Experimental Investigation On Grouting Into Rock Fracture With Flowing Water By Considering Its Roughness

The disasters of water burst from rock fractures seriously affect the safety of the underground engineering.Grouting is one of the most popular and important method to control the water burst and sand inrush in underground construction.It is necessary to strengthen the research of grouting effect under the condition of fissure and the related theory and technology.In this paper,the interaction between the factors is considered,simulation experiment of fissure water injection and the effect of each factor and its interaction on grouting water shutoff is analyzed.The experiments were carried out to study the influence of roughness of fractures with parallel test and the single fissure on sealing effect of hydrodynamic grouting.The effects of fracture roughness on water shutoff rate,grout propagation and retaining,seepage pressure in fracture were studied.The main contents and results are as follows:(1)The experiment was carried out to study the hydrodynamic velocity,the fracture aperture,the grouting flow and the gel time and their interaction.The results show that the factors for controlling effects followed by the fracture aperture D,hydrodynamic velocity A × fracture aperture D,grouting flow B × gelling time C.There is an interaction between the hydrodynamic velocity and the fracture aperture,between the grouting flow and the gel time,which has a significant effect on the water plugging rate.The optimum combination of the determined factors is: the hydrodynamic velocity A is 2cm / s,the grouting flow B is 200 ml / min,the gel time C is 99.8s and the fracture aperture D is 2mm.(2)A simulated rough fracture hydrodynamic grouting set up was assembled.Based on the Barton standard roughness grade profile curve,10 sets of simulation test with different roughness fracture grouting were carried out.The grout propagation morphology of grouting in rough fractures is divided into two types: the near-circular diffusion of the whole-moving type and the near-rectangular propagation across the displacement type.When the joint roughness coefficient JRC ? 8,the grouting diffusion morphology is nearly circular propagation of the whole-moving type,and the pre-diffusion process of the grouting is similar to the propagation process of the straight and smooth fracture under the same conditions.When the joint roughness coefficient JRC > 8,the grouting propagation morphology near the rectangular propagation across the displacement type.Fracture roughness has a great influence on the propagation distance and propagation area of the grout.The smaller joint roughness coefficient is,the more favorable the propagation of the grout.The greater the joint roughness coefficient is,the more difficult the propagation of the grout.(3)The curves of water flow changes of grouting into different roughness fracture are analyzed in the parallel test.The curves of water flow changes is divided into three categories: single peak decreasing type and multi-peak fluctuating and double platform type.It can be seen from the water shutoff rate,when the joint roughness coefficient JRC ? 10,the grouting effect belong to the type of "failure" and "very poor" level.And when JRC > 10,the water shutoff rate is better than that in the situation of JRC ? 10 situation.(4)The seepage pressure field of the different roughness fracturing grouting test is divided into four types: "single peak type","multi-peak type","platform type" and "fluctuation type".When the joint roughness coefficient JRC ? 8,the seepage pressure field is prone to "single peak" and "fluctuating" seepage pressure field.When the joint roughness coefficient JRC > 8,the seepage pressure field is basically "multi-peak" and "platform" "seepage pressure field.(5)In the experiment,the factors influencing the effect of grouting and water shutoff followed by the gel time,joint roughness coefficient and hydrodynamic velocity.(6)In the single fracture grouting test with flowing water,the joint roughness coefficient of the fracture determines the overall type of grout propagation,while the hydrodynamic flow rate and the gel time of have little effect on the grout diffusion morphology when the joint roughness coefficient is small.When the joint roughness coefficient is large,the greater the flow of water,the longer the gel time,the more serious crushing of the grout,blocking the worse.When the minimum flow rate,the grout will flow to the reverse flow rather than the direction of the flow.Joint roughness coefficient has a great influence on the change of water flow during grouting,while the change of hydrothermal velocity and the gel time has little effect on the change of water flow during grouting.