| As a low-permeability poor geological body widely distributed in underground projects such as mines and tunnels in China,argillaceous soft rock has remarkable characteristics such as water absorption,swelling,and disintegration,which seriously affect the safety and stability of engineering structures.Because the argillaceous soft rock has the distribution characteristics of millimeter-micron-nano multi-level pores and fissures,the injectability of conventional cement slurry to the micropores of rock mass is poor,and the anti-seepage and reinforcement effect of modified mudstone is not good.The sealing and consolidation of micropores through nanomaterial grouting are expected to solve the problem of poor injectability in the process of modifying mudstone with traditional cement slurry materials.Therefore,based on nanomaterials,seeking theoretical and technological breakthroughs,and studying good injectability,Inorganic nano-grouting materials with strong permeability are very important for the modification and anti-seepage reinforcement of argillaceous soft rock.Aiming at anti-seepage and reinforcement of argillaceous soft rock,this thesis uses comprehensive research methods such as literature review,theoretical analysis,laboratory test,analytical test,and physical simulation to characterize the gel properties and basic consolidation and anti-seepage laws of silica sol and to explore A high-efficiency grouting method for silica sol and argillaceous soft rock was developed,a silica sol-based composite slurry material with cross-scale and multi-particle sizes was developed,the basic grouting engineering characteristics of the cross-scale composite slurry material were analyzed,and the impact of the composite slurry material on Mechanism of anti-seepage and reinforcement of argillaceous soft rock.The main achievements of this thesis are as below:（1）The time-varying properties of viscosity,injectability,and surface properties in the process of silica sol-gel were analyzed in detail,and the time-varying law of the physical properties of slurry in the process of silica sol-gel was revealed.The volume stability,long-term physical and mechanical properties of the gel after solidification of silica sol,the permeability and reinforcement characteristics of silica sol-bonded argillaceous soft rock with microscopic pore structure of the gel were characterized,and the properties of argillaceous soft rock grouted with silica sol were clarified.Basic anti-seepage reinforcement features.The results showed that（1）the physical properties of the slurry material changed during the gelation process of silica sol,and there was an inflection point in the change of viscosity and injectability;（2）the volume stability of silica sol was excellent,and the gel stone rate reached 100%,and the volume shrinkage rate of 180 days of wet curing is 0.3～0.46%;（3）The silica sol structure is dense and anti-seepage performance is outstanding,the gel body is magnified 5000times,no colloidal pores-cracks are observed,and the permeability coefficient of cemented mudstone is reduced to 10-9 cm/s level.The sealing and anti-seepage effect of the rock mass can be significantly increased by silica sol grouting,but the strength of the gel is low,and the 180-day strength is only 386.79 k Pa.（2）COMSOL numerical simulation was used to verify the inefficiency of silica sol grouting in the low-permeability rock under high-pressure injection.Based on the capillary force between the micro-cracks of the low-permeability rock mass and the nanoscale slurry material,a silica sol self-absorption grouting method for the low-permeability rock mass was proposed,and the imbibition grouting of the 0.1-40 m D low-permeability core was realized.The law of filling and adsorption of grout to the multi-level pores of low-permeability rock mass in the process of imbibition grouting is studied,and the mechanism of imbibition grouting of silica sol is revealed from the microscopic scale.The pore size distribution law of rock mass before and after imbibition is analyzed,and the characteristics of grouting sealing of macro and micropores of rock mass by silica sol imbibition are clarified.The results show that the number of large pores and fractures in the rock mass is related to the injectability,the number of mesopores and small pores is related to the internal driving force of imbibition,and the capillary force and the injectability of the slurry material jointly affect the result of imbibition.After infiltration,the average pore diameter and total pore volume decrease of the rock mass first increase and then decrease with the increase of permeability.Silica sol imbibition grouting can meet the engineering requirements of nano-and micro-scale pore-fracture sealing in the rock mass.（3）Aluminate cement slurry was used as a modified reinforcing agent,and the optimal performance ratio of the modified slurry material was optimized through compounding tests.A high-injection and high-strength composite modified pulp material based on silica sol with nano-micron two-level particle size distribution has been developed.The main properties are as follows:the gel time is adjustable from 21to 114.5 minutes,the initial viscosity of the slurry is<5 m Pa·s,the stone formation rate is>97%,and the compressive strength is 13.67 MPa.（4）The gel and grouting properties of the composite-modified slurry were characterized,and the gel properties and modification enhancement mechanism of the aluminate-modified silica sol-based composite slurry were revealed.The results showed that（1）the composite pulp material had nano-micron two-level dominant particle size distribution characteristics,the nano-scale particle size distribution ranged from 4.85 nm to 5.66μm,and the micron-scale main particle size distribution range was about 2-70μm.（2）Composite pulp material has obvious early strength characteristics and excellent volume stability.The 7-day strength of the stone body was13.67 MPa,the 28-day strength was 14.5 MPa,and the 28-day volume shrinkage rate was 0.57%.（3）Si O2 nanoparticles in the composite slurry inhibited the conversion of CAH10 to C3AH6,and at the same time generated calcium aluminum feldspar hydrate,which improved the internal structural strength of the hydrate.（4）During the gelation process,a large number of hydrates nucleate and aggregate on the surface of nano-Si O2,filling the pores of the cement,and making the microstructure of the hydration structure denser.（5）The grouting percolation experimental device for broken rock mass is designed,the grouting permeation characteristics of silica sol,cement slurry,and composite slurry materials are compared and analyzed,and the grouting percolation law of granular grout materials in the broken rock mass is clarified.The results show that the cement slurry is significantly affected by the seepage of the rock mass,which leads to a significant reduction in the calculus rate and compressive strength of the deep rock mass,and seriously reduces the plugging and reinforcement effect of cement grouting on the deep rock mass.The impact of rock mass infiltration on composite slurry mainly affects the compressive strength of the bonded body,while the stability and stone rate of the slurry is less affected by infiltration.The composite slurry material can realize the dual functions of shallow reinforcement and deep sealing.（6）The macro-micro sealing law of the composite slurry material on the broken rock mass and the microstructure characteristics of the slurry-rock interface were characterized,and the anti-seepage and reinforcement mechanism of the composite modified slurry material grouting broken argillaceous soft rock was revealed.The results show that（1）Macroscopically,the airtightness of composite slurry-bonded rock mass is close to that of silica sol and far better than that of cement slurry.The minimum porosity of the rock mass bonded by the composite slurry material is 2.2%,and the minimum permeability coefficient is 2.34×10-8 cm/s.（2）Microscopically,the pore volume of composite grouted rock mass is mainly provided by large pores,and the sealing degree of small pores and medium pores is stronger than that of large pores,and it has a better sealing effect on the matrix system of mudstone.On the magma-rock interface,there is a smooth and dense transition area formed by the accumulation of nano-scale substances such as aluminum colloid and silica sol at the slurry interface of the composite slurry material,which fills the gaps in the magma-rock interface,thereby greatly improving the compactness of the magma-rock interface.This dissertation has 99 figures,27 tables,and 195 references,respectively. |
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