Grouting Parameters Research Articles

Diffusion Mechanism of Variable-Rate Grouting in Water Prevention and Control of Coal Mine

Regional grouting treatment is an effective technical means to prevent mine water disasters, and the grouting effect is affected by many factors. In actual grouting engineering, the single constant-rate grouting method is often transformed into a variable-parameter grouting process. However, research on grouting rates has been insufficient. This investigation focused on the issue of “the diffusion law of variable-rate grouting slurry in regional governance”. Methods such as theoretical analysis, numerical simulation, and field verification were used to evaluate the diffusion mechanism of variable-rate fracture grouting. The results indicated that the key parameters of variable-rate grouting, such as slurry diffusion distance and grouting pressure, were affected by the grouting rate. The decrease in the grouting rate reduced the migration speed of the slurry and the grouting pressure. The time for constant-velocity grouting and variable-velocity grouting to reach the same diffusion distance was 60 s and 108 s, respectively, which can be achieved with lower grouting pressure. When the grouting rate was 7.5 L/min and 30 L/min, the maximum grout diffusion distance was 2.81 m and 5.64 m, respectively, which required greater grouting pressure. The slurry diffusion rate decreased with the reduction in the grouting rate. Under the same diffusion distance conditions, variable-rate grouting took longer than constant high-rate grouting. In variable-rate grouting, the grouting pressure decreased stepwise with the grouting rate, with a final pressure drop of 77.4%. In grouting practice, the innovative use of the rate-reducing grouting method can greatly reduce the final grouting pressure under the premise of changing the slurry diffusion distance less, which can not only ensure the stability of surrounding rock but also reduce the cost of high-pressure grouting and the risk of grouting operation. The investigation results can provide scientific guidance for ground grouting renovation projects in deep coal mine water hazard areas.

Multicriteria risk assessment of water inrush in underground mines with large-scale curtain grouting: a mine disaster risk reduction strategy

This paper presents a synthetic method to assess the risk of mine water inrush before and after large scale curtain grouting based on GIS platform. Firstly, nine factors were selected from three aspects: geological conditions, hydrogeological conditions and curtain grouting parameters, to construct a multi factor assessment model. The combined weight of every factor was determined using the minimum deviation comprehensive weighting method, which can reduce the polarization effect of various assessment methods in multicriteria decision. Then, the effectiveness of the synthetic method was validated through the Maoping lead–zinc mine in Southwest China. The mining area was divided into five zones, namely safe zone, relatively safe zone, transitional zone, relatively dangerous zone, and dangerous zone. The assessment results show that the relatively dangerous and dangerous zones were significantly reduced, while the safe, relatively safe and transitional zones were significantly increased after large scale curtain grouting. Finally, we analyze the impact of curtain grouting on the risk of mine water inrush and the mechanism of zoning evolution from three aspects: water source control, pathway sealing, drainage, and pressure reduction. This work provides an effective strategy for mine disaster risk reduction.

Optimizing Grouting Parameters to Control Ground Deformation in the Shield Tunneling

In urban shield tunneling, reducing the disturbance of underground construction to the surrounding environment is important for both tunnel engineers and researchers. Among other factors, the quality of synchronous grouting is one of the crucial factors affecting the safe construction of shields. In order to determine a reasonable grouting pressure and grout amount during shield construction, the relationships among synchronous grouting pressure, grout amount and shield chamber pressure are analyzed using field monitoring data. Based on the tunnel face pressure and the ultimate yield conditions of the soil at the gap edge, a method for calculating the grouting pressure considering the overburdening load of the tunnel was proposed. Then, by linking the grout amount and the grouting pressure, an accurate calculation method for the simultaneous grout amount in shield construction was proposed. These methods were then used in the construction of the Jurong shield tunnel. The results show that the adopted grouting pressure and grout amount calculated by the proposed method, which considered the change of the overburdening load of the tunnel, can well control the ground deformation caused by the shield construction and significantly reduce the uneven settlement of the surface buildings. The proposed methods in this paper may provide a reference for other shield construction projects.

Study on the causes of interface damage of CRTS II slab ballastless track CA mortar based on grouting operation

In this work, the relationship between cement asphalt mortar (CAM) grouting operation and interface damage of CRTS II slab ballastless track was explored. The test method for the time-varying viscosity of CAM during the solidification process was optimized, and the curves of the time-varying viscosity of CAM at different temperatures were obtained through experiments. A generalized time-varying viscosity constitutive model with CAM temperature and time as parameters was constructed. A fluid dynamics model to simulate CAM grouting operation based on finite element method was established, which could take into account the time-varying viscosity of CAM. The influences of various grouting parameters on the interface state were analyzed with the dynamics model. The results show that the correlation coefficients between the time-varying viscosity constitutive model and the test results are greater than 0.96. It is verified that the CAM grouting operation is an important cause of interlayer damage. The time-varying viscosity of CAM is beneficial in reducing the area of the interface damage zone caused by CAM grouting operation. The area of the interface damage zone decreases with the reduction of the distance between the end vent and the end of prefabricated slab and the rise of grouting temperature. When the height of the prevent vortex grille cylinder is close to 0.4 m, the vortex effect at the position of the grouting hole can be effectively controlled, and the area of the interface damage zone can be significantly reduced.

Influence of component parameters on propagation characteristics of foaming polyurethane grout in rock fractures

Polyurethane grouting is an important technical solution used for seepage prevention and mechanical reinforcement of fractured rock. Various components of polyurethane grout significantly affect the grout properties and propagation behavior. The present study focuses on the crucial role of component parameters in controlling the propagation process and designing grouting parameters for foaming polyurethane grout. A coupled modeling approach combining chemical reactions and flow field analysis is developed to investigate the polyurethane foaming process. The proposed modeling approach is validated by comparing simulation results with experimental data from the literature. The influence of key component parameters: isocyanate index, initial water concentration and physical blowing agent, on the propagation characteristics (including propagation distance, maximum pressure, final density, reaction time and maximum temperature) of foaming polyurethane grout in rock fractures are further analyzed. The results reveal two distinct types of effects caused by the components, i.e., a monotonic relationship and a parabolic trend. Critical values are identified for the impact of isocyanate index on maximum propagation distance, final density and characteristic time, as well as for the influence of physical blowing agent on maximum propagation distance, final density and maximum pressure. Other parameters demonstrated a monotonic relationship. Additionally, a quantitative assessment is conducted to evaluate the impact of multiple components on propagation characteristics. The finding indicates that the initial water concentration has a significant effect on all properties, while isocyanate index exerts a more pronounced impact on reaction time and maximum temperature. The effect of the physical blowing agent is relatively minor compared to other factors. This study is helpful for material selection and proportioning of polyurethane grout in practical engineering applications.

Research on cooperative control method of comprehensive pressure relief and anchor grouting reinforcement in deep mining roadways

To address the surrounding rock control problems in high-stressed deep mining roadways, we used Suncun Coal Mine with maximum mining depth in China as the engineering background to analyze failure laws of surrounding rock of gob-side entry driving. Combined with field tests of anchor grouting parameters, we carried out numerical simulation with multi factors. The evolution of surrounding rock stress and displacement under different pressure relief parameters were clarified. On the basis, we proposed an integrated control method for the comprehensive pressure relief for coal and rock mass and anchor grouting reinforcement in deep mining roadway. We used geomechanical model test to compare gob-side entry driving method and this new method. The results showed that this new method can reduce average stress at the working face by 15.8% and peak stress of roadway shoulder by 12.5%. We applied this method in the field, which reduced roadway deformation by 535 mm.

Isolated overburden grout injection technology mining and grouting parameters discussion and optimization

Isolated overburden grout injection technology mining and grouting parameters discussion and optimization

A State-of-the-Art Review on the Study of the Diffusion Mechanism of Fissure Grouting

China is renowned for its extensive underground engineering projects and the complex geological and hydrological conditions it faces. Grouting treatment technology is widely employed in deep-buried mines and tunnels, where grouting parameters such as materials, pressure, volume, and hole arrangement significantly impact the effectiveness of grouting. This review paper comprehensively examines current research on grouting materials, theories, experiments, and numerical simulations. It summarizes the various factors that must be considered during the grouting process of fissures and explores the diffusion mechanisms of grout under their influence. Furthermore, further research is needed on the mechanisms and treatment methods for poor grouting in rock masses, the distribution patterns of fissures, optimization methods for grouting parameters, and grout quality assessment techniques. Future research should focus on developing more efficient experimental methods with higher accuracy levels while advancing grouting technologies. Establishing comprehensive and accurate rock mass models along with improving monitoring capabilities are also crucial aspects to consider. Therefore, studying the diffusion mechanisms of grout in fissured rock masses is of significant importance for the practical operation of underground engineering projects.

Study on key grouting blocking parameters of gas drainage boreholes in soft coal seams

The construction of gas extraction boreholes in soft coal seams is prone to collapse and deformation, and grouting reinforcement is one of the main methods to solve the problem of efficient sealing. However, the reasonable selection of key grouting parameters still needs further research. In response to the problem of selecting grouting sealing parameters for gas drainage drilling in soft coal seams, based on the “concentric ring” reinforcement sealing technology obtained in previous research, the key parameters and sealing technology of the “concentric ring” reinforcement were studied through theoretical calculation and numerical simulation experiments. The slurry diffusion morphology and range under different grouting pressures and grouting time slurry viscosity were obtained. Finally, in order to explore the application effect of key grouting parameters, on-site industrial tests were conducted in a soft and high gas coal seam. The research results indicate that the optimal grouting pressure for the “retaining wall rock hole ring” should not be less than 3 MPa, the reasonable grouting time should be 10–15 min, and the water material ratio of the grouting material should be greater than 1:1; The use of new reinforcement sealing and grouting technology can ensure long-term good extraction effect. Compared to the testing of drilling sealing effect using ordinary cloth bags with two plugs and one injection, The adoption of new reinforcement sealing technology can effectively prevent the deformation and collapse of the borehole before sealing, and due to two rounds of grouting and pre reinforcement of fractured coal, the sealing effect of the borehole is also relatively good. The research results have important theoretical value for guiding the drilling and sealing grouting engineering of gas extraction in soft coal seams.

A computational method proposal on the determination of grouting parameters for shield construction in water-rich earth materials

A computational method proposal on the determination of grouting parameters for shield construction in water-rich earth materials

Numerical modeling for controlled compensation grouting

This article analyzes the numerical modeling of the stress-strain state of a gravity structure sand base during grouting works using the controlled compensation grouting technique. The modeling is performed using the finite element method and physical nonlinear soil models that take into account the Coulomb-Mohr strength condition. The modeling is done in the computational software JuliS as well as the universal software complex PC ZSoil. The goal of the research is to study the impacts of compensation grouting parameters on the elevation value of base slab. A model was created for the grout body as an expanding spheroid whose volume changes as cement grout is fed in the soil. The authors developed a grouting sequence for grouting solutions based on the location of grout body in the grouting pillar. It is more efficient to feed the grout starting from the lower grout body. The grouting solution feed mode is selected depending on the soil strength condition and accounting for the prevention of hydraulic fracture. As a result of the research, the initial subsidence of the soil on the daytime surface above the injection zone was obtained, which requires experimental confirmation and is a matter for discussion.

Field study on pile side grouting reinforcement for in-service pile foundation using segmental localized grouting

Grouting is an effective method to enhance the bearing capacity of in-service pile foundations. The effect of optimizing grouting parameters for in-service pile foundation grouting reinforcement was verified through static load tests. The field tests of the pileless stratum show that the cement-sodium silicate slurry is more favourable for increasing the grouting pressure and more convenient to control the slurry diffusion than cement slurry. The grouting parameters of cement-sodium silicate slurry were determined according to the maximum grouting pressure and quantity. The slurry grouting parameters were cement slurry 1.6g/cm3 and cement slurry to sodium silicate ratio 2.29:1. Moreover, the effective range of segmental localized grouting reinforcement was detected by the resistivity method and in-situ standard penetration test, and the grouting position should be less than 2m from the side of the in-service pile foundation. Finally, it is found that pile side grouting can improve the bearing capacity of in-service pile foundation by 98% through static load test. The research results have reference value and guiding significance for the design and effect detection of pile foundation grouting reinforcement.

Analysis of the effect of grouting parameters on pile-soil interaction of grouted piles

Reasonable control of grouting parameters was the key to improving the pile-soil interaction. However, quantitative analysis on the effect of grouting parameters on the pile-soil interaction was still lacking. This article developed an intelligent post-grouting system for precise control and quantitative analysis of grouting parameters. The conventional preparation method for shear tests were improved in this article. By changing the normal stress of the pile-soil interface during grouting, the test sample could simulate the grout distribution of the pile-soil interface at different depths. Through the improved experimental methods, a more accurate analysis of the mechanism for the pile-soil interaction was achieved. And the effectiveness of the intelligent post-grouting system was further verified by the case application. The results indicated that increasing the grout volume could improve the interface shear strength when the normal stress and grouting pressure were constant. This improvement effect caused by increasing grout volume decreased when the normal stress was high. Increasing the grouting pressure increased the interface shear strength when the normal stress and the grout volume remained constant. This improvement effect caused by increasing grouting pressure decreased when the grout volume was small. By appropriately controlling the two grouting parameters, the cohesion and the shear strength of the pile-soil interface were increased by 5.8–18.8 times and 1.16–2.91 times, respectively. The results indicated that the intelligent post-grouting system could accurately control the grouting parameters and effectively improve the pile-soil interaction of bored piles. The intelligent post-grouting system effectively reduced geotechnical engineering risks and improved the bearing capacity of pile.

A Numerical Study on the Cement Slurry Penetration Performance of the Cyclic Grouting Method with High-Frequency Pulsating Pressure

The performance of traditional steady grouting is sometimes limited; therefore, a new high-frequency pulsed grouting method is proposed. Through the CFD method, this paper studies the cement slurry penetration performance of cyclic grouting under the influence of pulsating pressure and steady pressure. Firstly, the penetration shape and flow fields of the two grouting methods are investigated. Secondly, the effects of pulsation parameters on penetration performance are studied. Finally, the influence of various working conditions, such as soil properties, grout parameters, grouting pipe length, and back pressure, on penetration distance is also investigated. The results show that pulsating grouting achieves better penetration performance compared with steady pressure grouting. With the increase in frequency, pulsating grouting exhibits superior performance, while with the increase in pulsation amplitude, the penetration distance initially increases and then decreases. This is because part of the pulsating pressure is lower than the back pressure, which weakens the pulsating effect. As viscosity and back pressure increase and as porosity and particle size decrease, the proportion of lateral diffusion in pulsating grouting relative to steady pressure grouting increases. This indicates that lateral penetration performance achieves optimal results under high-flow-resistance conditions. However, when the flow resistance becomes excessively high, the vertical penetration distance may be affected. This study is expected to improve the grouting efficiency and provide a better understanding of pulsating grouting design and operation.

Experimental Investigation on Reinforcement Application of Newly Permeable Polymers in Dam Engineering with Fine Sand Layers

The grinding reinforcement of fine sand layers is a difficult problem in dam engineering construction. As a new type of grouting material, permeable polymer with excellent impermeability and high strength is widely used in dam engineering. In this paper, a series of compressive tests were designed considering different grouting pressures, curing days, moisture content, and porosity of fine sand. The influence of grouting parameters and sand layer conditions on the strength of fine sand layers reinforced by permeable polymers was analyzed. SEM and XDR tests were conducted to analyze the microscopic characteristics of the grouting stone. The functional calculation model of the strength and the influencing factors was established to explore the main factors influencing grouting stones. The compressive strength of grouted stones increases rapidly from the 7th to the 14th day, reaching about 96% of the maximum strength. The degree of influence of different factors is grouting pressure > moisture content > porosity. The compressive strength of the grouted stones increases with the increase of grouting pressure and the number of curing days. The compressive strength decreases with the sand layer’s increasing moisture content and porosity.

Study of Grouting in the Hydraulically Activated Subfoundation Soils Using the Comprehensive Approach

Introduction. The large-scale “wet” closure of collieries had led to irreversible changes in the underworked rock mass. First of all, there took place the mine-water level rise and hydraulic activation of buildings’ subfoundation soils, which induced the new geodynamic effects and hazardous deformations of buildings. Therefore, it is necessary to carry out the reconstruction of buildings’ subfoundations on the underworked territories. Under these circumstances, the high-pressure jet grouting with viscoplastic grouts using the hydraulic fracturing is considered a highly-promising trend of soil grouting. The work aims at studying the parameters of grouting and the degree of consolidation of hydraulically activated soils on the underworked territories.Materials and Methods. The research was carried out with the rock full scale specimens, taking into account their physical-mechanical and strain-strength properties. The comprehensive approach to research implied studying the geotechnical conditions and the technological parameters of rock grouting along with the quality of stabilisation and waterproofing of hydraulically activated soils.Results. In accordance with the comprehensive research methodology, at the first stage, the geotechnical and miningengineering analysis of the underworked territories were carried out and the geostructural typification of the ShakhtinskNesvetaevsky district territories was substantiated depending on the thickness of the covering deposits. At the second stage, the grout pad formation parameters at contact with the parent rocks were analytically determined. Moreover, for dispersive decompacted rocks the consistent patterns and the degree of filtration consolidation were established in the empirically-analytical way by viscoplastic grout injection. Using the computer and physical modeling method, the consistent patterns of subfoundation soils deformation before and after grouting were obtained for three geostructural types. At the third stage, the field studies of the grouting parameters and quality were carried out during the subfoundations reconstruction of two buildings in the city of Shakhty. It was proved that grouting in the hydraulically activated soils increases their strength up to 0.4 MPa and reduces subfoundations deformation by 2–2.5 times.Discussion and Conclusions. Application of the comprehensive methodology to the study of grouting in the hydraulically activated soils of the underworked territories made it possible to substantiate the process flow schemes and parameters of consolidation and waterproofing of dispersive and fractured hard rocks. Based on the analytical, computer, laboratory and field study results, the consistent patterns and the degree of variation in the deformation-strength properties of the hydraulically activated subfoundation soils after viscoplastic grouting were established.

Experimental study on the diffusion characteristics of nonaqueous reactive expansive polymers in sand and gravel media under dynamic water conditions

Grouting is an effective method to solve water inrush from sand and gravel. However, due to the self-expandability of nonaqueous reactive expandable polymers, the diffusion behaviour of polymers in injected media becomes more complex, which brings great uncertainty to the selection of grouting parameters in grouting practice. For this reason, a series of diffusion experiments of nonaqueous reactive expansive polymers in sand and gravel media under dynamic water conditions were carried out using a homemade experimental device. The effects of grouting parameters such as dynamic pump pressure, mass fractal dimension, and grouting volume on the effective diffusion length and water plugging rate of the slurry were revealed. The results show that (1) the diffusion behaviour of nonaqueous reactive expansive polymers in sand and gravel media can be summarized as edge dispersion, downstream diffusion, and expansion diffusion. (2) The diffusion consolidated bodies of nonaqueous reactive expansive polymers mostly exhibit a hemispherical or columnar shape with a wide top and a narrow bottom. (3) The greater the pressure of the moving water pump is, the smaller the effective diffusion length of the slurry. Under the same grouting volume, with increasing mass fractal dimension, the effective diffusion length of the slurry first increases and then decreases. (4) Under the conditions of high dynamic water pump pressure and low mass fractal dimension, increasing the grouting volume has a better water plugging effect.

Grouting anchor cable active advanced support technology for mining roadways

Because of the deficiencies in safety and economy of the single hydraulic prop passive advanced support, the grouting anchor cable active advanced support technology is proposed with the Changping Coal Mine 53,081 roadway as the engineering background. By using a combination of theoretical analysis, laboratory tests, numerical simulation, and field tests, the influence of different grouting parameters on the diffusion law of grout is studied. Considering the effect of the stress field on grout migration, a grout seepage-stress coupling model is established. Grouting material ratio tests are carried out and grout parameters are tested. The grouting part of the advanced grouting anchor cable is modeled and solved using the COMSOL Multiphysics numerical software. The results show that the grouting material selected is Portland cement 42.5 and water glass double liquid grout, with a slurry ratio of 15% ACZ-1 type additive and 4% water glass content, and a water–cement ratio of 0.6. The grouting pressure for the 53,081 roadway grouting anchor cable advanced support is 5 MPa, the grouting time is 6 min, and the grouting anchor cable spacing is 2000 mm × 1000 mm. The engineering application shows that the maximum roof subsidence is 180 mm, the maximum separation value at a depth of 9 m is 24 mm, and the maximum separation value at a depth of 3 m is 90 mm. The research results have achieved effective advanced support for the 53,081 roadway, replacing the single hydraulic prop, and provided a theoretical basis for the subsequent design of advanced support parameters for mining roadways.

Study on diffusion mechanism of viscosity time-varying slurry in unsaturated soil based on displacement effect

Taking Bingham slurry as the research object, an infiltration diffusion model of Bingham slurry in unsaturated soil is established based on the seepage theory of unsaturated porous media, which takes into account the displacement effect and the viscosity time-varying characteristics of slurry. Combined with the seepage motion equation, relevant boundary conditions and interface conditions, the Bingham slurry diffusion equation considers grouting parameters and mechanical parameters is obtained. The research results are degraded to the saturated state and compared with the existing theoretical results. Numerical examples are used to study the influence of the above parameters on grouting pressure and slurry diffusion radius, then the diffusion mechanism of Bingham slurry is verified and analysed by model test. The above analysis and test results confirm the effectiveness and applicability of the research results, which can provide reliable theoretical support and technical reference for the design and construction of grouting engineering in unsaturated soil areas.

Three-dimensional reliability stability analysis of earth-rock dam slopes reinforced with permeable polymer

Polymer is a new repair and reinforcement material for earth-rock dams developed in recent years. Models are developed where spatial variability is incorporated into the analytical framework to evaluate the stability and reliability of reinforced three-dimensional dam slopes. The Karhunen-Loeve (K-L) expansion method is employed to generate three-dimensional random fields. The simplified Bishop method and Monte Carlo method are used to calculate the safety factors and failure probabilities of the dam slopes. With the implementation of polymer grouting reinforcement, the safety factors are improved and the failure probabilities are reduced. The reinforcement effect will be affected by the amount of polymer dosing, dam slope characteristics, and polymer grouting parameters. The impact of various longitudinal autocorrelation distances on reliability is influenced by the length of the dam slope itself. An increase of the safety factor by approximately 37% can be achieved through a polymer dosing of around 3%. Nevertheless, with the elevation of dam slope height and slope ratio, the effectiveness of polymer reinforcement is diminished.