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.

RESEARCH ON DEEP COAL SEAM MINING FLOOR STARTA WATER BURSTING INFLUENCED FACTORS BASED ON ANALYTIC HIERACHY PROCESS

Deep coal seam mining floor strata water bursting is a complicate nonlinear system, whose factors are coupling and influencing themselves. It built the analytic structure model for deep coal seam mining floor strata water bursting, the judgment matrix was found by the expert scoring method, the contribution weights of the influenced factors were given out by the equation analytic process. The thirteen controlling factors and five main controlling factors were put award by analyzing weights, so the result was basically conform to the field practice. The expert scoring method and analytic process can convert the objective fact to the subjective cognition, so it is a method that can turn the qualitative into the quantitative. This can be relative objectively and precisely to study the question of many factors and grey box.

Application of high-pressure water jet technology and the theory of rock burst control in roadway

This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.

Catastrophe theory-based risk evaluation model for water and mud inrush and its application in karst tunnels

This paper presents a risk evaluation model of water and mud inrush for tunnel excavation in karst areas.The factors affecting the probabilities of water and mud inrush in karst tunnels are investigated to define the dangerousness of this geological disaster.The losses that are caused by water and mud inrush are taken into consideration to account for its harmfulness.Then a risk evaluation model based on the dangerousness-harmfulness evaluation indicator system is constructed,which is more convincing in comparison with the traditional methods.The catastrophe theory is used to evaluate the risk level of water and mud inrush and it has great advantage in handling problems involving discontinuous catastrophe processes.To validate the proposed approach,the Qiyueshan tunnel of Yichang-Wanzhou Railway is taken as an example in which four target segments are evaluated using the risk evaluation model.Finally,the evaluation results are compared with the excavation data,which shows that the risk levels predicted by the proposed approach are in good agreements with that observed in engineering.In conclusion,the catastrophe theory-based risk evaluation model is an efficient and effective approach for water and mud inrush in karst tunnels.

Protection against water or mud inrush in tunnels by grouting:A review

Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering. In this paper, the current situation of control and prevention of water and mud inrush is summarized and recent advances in relevant theories, grout/equipment, and critical techniques are introduced. The time-variant equations of grout viscosity at different volumetric ratios were obtained based on the constitutive relation of typical fast curing grouts. A large-scale dynamic grouting model testing system （4000 mm × 2000 mm × 5 mm） was developed, and the diffusions of cement and fast curing grouts in dynamic water grouting were investigated. The results reveal that the diffusions of cement grouts and fast curing grouts are U-shaped and asymmetric elliptical, respectively. A multi-parameter real-time monitoring system （＆#981; = 1.5 m, h = 1.2 m） was developed for the grouting process to study the diffusion and reinforcement mechanism of grouting in water-rich faulted zone. A high early strength cream-type reinforcing/plugging grout, a high permeability nano-scale silica gel grout, and a high-expansion filling grout were proposed for the control of water hazards in weak water-rich faulted zone rocks, water inrush in karst passages, and micro-crack water inrush, respectively. Complement technologies and equipment for industrial applications were also proposed. Additionally, a novel full-life periodic dynamic water grouting with the critical grouting borehole as the core was proposed. The key techniques for the control of water inrush in water-rich faulted zone, jointed fissures and karst passages, and micro-crack water inrush were developed.

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.

Provenance analysis of surface sediments in the Holocene mud area of the southern coastal waters off Shandong Peninsula,China

The sedimentary record of mud areas is an important carrier of information on the Holocene evolution of marine environments. Based on fine interpretations of the shallow stratigraphic section data, a small mud deposit area has been found in the southern coastal waters off Shandong Peninsula. This mud area is mainly distributed in coastal waters north of Laoshantou to the vicinity of Rushan Estuary. Overall, it is parallel to the coastline and spreads in a banded pattern, gradually thinning from offshore to the sea. The isopach map of depth distribution is parallel with the shoreline, and the depocenter lies in coastal waters of the Aoshan Bay where the maximum thickness is up to 22.5 m. Accelerator mass spectrometry（AMS） ^（14）C dating shows that the mud area was formed in the Holocene. The test data of surface sediments from the mud area, including particle size, mineral characteristics, and rare earth element contents, are used in comparisons with the composition of materials from the major surrounding medium and small rivers flowing into the sea and the Huanghe（Yellow） River. In this paper, the sedimentary characteristics and provenance of the mud deposit area are discussed. The results show that the formation of this mud area resulted from the joint action of the Huanghe River and surrounding rivers flowing into the sea.

Numerical Modeling of Water Wave Interaction with A Soft Mud Bed

A vertical 2-D numerical model is presented for simulating the interaction between water waves and a soft mud bed. Taking into account nonlinear rheology, a semi-empirical rheological model is applied to this water-mud model, reflecting the combined visco-elasto-plastic properties of soft mud under such oscillatory external forces as water waves. In order to increase the resolution of the flow in the neighborhood of both sides of the inter-surface, a logarithmic grid in the vertical direction is employed for numerical treatment. Model verifications are given through comparisons between the calculated and the measured mud mass transport velocities as well as wave height changes.

Cr （Ⅲ） Removal from Synthetic Waste Water by Using Water Pond Mud

The pollution of aquatic ecosystem by heavy metals has assumed serious proportions due to their toxicity and accumulative behavior. The toxicity metal is dependent on its chemical form and therefore removal of metal is more meaningful than the estimation of its concentrations. In this study, the batch experiments were carried out under 30℃ to study the effect of pH, initial Cr concentration, adsorbent dose and contact time on the removal of Cr （lII）. The maximum adsorption efficiency （99%） was observed when 1.5 g of pond mud was used for removal ofCr （Ⅲ） from test solution containing 150 mg·Cr / 100 ml. The optimal pH and contact time recorded during the study were 6 and 10.0, respectively.

The sensitivity of the array resistivity log to mud filtrate invasion and its primary five-parameter inversion for improved oil water recognition

In order to improve reservoir fluid recognition, the sensitivity of array resistivity response to the difference of the invasion properties in both oil-bearing layers and water layers is analyzed. Then the primary inversion is carried out based on the array resistivity log. The mud invasion process is numerically simulated based on the oil-water flow equation and water convection diffusion equation. The results show that the radial resistivity of a fresh mud-invaded oil-bearing layer presents complex distribution characteristics, such as nonlinear increase, increasing to decreasing and low resistivity annulus, and the resistive invasion profile of a water layer is monotonic. Under specific conditions, array resistivity log can reflect these changes and the array induction log is more sensitive. Nevertheless, due to the effect of factors like large invasion depth, reservoir physical and oil-bearing properties, the measured apparent resistivity may differ greatly from the actual mud filtrate invasion profile in an oil-bearing layer. We proposed a five-parameter formation model to simulate the complex resistivity distribution of fresh mud-invaded formation. Then, based on the principle of non-linear least squares, the measured array resistivity log is used for inversion with the Marquardt method. It is demonstrated that the inverted resistivity is typically non-monotonic in oil-bearing layers and is monotonic in water layers. Processing of some field data shows that this is helpful in achieving efficient reservoir fluid recognition.

Thermo-Mechanical Analysis of Water-Cooled Gun Barrel During Burst Firing

The thermo-mechanical stress and deformation of water-cooled gun barrel during burst firing are studied by finite element analysis (FEA). The problem is modeled in two steps: 1) A transient heat transfer analysis is first carried out in order to determine temperature evolution and to predict the residual temperatures during the burst firing event; 2) The thermo-mecha- nical stresses and deformation caused by both the residual temperature field and the gas pressure are then calculated. The results show that the residual temperature field tends to a steady state with the increasing of rounds. The residual temperature field has much effect on the gun barrel stress and deformation, especially on the assembly area between barrel and water jacket. The gage between the barrel and water jacket is the critical factor to the thermo- mechanical stress and deformation. The results of this analysis will be very useful to develop the new strength design theory of the liquid-cooled gun barrel.

Structural mechanism and construction method of mud and water inrush in Xiangyun tunnel of Guangtong-Dali railway

Mud and water inrush in tunnel is a common problem in the construction process. Nowadays, the research and classification on this are mostly focused on karst situations. According to the characteristics of the surrounding rock and damage forms of the tunnel in the studied area, the author analyzed the geological and structural characteristics of mud and water inrush in tunnel and obtained their construction type. Meanwhile, the advanced water detection under the complex geological conditions was studied by using induced polarization method, transient electromagnetic method and three-dimensional seismic method, it can be concluded that the water-rich fracture zone exists within the detection range with a risk of large mud and water inrush disaster. The concrete construction treatment measures are put forward:①cement-water glass binary slurry is selected as the material for ground and hole grouting, its advantage is that the gel time can be controlled, and it has certain grout ability in the strata with large permeability coeffcient, which is conducive to excavate construction immediately after grouting.②applying the mature retrograde grouting construction can reduce grouting time and improve the excavation efficiency.

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.

Physical and chemical changes of water in the deep interior of the Earth―Decrepitation-style mud-volcano-earthquake―A bright lamp to shed light on the mysteries of the deep interior of the Earth

The 2008-05-12 Wenchuan mud-volcano-earthquake was accompanied with eruption of a huge volume of gas and stone,revealing that earthquakes generally result from instant reverse phase explosion of supercritical water(SCW) at the supercritical point.In the deep parts of the crust and mantle there still exists a large amount of supercritical water equivalent in order of magnitude to that of the Earth's hydrosphere.Soft fluids which exist in the MOHO at the top of the upper mantle are the so-called deep supercritical fluids(SCWD).Supercritical water(SCW) has n×103 times strong capability to dissolve gas.Its viscosity is extremely low and its diffusivity is extremely strong.Therefore,it can naturally migrate toward a region with relatively negative pressure.In the steep break zone of the MOHO at the 57-65 km depth beneath the earthquake belt,due to mutation of overburden pressure,SCWD can automatically separate out CaSiO3 and other inorganic salts,evolving into the SCW(H2O-CO2-CH4O system.In going upwards to the 10-20-km depth of the crust SCW will be accumulated as an earthquake-pregnant reservoir in the broken terrain.The phase-transition heat of SCW is estimated at 606.62 kJ/kg and the reverse phasing kinetic energy is 2350.8 kJ/kg.When automatic exhaust at the time of decompression reaches the critical pressure(Pc),the instant explosion reverse phase will be normal-state air water.It will release a huge volume of energy and high-kinetic-energy gas which has been expanded by a factor of 1000,leading to the breaking of the country rocks overlying the earthquake-pregnant reservoir,thus giving rise to a Ms 8.0 earthquake.As a result,there were formed eruptive and air-driven(pneumatic) debris flows whose volumatric flow rate reaches n×1014 m3/s,and their force greatly exceeds the power of INT explosive of the same equivalent value.

Removal of cadmium from aqueous solutions using red mud granulated with cement

A novel adsorbent was prepared from granular red mud mixed with cement and its potential to be a suitable adsorbent for the removal of cadmium ions from aqueous solutions was evaluated. The wet red mud was directly mixed up with cement at different mass fractions of 2%-8% and their properties were investigated. Based on the textural characteristics and strength, the granular red mud with 2% addition of cement maintaining for 6 d is identified to have better properties. The batch adsorption experiments for adsorption of Cd2+ ions from solution were performed at 30, 40 and 50 °C at different initial concentrations under the condition of constant pH of 6.5. The equilibrium adsorption was found to increase with the increase of temperature during the adsorption process. Langmuir adsorption isotherm model was found to match the experimental adsorption isotherm better. The kinetics of adsorption was modeled using a pseudo second order kinetic model and the model parameters were estimated.

Early-warning of Mud Expansion in Sewage Treatment Plants by A/O Technology

Early-warning is an effective way to control mud expansion in sewage treatment plants with A/O technology. In the research, warning indices and technology of active mud were explored and it is concluded that bacteria growth in mud can be obtained by observation of mud appearance and microorganism variety, and measurement of the number of filamentous bacteria, water quality, mud load and age, dissolved oxygen, temperature and pH. Furthermore, filamentous bacteria in mud can be researched through fluorescence in situ hybridization, PCR-temperature denaturing gradient gel electrophoresis and PCR-single-stranded conformation polymorphism in order to determine the characters and states of active mud to achieve early warning of mud expansion.

基于WaterGEMS的供水管网建模及爆管分析研究

利用WaterGEMS建模软件及某市高新区自来水公司收集到相关数据,研究分析城市供水管网爆管事故,利用黄金分割法研究漏失水量,通过建模与计算机技术相结合进行动态分析,比较建立管网微观模型能够较好预测出供水管网发生爆管事故位置及漏失水量.

THE WAVE ATTENUATION ON THE MUD BED

In the paper the wave attenuation in a two layer fluid system is studied.The fluid in the top layer is ideal and that in the lower layer is the Voigt model of the viscoelastic medium.A dispersion relation is derived and the rate of the wave decay is computed.The approximate explicit expressions of the decay rate for different water depth are given,where the viscoelasticity is either very large or very small.Compared with the numerical results,our results are very accurate,which can be used by an engineer.

Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.

Experimental and numerical investigation on failure characteristics and mechanism of coal with different water contents

Water injection, as a widely used technique to prevent coal burst, can restrain the fractured coal seam and released the energy storage. In this study, laboratory tests were frstly carried out on standard coal specimens with fve diferent water contents (i.e., 0%, 0.6%, 1.08%, 1.5%, 2.0%, and 2.3%). The failure mode, fragment size, and energy distribution characteristics of coal specimens were investigated. Experimental results show that strength, elastic strain energy, dissipated energy, brittleness index, as well as impact energy index decrease with increasing water content. Besides, the failure mode transitions gradually from splitting ejection to tensile-shear mixed failure mode as water content increases, and average fragment size shows positively related to water content. Moreover, scanning electron microscope tests results indicate that water in coal sample mainly causes the mineral softening and defects increase. Furthermore, a numerical model containing roadway excavation was established considering the water on coal burst prevention. Modelling results revealed that water injection can reduce degree of coal burst and ejection velocity of coal blocks, while it will raise up the depth of crack zone and surface displacement of roadway. Combined with laboratory tests and numerical results, the micro mechanism, energy mechanism, and engineering signifcance of water injection on coal burst prevention were fnally analyzed.