Experimental and applied research on a composite grouting material with the functions of permeable and splitting
In view of the problem of water and mud inrush when the #5 construction branch tunnel of Xianglu Mountain in Central Yunnan passes through the fragmented powder rock,guided by the engineering geological characteristics of fragmented powder rock as the,and proposes for the first time to develop a new type of grouting material(PSCG)that integrates infiltration cementation and splitting reinforcement through organic-inorganic material composite to realize multi-mode reinforcement of fragmented powder rock stratum.By compounding sodium acrylate solution with sulphoaluminate cement,making full use of the percolation characteristics of fragmented powder rock stratum,under the grouting pressure,the sodium acrylate solution diffuses into the pores of fragmented powder rock particles with its high permeability characteristics,and the sulphoaluminate cement forms a splitting slurry vein in the fragmented powder rock stratum.The synergistic effect of organic-inorganic materials is used to overcome the engineering problem of"water can penetrate,but slurry cannot penetrate"of fragmented powder rock.In this paper,the feasibility of the above material development idea was verified through laboratory mechanical test and grouting simulation experiment,and the key indicators required for the reinforcement of fragmented powder rock were selected for physical and mechanical properties test(setting time,water holding rate,impermeability of stone body,strength and volume shrinkage),and the grouting reinforcement mechanism of the new material was revealed by microscopic testing methods(SEM and FTIR).Finally,the reinforcement effect of PSCG on fragmented powder rock geology was studied by field test.The results show that the PSCG material has the simultaneous reinforcement effect of the combined infiltration and splitting mode.There are organic-inorganic composite effect,micro-crack filling effect and hydrodynamic anti-dispersion effect in the stone body in the splitting zone,that is,sodium acrylate polymerization generates network polymer structure,which penetrates with cement hydration products and cement particles to form three-dimensional interpenetrating spatial structure with anti-dispersion effect.In addition,the contact interface between organic-inorganic materials is improved and cracks are filled.The strength of the stone body can reach 27.01 MPa at 7 days.There are capillary adsorption,chemical bond and physical lock cooperation in the stone body of the infiltration zone,that is,the sodium acrylate solution penetrates into the pores of the fragmented powder rock particles under the action of grouting pressure and capillary action and undergoes polymerization reaction,and the fragmented powder rock particles are locked into the overall structure.At the same time,the metal in the fragmented powder rock and the carboxylic acid group in the gel form a strong coordination effect,which increases the crosslinking density of the polymer network and improves the mechanical properties of the gel.The strength of the stone body in the infiltration zone can reach 2.4 MPa in 7 days,and the permeability coefficient is as high as 5.9x10-7 cm/s.Combined with the field test results,PSCG material has the dual effects of water plugging and reinforcement on the fragmented powder rock stratum.
construction materialsdiversion of water from central Yunnanthe fragmented powder rockgrouting materialspenetration and splittingthe mechanism of reinforcementengineering application
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