Study On The Diffusion Characteristics Of Polymer In The Vertical Fractures Of The Pisha-sandstone

The problem of soil erosion in the arsenic sandstone area located on the border of Shanxi,Shaanxi and Mongolia is very serious,and it is the core area of the source of coarse yellow sand.The main cause of serious soil erosion is the special lithology of arsenic sandstone.Arsenic sandstone,commonly known as " pork belly",has a layered structure and is mainly composed of white sandstone,sand shale,and red muddy sandstone.Due to low diagenesis,poor cementation between particles,and high montmorillonite content,it easily expands and collapses in water.Dissolve mud.The massive gravity erosion phenomenon with collapse as the main form is very prominent,and its occurrence is sudden,and the erosion amount and destructiveness generated are relatively large,which is the main source of erosion and sand production.The massive gravity erosion occurs mainly in white arsenic sandstone layers with relatively high strength and stability.The main cause of massive gravity erosion is the existence of vertical fissures in the white arsenic sandstone,which becomes the channel of water flow.Under the action of water erosion,the fissures continue to cut down,separating the arsenic sandstone from the parent slope.Under the action of water flow,freezethaw,etc.,the lower red arsenic sandstone layer accelerates erosion,causing the upper arsenic sandstone to gradually lose support,and collapses when it reaches a certain limit state.Filling the vertical fissures of the white arsenic sandstone layer by grouting and blocking the water flow channel is one of the important ways to control the gravitational erosion of the arsenic sandstone block.However,traditional grouting materials mostly use water as the solvent or main component,which will destroy the arsenic structure and make it difficult to achieve the treatment effect.In response to this problem,based on the concept of waterless grouting,it is planned to introduce nonaqueous reactive polymer grouting materials into block-shaped gravity erosion control.Therefore,mastering the migration mechanism of polymer grout in vertical fractures of arsenic rock has important guiding significance for grouting construction.For this reason,this paper adopts a combination of model test and simulation analysis to study the diffusion law of polymer slurry in vertical fissures.The main work carried out is as follows:(1)Designed and manufactured a vertical crack grouting model test device for polymer slurry,which consists of a visual vertical crack test bench,a polymer grouting system,a pressure monitoring system,etc.,to realize visual observation of the slurry diffusion process,It laid the foundation for the grouting model test of polymer vertical cracks.(2)Carried out the grouting model test of polymer vertical crack under different grouting amount,and studied the diffusion law of polymer slurry in vertical crack.The test results show that under the designed test conditions,the diffusion morphology of the polymer slurry in the vertical fissures is approximately semi-circular,and the diffusion range of the slurry increases with the increase of the grouting amount.The vertical line where the grouting holes are located is basically symmetrically distributed;the horizontal diffusion distance of the slurry is greater than the vertical distance.The larger the grouting amount,the greater the horizontal diffusion distance;the polymer slurry is in the time of 0s?30s The diffusion rate is the fastest in the segment,and the diffusion rate gradually slows down in the period of 30s?40s,and the diffusion gradually stops around 40 s.The corresponding slurry pressure increases sharply in the time period from 0s to 30 s,and the pressure continues to rise in the time period from 30 s to 40 s,but the increase trend slows down.The pressure can basically reach the highest value at about 40 s,and the subsequent pressure tends to remain unchanged or Slowly decrease;the maximum slurry pressure is always near the grouting hole.The larger the amount of grouting,the more heat is released in the chemical reaction of the polymer and the higher the temperature.The density change trend of the polymer slurry under different working conditions was basically the same,and all showed a negative exponential change,and the final density of the slurry after curing was relatively close.(3)Based on the finite volume method(FVM)and VOF principle,a simulation model for the flow and diffusion of polymer slurry in vertical cracks was established.The numerical model was tested in combination with the test data.The results showed that the calculated slurry diffusion patterns and ranges at different times were basically consistent with the test results.,Proved the applicability of the simulation model;on this basis,the diffusion process of the polymer slurry in the vertical fissure under different working conditions was simulated and analyzed,and the development of the diffusive form and range of the slurry in the fissure under different conditions was analyzed.Variation law,proved flow field distribution characteristics during slurry diffusion,and comparatively analyzed the diffusion of polymer slurry in vertical cracks with and without gravity.The results show that the slurry in the horizontal direction under gravity The diffusion distance is greater than the diffusion distance without considering gravity,while the diffusion along the vertical direction is the opposite.The results of this paper reveal the diffusion characteristics of polymer slurry in vertical fissures,and provide a theoretical reference for the development of arsenic sandstone vertical fissure polymer grouting technology,for the control of blocky gravitational erosion of arsenic sandstone blocks,reducing water and soil loss and coarsening in the middle Yellow River Sediment into the yellow has a positive significance.