Identification of Mine Water Inrush Source Based on PCA-BP Neural Network

It is of great significance to analyze the chemical indexes of mine water and develop a rapid identification system of water source, which can quickly and accurately distinguish the causes of water inrush and identify the source of water inrush, so as to reduce casualties and economic losses and prevent and control water inrush disasters. Taking Ca2+, Mg2+, Na+ + K+, , , Cl-, pH value and TDS as discriminant indexes, the principal component analysis method was used to reduce the dimension of data, and the identification model of mine water inrush source based on PCA-BP neural network was established. 96 sets of data of different aquifers in Panxie mining area were selected for prediction analysis, and 20 sets of randomly selected data were tested, with an accuracy rate of 95%. The model can effectively reduce data redundancy, has a high recognition rate, and can accurately and quickly identify the water source of mine water inrush.

Study on Mechanism of Water Inrush of Karst Tunnels

Water inrush,which is one of the challenging issues and hot topics in the tunneling industry,is very easy to occur during the construction of karst tunnels.The mechanism of water inrush of karst tunnels is discussed and analyzed in the paper:the water inrush of karst tunnels is generally divided into three steps,i.e.,the forming of the hazard source,the forming of the water inrush passage and the failure of the anti-inrush rock mass.The failure of the anti-inrush rock mass of karst tunnels are classified into 5 types,i.e.,the integral tensile-shear failure,the hydraulic fracturing,the infiltration induced sliding of the filling medium,the loss of key blocks and the comprehensive water inrush mode.The failure mechanism is studied on basis of typical cases and by means of numerical simulation or theoretical analysis.Conclusion is drawn that most of the water inrushes in actual tunneling are comprehensive water inrushes,which are the comprehensive results of the interrelation and interaction of various water inrush types,and that different types of water inrushes have related continuity and progressive evolution relationships under certain conditions.

Mechanical model of water inrush from coal seam floor based on triaxial seepage experiments

In order to study the mechanism of confined water inrush from coal seam floor,the main influences on permeability in the process of triaxial seepage experiments were analyzed with methods such as laboratory experiments,theoretical analysis and mechanical model calculation.The crack extension rule and the ultimate destruction form of the rock specimens were obtained.The mechanism of water inrush was explained reasonably from mechanical point of view.The practical criterion of water inrush was put forward.The results show that the rock permeability "mutation" phenomenon reflects the differences of stress state and cracks extension rate when the rock internal crack begins to extend in large-scale.The rock ultimate destruction form is related to the rock lithology and the angle between crack and principal stress.The necessary condition of floor water inrush is that the mining pressure leads to the extension and transfixion of the crack.The sufficient condition of floor water inrush is that the confined water’s expansionary stress in normal direction and shear stress in tangential direction must be larger than the internal stress in the crack.With the two conditions satisfied at the same time,the floor water inrush accident will occur.

Hydrogeochemical Characteristics and Groundwater Inrush Source Identification for a Multi-aquifer System in a Coal Mine

Correct identification of water inrush sources is particularly important to prevent and control mine water disasters.Hydrochemical analysis,Fisher discriminant analysis,and geothermal verification analysis were used to identify and verify the water sources of the multi-aquifer groundwater system in Gubei coal mine,Anhui Province,North China.Results show that hydrochemical water types of the Cenozoic top aquifer included HCO3-Na+K-Ca,HCO3-Na+K-Mg and HCO3-Na+K,and this aquifer was easily distinguishable from other aquifers because of its low concentration of Na++K+and Cl-.The Cenozoic middle and bottom aquifers,the Permian fissure aquifer,and the Taiyuan and Ordovician limestone aquifers were mainly characterized by the Cl-Na+K and SO4-Cl-Na+K or HCO3-Cl-Na+K water types,and their hydrogeochemistries were similar.Therefore,water sources could not be identified via hydrochemical analysis.Fisher model was established based on the hydrogeochemical characteristics,and its discrimination rate was 89.19%.Fisher discrimination results were improved by combining them with the geothermal analysis results,and this combination increased the identification rate to 97.3%and reasonably explained the reasons behind two water samples misjudgments.The methods described herein are also applicable to other mines with similar geological and hydrogeological conditions in North China.

A state‑of‑the‑art review on rock seepage mechanism of water inrush disaster in coal mines

Water inrush is one of the most dangerous disasters in coal mining.Due to the large-scale mining and complicated hydrogeological conditions,thousands of deaths and huge economic losses have been caused by water inrush disasters in China.There are two main factors determining the occurrence of water inrush:water source and water-conducting pathway.Research on the formation mechanism of the water-conducting pathway is the main direction to prevent and control the water inrush,and the seepage mechanism of rock mass during the formation of the water-conducting pathway is the key for the research on the water inrush mechanism.This paper provides a state-of-the-art review of seepage mechanisms during water inrush from three aspects,i.e.,mechanisms of stress-seepage coupling,fow regime transformation and rock erosion.Through numerical methods and experimental analysis,the evolution law of stress and seepage felds in the process of water inrush is fully studied;the fuid movement characteristics under diferent fow regimes are clearly summarized;the law of particle initiation and migration in the process of water inrush is explored,and the efect of rock erosion on hydraulic and mechanical properties of the rock media is also studied.Finally,some limitations of current research are analyzed,and the suggestions for future research on water inrush are proposed in this review.

Super-absorbent swellable polymer as grouting material for treatment of karst water inrush

Grouting is the most commonly used method to control water inrush in underground engineering.Traditional cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-velocity water inrush.To address these deficiencies,a new type of polymer grouting material with an excellent expansion ratio was synthesised.The material quickly absorbs water and has an expansion ratio of 1:300.The material is composed of a superabsorbent polymer(SAP),glycerol,and ethanol.The effects of water quality on the expansion ratio and expansion rate of the material were examined,and the best solid–liquid ratio for the slurry was determined by fluidity measurements.A karst specially designed pipeline water inrush test device showed that 800 g of SAP can achieve 0.6 m/s water flow blockage in the smooth pipeline,demonstrating that the ability of the SAP slurry to block water inrush is superior to those of other materials.This study provides a reference for water inrush plugging,and has important implications for the reduction and control of karst pipeline-type water inrush disasters,ensuring the safety of construction sites and preventing loss of life and damage to property.

Construction of multi-factor identification model for real-time monitoring and early warning of mine water inrush

As a new technical means that can detect abnormal signs of water inrush in advance and give an early warning,the automatic monitoring and early warning of water inrush in mines has been widely valued in recent years.Due to the many factors affecting water inrush and the complicated water inrush mechanism,many factors close to water inrush may have precursory abnormal changes.At present,the existing monitoring and early warning system mainly uses a few monitoring indicators such as groundwater level,water influx,and temperature,and performs water inrush early warning through the abnormal change of a single factor.However,there are relatively few multi-factor comprehensive early warning identification models.Based on the analysis of the abnormal changes of precursor factors in multiple water inrush cases,11 measurable and effective indicators including groundwater flow field,hydrochemical field and temperature field are proposed.Finally,taking Hengyuan coal mine as an example,6 indicators with long-term monitoring data sequences were selected to establish a single-index hierarchical early-warning recognition model,a multi-factor linear recognition model,and a comprehensive intelligent early-warning recognition model.The results show that the correct rate of early warning can reach 95.2%.

Prevention and treatment technologies of railway tunnel water inrush and mud gushing in China

Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geological sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in extent. Furthermore, due to the different heights of mountains and the lengths of tunnels, the locations of the unfavorable geological sections cannot be fully determined before construction, which increases the risk of water inrush and mud gushing. Based on numerous cases of water inrush and mud gushing in railway tunnels, the paper tries to classify water inrush and mud gushing in railway tunnels in view of the conditions of the surrounding rocks and meteorological factors associated with tunnel excavation. In addition, the causes of water inrush and mud gushing in combination of macroand micromechanisms are summarized, and site-specifc treatment method is put forward. The treatment methods include choosing a method of advance geological forecast according to risk degrees of different sections in the tunnel, determining the items of predictions, and choosing the appropriate methods, i.e. draining-oriented method, blocking-oriented method or draining-and-blocking method. The treatment technologies of railway water inrush and mud gushing are also summarized, including energy relief and pressure relief technology, advance grouting technology, and advance jet grouting technology associated with their key technical features and applicable conditions. The results in terms of treatment methods can provide reference to the prevention and treatment of tunnel water inrush and mud gushing.

Risk assessment of fault water inrush during deep mining

With the gradual depletion of shallow coal resources,the Yanzhou mine in China will enter the lower coal seam mining phase.However,as mining depth increases,lower coal seam mining in Yanzhou is threatened by water inrush in the Benxi Formation limestone and Ordovician limestone.The existing prediction models for the water burst at the bottom of the coal seam are less accurate than expected owing to various controlling factors and their intrinsic links.By analyzing the hydrogeological exploration data of the Baodian lower seam and combining the results of the water inrush coefficient method and the Yanzhou mine pressure seepage test,an evaluation model of the seepage barrier capacity of the fault was established.The evaluation results show the water of the underlying limestone aquifer in the Baodian mine area mainly threatens the lower coal mining through the fault fracture zone.The security of mining above confined aquifer in the Baodian mine area gradually decreases from southwest to northeast.By comparing the water inrush coefficient method and the evaluation model of fault impermeability,the results show the evaluation model based on seepage barrier conditions is closer to the actual situation when analyzing the water breakout situation at the working face.

Treatment Design and Construction Strategy for Tunnel Mud and Water Inrush Disaster

With the rapid development of the transportation industry in China,the number and scale of tunnel construction are increasing.Tunneling through fault zones and other complex geological environments is becoming more and more common.In the construction of highway tunnels,due to the special geographical environment and complex geological conditions,mud and water inrush often occur in the tunnel.Water inrush disasters pose a major risk to the construction of highway tunnels and affect the normal construction of highway tunnels.This paper combines the engineering background of the tunnel mud and water inrush accidents,carries out evaluation on the accident treatment measures and the treatment efficiency,and summarizes the main concerns in the construction process and the technical guidelines for dealing with the tunnel mud and water inrush.

Influential factors and control of water inrush in a coal seam as the main aquifer

In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme. On the basis of revealing and analyzing the coal seam as the main aquifer in western coal mine of Xiao Jihan coal mine, the simulation software of PHASE-2D was applied to analyze the water inflow under different influencing factors. The results showed that water inflow increases logarithmically with the coal seam thickness, increases as a power function with the permeability coefficient of the coal seam, and increases linearly with the coal seam burial depth and the head pressure; The evaluation model for the factors of coal seam water inrush was gained by using nonlinear regression analysis with SPSS. The mine water inrush risk evaluation partition within the scope of the mining field was obtained,through the engineering application in Xiao Jihan coal mine. To ensure the safe and efficient production of the mine, we studied the coal mine water disaster prevention and control measures of a main aquifer coal seam in aspects of roadway driving and coal seam mining.

Analysis of insidious fault activation and water inrush from the mining floor

Based on the stress field distribution rule of the mining floor under abutment pressure, we have established a simplified mechanical model, which contains multiple factors relating to activation and evolution of insidious water-conductive faults. The influence of normal and shear stresses on fault activation and effective shear stress distribution in the fault plane was acquired under mining conditions.Using fracture mechanics theory to calculate the stress intensity factor of an insidious fault front, we have derived the criterion for main fault activation. Results indicate that during the whole working face advance, transpressions are exerted on fault planes twice successively in opposite directions. In most cases, the second transpression is more likely to lead to fault activation. Activation is influenced by many factors, predominant among which are: burial depth of the insidious fault, friction angle of the fault plane, face advance direction and pore water pressure. Steep fault planes are more easily activated to induce a sustained water inrush in the face.

Numerical analysis of water inrush from working-face floor during mining

Confined water in the Ordovician limestone is one of the hidden troubles that threaten safe production of mines in north China. A numerical model of the key strata was developed. It included the structural characteristics and mechanical properties of the floor rock at the working face of a particular coal mine. The model was used to predict failure modes and to help establish rules for safe mining above the aquifer. The distribution of deformation, failure and seepage was simulated by using Dilian Mechsoft's Real- istic Failure Process Analysis (RFPA2D) program. The stress distribution, the deformation and the flow vectors were also obtained. The results indicate that: 1) The original balance of the stress and seepage fields is disturbed due to coal mining; and 2) As the working face advances different deformation, or failure, appears in the surrounding rocks, the water-resisting strata in floor may be destroyed and the passage of water from the aquifer into the mine may occur. The combined action of mining stress and water pressure ultimately lead to water inrush from the floor.

Formation mechanisms of water inrush and mud burst in a migmatite tunnel：a case study in China

This paper presents a case study of water inrush and mud burst occurring in a migmatite tunnel to study its formation mechanisms. The geological investigation and mineralogical analysis showed that water inrush and mud burst in the migmatite was closely related to the component of the host rock. High content of soluble minerals,e.g.,calcite and dolomite,would make the migmatite rock prone to be fragmentized,isintegrated and eventually form different sorts of connected or semi-connected veins. The field exploration revealed most cavities in the magmatite tunnel were eroded by groundwater and formed large interconnected networks. The two faults and the dike in the magmatite tunnel became the preferred paths and provided great convenience for plenty of precipitation and mud slurry. Due to high water pressure and blast disturbance,the cavities can soon connect each other as well as all sorts of veins,forming a complex ground channel for water inrush and mud burst. To estimate the potential occurrenceof water inrush and mud burst,the water bursting coefficient was employed. The results showed the water bursting coefficient of the magmatite tunnel was much bigger than the threshold values and it can be used to explain the accident of water inrush and mud burst occurring in the magmatite tunnel.

Water inrush evaluation of coal seam floor by integrating the water inrush coefficient and the information of water abundance

The method of singular coefficient of water inrush to achieve safety mining has limitation and one sidedness. Aiming at the problem above, large amounts of data about water inrush were collected. Then the data, including the maximum water inrush, water inrush coefficient and water abundance in aquifers of working face, were processed by the statistical analysis. The analysis results indicate that both water inrush coefficient and water abundance in aquifers should be taken into consideration when evaluating the danger of water inrush from coal seam floor. The prediction model of safe-mining evaluation grade was built by using the support vector machine, and the result shows that this model has high classification accuracy. A feasible classification system of water-inrush safety evaluation can be got by using the data visualization method which makes the implicit support vector machine models explicit.

MECHANISM ON PROGRESSIVE INTRUSION OF PRESSURE WATER UNDER COAL SEAMS INTO PROTECTIVE AQUICLUDE AND ITS APPLICATION IN PREDICTION OF WATER INRUSH

This article proposes a water inrush mechanism of progressive intrusion of pressure water up into the coal floor aquiclude according to injection tests and observations. A numerical model and a criterion of water inrush are established based on the mechanism. The theory is succesSfully used in predictions of water inrush.

Analysis and control on anomaly water inrush in roof of fully-mechanized mining field

从水流入的矿房顶的探穴由于异常压力是能在生产期间发生在矿的主要灾难和事故之一。房顶水流入能触发大量房顶倒塌，引起从打破房顶支持的主要事故当时探穴。这些失败充满井并且做很多损坏到矿并且危及矿安全。我们的目的到在工作的 #6301 压碎支持的水流入的异例在 Yanzhou 采矿组的 Jisan 煤矿面对的分析。通过到房顶的水流入的信息，损坏由构造运动引起了，损坏的信息在矿桥墩关于压力的分发由房顶倒塌和理论引起了，我们调整工作的脸的长度和打开离开的位置的忠告相对切了到富有的水区域。在异常房顶压力的情况中，我们应该开发一个州的方程估计有鈥渢r ansferring 的预防措施摇横梁鈥 ? 理论。同时，我们在宝库改进排水设备和保证的足够的水保留的能力。这些都是主要技术对异常的水流入在房顶引起的事故保证控制和预防，因此在一个煤矿的生产过程保证安全。

Relationship between water inrush from coal seam floors and main roof weighting

A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.