Polymer Grouting Research Articles

Seismic Performance Evaluation of Pipelines Buried in Sandy Soils Reinforced with FRP Micropiles: A Numerical Study

Unstable sandy soil poses significant challenges for buried pipelines, particularly due to the increased risk of displacement and stress-induced fractures resulting from soil settlement and earthquake-induced ground deformation. These concerns are especially critical in seismically active regions where underground infrastructure is at higher risk. Fiber-reinforced polymer (FRP) composites present a promising and sustainable alternative for deep foundations, offering durability and reduced maintenance costs compared to conventional materials. This study introduces a novel approach to enhancing the seismic performance of pipelines buried in sandy soils by numerically investigating a three-dimensional (3D) multipipe grouting micro anti-slide pile system, utilizing a polyurethane polymer slurry as the grouting material. Key parameters such as pile spacing, diameter, and length, along with the effects of soil wetting and various earthquake intensities, were examined under the influence of surface loads exerted by a fully loaded truck. The results demonstrate that using polymer micropiles significantly reduces soil and pipeline settlement by 15% to 50%, with larger pile diameters and lengths further decreasing settlement and strain on pipelines. While seismic excitation increases settlement, polymer grouting effectively mitigates this impact, leading to substantial reductions in settlement.

Study on the Diffusion Characteristics of Polymer Grouting Materials Applied for Crack Filling in Underground Mines Based on Numerical Simulation and Experimental Methods.

Polymer grouting materials are increasingly used in the filling of mine fissures. Unlike conventional inorganic grouting materials, the self-expansion of polymers adds complexity to their diffusion process within the crack. The objective of this research was to examine how polymer grouting material spreads in cracks at ambient temperatures and pressure. The investigation involved conducting grouting tests and performing numerical fluid simulation calculations using the finite-volume method in the computational fluid dynamics software, ANSYS FLUENT 2022 R1. The fluid volume approach was employed to determine the boundary between fluid and air and to ascertain the variation patterns of density in the slurry and the fracture system. This study applied the principles of fluid mechanics to investigate the patterns of variation in the physical characteristics of polymer grouting materials, including their density, pressure, flow velocity, and movement distance, during the diffusion process. The results indicated that the density of the polymer grouting material decreased exponentially over time throughout the diffusion process. With the increase in the grouting's volume, the grout's pressure and the permeable distance of the grout increased. The slurry's pressure near the grouting hole exceeded the other points' pressure. The physical parameters of the slurry were numerically simulated by ANSYS FLUENT 2022 R1 software, and the results were compared with the experimental data. After comparing the numerical simulation results with the test data, it was clear that the numerical simulation method was superior in accurately predicting the distribution pattern of each parameter of the polymer slurry during diffusion. The grouting volume, pressure distribution, and real-time change in the position of the flow of slurry could be efficiently determined through numerical calculation and simulated grouting tests. This work can offer valuable information for designing polymer grouting materials used in underground mine fissures.

Study on Bonding Characteristics of Polymer Grouted Concrete-Soil Interface.

The issue of interfacial shear damage has been a significant challenge in the field of geotechnical engineering, particularly in the context of diaphragm walls and surrounding soils. Polymer grouting is a more commonly used repair and reinforcement method but its application to interface repair and reinforcement in the field of geotechnical engineering is still relatively rare. Consequently, this paper presents a new polymer grouting material for use in grouting reinforcement at the interface between concrete and soils. The bonding characteristics and shear damage mode of the interface after grouting were investigated by the direct shear test, and the whole process of interface shear damage was investigated by digital image correlation (DIC) technology. Finally, the reinforcement mechanism was analyzed by microscopic analysis. The results demonstrate that the permeable polymer is capable of effectively filling the pores of soil particles and penetrating into the concrete-soil interface. Through a chemical reaction with water in the soil, the polymer cements the soil particles together, forming chemical adhesion at the interface and thereby achieving the desired reinforcement and repair effect. In the shear process, as the normal stress increased, the horizontal displacement and horizontal compressive strain at the distal end of the loading end decreased, while the maximum vertical displacement and maximum vertical strain of the cured soil also decreased. The results of scanning electron microscopy (SEM) demonstrated that the four groups of test polymers exhibited a reduction in soil porosity of 53.47%, 58.79%, 52.71%, and 54.12%, respectively. Additionally, the form of concrete-soil interfacial bonding was observed in the concrete-cohesive layer-cured soil mode. The findings of this study provide a foundation for further research on diaphragm wall repair and reinforcement.

Molecular dynamics simulation of water permeation mechanism in polymer grouting material

Polyurethane (PU) grouting materials are commonly used in infrastructure trenchless rehabilitation projects and are frequently exposed to water environments. However, the underlying microscopic mechanism of polymer damage caused by water infiltration has not been systematically investigated. In this paper, we employed molecular dynamics (MD) simulation to explore the wetting behavior of water on the PU surface and the permeation behavior of PU under pressure. The results showed that when sufficiently high water pressure is applied, PU deforms and creates voids. Subsequently, water molecules begin to penetrate the interior of the PU. For PU models with thicknesses of 10 Å, 15 Å, and 20 Å, penetration behavior was observed at water pressures of 189 MPa, 256 MPa and 314 MPa, respectively. Moreover, with PU models of identical thickness, the depth of water molecules penetration and the volumetric water content of the PU increased with rising water pressure. Furthermore, it was observed that PU has many small interatomic pores in its free state. Under the influence of water, distribution of these pores deviates from a normal distribution and becomes irregular. These findings provide valuable insights into the microscopic mechanism underlying infiltration damage of PU grouting materials at the molecular level.

Study on Ratio Optimization and Diffusion-Gelation Process of Polymer Grouting Materials for Fracture Filling in Underground Mines.

The existence of fissures poses a serious threat to the safe production of underground mines, and this paper investigates a polymer grouting material for filling fissures in underground mines. To optimise the ratio of polymer grouting materials, this paper designed 16 test groups using the orthogonal test method to find the most reasonable slurry ratio. In order to study the gel diffusion process of polymer slurry in the fissure and to explore the changes of various parameters of the slurry after injection, simulated grouting tests were carried out, and the distribution laws of viscosity, pressure, and diffusion distance of the slurry were discussed. The findings indicate that when the proportion of ethylenediamine polypropylene oxide tetrol: glycerol polyether: catalyst: foam stabiliser is 10:8:0.5:0.4, the polymer grouting material has excellent compressive strength, and the maximum compressive strength can reach 12.31 MPa. Prior to reaching the gel time point, the viscosity of the polymer slurry was nearly constant, which is basically maintained at 0.772 Pa·s under normal temperature and pressure, but after reaching the gel time point, it abruptly rose. As the slurry mass increased, so did the penetration distance and pressure; in the simulated grouting test, when the slurry mass was 400 g, the maximum diffusion distance of the slurry reached 39 cm. Conversely, as the fracture pore size increased, the diffusion distance and pressure of the slurry decreased. Along the diffusion path, the slurry pressure progressively drops, but this change is not synchronised with the diffusion distance's change. This work can serve as a reference for the configuration of polymer slurry and aid in comprehending the diffusion law of the slurry within the fissure.

Intelligent design and seawater mixing performance of new synchronous grouting materials in a pure-solid-waste framework

Solid waste, as a reliable raw material substitute for synchronous grouting materials in shield tunneling, addresses the issue of recycling traditional waste. Additionally, geopolymer slurries utilizing waste exhibit excellent physical and chemical properties, meeting requirements for the stability and long-term performance of synchronous grouting materials. In this study, an environmentally friendly polymer grouting material based on pure solid waste was developed using sunflower stalk ash, blast furnace slag, and fly ash as raw materials. By varying the proportions of binder materials and quantity of seawater introduced, we systematically analyzed the applicability of grouting materials and reliability of seawater as a mixing medium in a comprehensive solid waste framework. We utilized an artificial intelligence integrated algorithm to predict the compressive strengths of cementitious materials with different ratios through forward performance prediction. The proportions were then inverted using a simulated annealing algorithm according to the strength required for actual engineering applications. The results demonstrated that under the dual effects of sunflower stalk ash alkalinity and seawater composite salts, more active Si and Al ions were released during the hydration process. The solid waste filling and accelerating effects of composite salt hydration can effectively improve the pore structure, resulting in a significant increase in early compressive strength. The artificial intelligence ensemble algorithm proved to be an effective model for predicting compressive strength and the simulated annealing algorithm successfully determined the optimal ratios for meeting practical production requirements. These findings provide a foundation for solid waste treatment and underground engineering using seawater resources, contribute to the preparation of high-performance slurries, and facilitate green development.

Intelligent prediction model of a polymer fracture grouting effect based on a genetic algorithm-optimized back propagation neural network

Polymer grouting can effectively improve the stability of surrounding rock fractures. However, in practical construction, it is difficult to judge the degree of coupling between the slurry and the rock, and the effective grouting range after grouting. Therefore, early prediction of the effect of grouting on the surrounding rock is crucial. In this paper, a new artificial intelligence method is proposed to predict the polymer fracture grouting effect. The genetic algorithm optimized back propagation neural network (GA-BP) is employed to construct an intelligent prediction model. To acquire a substantial dataset for constructing the model, an easily assembled/disassembled test apparatus for polymer fracture grouting is designed. The maximum coupling degree of the fractures and slurry diffusion distance are chosen as the evaluation metrics for the grouting effectiveness. The influences of the fracture characteristic parameters and grouting volume on the grouting effect are investigated. Furthermore, a comprehensive analysis is conducted on the spatiotemporal diffusion characteristics and slurry-rock coupling mechanism of polymer grouting. Compared to traditional BP neural networks, and three other machine learning algorithms (decision trees, random forests and gradient boosting decision trees), the GA-BP model outperforms them in terms of R2 (coefficient of determination), MSE (mean squared error), MBE (mean bias error), MAE (mean absolute error) and RMSE (root mean squared error) in both the test and training sets. The GA algorithm significantly improves the accuracy and robustness of the prediction model. The optimized model demonstrates significant accuracy in predicting grouting results and assessing efficiency, providing a practical reference for grouting construction.

Experimental Study on Compressibility and Microstructure of Loess Solidified by Permeable Polymer

This study aims to investigate the compressive and microstructural properties of loess before and after treatment with a new permeable polymer. To enhance the compressive properties of loess, specimens were infused with the new polymer, and one-dimensional consolidation tests were performed to assess the compressibility of solidified loess (SL) and unsolidified loess (UL) at different water contents. Additionally, the microstructure and pore morphology of UL and SL were examined using a scanning electron microscope (SEM) and the Particles (Pores) and Cracks Analysis System (PCAS). Statistical methods were employed to analyze the relationships between microstructural parameters and compression modulus. The experimental results demonstrate a significant improvement in the compressibility of loess when treated with the polymer. The complexity of pore structure and variability in pore size are reduced, leading to a more uniform pore distribution. Moreover, all microstructural parameters exhibit a strong correlation with the compression modulus. The results pertaining to the compressive and microstructural properties of loess reinforced with permeable polymer grouting can provide insights into the variations in the curing effect, serving as a theoretical foundation for the application of permeable polymer in loess treatment.

Splitting tensile properties and damage characterization of polymer grouting materials: Density, geometry and size effects

Splitting tensile properties play a crucial role in evaluating the safety of polymer grouting reinforced underground infrastructure. However, the influence of density, geometry and size effects on splitting tensile properties is remains unclear. This study employed static splitting tensile and Brazilian disc tests to investigate these influences, analyzing the damage evolution process of polymer grouting materials through the acoustic emission-digital image correlation (AE-DIC) system. The results show that the splitting tensile strength of polymer grouting materials decreases with the increase of specimen density, edge length, height, diameter and splitting cross-sectional area. Moreover, the splitting tensile strength and specimen density, as well as the splitting tensile cross-sectional area, exhibit a satisfying power function relationship. Furthermore, during the splitting tensile loading process of polymer grouting materials, energy release primarily occurs at the instant of specimen failure. The greater the density, the more energy is released during failure damage, resulting in more significant brittle damage characteristics.

Study on the Gelation Process and Mechanical Properties of Organic Polymer Grouting Materials Applied to Fissure Sealing in Underground Mines.

In this study, organic polymer polyurethane grouting materials were prepared using isocyanate and polyether polyol as the main agents and various additives, the slurry coagulation process was investigated, and the mechanical properties of the polymer samples were tested to explore the influence of the density and soaking time of the polymer on the strength of the samples. The microstructure of the polymer was observed via electron microscopy, and relying on image analysis software, the structural parameters of the polymer cell were analyzed and calculated; the model equation between density and yield strength was established based on the strength model of porous materials developed by Gibson and Ashby. The results show that the initial viscosity and gel time of the polyurethane slurry decrease with the increase of the initial temperature, and the viscosity changes abruptly when the slurry reaches the gel point. The mechanical properties of the polymer increased with increasing density and decreased with increasing soaking time. The interior of the polymer is a porous structure and the pores are approximately spherical; the higher the density of the polymer material, the more uniform the stress distribution of the material, and the higher the percentage of the matrix, which in turn leads to better mechanical properties of the material. The diameter of the polymer cell is negatively correlated with the density, and the model established based on the microscopic parameters of the cell can better predict the yield strength of the polymer. This study helps to deepen the understanding of the microstructure and mechanical properties of polyurethane and provides a certain reference for the application of polyurethane in underground mine reinforcement engineering.

Investigations on the seepage characteristics of polymer grouting body for repairing HDPE geomembrane defects based on LF NMR

As high-density polyethylene (HDPE) geomembranes in landfill liner systems increasingly age and damage, seepage incidents frequently occur and severely threaten the surrounding ecological environment and groundwater safety. Targeted injection grouting with polymer materials can rapidly restore the barrier function by repairing defects in damaged geomembranes. To investigate the sealing mechanisms of polymer grouting bodies with various densities, this study used low-field nuclear magnetic resonance (LF NMR) techniques to monitor and visualize the permeation process within the grouting bodies. The results revealed two failure modes of the grouting bodies under water flows: 1) insufficient interfacial shear strength between the low-density polymer and geomembrane, leading to interfacial leakage; 2) gradual buildup of permeation pressure puncturing the foam cells of the polymer matrix and inducing permeation channels. Selecting polymers with suitable expansion ratios to produce appropriate expansive pressures is crucial to enhance interfacial shear strength while avoiding secondary damages to geomembranes. Increasing the density of the polymer grouting body can also enhance the compressive strength of foam cells and interfacial shear resistance. These are crucial for enabling grouting repair of defects in geomembranes and improving their barrier performance.

Propagation Analysis of Polymer Grout in Vertical Fractures: An Experimental and Numerical Study

The use of non-aqueous reactive polymer grouting is a proven technique for preventing gravity erosion in Pisha sandstone through the filling of vertical fracture. However, the diffusion behavior of the polymer grout within vertical fractures remains unclear and requires further investigation for effective grouting design. This study conducts laboratory experiments to examine the effects of grouting quantity on the spread pattern, diffusion distance, and pressure distribution of polymer grout within a visual vertical fracture. The maximum pressure is 6.25 kPa for a grouting quantity of 120 g, 7.5 kPa for 227 g, and reaches about 9.4 kPa for a quantity of 350 g. A numerical model, incorporating time-dependent density and viscosity, is then developed and validated using experimental results. Finally, the influence of initial viscosity 0.05 Pa·s, 0.1 Pa·s, and 0.5 Pa·s on the flow pattern of polymer grout within the vertical fracture is analyzed. The results show that initially gravity causes a dominant downward flow of polymer grout in a vertical fracture. However, as the grout expands due to the chemical reaction, it propagates in all directions. Furthermore, the gravity causing the dominant downward flow of polymer grout decreases with increasing initial viscosity, and the diffusion distance increases in the horizonal direction but decreases in the vertical direction. On this basis, suggestions for optimal grouting hole arrangement are provided to enhance grouting design.

Mechanical and Impermeability Properties of Polymer Grouting Materials for Hydraulic Expansion Joints

Mechanical and Impermeability Properties of Polymer Grouting Materials for Hydraulic Expansion Joints

Properties of Low-Exothermic polymer grouting materials and its application on highway

Frost heaving and thawing settlement are the main problems in highways in permafrost regions. Non-aqueous reacting polymer is a relatively effective and environmentally friendly material to repair highways. However, its expansion and heat release influence on different strata in perma-frost areas remains unclear. Thus, a low-exothermic polymer was used to conduct grouting tests in different strata of frozen soil. The heat release characteristics and thermal conductivity of low exothermic polymers during the reaction were studied by laboratory experiments. Then it was applied to the protection of freeze-heave and thaw subsidence of highway in frozen soil area. Sensors were arranged to dynamically monitor the influence of polymer grouting, diffusion, expansion, and exothermic processes on different layers of frozen soil. The results showed that the thermal conductivity of low exothermic polymerwas affected by density, the higher the density, the higher the thermal conductivity. The maximum temperature, maximum displacement, and maximum pressure of polymer grouting on each layer were less than 36 °C, 1.4 mm, and 280 kPa, respectively, and the soil of each layer recovered to its initial state 60 min after grouting was completed. Polymer grouting had significant effects on the artificial road bases with a depth of more than 80 cm, and the affected depth of semi-rigid bases was less than 40 cm. Because of serious damage in the driving direction, the grout preferentially diffused to the driving side. Therefore, repairing roadbed diseased in the permafrost region using a low-exothermic polymer is feasible.

Degradation Mechanism of Nonaqueous Reactive Polymer Grouting Materials under Chemical Corrosion Environment

Degradation Mechanism of Nonaqueous Reactive Polymer Grouting Materials under Chemical Corrosion Environment

Improving the Anti-washout Property of Acrylate Grouting Material by Bentonite: Its Characterization, Improving Mechanism, and Practical Application.

Acrylate is a popular polymer grouting material that has been widely used to control groundwater seepage. However, the vulnerability of acrylate slurry to dynamic water washout restricts its application in groundwater environments characterized by high flow velocity and water pressures. In this paper, lithium bentonite (Li-B) was used to modify the traditional magnesium acrylate (AC) grouting material. The influence of Li-B to AC ratios on the modified materials' washout resistance was explored, and the modification mechanism was analyzed using X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). Finally, the anti-washout ability of the modified slurry was verified through engineering applications. Results revealed that LiB-AC grout had adjustable setting times (10.5 to 395.6 s), minimal bleeding (0.1%), higher viscosity (65 mPa·s) and expansibility (350%), stronger anti-water dispersibility (24 times that of pure AC slurry), higher mechanical strength (compressive strength is 0.386 MPa, tensile strength is 0.088 MPa), and better impermeability (2.23 × 10-8 m/s). The lithium bentonite was beneficial to the setting time, bleeding, viscosity, slurry retention rate, impermeability, and mechanical strength of the acrylate grout. However, it diminished the expansibility of the acrylate grout. At the optimal acrylate content (20%), the mechanical strength and impermeability of the LiB-AC grout were the highest. The better performance of LiB-AC grout was attributed to the formation of a more stable and dense interlaced spatial network structure after the modification by Li-B. The LiB-AC grout was used in the dynamic water grouting project of a metro shield tunnel segment and achieved better anti-washout performance than cement-water glass and pure AC slurry.

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.

Seismic Response Analysis of Secondary Lining Polymer Grouting Debonding Repair for Tunnel Construction Based on Parameter Inversion

The void phenomenon behind the tunnel lining has become the main cause of tunnel disease, easily triggering tunnel lining structure damage, shedding, water seepage, and other diseases that seriously threaten the normal operation of the tunnel. The void area behind the lining seriously reduces the seismic capacity of the tunnel. In this paper, the mechanical parameters of the surrounding rock are calculated by optimizing the inversion of the improved system identification sensitivity analysis method, and the numerical model of the tunnel’s dynamic response is optimized using the improved inversion results to study the repair effect and seismic capacity of the Longmenshan tunnel using polymer grouting to repair the void area behind the lining under the action of a seismic load. The results show that the displacement and stress at the top of the tunnel secondary lining void area are significantly reduced and close to normal after the repair of polymer grouting; however, the stress and displacement at the top of the secondary lining are significantly different under the action of seismic waves at the same peak at different site conditions, which indicates that the dynamic response of this tunnel model has obvious sensitivity to the seismic wave spectrum.

Experimental and practical investigation of reinforcement mechanism on permeable polymer in loose area of drainage pipeline

Permeation grouting is one of the important methods of anti-seepage reinforcement when the drainage pipes crosses loose diseases caused by leakage. With the development of grouting materials, permeable polymer slurry is widely used in engineering practice. Due to its low viscosity, fast reaction and micro-expansion, the diffusion and reinforcement law of slurry in loose area of drainage pipeline is more complex. To better understand the effects of water head pressure, grouting pressure, sand particle size and clay content on the anti-seepage and reinforcement effect of permeable polymer grouting in loose area of drainage pipeline, several types of tests, including permeability and uniaxial compressive strength tests, were performed. Then, based on the model test results, a BP neural network prediction model for the anti-seepage reinforcement effect of permeable polymer grouting in loose area of drainage pipeline is constructed, and the research results are applied to the treatment project of loose area of drainage pipeline for verification. The results show that: 1) after grouting, the order of magnitude of permeability coefficient of the consolidated body is reduced to 10-7cm/s, the anti-seepage performance of the sand layer is greatly improved, and the grouting pressure is the main controlling factor affecting the anti-seepage performance of the consolidated body. 2) The compressive strength of the consolidated body is obvious different under different working conditions. The water head pressure is the main controlling factor affecting the strength of the consolidated body. 3) Due to the limitation of test conditions, the relative error between the predicted value of BP neural network model and the actual value is about 20%, which can meet the general prediction needs.

Identification of Cement Pavement with Temperature Effect and Evaluation of Polymer Grouting Effect.

The falling weight deflectometer (FWD) detection system benefits from its outstanding characteristics of no damage, fast speed, and high precision. The warping deformation of cement concrete pavement occurs due to the temperature difference along the depth of the slab, which makes FWD detect different results under different temperature fields. In this study, we systematically carried out the cement pavement's temperature field and deflection test. The experimental data were analyzed to obtain the temperature variation law of the top and bottom of the pavement slab every day. By establishing a three-dimensional finite element model of cement pavement with a multi-layer elastic foundation type, the influence of the temperature difference at the bottom of the slab on the deflection of the center point of the slab corner load under different working conditions, different seasons, different loads and whether there is polymer filling in the void area was studied. We summarize the correlation between the temperature difference and the influence coefficient and propose the cement pavement void identification and polymer grouting effect evaluation method considering the temperature effect.