Mud Inrush Research Articles

Retraction Note: A hybrid DEM+SPH coupling method and its application in modeling water and mud inrush disasters

Retraction Note: A hybrid DEM+SPH coupling method and its application in modeling water and mud inrush disasters

Failure mechanism analysis for tunnel construction crossing the water-rich dense fracture zones: A case study

For deep tunnel crossing the fracture zones with water-rich strongly weathered granite, water inrush and collapse disasters occur frequently. Based on a high-risk tunnel under construction, this research tests and analyzes the engineering properties and the spatial distribution characteristics of unfavorable geological structures through the innovative comprehensive unfavorable geological exploration technology composed of UAV with lidar-high power geophysical prospecting technology-TSP advances geological prediction test. Then the space–time evolution law of tunnel vault settlement is analyzed and the exploration results of unfavorable geology is checked out based on the tunnel field test. Then, the fluid–solid coupling numerical calculation model for deep-buried tunnel crossing the densely distributed fracture zones with rich water by three benches seven steps method is established. It is found, under the influence of coupling disturbance of multiple fracture zones, the plastic zone area of the surrounding rock increases sharply, which is 4–5 times of the plastic zone area in the stable tunnel sections. And the pore water pressure in the surrounding rock will fluctuate more significantly when crossing the fracture zone with the larger mileage stake number (the larger the serial number), the pore water in the surrounding rock will flow more rapidly, and high-pressure pore water in the rock mass at the far end is more likely to converges into the tunnel arch foot and the lower part. Compared with other excavation parts, tunnel upper bench and tunnel face will become the main water gushing positions during tunnel construction, which are the best positions for the tunnel directional advance drainage. Advance small conduits grouting shall be carried out at the tunnel vault, and secondary grouting shall be carried out at the tunnel vault, and accurate grouting shall be carried out at the tunnel arch foot and the lower position, which can effectively reduce the occurrence of tunnel disasters such as tunnel collapse, mud inrush and water inrush.

Experimental Study on the Mechanism of Intermittent Water and Mud Inrush Caused by Dredging and Rainfall Considering Sedimentary Characteristics in Karst Tunnels

The mechanism of intermittent water and mud inrush is a difficult problem faced by disaster prevention and safe construction in karst tunnels. Aiming at revealing the mechanism of intermittent water and mud inrush, we developed an integrated testing system for filling medium deposition in karst caves and intermittent water and mud inrush. By conducting a serial of laboratory experiments, we analyzed the sedimentary characteristics of the filling medium in karst caves and the catastrophic process of intermittent water and mud inrush induced by dredging and rainfall under realistic sedimentary conditions. The results show that the filling medium exhibits layered deposition characteristics, which are affected by the water circulation time, the amount of sediments carried by water and the water flow rate. The first inrush incubation time reduces with the water head increases. The critical water head and the disaster incubation time increase with the deposition height increases. Under the same conditions, the first inrush incubation time of gravel type, silt type, and clay type filling medium decrease sequentially. The results can provide a theoretical basis for preventing intermittent water and mud inrush disasters in karst tunnels.

Study on the Safety Thickness of Rock Strata for Outburst Prevention in Deep Tunnel Based on Numerical Modeling and Backpropagation Neural Network

Water inrush and mud inrush pose a serious threat to safe construction in underground engineering, but it is very difficult to determine the safe distance of outburst prevention rock mass. Based on deep-buried tunnel engineering, this paper proposes a method to determine the safe distance from water inrush disaster between the tunnel and the fault fracture zone. This method combines numerical modeling and backpropagation (BP) neural network. By means of numerical simulation, the internal influence law of the water pressure, lateral pressure coefficient, fault fracture zone width, and tunnel burial depth on the surrounding rock is analyzed. The evolution law of the minimum safe strata thickness under a single variable and the correlation degree between minimum safe strata thickness and various disaster factors are revealed. Based on the BP neural network analysis of the simulation results and the measured data of Wulaofeng Tunnel, the calculated values of safe strata thicknesses of fault fracture zone (F10) were determined. The results show that the thickness of the safe rock strata increases with increasing water pressure, lateral pressure coefficient, fault fracture zone width, and tunnel burial depth. The minimum safe thickness of F10 of the tunnel ranges from 7.1 m to 7.4 m, and 10 m is reserved in the actual project. The calculated results are consistent with the reserved thickness value in the construction. This conclusion can provide a reference for similar projects.

Identification and Treatment of Collapse and Mud Inrush Caused by Deep Karst Trough in Tunnels

To predict and prevent the collapse and mud inrush caused by the deep karst trough in tunnels, an engineering case is studied. Firstly, a comprehensive identification method for the hazard-causing structure of the deep karst trough in tunnels is proposed and successfully applied. Secondly, the morphological characteristics and developmental mechanism of the deep karst trough are studied. The hazard-causing structure is mainly developed at the entrance section of the karst tunnel, which is funnel-shaped, mostly filled with clay and a small amount of gravel. The development scale is affected by the geological structure, tectonic movement, formation lithology and inclination, sunshine and precipitation, and surface soil. Thirdly, four hazard-causing modes of the collapse and mud inrush are proposed, i.e., rock mass failure of tunnel face, direct exposure of tunnel face, direct exposure of tunnel roof, and rock mass failure of tunnel roof. Finally, a treatment technology for collapse and mud inrush is put forward. The treatment technology is to “remove the mud, fill the karst cave, conduct advance grouting, strengthen the support, waterproof the collapse area, backfill the collapse pit.” The collapse and mud inrush of Qiyueshan Tunnel was successfully treated by using the above technology.

Characterisation of Fine Particles Generated at Draw points During Sub-Level Cave Mining for Assessment of Mud Inrush Hazard

The inundation of mud, known in the industry as ‘mud inrush’ is a hazard associated with caving mining methods. Ineffective inrush management strategies can result in sections of the mine lost, or in some cases, fatalities. Previous studies have focused on water and various percentages of fines (particles <2mm - <5cm) in draw points as risk indicators for the hazard. Standardised material tests were conducted on samples collected from a sub-level caving operation in Australia. Concrete slump tests were carried out on two in-situ mud samples based on their observed mobility. The immobile sample had 6% more material below 300μm and required a 2% higher moisture content to begin slumping and turn from plastic to soft flow. Shear strength tests reflected the higher plasticity of the immobile sample with a cohesive strength of 23.08 kPa compared to the second mobile sample of 9.16 kPa. The elemental assay revealed the mobile sample had lower iron oxide, and higher silicon oxide content than the immobile sample. The work presented in this paper indicates that fine fractions <0.6mm noticeably affect laboratory test results that are hypothesised to relate mud flowability and potential hazard.

RETRACTED ARTICLE: A hybrid DEM+SPH coupling method and its application in modeling water and mud inrush disasters

RETRACTED ARTICLE: A hybrid DEM+SPH coupling method and its application in modeling water and mud inrush disasters

Numerical simulation of the fluid-solid coupling mechanism of water and mud inrush in a water-rich fault tunnel

This study developed a new model, a 3D coupled computational fluid dynamics (CFD)-discrete element method (DEM) model, by coupling two software programs, ABAQUS and PFC3D, to solve problems related to fluid-solid interaction systems. The complete governing equations and the two-way coupling process between the two software are presented herein. Via Transmission Control Protocol (TCP) socket communication with Python scripting, information between the two software is exchanged in real-time. Then, the classic example in the PFC5.0 documentation was used to verify the model. In the end, the ABAQUS-PFC3D model was employed to simulate the process of water and mud inrush in a water-rich fault tunnel, which could reflect the evolution process of water and mud inrush and track particle movement in a fault zone. The results show that the particles that collapsed inside the fault formed an ellipsoidal distribution during the water and mud inrush in a water-rich fault tunnel. With the continuous loss of particles in the fault into the tunnel, the migration of particles is discontinuous, and a large void appears inside the fault zone. The rapid change of the groundwater flow velocity caused the negative pore pressure. The pressure arch force structure is formed above the ellipsoidal collapse area inside the fault. The principal force field of the fault areas changes from close to the dip of the fault to close to the perpendicular to the fault.

Research on the Safety Thickness of Tunnel Outburst Prevention in Water-Rich Fault Fracture Zone Based on Janssen’s Theory

In the construction of tunnel in water-rich fault fracture zone, when the thickness of outburst prevention is insufficient, it is very easy to cause water and mud inrush engineering accident. Therefore, it is very necessary to study the safety thickness of outburst prevention for this type of tunnel. In this paper, the expression of in situ stress in water-rich fault fracture zone is derived based on Janssen’s theory. Two mechanical models of outburst prevention rock mass are established, and according to the shear balance theory, the calculation formula for the safe thickness of outburst prevention is determined and the parameter sensitivity analysis is carried out. Finally, it is verified by engineering examples and numerical simulation. The results show that: (1) the calculation formula of outburst prevention thickness proposed in this paper is more perfect and shows good prediction effect for deep- and shallow-buried tunnels; (2) the greater the angle α between tunnel axis and fault zone and the dip θ of fault fracture zone, the smaller the critical safety thickness of outburst prevention and the safer it is for tunnel construction; (3) when the fault fracture zone inclines inward relative to the tunnel face, the gravity of the rock mass in the fault zone will lead to an increase in the safety thickness of outburst prevention, and reinforcement measures should be taken during actual construction.

Prevention of water and mud inrush in longwall top coal cave mining under shallow buried thin bedrock

Prevention of water and mud inrush in longwall top coal cave mining under shallow buried thin bedrock

Study on the Microscopic Mechanism of Grouting in Saturated Water-Bearing Sand Stratum Based on VOF-DEM Method

During the construction of tunnels in saturated water-bearing sand stratum, water and mud inrush disasters often occur. Grouting is the most convenient and effective method to improve the mechanical properties of the soil and prevent groundwater seepage. The reasonableness of the Discrete Element Method (DEM) contact parameters is verified by comparing the repose angle test with that obtained by simulations. The grouting model of saturated water-bearing sand stratum was established based on the Volume of Fluid-Discrete Element Method (VOF-DEM). Then, the effects of sand stratum porosity and grouting pressure on grouting were discussed. The results show that (1) in dense sands, the permeation diffusion of the slurry dominates, whereas in loose sands, the compaction zone is well developed. (2) Loose sand has a wider propagation of stress and dense sand has a larger increase in the stress state. (3) In loose sand the slurry diffusion is significantly affected by gravity, whereas in dense sand the slurry diffusion along the dominant path of the grouting pipe wall boundary is obvious. (4) The range of slurry diffusion and compaction zone is positively related to the porosity and grouting pressure. (5) In loose sand with grouting pressure below 200 kPa, no compaction diffusion occurs during the grouting process, whereas in dense sand, when the grouting pressure is below 500 kPa no compaction diffusion occurs during the grouting process.

Investigation on the evolution mechanism of water and mud inrush disaster in fractured rock mass of mountain tunnel

Water inrush is one of the major disasters during tunnel construction. Due to its characteristics of great harm and difficult prediction, it has always been the focus of research. In order to reveal the mechanism of fault water inrush, a laboratory experiment is adopted to simulate tunnel excavation. The results show, firstly, the pore water pressure and soil pressure of model are unchanged before the fault is exposed; after the fault is exposed, the pore water pressure and soil pressure of vault decrease first, followed by the arch and haunch, and the decline of arch and vault is greater than that of haunch. Secondly, excavation has the greatest impact on the displacement of rock mass directly above the tunnel axis, and the farther away from the axis, the smaller the impact. Thirdly, the seepage channel around vault begins to expand, and clear water begins to seep out after the fault exposure. As the sediment in the crack is carried out by water flow, the clear water gradually becomes turbid, seepage channel changes from pore flow to fissure flow and then to pipe flow. Finally, Comsol is used to analyze the fault water inrush mechanism from the perspective of permeability change, and the correctness of model test is verified by comparing with engineering practice.

Development of Similar Materials for Liquid-Solid Coupling and Its Application in Water Outburst and Mud Outburst Model Test of Deep Tunnel

In order to explore the evolution mechanism of water and mud inrush, based on the fluid-solid coupling similarity theory and a large number of matching tests, fault similar materials with mountain sand, gravel, and red clay as raw materials and surrounding similar rock materials with mountain sand, red clay, cement, and water as raw materials are developed. Similar materials’ physical and mechanical properties and hydraulic properties with different ratios are tested and analyzed. The results show that the red clay content influences the mechanical properties of similar materials and their hydraulic properties, and the gravel substrate mainly influences the fault permeability coefficient. Similar material can be adjusted within a certain range of mechanical parameters. The material is simple and suitable for developing similar materials for different low and medium strength rock masses. Finally, a similar material was used in a model test of the tunnel fault fracture zone to reveal the mechanism of water and mud bursts in the tunnel. The study results can be used as a reference for the development of similar materials for tunnel fracture zone surrounding rocks.

Causes of Tunnel Diseases in a Karst Stratum and Remediation Measures: A Case Study

Highway tunnels operated in karst areas are prone to serious structural diseases such as water–mud inrush, lining tension and cracks, and road humps. This article reviews the historical diseases of the tunnel based on the Nanshibi Tunnel project. The cause analysis of the structural diseases of Nanshibi Tunnel was performed on the basis of a refined geophysical prospecting scheme for the complex karst geological structure environment. A series of comprehensive treatments were conducted to address the tunnel diseases in the karst area. The treatments included surrounding rock grouting, lining replacement, and adding inverted arches. The results show that the refined geophysical prospecting scheme and disease remediation idea for the complex karst geological structure environment proposed herein can realize the full coverage and accurate detection of karst structures, water passage, and tunnel-lining diseases. The proposed scheme can effectively solve the technical problems of karst tunnel diseases that occur repeatedly and are difficult to be completely rectified. Finally, specific engineering practice suggestions were proposed for tunnel disease remediation in the karst area.

Evolution and modeling of mine water inflow and hazard characteristics in southern coalfields of China: A case of Meitanba mine

In this paper, the hydrogeological characteristics in the southern coalfields of China are first briefly outlined. Then, taking the Meitanba mine as an example, the evolution and modeling of mine water inflow are studied. Finally, the hazard characteristics related to mine water and mud inrush are analyzed. The results show that the main mine water sources in the Meitanba mine area are groundwater, surface water and precipitation. The evolution of mine water inflow with time indicates that the water inflow is closely related to the development of karst structures, the amount of water from rainfall infiltration, and the scope of groundwater depression cone. The mine water inflow increases with time due to the increase in mining depth and the expansion of groundwater depression cone. Using the big well method and following the potential superposition principle, a hydrogeological model considering multi-well interactions has been developed to predict the mine water inflow. Based on the monitored data in the Meitanba mine area over a period of nearly 60 years, it is found that with increasing mining depth, the number of water and mud inrush points tended to decrease. However, the average water and mud flow rate per point tended to increase.

Shear Properties of Grout-Rock Interface for Treatment of Mud Inrush

Shear Properties of Grout-Rock Interface for Treatment of Mud Inrush

Disaster Risk Evaluation of Superlong Highways Tunnel Based on the Cloud and AHP Model

Comprehensive evaluation of the geological disaster risk of super long tunnels is significant for safety construction. In this paper, we establish a comprehensive evaluation system based on the cloud model and analytic hierarchy process (AHP) theory, considering four kinds of geological hazards, such as water and mud inrush, large deformation, rock burst, and collapse. Then, based on a super long highway tunnel of the Chizhou‐Qimen expressway in China, the construction risk evaluation is carried out. The results show that the evaluation system can accurately judge the disaster risk level of the tunnel under different conditions surrounding a rock. The cloud model theory can realize the mutual transformation of qualitative indicators and quantitative indicators and avoid the problem of intense subjectivity of evaluation indicators. The evaluation system can be used as a new approach to evaluate tunnel risks in similar projects.

DEM-CFD investigation on the effects of angularity and roughness on the mass loss of soil rock mixtures

The migration of soil rock mixture (SRM) in filling is a widespread problem in the research of water and mud inrush. Therefore, the discrete element method coupled with computational fluid dynamics (DEM-CFD) was used to simulate particle migration of SRM materials. In this work, a 3D random mesostructure modelling system of SRM materials was developed and used to generate SRM materials with different angularity. Based on the governing equations of particle migration and fluid flow, numerical simulation is carried out to characterise the variable mass loss of SRM materials with various angularity and roughness. The results demonstrate that the development and production of secondary development of particle loss would be inhibited when the angularity of rock is more than 0.110, and the loss characteristics of SRM materials which has less than 0.110 angularity would tend to be that with non-angular rock. It can be also found that the smaller the rock or soil roughness, the earlier the start time of the secondary particle loss, the longer the duration of secondary particle loss and the greater the loss quality induced by secondary water inrush. The settlement of SRM materials is positively correlated with the particle mass loss. Moreover, the feasibility and rationality of the model are validated by comparing the experimental results with numerical results. This work provides a valuable reference to study the particle migration of SRM materials during water inrush in tunnel engineering.

Prediction of water–mud inrush hazard from weathered granite tunnel by an improved seepage erosion model

Prediction of water–mud inrush hazard from weathered granite tunnel by an improved seepage erosion model

Smart Risk Assessment Model of Water Inrush in Submarine Tunnel through AHP-TOPSIS and Intelligent Computing

In tunnel construction, water and mud inrush disasters are prone to occur when the tunnel traverses water-rich faults, which leads to structural damage and tunnel instability, which is one of the most severe hazards in tunnel excavation and construction. This paper proposes a method of combining AHP and TOPSIS. The weights are determined through the analytic hierarchy process utilizing expert scoring. The determined weights are evaluated and predicted by TOPSIS for water inrush risk. The Jiaozhou Bay Subsea Tunnel is used as a case to carry out the tunnel crossing the fault zone. Water inrush risk prediction provides a new idea for water inrush risk prediction.