| The slurry pipe jacking is a special construction method for crossing water rich sand layers.Due to the lack of research on the interaction characteristics of pipe-soilslurry,the control of friction resistance has become a technical bottleneck that restricted the safe and efficient construction of slurry pipe jacking engineerings and also constrainted its application and promotion in underground space.Therefore,this article took the Haikou Meilan Airport Phase II external drainage pipe group project as the background,combined theoretical analysis,indoor testing and on-site testing techniques,and systematic research was focused on the infiltration and diffusion of slurry in waterrich sandy layer,the mechanical characteristics of the stress and strain field after slurry permeability and compaction expansion,the formation process and variation law of the pipe-soil contact force,calculation model for the pipe-soil contact force and friction resistance of slurry pipe jacking in water rich sand layers,and the design of grouting control parameters.The following were the paper’s primary findings and contributions:(1)Performance requirements and indicators for slurry were established based on the features of water-rich sandy layer.The optimized ratio of slurry and its rheological characteristics was produced as a power-law fluid through the use of indoor experiments and rheological tests.A power-law mud motion equation and a cylindrical permeability diffusion microscopic model were developed based on the pore properties of water-rich sandy layer.It discovered how the slurry sleeve forms in water-rich sand layer and the influence of the slurry’s characteristics,grouting parameters,and hydrogeological circumstances on the slurry’s permeability diffusion depth.(2)Based on the coupling effects of particle sedimentation-pore structureformation stress in water-rich sandy layer after grouting,porosity of sand was proposed to decompose the grouting pressure,and a mechanical model for slurry permeability and compaction expansion was established,the analytical solution of elastic-plastic stress and strain in water-rich sandy layer after grouting was obtained.It was found that the porosity of sand,grouting pressure,and hydrostatic pressure have varying degrees of influence on the pore stress,effective stress,radial total stress,and radial displacement of sand after grouting,and grouting pressure was the most active factor for slurry displacement seepage and pore expansion.(3)The influence of grouting on the pipe-soil contact force and contact state of slurry pipe jacking in the water-rich sandy layer was investigated,as well as the coupling impact between the pipeline,sand and slurry.The contact force and contact angle between the pipe and the soil were analytically solved and a theoretical calculation model for the frictional resistance was constructed,revealing the pipe-soil-slurry interaction mechanism.According to the research findings,radial tunnel walls grew as a result of slurry permeability and compaction expansion,and slurry filled the space between the expanded tunnel wall and the pipe.The pipeline floated or sunk as a result of the slurry pressure difference,creating pipe-soil contact force when it came into touch with the water-rich sand on the tunnel wall.(4)By comprehensively utilizing geological radar detection technology and on-site monitoring technology for pipe-soil contact force,a field test for friction resistance was developed.During the initial stage of jacking,testing conducted on-site revealed that the slurry was unable to reach the nearby water-rich sandy layer in time,and the water-rich sand collapsed over the pipeline.The slurry steadily permeated and dispersed into the water-rich sand as the jacking distance grew,effectively supporting the tunnel wall.The grouting effect greatly lowered the contact force between the pipe and the soil.The gap between the on-site measured value of friction resistance and the predicted value of the theoretical calculation model was about 10%,which significantly verified the rationality and feasibility of the friction resistance theoretical calculation model.(5)A theoretical design method for grouting control parameters was proposed based on pipe-soil-slurry interaction mechanism.The minimum grouting pressure was designed according to the critical state of the stability limit equilibrium after grouting and the elastic stress solution of slurry permeability and compaction expansion.,the maximum grouting pressure was designed in the light of the limit state of slurry expansion and the plastic stress solution of slurry permeability and compaction expansion.The minimum grouting pressure depended on the radial water and soil pressure on pipeline,while the maximum grouting pressure was related to static water pressure,sand porosity,internal friction angle,etc.Figure [77] Table [37] Reference [147]... |
PDF Full Text Request