Study On Grouting Diffusion And Reinforcement Mechanism Based On Flowing Regularity Of Suspension

Grouting is a major method for treating geological hazards in underground construction,which can achieve a series of goals such as improving the mechanical property of fractured zone,reducing subsidence and preventing water and mud inrush.The constitutive relation of the grout and the interaction between the grout and injected medium are crucial factors which limit the development of grouting theory.The traditional cement-based grout and the swelling particle grout belong to suspension,which has many similarities in rheology.The main goal of this thesis is comprehensive study of the flow regularity and grouting mechanisms of suspension by theoretical analysis and numerical simulation.For fracturing grouting and ground reinforcement,three kinds of medium of the formation were considered:cohesive medium,particulate medium,and soil-rock mixture.The fracturing-permeating diffusion mode was analyzed.The influence of grouting pressure,grout property,composition of the medium and the stress condition were revealed.For grouting against flowing groundwater,a new constitutive law and flowing equation for swelling particle grout were proposed.The flow regularity of grout suspension in a Karst channel and in a planar fracture was analyzed.The main conclusions of this work are as follows:(1)A theoretical model of fracturing grouting with a planar flow path in cohesive medium was proposed.The solution of flowing equation was acquired by approximation method.The shape of the fracturing path at different grout viscosity,flow rate and deformation modulus of the medium were calculated.(2)For particulate medium,the microscopic mechanism of the interaction between the particles of the medium and suspension were analyzed,on the basis of which a fracturing-permeating diffusion model was established.The regularities of grouting and the deformation of the medium were acquired in fracturing dominant condition,permeating dominant condition and the jointed dominant condition.(3)For multiphase medium comprising several constituents such as clay,sand and rock block,numerical models were built to analyze grout diffusion and the mechanical behavior of the reinforced body.Two important parameters called "grout vein uniformity"and "skeleton converted ratio" were proposed to characterize the mechanical behavior of grouted medium.Based on the morphological characteristics of the grout vein,an empirical equation was established for estimating the compressive strength of the grouted medium.(4)Working performance of the swelling particle suspension was measured by regarding super absorbent resin particles as a typical research object.The influence of particle swelling on the rheological property of the.suspension was analyzed.A constitutive model of swelling particle suspension was proposed.(5)A theoretical model for grouting against flowing water in a Karst channel was proposed based on the coupling effect between particle swelling and the change of flow field.The grouting process was calculated by considering different viscosity-time function.The flow regularity of swelling particle suspension in a Karst channel with flowing water was revealed.(6)A CFD-DEM numerical model was proposed for grout diffusion of swelling particle suspension.The grouting process of Karst channel and planar fracture were simulated.The interaction between particle and fluid and the influence of particle swelling on the flow field were analyzed.The groundwater plugging mechanism of particle swelling grout was revealed.