity,a field equation coupling the permeation field and stress field considering tortuosity was established to construct a geological grouting diffusion model with the soil-rock mixture as the grouting medium.By comparing the diffusion range of grouting at different times,the self-similarity of the diffusion boundary of the cement slurry in the soil-rock mixture was explored,and the relationship between fractal dimension and maximum diffusion radius of grouting was analyzed.The results showed that the migration boundary during grouting had fractal characteristics;the rock blocks in the grouted medium had a certain obstructive effect on grouting diffusion,and the diffusion path was also changed due to the presence of rock blocks.The fractal dimension of the local boundary of grouting diffusion could be quantitatively determined by using the box counting method.The fractal characteristics of pores and tortuosity had a significant influence on the diffusion law of slurry in the porous medium.(3)The mechanical properties and fractal characterization of soil during grouting diffusion were analyzed.The influence of microscopic structural parameters of soil-rock mixture and grouting diffusion range on soil parameters was analyzed.The grouting diffusion process was simulated under the same grouting loading mode,slurry viscosity,and grouting pressure considering fractal characteristics of pores and tortuosity.The dynamic changes of the average fractal dimension of tortuosity and pores during grouting were explored,and the relationship between the average soil parameters,stress,and fractal dimension of the soil-rock mixture during grouting was analyzed.The results showed that during grouting,the average soil parameters increased gradually.When the grouting diffusion range was constant,the soil stress changed significantly,and the fractal dimension of the pore and tortuosity also changed,indicating that grouting had a certain effect on the pore structure of the geological formation.(4)The analysis of the bearing capacity of the ground after injection consolidation based on fractal dimension was conducted.The impact of the microstructure parameters of the soilrock mixture and the spatial distribution of the cobbles on the average strength of the ground was analyzed.The changes in the average Mises pressure of the ground after injection under different injection loading pressures and different fractal dimension soils were simulated.The relationship between the average strength of the ground after injection and different injection loading pressures and different fractal dimension soils was discussed.The mechanical analysis and bearing capacity evaluation of the ground reinforced by injection were carried out.The results showed that the pore fractal dimension and tortuosity fractal dimension of the injection soil would affect the effect of the ground injection treatment.The study of the pore fractal characteristics and tortuosity fractal characteristics of the soil-rock mixture injection consolidation process is of great significance for predicting the mechanical behavior of the soil after injection and selecting appropriate injection materials and processes.