The viscosity evolution for different temperatures was studied experimentally.A time-varying viscosity model was derived and the influence of the initial temperature on gel time was analyzed.The experimental results s...The viscosity evolution for different temperatures was studied experimentally.A time-varying viscosity model was derived and the influence of the initial temperature on gel time was analyzed.The experimental results show that the viscosity of polymer grout increases exponentially with time.It can be divided into two phases.Before gelation,the viscosity variable quantity is very small.At the gel point,there is a sudden increase in viscosity.The initial viscosity and gel time decrease with the increasing initial temperature within a certain range,The study contributes to deepening understanding of the rheological properties of polymer grout,which can provide some references for polymer grouting construction.展开更多
To analyze the effects of a time-varying viscosity on the penetration length of grouting,in this study cement slur-ries with varying water-cement ratios have been investigated using the Bingham’sfluidflow equation and ...To analyze the effects of a time-varying viscosity on the penetration length of grouting,in this study cement slur-ries with varying water-cement ratios have been investigated using the Bingham’sfluidflow equation and a dis-crete element method.Afluid-solid coupling numerical model has been introduced accordingly,and its accuracy has been validated through comparison of theoretical and numerical solutions.For different fracture forms(a single fracture,a branch fracture,and a fracture network),the influence of the time-varying viscosity on the slurry length range has been investigated,considering the change in the fracture aperture.The results show that under different fracture forms and the same grouting process conditions,the influence of the time-varying viscosity on the seepage length is 0.350 m.展开更多
To address the fact that the mechanism of split grouting in deep weak rock formations lags far behind engineering practice,this study develops a theoretical model for splitting diffusion in a single fracture by integr...To address the fact that the mechanism of split grouting in deep weak rock formations lags far behind engineering practice,this study develops a theoretical model for splitting diffusion in a single fracture by integrating the fracture propagation morphology and slurry flow behavior.Using coupled theoretical equations within the numerical simulation software,a numerical model of grouting-induced splitting in weak rock formations was developed considering the rheological properties of the slurry viscosity.Based on the numerical simulations investigating the effects of the formation depth,slurry viscosity,and grouting rate on the effectiveness of split grouting diffusion,during split grouting operations in deep rock formations,a relatively high initial grouting rate and pressure is recommended to be adopted in the early stage to initiate or connect fractures.Following grouting pressure stabilization,the slurry viscosity should be appropriately increased to promote rapid gelation along the fracture surfaces,thereby effectively sealing the fractures.A grouting control strategy featuring initial high-pressure,high-flow injection followed by low-rate consolidation was systematically developed and successfully applied to the reinforcement of fractured surrounding rock in the-1000 m floor slab of the vehicle yard roadway in the eastern section of Guqiao Mine,achieving notable engineering results.展开更多
Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizin...Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizing the increase in porosity that will follow from the ultimate dissolution and erosion of this component. They have to be low-viscous and gain strength early after injection and packing theory can assist designers in selecting suitable proportions of various grout components. Optimum particle packing means that the porosity is at minimum and that the amount of cement paste needed to fill the voids between aggregate particles is very small. Low porosity and microstructural stability must be guaranteed for long periods of time. Organic additives for reaching high fluidity cannot be used since they can give off colloids that carry released radionuclides and talc can be an alternative superplasticizer. Low-pH cement reacts with talc to give high strength with time while Portland cement gives early but limited strengthening. The clay mineral palygorskite can be used for early gelation because of its thixotropic properties. Once forced into the rock fractures or channels in soil it stiffens and serves as a filter that prevents fine particles to migrate through it be lost. However, its hydrophilic potential is too high to give the grout a high density and high strength. According to the experiments carried out, most of the investigated grouts are injectable in fractures with apertures down to 100 μm.展开更多
In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high grou...In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high groundwater pressure conditions deep underground. In this research, a review of existing grout penetration models in Japan and foreign countries and a trial analysis are conducted with a goal of describing the gout penetration with accuracy on site. Specifically, the applicability of the model developed by Gustafson ＆ Stille to the laboratory penetration tests was studied. The results show that the calculated values from the Gustafson ＆ Stille model agree well with values of laboratory penetration tests.展开更多
基金Funded by the National Key Research and Development Plan(Nos.2017YFC0504503 and 2018YFB1600200)the Program for Science and Technology Innovation Talents in Universities of Henan Province(No.19HASTIT041)+4 种基金the National Natural Science Foundation of China(Nos.51908514,51878624,51878622,and U1404525)the Natural Science Foundation of Henan Province(No.202300410746)the Key Research Projects of Higher Education in Henan Province(No.18A580001)the Program for Innovative Research Team(in Science and Technology)at the University of Henan Province(No.18IRTSTHN007)the Major Scientific and Technological Special Project in Henan(No.181100310400)。
文摘The viscosity evolution for different temperatures was studied experimentally.A time-varying viscosity model was derived and the influence of the initial temperature on gel time was analyzed.The experimental results show that the viscosity of polymer grout increases exponentially with time.It can be divided into two phases.Before gelation,the viscosity variable quantity is very small.At the gel point,there is a sudden increase in viscosity.The initial viscosity and gel time decrease with the increasing initial temperature within a certain range,The study contributes to deepening understanding of the rheological properties of polymer grout,which can provide some references for polymer grouting construction.
基金supported by the National Natural Science Foundation of China(Grant Numbers:U22A20234,42277170)the Key Research and Development Project of Hubei Province(Grant Number:2020BCB073).
文摘To analyze the effects of a time-varying viscosity on the penetration length of grouting,in this study cement slur-ries with varying water-cement ratios have been investigated using the Bingham’sfluidflow equation and a dis-crete element method.Afluid-solid coupling numerical model has been introduced accordingly,and its accuracy has been validated through comparison of theoretical and numerical solutions.For different fracture forms(a single fracture,a branch fracture,and a fracture network),the influence of the time-varying viscosity on the slurry length range has been investigated,considering the change in the fracture aperture.The results show that under different fracture forms and the same grouting process conditions,the influence of the time-varying viscosity on the seepage length is 0.350 m.
基金supported by the National Key Laboratory Open Fund for Coal Mine Disaster Prevention and Control(No.SKLCMDPC202501)the National Natural Science Foundation of China(No.42307244)+1 种基金the Anhui Provincial Department of Education Natural Science Fund Key Project(No.2023AH052181)the Talent Research Fund Project of Hefei University(No.23RC19)。
文摘To address the fact that the mechanism of split grouting in deep weak rock formations lags far behind engineering practice,this study develops a theoretical model for splitting diffusion in a single fracture by integrating the fracture propagation morphology and slurry flow behavior.Using coupled theoretical equations within the numerical simulation software,a numerical model of grouting-induced splitting in weak rock formations was developed considering the rheological properties of the slurry viscosity.Based on the numerical simulations investigating the effects of the formation depth,slurry viscosity,and grouting rate on the effectiveness of split grouting diffusion,during split grouting operations in deep rock formations,a relatively high initial grouting rate and pressure is recommended to be adopted in the early stage to initiate or connect fractures.Following grouting pressure stabilization,the slurry viscosity should be appropriately increased to promote rapid gelation along the fracture surfaces,thereby effectively sealing the fractures.A grouting control strategy featuring initial high-pressure,high-flow injection followed by low-rate consolidation was systematically developed and successfully applied to the reinforcement of fractured surrounding rock in the-1000 m floor slab of the vehicle yard roadway in the eastern section of Guqiao Mine,achieving notable engineering results.
文摘Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizing the increase in porosity that will follow from the ultimate dissolution and erosion of this component. They have to be low-viscous and gain strength early after injection and packing theory can assist designers in selecting suitable proportions of various grout components. Optimum particle packing means that the porosity is at minimum and that the amount of cement paste needed to fill the voids between aggregate particles is very small. Low porosity and microstructural stability must be guaranteed for long periods of time. Organic additives for reaching high fluidity cannot be used since they can give off colloids that carry released radionuclides and talc can be an alternative superplasticizer. Low-pH cement reacts with talc to give high strength with time while Portland cement gives early but limited strengthening. The clay mineral palygorskite can be used for early gelation because of its thixotropic properties. Once forced into the rock fractures or channels in soil it stiffens and serves as a filter that prevents fine particles to migrate through it be lost. However, its hydrophilic potential is too high to give the grout a high density and high strength. According to the experiments carried out, most of the investigated grouts are injectable in fractures with apertures down to 100 μm.
文摘In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high groundwater pressure conditions deep underground. In this research, a review of existing grout penetration models in Japan and foreign countries and a trial analysis are conducted with a goal of describing the gout penetration with accuracy on site. Specifically, the applicability of the model developed by Gustafson ＆ Stille to the laboratory penetration tests was studied. The results show that the calculated values from the Gustafson ＆ Stille model agree well with values of laboratory penetration tests.
