| With the increase of the depth and design capacity of underground construction, a large number of traffic tunnels, mining roadways and urban underground space are being in construction. Faced with more and more complicated hydrogeological conditions, the construction often encounters water gushing and collapse are often caused by water-rich broken strata, which seriously threatens the human lives, possession and the construction. Therefore, the theories and techniques for grouting reinforcement of water-rich broken rock mass are in urgent need to be solved in the underground construction projects. In this research, combining with the hydrogeological characteristics of water-rich broken strata, the property deficiencies of grouting materials and engineering experience, a new kind of cement-based grouting material (CGM) mainly prepared by steel slag powder was developed, it is applicable for grouting reinforcement on water-rich broken rock mass and the economic efficiency of the project was guaranteed. Based on physical and mechanical property tests of CGM and grouting simulation tests of water-rich broken rocks, the property advantages of CGM grouting material were compared and analyzed, scanning electron microscope technology and X-ray testing technology were combined to analyze the rock-slurry cementation modes, standards of division and the reinforcement mechanism of different grouted materials. The industrial production of CGM grouting material was achieved and the application test of project site was carried out, and a series of research results were obtained.(1) Based on the principle of composite material technology, the optimized composition was was determined with orthogonal method and factorial method:75.33% content of clinker,5.09% content of steel slag power,3.67% content of hydroxyl polymer, 0.15% content of hydroxychloride,5.60% content of sulfate,2.03% content of superplasticizer,1.52% content of aluminate and 7.61% content of silicide.(2) According to the characteristics of grouting material for water-rich broken rocks, the influence of different components on the physical and mechanical properties of the CGM were determined by laboratory tests. The mixed grinding time of CGM grouting material should not exceed 45min, the initial setting time of the slurry was achieved in 39-85min at the temperature range of 5-40 ℃, and the final setting time was controlled effectively at the range of 69-141 min. The content of steel slag can be dynamically adjusted to meet the strength requirements while stones, and can reduce the production cost of materials and improve the economic efficiency of projects.(3) By comparison tests with the traditional cement material, The mechanism for the volume evolution of CGM concretion and the viscosity evolution of the slurry was analyzed, and the influence of the components on the slurry volume stability and the viscosity was analyzed. The slurry stability and anti-dispersion property was tested. The optimized water-cement ratio is 0.8:1 to 1.2:1, the stone of slurry has the property of micro-expansion, viscosity was affected weakly by temperature, the stability and anti-permeability is good, the retention of stone body (1.2:1 water-cement ratio) was 72% at 0.5 m/s of water flow rate, which is significantly higher than traditional cement material.(4) The durability evaluation of CGM concretion stone was carried out. By analyzing the impacts of chloridion and sulfate ion on the concretion of grouting materials, the types of corrosion was classified and the influence of the CGM components and slurry preparation conditions on the anti-erosion properties of concretion was determined. Compared with traditional cement material, the chloride ions in CGM mainly exist in the combined-state form, the content of chlorine is low and the broken probability of chlorine ion erosion is small. In the sulfate environment, the protective layers were formed early in CGM stones to resistance the sulfate ions, the steel slag powder and silicide absorbed the active calcium to prevent crackings caused by gypsum or ettringite in the later hydration, and it can improve the durability of the material.(5) An indoor grouting simulation test platform of independent design was used to carry out grouting simulation test for water-rich broken rocks, the mechanism of grouting was revealed from the microscopic point of view. It is determined that the main factor of grouting effect is the grouting material, followed by the grouting pressure and filling media. For cement-based materials, the more hydrated minerals in the rock-slurry interface, the crystal orientation exist stronger and the bond strength is higher. The bonding modes in the rock-slurry interface is mainly determined by the property lithology, high density of limestone rocks is approximately to the Ollivier-Grandet model, and the porous sandstone rock accords with the Zimbelinan model. The physical and chemical changes exist in the surface of rocks during the process of grouting. The generated minerals in the interface areas can improve the bonding strength and the strengthen effects.(6) The industrialization production of CGM was realized and the control technique for CGM’s industrialization was established. The application test of project site was carried out and the grouting technique applicable for CGM was established, it was verified the new material has significant performance advantages. The CGM was successfully used in solving the water inrush in the broken surrounding rock in the western transporting roadway in Xinyang Energy Ltd, the satisfactory effect and economic benefit were obtained, which has a promising prospect in engineering application. |
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