Grouting Pressure Research Articles

Analysis of Shield Tunneling Parameters and Research on Prediction Model of Tunneling Excavation Speed in Volcanic Ash Strata of Jakarta–Bandung High-Speed Railway Project

Insufficient investigations have been conducted on the analysis of shield tunneling parameters and the prediction of the tunneling excavation speed in formations composed of volcanic ash strata. To address this issue, we employ a comprehensive approach utilizing literature research, mathematical statistics, and other methodologies, centered on the analysis of the No. 1 Tunnel of the Jakarta–Bandung High-Speed Railway. Our focus is on examining the evolution patterns and inter-relationships of shield tunneling parameters within volcanic ash strata. Subsequently, we propose an optimized strategy for these tunneling parameters. By employing six machine-learning algorithms to construct prediction models, we compare and analyze their performance in predicting the tunneling excavation speed. The results indicate a positive correlation between slurry pressure and tunnel depth in volcanic ash strata, suggesting that the grouting pressure should exceed the slurry pressure by approximately 0.22 MPa. In the composite stratum of “volcanic ash debris + round gravel”, the cutter torque exhibits a strong negative correlation with the total thrust (−0.77). Due to tool wear and ground resistance, the excavation speed and cutter speed are weakly negatively correlated. Compared to other strata, shield tunneling in volcanic ash strata exhibits larger grouting pressure fluctuations, slower tunneling excavation speed, greater total thrust, higher cutter torque, and lower cutter speed. Regarding shield tunneling excavation speed prediction, the ranking of the algorithm performance is RF > DNN > ANN > BPNN > MNR > SVM, with RF achieving a decision coefficient of 0.829. The RF model is well-suited for predicting the shield structure tunneling excavation speed.

Study on the Diffusion Parameters of Newtonian Fluid in High-Pressure Jet Disturbance Grouting

In order to investigate the diffusion mechanism of slurry in post-pile grouting, this study develops a formula for calculating the diameter and the climb height of the cement core of jet grouting (CCJG). This research conducts field orthogonal tests using a self-developed grouting nozzle to analyze the effects of disturbance pressure (DP), disturbance time (DT), grouting pressure (GP), and the water–cement ratio (W/C) on the dimensions and strength of the CCJG. The findings revealed that the theoretical formula for calculating the diameter of the CCJG deviates by approximately 8% from the field test results, confirming the formula’s validity. In addition, the DP and DT significantly influence the volume of the CCJG, displaying a linear increase with their augmentation. Conversely, the W/C and DP predominantly affect the CCJG’s strength. Notably, an increase in the W/C results in diminished strength, whereas an increase in the DP enhances it. In addition, soil reinforcement is achieved through replacement, mixing, and compaction as the grout flows outward from the center of the grouting hole. These insights offer a theoretical foundation and technical support for effective grouting construction practices.

Complex variable solution for ground deformation responses considering the grouting pressure of shallow shield

During shield tunneling in shallow strata, ground deformation is highly sensitive to grouting pressure response. Excessive grouting pressure can cause ground uplift, and an excessively low grouting pressure can cause excessive ground settlement, affecting the surrounding environment. Current studies seldom analyze the influence of shield excavation on ground deformation when the grouting pressure is considered. To ensure micro-disturbance of the surrounding environment during shield tunneling, this study presents a complex variable analysis method for analyzing the influence of grouting pressure on surface settlement. This solution maps the semi-infinite strata outside the segment into circular domains by introducing a complex function conformal mapping method. The nonuniform convergence deformation pattern BC-4 was introduced as the boundary condition for the displacement around the tunnel. The Laurent series expansion of the analytical function considering the grouting pressure in the circular domain was substituted into each boundary condition to solve the analytical function. Subsequently, the accuracy of the analytical method was verified by combining it with a finite element numerical method. Finally, the influence of grouting pressure on ground deformation under different working conditions was analyzed through parameterization. This analytical method can provide a theoretical basis for controlling grouting pressure parameters in shield tunnels.

Experimental investigation of tail void grouting pressure evolution for super-large diameter shield tunnels

The shield tunneling method is widely used in underground construction. Factors such as the variations in grouting pressure and stiffness/strength evolution over space and time directly affect ground deformation and system stability. To investigate the effect of grouting pressure variation, grouting influence zone, and hydromechanical properties on the model responses (e.g., surface settlement and lining forces), an innovative model test setup was developed to simulate the tunneling process wherein the lining could settle or float during grout injection. This setup included tunnel shrinking, loading-unloading, grout injection, and sample preparation systems. The experimental results show that the grouting pressure evolution law may be significantly affected by the tunnel translation. When the tunnel centerline was fixed in the traditional model tests, the resulting grouting pressure in the tail void was lower than that when the tunnel was free to move. This is because the tunnel translation changed the shape of the annular gap and contributed to the measured grouting pressure. The proposed setup is capable of revealing a more realistic law of grouting pressure evolution, and the subsequent spatio-temporal grouting-induced soil/lining behavior is currently being investigated.

Study on the escaping condition of backfill grouting based on two-phases flow for shield tunnelling during whole section rock

During the process of full section surrounding rock shield tunneling, the occurrence of synchronous grout escaping can seriously affect the assembly quality of the detached shield tail segment ring. The segment is prone to quality accidents such as floating, misalignment of the tunnel pipes, and even cracking, and even a large number of rock fractures in the shield tail gap mix with water flow towards the excavation face and pressure chamber, leading to frequent fissure water gushing out of the screw conveyor. Taking the shield tunnelling section of Nanjing Metro Line 6 as the engineering background, this paper uses the finite element software Ansys Fluent to establish the two-phases flow shield tail escaping grout model, and analyzes the influence laws of the grout properties, grouting pressure difference, grouting escaping thickness and other factors in the process of grout escaping behind the shield tail wall based on Bingham fluid. The results show that the amount of synchronized grout escaping increases linearly with the increase of grouting pressure difference and grouting escaping thickness, and decreases with the increase of grout shear yield stress. The paper also discusses the three-dimensional curved surface of grout escaping volume, grouting pressure difference and grouting fluid properties behind shield tunnel tail in a full section surrounding rock shield project of Nanjing Line 6, and gives the measures to prevent grout escaping when the allowable grout escaping volume is not more than 1m3: when the grouting escaping thickness is 20mm, the grouting pressure difference should be controlled within 0.20∼0.25MPa, and the shear yield stress of the grouting fluid should be controlled within 300∼350Pa.

Similarity Solutions for Spherical Cavity Expansion in Strain-Softening Soils and its Application in Cone Penetration Test

The cavity expansion theory is commonly employed to predict the grouting pressure and cone penetration resistance. However, existing theoretical solutions for cohesive-frictional soils with dilation fail to simultaneously consider both the elastic deformation in the plastic zone and strain-softening behaviour of soils. To address this limitation, a similarity solution was derived for the expansion of spherical cavities from a zero initial radius with an initial confining pressure in strain-softening Mohr–Coulomb materials. The results demonstrate good agreement with previous theories, predicting an ultimate pressure higher than that obtained by neglecting elastic deformation in the plastic zone but lower than that calculated by neglecting softening characteristics. Moreover, several influential factors affecting the radius of the plastic zone and ultimate pressure were meticulously examined. On-site cone penetration test data and the theoretical results showed notable agreement. This indicates that the proposed solution exhibits a better conformance with the field data than do the previous solutions.

Study on the Properties of Waste Stone Powder-clay Slurry based on the Influence of Filter Press

A grouting material pressure effect simulation device (FSD) was used to study the performance of grout considering grouting pressure, slurry rheology, clay ash, slurry concentration and particle size composition of waste stone powder (FSD influencing factors). After the effect of filter pressing, the alkaline environment of the slurry became stronger, the number of active particles increased, and the CaCO3 and clay crystals were fully agglomerate, and the degree of crystallization increased. The cation exchange capacity increased, and the formation of calcium-silicon-aluminum matrix phase and aluminosilicate aggregates increased. The surface water between the matrix particles supports the crystal layer, and the plastic viscosity and yield stress are reduced. The free calcium oxide decreased, and the consolidation shrinkage rate after slurry hardening was less than 1%. The water-cement ratio is reduced, and the total time for slurry to be poured into the fracture to consolidate and form a mold and intermittent is shortened. The use of waste stone powder and clay in the coal mine grouting industry can not only reduce project costs, but also reduce soil erosion and soil pollution.

Ground Deformation of Shield Tunneling through Composite Strata in Coastal Areas

In order to mitigate ground deformation during shield construction in both upper soft and lower hard strata of coastal areas, a numerical simulation was executed. This simulation assessed surface deformation under varying stratum ratios, grouting pressures, and earth bin pressures. The evaluation was primarily based on the amount of ground deformation, which revealed that hard rock strata offer superior settlement control compared to soft rock strata. The excavation of the right tunnel line increased disturbance to the left line at higher stratum ratios. Surface deformation demonstrated a linear correlation with earth pressure, with 130 kPa identified as the optimal point. Higher pressures resulted in extrusion deformation and ground uplift. Grouting pressure had a minimal impact on stratum deformation over time. The stratum ratio exerted the most significant influence on settlement, followed by earth pressure, with grouting pressure having the least impact. In the context of coastal tunnel construction, hard rock excavation is favored. Earth pressure must be balanced to prevent subsidence or uplift, while excessive grouting pressure does not significantly reduce subsidence. Grouting pressure should ensure the complete filling of voids.

Economic Study of Strengthening of Existing RCC Building

Many structures fail or deteriorate before completion of its intended life span due to poor quality of material used, lack of mix design, poor workmanship, attacked by environmental agencies, etc. Sometimes due to slenderness of column or less reinforcement provided than actual requirements, less depth/thickness provided in flexural members, etc. feels excessive vibration during walking on floor ultimately develops cracks. Strength of such structural elements can be found by using non-destructive tests like Rebound hammer test, ultrasonic pulse velocity test, etc. If strength of existing structural elements is less than desired strength then structural consultant suggested strengthening of structural elements. There are various methods used in strengthening of existing structural elements like pressure grouting, fibre wrapping, chemical treatment, structural steel support, jacketing, etc. But these techniques are very costly and need precise quality control activity. In the present of investigation, strengthening of beam and column elements of a building by ferrocement techniques and steel jacketing were carried out and cost and cost comparison and strength results before and after strengthening are presented. It is observed that the strength og structural by ferrocement technique is cost effective than steel jacketing technique. And also has increase in the strength of RCC elements

Research on the Pressure Distribution Law of Synchronous Grouting in Shield Tunnels and the Force on Segments

The pressure distribution and the force on tunnel segments of synchronous grouting in the shield tail gap channel of shield tunnels are key to controlling the stability and surface settlement of the strata surrounding such tunnels. Based on the basic principles of fluid mechanics and the limit equilibrium method, this study establishes a mathematical model of synchronous grouting in shield tunnels, derives the expressions of the grouting pressure and the force on tunnel segments in the shield tail gap channel, and verifies them using an engineering case study. Studies have shown that the force on tunnel segments and the speed of shield excavation are increasing. An excessive shield excavation speed will cause the load on tunnel segments to increase, which exacerbates the uneven distribution of the grouting pressure. The force on tunnel segments and the grouting pressure also have a positive relationship with the thickness of the shield tail gap, but the impact is limited to a certain range. With an increase in the tunnel radius, the number of grouting holes should be appropriately increased to balance the water and soil pressure in the surrounding strata. These research results can provide a theoretical reference for the design of synchronous grouting for shield tunnels in the future.

Calculation of additional load and deformation of the receiving well enclosure structure caused by shield tunneling.

The bulkhead additional thrust during shield tunneling, the force of friction between shield and soil, and the additional grouting pressure can cause additional stress in the surrounding soil, thereby disturbing existing buildings and structures. However, few studies focused on the disturbance situation when the shield tunneling machine approaches the receiving well. If the additional stress and deformation of the receiving well are too excessive, it could result in the collapse of the receiving well. Based on the two-stage method, this study derived the calculation formula of the additional stress and deformation of the receiving well enclosure structure caused by shield tunneling. Taking a shield machine receiving engineering as the context, this study established a numerical simulation model and compared theoretical calculation, the results of numerical simulation model and on-site monitoring data. Finally, the additional stress of the receiving well is analyzed. The research findings demonstrate that the theoretical prediction results, numerical simulation calculation results, and on-site monitoring data exhibit relatively small calculation errors, which validated the applicability of the theoretical prediction formula and numerical simulation model. As the distance between the shield machine and the receiving well decreases, the disturbance to the receiving well increases sharply. When the distance between the cutter head and the receiving well is less than three times the shield length, it is crucial to enhance the deformation monitoring of the receiving well. The primary factors affecting the additional load and deformation of the receiving well enclosure structure are the force of friction between shield and soil and the additional thrust of the cutterhead. The disturbance caused by the additional grouting pressure on the enclosure structure can be ignored.

Constructing a cut-off dam inside a water-filled circular tunnel with backfill grouting

This study employs laboratory model tests for backfill grouting and numerical analyses (coupled analysis of the discrete element method and computational fluid dynamics, DEM-CFD coupling analysis) to investigate the feasibility of constructing a cut-off dam inside a water-filled circular tunnel using the backfill grouting method from the ground surface. Several improved backfill methods were studied to enhance the effectiveness of the cut-off dam. These methods include: (a) adding an additional backfill grouting hole between the double-row cut-off dam and applying pressurized grouting; (b) adjusting the number of backfill grouting holes per row of the cut-off dam; (c) simultaneously grouting the double-row cut-off dams to minimize the formation of interface fissures and voids; (d) adjusting the grout hole spacing of the double-row cut-off dams to reduce the volume of backfill material. Additionally, pressurized mortar grouting is a critical mass to ensure the water tightness of the cut-off dam. The implementation of these backfilling arrangements improves the effectiveness and watertight of the cut-off dam, thereby reducing the construction time and cost. The findings of this study can serve as a reference for water-filled tunnels and subsequent rehabilitation works in the future.

An extended discontinuous deformation analysis for simulation of grouting reinforcement in a water-rich fractured rock tunnel

Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength. Nevertheless, there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata. In this study, the hydro-mechanical coupled discontinuous deformation analysis (HM-DDA) is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network (DFN), including the slurry migration, fracture dilation, water plugging in a seepage field, and joint reinforcement after coagulation. To validate the capabilities of the developed method, several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry. The simulation results closely align with the analytical solutions. Additionally, a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints. An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established. The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster. The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.

Experimental Study on Water-Plugging Performance of Grouted Concrete Crack.

In this paper, ordinary Portland cement, ultrafine cement, polyurethane, and epoxy resin were selected as typical grouting materials. Grouting simulation tests were first conducted to prepare the grouted concrete crack sample. The effect of concrete crack parameters (i.e., crack aperture and roughness), grout water-cement ratio, and grouting pressure on the water-plugging performance of different grouting materials was explored through the impermeability test. The microstructure of grouted concrete cracks was analyzed by means of scanning electron microscopy (SEM) and computed tomography (CT), and the difference in water-plugging performance of different grouting materials was explained at the micro level. The results show that the impermeability of the four grouting materials was ranked as follows: Epoxy resin > polyurethane > ultra-fine cement > ordinary Portland cement. The concrete cracks grouted by epoxy resin have the highest plugging failure water pressure and the lowest permeability, which is the optimal grouting material. The effectiveness of crack grouting in water-plugging was directly proportional to the grouting pressure, provided the pressure did not exceed a certain value. When the pressure surpassed the threshold, the increase in pressure did not have a significant impact on the water plugging performance. For the two cement-based materials, the threshold pressure was 1 MPa, while for the other two chemical grouts, it was 2 MPa. The two cement-based grouts with a water-cement ratio of 0.8 showed optimal water-plugging performance. The water-plugging performance of ordinary Portland cement paste, ultra-fine cement pastes, and polyurethane grout was negatively correlated with crack aperture and positively correlated with crack roughness. However, the water-plugging performance of epoxy resin grout was not affected by crack aperture or roughness.

Experimental Study on Grout–Soil Interaction Effects in Sandy Soil under Different Water-to-Cement Ratios

Due to the unique characteristics of sandy soil layers, there is often a coupling effect of multiple grout diffusion patterns in the grouting process, and different slurry diffusion modes may lead to different responses of soil structures. In this study, laboratory grouting model tests were conducted with homogeneous sand under different water-to-cement (w/c) ratios to reveal the temporal variations in grouting pressure, soil stress fields, and displacement fields during the grout diffusion process. The results show that, during the grouting process in the fine sand layer, the grout mainly exhibited a compaction–splitting diffusion mode. The farther away from the grouting center, the more pronounced the hysteresis effect of soil pressure caused by grout diffusion. Meanwhile, as the w/c ratio increased, the diffusion mode between the slurry and the soil was in a transitional state. At w/c > 1.2, the primary pattern changed from the fracture–compaction pattern to the permeation–fracture–compaction pattern and fracture–permeation pattern. And the overall trend of the grouting pressure curve was similar under all of the w/c ratio conditions, showing a trend of increasing to the maximum value of the pressure first and then decreasing. With the increase in the water–cement ratio, the overall value of the grouting pressure curve showed a decreasing trend, the pressure value increased more slowly with time before reaching the maximum value, and the more obvious the influence of water–cement ratio was when w/c > 1.2. Additionally, the surface displacement also exhibited an overall decreasing trend, and it had no obvious lifting value under the condition of w/c = 1.6.

Magnesium ion corrosion in subsea tunnel grouting: Insights, mechanisms, and optimization strategies for enhanced durability

In the construction of subsea tunnels, grouting reinforcement is crucial for enhancing tunnel strength, impermeability, and stability. This article investigates the impact of prolonged exposure to seawater, specifically magnesium ion corrosion, on the degradation of the C-S-H gel and the weakening of grouting compounds. Utilizing erosion acceleration theory, an experimental setup simulating seawater flow is designed to explore erosion patterns and mechanisms. Macroscopic and microscopic experiments and analyses reveal that magnesium ion corrosion products, Mg(OH)2 and M-S-H, lack cementation ability, leading to detachment from the grouting compound. This detachment results in increased porosity, crack formation, and reduced strength and impermeability. The study recommends reducing the water–cement ratio and increasing grouting pressure to enhance composite strength and impermeability, with attention to boundary effects and prevention of magnesium ion corrosion product shedding. These findings have significant implications for optimizing subsea tunnel construction by improving grouting reinforcement design and ensuring long-term durability.

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.

Analysis of the Impact of Shield Tunneling Under Existing Subway Station

To ensure the safety of existing subway station structures and the normal operation of the metro, this study focuses on a specific engineering case in Suzhou’s metro, where shield tunnels were initiated at a close distance to pass beneath an existing subway station. Numerical simulation method was employed to analysis the impact of shield tunneling parameters on the deformation of the existing station structure under conditions with and without pre-reinforcement boundaries. Additionally, the study involved a comparison with monitoring data to validate the reliability of the numerical simulation approach. The results indicate that: 1) Controlling the shield tunneling parameters, such as setting appropriate shield tunneling face support force and tail grouting pressure, is beneficial in managing the deformation of the existing station; 2) The elastic modulus of an equivalent grouting layer has the greatest impact on settlement. Choosing the appropriate grouting material during construction is a key approach to control settlement. 3) Strengthening the soil strength in the reinforcement area and increasing the thickness of the track slab have a minimal impact on the settlement of the track slab at the existing station. However, the former is beneficial for the stability of the shield excavation face. The latter enhances the existing structure’s resistance to deformation.

Experimental Study of the Injectability of Infiltration Grouting in Surface Moraine of Pulang Copper Mine

In order to effectively reduce the risk of underground debris flow, surface moraine is solidified and modified by using grouting technology to realize the change in fine-grained moraine from “powder” to “block” to change the source conditions of underground debris flow and to reduce the risk of moraine from the root. In this paper, the effects of grouting pressure, porosity, and pore diameter on the spillability of moraine are investigated experimentally. The results show that the grouting depth increases linearly with increasing sample porosity. For the same sample density, the grouting pressure is proportional to the grouting depth. As the pore diameter of the sample increases, the longitudinal grouting depth of the sample increases, but the transverse diffusion distance decreases. The chemical grout in the moraine is mainly split-infiltration grouting mode. The present research results can provide effective support for the prevention and control of underground debris flow in Pulang Copper Mine.

Exploration and prediction of high pressure dynamic water hidden collapse column in coal mines

Hidden collapse column associated with high pressure dynamic water is a main cause of major water inrush accidents in North China type coal fields. Taking the structural abnormality area discovered in 11603 working face of Daizhuang Coal Mine as an example, underground three-dimensional high-density electrical method, advanced exploration of underground drilling and curtain grouting were used to detect the existence of collapse column, and analyzed the water conductivity of collapse columns based on the hydraulic connection analysis of the 13th limestone and Ordovician limestone aquifers. Finally, it is determined that this abnormal area is a strong water filling collapse column originating from the upper Ordovician strata runoff zone (inferred to be within a range of 30 to 100 m below the Ordovician limestone top interface), developed to a height of 12th limestone. Based on the fact that the water yield and water pressure of underground directional drilling, the grouting pressure of curtain grouting, and the amount of cement injected are external quantitative factors that reflect the existence of hidden karst collapse columns during the process of detecting hidden karst collapse columns, and in combination with the feature that deep learning can fully independently learn abstract knowledge expression, a prediction model based on convolutional neural networks is constructed. According to the established network model, it was found that among the 12 sets of actual measurement data, only one data point indicated the absence of a collapse column. The prediction accuracy reached 91.6%, which meets the practical needs.