Development of grouting test device for fractured rock and analysis of slurry diffusion law under high temperature water rich conditions

To study the diffusion law of the slurry into the fractured rock mass in the tunnelling engineering under the hightemperature waterrich conditions,a set of grouting test device for the fractured rock mass under hightemperature waterrich conditions was developed with the fractured surrounding rock of Gaoligongshan Tunnel as the research object. Rock blocks with particle size 2-5 mm were used to simulate the structure of broken strata,and the simulated strata were compressed by applying the reverse force to the test device,so that the formation porosity error of each group was controlled within 0.5%. Multiple sets of fracture grouting tests were conducted using the uniform design method,and the sensitivity of geotemperature,unit time flow rate,watercement ratio and other factors on the slurry diffusion were analyzed. The characteristics of slurry body shape with the increase of slurry flow rate under the effect of temperature were discussed. Results show that the developed test device can meet the grouting test requirements of the fractured rock under hightemperature waterrich conditions,and the error values on average between test and theoretical values of compression deformation and porosity of the simulated broken strata structure are less than 0.1%. The device can control the hightemperature water and hightemperature action time,which verifies the rationality of the device. The influence of temperature,watercement ratio and grouting flow rate on the slurry diffusion range is not linear but a multivariate power function relationship based on the experimental data. The corresponding formula of the slurry diffusion range is constructed,and the singlefactor and multifactor of parameters influencing the slurry diffusion range are analyzed based on the solution formula. Under these test cases,the main factors affecting the slurry diffusion range is the unit time flow rate,the temperature is the smallest,and the watercement ratio is in the middle. The effect degree of the later two factors on the slurry diffusion range is not significant. The diffusion form of slurry is mainly filled and compacted with the change of the flow rate per unit time from small to large. The shape of the stoned body gradually transitions from a cake to a conical body,and then to a shape similar to that of a spherical car blocking stone. With the flow rate increase,the increase in the diameter of the sphere is greater than the diameter of the cake structure,and finally the shape approximates to a complete spherical structure.