Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a num...Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a numerical percolation model of random fractured rock of a tunnel underpassing a water reservoir is established to study the seepage characteristics of surrounding rock,the law of water inflow,and the change of lining water pressure,considering the local artificial boundary conditions for seepage in large rock mass,.In addition,the influences of rock permeability,fracture aperture,grouting circle thickness,and penetration are analyzed.The results show that:(1)Only fractures with aperture wider than 0.1 mm can play a significant role in water conduction in rocks with the permeability lower than 10^(-11)m^(2);(2)The greater the permeability difference between the fractures and rocks,the more remarkable the effects of fractures on the surrounding rock seepage field and cavern water inflow;(3)The sensitivity of grouting waterproof function to grouting circle thickness,grouting ring penetration,and rock permeability is significantly higher than that of tunnel buried depth and fracture aperture;(4)The lining water head is much more sensitive to the grouting circle thickness and penetration than to the tunnel buried depth;(5)With the grouting range enlarging,the impact of grouting circle permeability on the precipitation pressure role of the grouting ring increases;(6)For the interesting tunnel designed to be built at the depth of 70 m,the grouting circle with the thickness of 0.5 m and permeability of 10-^(14)m^(2)is recommended.展开更多
Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied....Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied.This study proposes a dynamic water inflow prediction method specifically designed for mountain tunnels.The method is based on groundwater dynamics theory,employing nonDarcian law as the governing equation and deriving analytical solutions applicable to both confined and phreatic aquifer conditions.The method incorporates spatiotemporal variations along the tunnel alignment,enabling both short-term and long-term dynamic predictions of water inflow.The study examines the nonlinear characteristics of the seepage field during tunnel water inrush.The research findings indicate that the predictive results are consistent with the hypothesized two-stage water inflow pattern,with relative errors for key parameters,such as maximum water inflow,normal water inflow,and duration of water inflow,remaining within 10%.The magnitude of water inflow is positively correlated with the permeability coefficient,head height;it is negatively correlated with the axial distance to the tunnel face and the non-Darcian influence coefficient.Both water inflow and water pressure are subject to non-Darcian effects within a defined influence zone extending approximately 1.3 times the tunnel diameter.Comparisons with established predictive methods,numerical simulations,and data from existing tunnel projects confirm the effectiveness of the proposed method.Moreover,the method was successfully applied to a mountain tunnel in the Tibet Plateau region in southwestern China,where it achieved prediction errors within 3%to 8%,demonstrating high reliability.展开更多
Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the str...Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.展开更多
In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groun...In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection(PWOD) method in which heavy rainfall(>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.展开更多
This study was conducted to establish a Support Vector Machines(SVM)-Markov Chain prediction model for prediction of mining water inflow. According to the raw data sequence, the Support Vector Machines(SVM) model was ...This study was conducted to establish a Support Vector Machines(SVM)-Markov Chain prediction model for prediction of mining water inflow. According to the raw data sequence, the Support Vector Machines(SVM) model was built, and then revised by means of a Markov state change probability matrix. Through dividing the state and analyzing absolute errors and relative errors and other indexes of the measured value and the fitted value of SVM, the prediction results were improved. Finally,the model was used to calculate relative errors. Through predicting and analyzing mining water inflow, the prediction results of the model were satisfactory. The results of this study enlarge the application scope of the Support Vector Machines(SVM) prediction model and provide a new method for scientific forecasting water inflow in coal mining.展开更多
In order to prevent and control the water inflow of mines, this paper built a new initial GM（1, 1） model to torecast the maximum water inflow according to the principle of new information. The effect of the new init...In order to prevent and control the water inflow of mines, this paper built a new initial GM（1, 1） model to torecast the maximum water inflow according to the principle of new information. The effect of the new initial GM（1, 1） model is not ideal by the concrete example. Then according to the principle of making the sum of the squares of the difference between the calculated sequences and the original sequences, an optimized GM（1, I） model was established. The result shows that this method is a new prediction method which can predict the maximum water inflow accurately. It not only conforms to the guide- line of prevention primarily, but also provides reference standards to managers on making prevention measures.展开更多
Based on the theory of grey system, established GM （1, 1） grey catastrophe predict model for the first time in order to forecast the catastrophe periods of mine water inflowing （not the volume of water inflowing）....Based on the theory of grey system, established GM （1, 1） grey catastrophe predict model for the first time in order to forecast the catastrophe periods of mine water inflowing （not the volume of water inflowing）. After establishing the grey predict system of the catastrophe regularity of 10 month-average volume of water inflowing, the grey forewarning for mine water inflowing catastrophe periods was established which was used to analyze water disaster in 400 meter level of Wennan Colliery. Based on residual analysis, it shows that the result of grey predict system is almost close to the actual value. And the scene actual result also shows the reliability of prediction. Both the theoretical analysis and the scene actual result indicate feasibility and reliability of the method of grey catastrophe predict system.展开更多
Based on the data collation of rainfall from September 2019 to August 2020 in a mining area in Yunnan and monitoring indicators of groundwater quality in the mining area, such as pH, total phosphorus, fluoride, tin an...Based on the data collation of rainfall from September 2019 to August 2020 in a mining area in Yunnan and monitoring indicators of groundwater quality in the mining area, such as pH, total phosphorus, fluoride, tin and water inflow, the specific impact of rainfall on the content of pH, ammonia nitrogen, fluoride and tin in groundwater quality and water inflow in the mining area was analyzed. It provides a certain reference for the regional environmental quality work.展开更多
To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is...To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is heterogeneous isotropy,the formula for calculating water inflow of tunnel with the nonlinear variation of permeability coefficient is deduced.By the contrast analysis with the existing formulas,the presented method has the similar value to them;moreover,the presented method has more simple form and easy to use.Due to parameter analysis,the water inflow decreases after considering the nonlinear variation of permeability coefficient.When the attenuation coefficient a>0,the water inflow increases first till reaches the maximum at a certain depth,then decreases and is close to 0 finally if deep enough.Thus,it is better to keep away from the certain depth where it is with the maximum water inflow for safe operation and economical construction,and reduce the water damage.Based on the analysis,the radius of tunnel has less impact on the amount of water inflow,and the water inflow just increases by 6.7% when the radius of tunnel increases by 1 m.展开更多
Water ramjets using outer water as an oxidizer have been demonstrated as a potential propulsion mode for underwater High Speed Supercavitating Vehicles (HSSVs) because of their higher energy density, power density, an...Water ramjets using outer water as an oxidizer have been demonstrated as a potential propulsion mode for underwater High Speed Supercavitating Vehicles (HSSVs) because of their higher energy density, power density, and specific impulse, but water flux changes the shapes of supercavity. To uncover the cavitator drag characteristics and the supercavity shape of HSSVs with water inflow for ramjets, supercavitation flows around a disk cavitator with inlet hole are studied using the homogenous model. By changing the water inflow in the range of 0-10 L/s through cavitators having different water inlet areas, a series of numerical simulations of supercavitation flows was performed. The water inflow flux of ramjets significantly influences the drag features of disk cavitators and the supercavity shape, but it has little influence on the slender ratio of supercavitaty. Furthermore, as the water inlet area increases, the drag coefficient of the cavitators' front face decreases, but this increase does not influence the diameter of the supercavity's maximum cross section and the drag coefficient of the entire cavitator significantly. In addition, with increasing waterflux of the ramjet, both the drag coefficient of cavitators and the maximum diameter of supercavities decrease stably. This research will be helpful for layout optimization and supercavitaty scheme design of HSSVs with water inflow for ramjets.展开更多
Through a systematic observation of water level and temperature, and a comprehensive analysis of the data on major/trace elements, nitrite, hydrogen-oxygen isotopes, the conclusion has been drawn that there are two re...Through a systematic observation of water level and temperature, and a comprehensive analysis of the data on major/trace elements, nitrite, hydrogen-oxygen isotopes, the conclusion has been drawn that there are two relatively independent groundwater systems (cool water and hot water), and the geochemical indicators of hot/cool waters are described. The cool water system is relatively enriched in Ca2+, Mg2+ and HCO3-. Its TDS is relatively low, about 1400–1800 mg/L. The hot water system is relatively enriched in K+, Na+, Cl- and SO42-. Its TDS is relatively high, about 2200–2300 mg/L. The cool water system is enriched in Ba, Ga, Cd, and the hot water system is enriched in B, Ti, Cr, Ni, Cu, Mo, Rb, and Cs, relatively. Especially, the contents of Rb and Cs in the hot water system are more than five times as high as those in the cool water system. The NO3- contents of cool water discharged from the gold mine are relatively high, and those of hot water are extremely low. The δD and δ18O values follow an increasing order of surface water>mine cool water>mine hot water. The cool water comes mainly from the lateral supply of phreatic water, while the hot water comes mainly from the vertical supply of deeply circulating structure-fracture water. The ratio of cool water over hot water was estimated to be about 1:1 by a water quality model..展开更多
Water sealing performance is important for underground water-sealed oil storage(UWSOS).The key issues concerning water sealing performance mainly include the permeability of fractured rock mass(FRM),water-sealed safet...Water sealing performance is important for underground water-sealed oil storage(UWSOS).The key issues concerning water sealing performance mainly include the permeability of fractured rock mass(FRM),water-sealed safety(WSS),water curtain performance,and prediction and control of water inflow.This paper reviews the progress of above four key issues on water sealing performances.First,the permeability of an FRM is the basis of water sealing performance,and several commonly used permeability test methods and spatial variation characteristics of permeability are outlined.Second,the current water sealing criteria are compared,and the evaluation methods of WSS are summarized.Third,the design parameters and efficiency evaluation of water curtain systems(WCSs)are introduced.The water inflow of oil storage caverns(OSCs)can reflect the water sealing effect,and the prediction methods and control measures of water inflow are also summarized.Finally,the advantages and disadvantages of the current research are discussed,and the potential research directions are pointed out,such as optimization of water sealing criteria and FRM model,quantitative evaluation of WCS efficiency,accurate prediction of water inflow,and improvement of grouting technology.展开更多
The intricate interplay between rock mechanics and fracture-induced fluid flow during resource extrac-tion exerts profound effects on groundwater systems,posing a pivotal challenge for promoting green and safe develop...The intricate interplay between rock mechanics and fracture-induced fluid flow during resource extrac-tion exerts profound effects on groundwater systems,posing a pivotal challenge for promoting green and safe development in underground engineering.To address this,a novel numerical model with an explicit coupling simulation strategy is presented.This model integrates distinct modules for individual physical mechanisms,ensuring second-order accuracy through shared time integration,thereby overcoming lim-itations in simulating mining-induced strata damage,water flow,and permeability dynamics.A novel mathematical model is incorporated into the mechanical simulation to characterize the abrupt increase in permeability resulting from rock fracture propagation.This increase is quantified by evaluating the plastic damage state of rocks and incorporating a damage coefficient that is intrinsically linked to rock strength.The mechanical model tracks permeability changes due to mining.The flow model simulates aquifer-mine water interactions by calculating hydraulic conductivity and using dynamic zoning,adapt-ing to mining progress.When applied to a case study of a complex mine,this approach significantly improved the accuracy of water inflow rate predictions by 57%.展开更多
Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging par...Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.展开更多
This paper aims to quantitatively assess water losses of Badovc Lake-Kosovo based on both water balance of the lake and water hydrochemistry. This attempt was strongly prompt by both the importance of this lake for wa...This paper aims to quantitatively assess water losses of Badovc Lake-Kosovo based on both water balance of the lake and water hydrochemistry. This attempt was strongly prompt by both the importance of this lake for water supply of Prishtina city and the lack of water. According to lake water balance, a water loss of 3,738,905 m^3 and 1,722,552 m^3 for the hydrologic year 2014 and the period January-May （2015） was evaluated. These consistent data favour the opinion that a continuous groundwater outflow from the lake is present and it is conditioned by the intensively developed fracture system in the lake basement formations. This was also supported by the chemical data （chloride, sulphate, hardness and electric conductivity etc.） of the water. Water from the leakages on the right side of the dam shows the same chemical signature as the water from the lake. Whereas, water from the piezometer, monitoring well and the gallery of Hajvalia mine show similar values with those of the water from the lake. The calculations of the chloride mass balance showed that the fractions of lake and rainfall waters in the water mixture of Hajvalia mine were 67% and 33% respectively.展开更多
文摘Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a numerical percolation model of random fractured rock of a tunnel underpassing a water reservoir is established to study the seepage characteristics of surrounding rock,the law of water inflow,and the change of lining water pressure,considering the local artificial boundary conditions for seepage in large rock mass,.In addition,the influences of rock permeability,fracture aperture,grouting circle thickness,and penetration are analyzed.The results show that:(1)Only fractures with aperture wider than 0.1 mm can play a significant role in water conduction in rocks with the permeability lower than 10^(-11)m^(2);(2)The greater the permeability difference between the fractures and rocks,the more remarkable the effects of fractures on the surrounding rock seepage field and cavern water inflow;(3)The sensitivity of grouting waterproof function to grouting circle thickness,grouting ring penetration,and rock permeability is significantly higher than that of tunnel buried depth and fracture aperture;(4)The lining water head is much more sensitive to the grouting circle thickness and penetration than to the tunnel buried depth;(5)With the grouting range enlarging,the impact of grouting circle permeability on the precipitation pressure role of the grouting ring increases;(6)For the interesting tunnel designed to be built at the depth of 70 m,the grouting circle with the thickness of 0.5 m and permeability of 10-^(14)m^(2)is recommended.
基金the financial support provided by the Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University(Grant Nos.TUL2024-05)。
文摘Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied.This study proposes a dynamic water inflow prediction method specifically designed for mountain tunnels.The method is based on groundwater dynamics theory,employing nonDarcian law as the governing equation and deriving analytical solutions applicable to both confined and phreatic aquifer conditions.The method incorporates spatiotemporal variations along the tunnel alignment,enabling both short-term and long-term dynamic predictions of water inflow.The study examines the nonlinear characteristics of the seepage field during tunnel water inrush.The research findings indicate that the predictive results are consistent with the hypothesized two-stage water inflow pattern,with relative errors for key parameters,such as maximum water inflow,normal water inflow,and duration of water inflow,remaining within 10%.The magnitude of water inflow is positively correlated with the permeability coefficient,head height;it is negatively correlated with the axial distance to the tunnel face and the non-Darcian influence coefficient.Both water inflow and water pressure are subject to non-Darcian effects within a defined influence zone extending approximately 1.3 times the tunnel diameter.Comparisons with established predictive methods,numerical simulations,and data from existing tunnel projects confirm the effectiveness of the proposed method.Moreover,the method was successfully applied to a mountain tunnel in the Tibet Plateau region in southwestern China,where it achieved prediction errors within 3%to 8%,demonstrating high reliability.
基金supported by the Chongqing Natural Science Foundation(No.cstc2020jcyjmsxm X0904)the Chongqing Talent Plan(No.CQYC2020058263)+3 种基金the Chongqing Technology Innovation and Application Development Project(No.cstc2021ycjh-bgzxm0246)the China Postdoctoral Science Foundation(No.2021M693739)the Sichuan Science and Technology Program(No.2021YJ0539)the Natural Science foundation of Jiangsu higher education institutions of China(Grant No.19KJD170001)。
文摘Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.
基金supported by the National Key Research and Development Project (Grant No.2016YFC0801604)Natural Science Foundation of Shandong Province (Grant No.ZR2017MEE070)
文摘In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection(PWOD) method in which heavy rainfall(>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.
文摘This study was conducted to establish a Support Vector Machines(SVM)-Markov Chain prediction model for prediction of mining water inflow. According to the raw data sequence, the Support Vector Machines(SVM) model was built, and then revised by means of a Markov state change probability matrix. Through dividing the state and analyzing absolute errors and relative errors and other indexes of the measured value and the fitted value of SVM, the prediction results were improved. Finally,the model was used to calculate relative errors. Through predicting and analyzing mining water inflow, the prediction results of the model were satisfactory. The results of this study enlarge the application scope of the Support Vector Machines(SVM) prediction model and provide a new method for scientific forecasting water inflow in coal mining.
文摘In order to prevent and control the water inflow of mines, this paper built a new initial GM（1, 1） model to torecast the maximum water inflow according to the principle of new information. The effect of the new initial GM（1, 1） model is not ideal by the concrete example. Then according to the principle of making the sum of the squares of the difference between the calculated sequences and the original sequences, an optimized GM（1, I） model was established. The result shows that this method is a new prediction method which can predict the maximum water inflow accurately. It not only conforms to the guide- line of prevention primarily, but also provides reference standards to managers on making prevention measures.
文摘Based on the theory of grey system, established GM （1, 1） grey catastrophe predict model for the first time in order to forecast the catastrophe periods of mine water inflowing （not the volume of water inflowing）. After establishing the grey predict system of the catastrophe regularity of 10 month-average volume of water inflowing, the grey forewarning for mine water inflowing catastrophe periods was established which was used to analyze water disaster in 400 meter level of Wennan Colliery. Based on residual analysis, it shows that the result of grey predict system is almost close to the actual value. And the scene actual result also shows the reliability of prediction. Both the theoretical analysis and the scene actual result indicate feasibility and reliability of the method of grey catastrophe predict system.
文摘Based on the data collation of rainfall from September 2019 to August 2020 in a mining area in Yunnan and monitoring indicators of groundwater quality in the mining area, such as pH, total phosphorus, fluoride, tin and water inflow, the specific impact of rainfall on the content of pH, ammonia nitrogen, fluoride and tin in groundwater quality and water inflow in the mining area was analyzed. It provides a certain reference for the regional environmental quality work.
基金Projects(51478477,51508562,51508563)supported by the National Natural Science Foundation of China
文摘To assess the water inflow which is more suitable to the actual conditions of tunnel,an empirical correlation about the permeability coefficient changing with depth is introduced.Supposing that the surrounding rock is heterogeneous isotropy,the formula for calculating water inflow of tunnel with the nonlinear variation of permeability coefficient is deduced.By the contrast analysis with the existing formulas,the presented method has the similar value to them;moreover,the presented method has more simple form and easy to use.Due to parameter analysis,the water inflow decreases after considering the nonlinear variation of permeability coefficient.When the attenuation coefficient a>0,the water inflow increases first till reaches the maximum at a certain depth,then decreases and is close to 0 finally if deep enough.Thus,it is better to keep away from the certain depth where it is with the maximum water inflow for safe operation and economical construction,and reduce the water damage.Based on the analysis,the radius of tunnel has less impact on the amount of water inflow,and the water inflow just increases by 6.7% when the radius of tunnel increases by 1 m.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 51579209, 51409215 and 51679202
文摘Water ramjets using outer water as an oxidizer have been demonstrated as a potential propulsion mode for underwater High Speed Supercavitating Vehicles (HSSVs) because of their higher energy density, power density, and specific impulse, but water flux changes the shapes of supercavity. To uncover the cavitator drag characteristics and the supercavity shape of HSSVs with water inflow for ramjets, supercavitation flows around a disk cavitator with inlet hole are studied using the homogenous model. By changing the water inflow in the range of 0-10 L/s through cavitators having different water inlet areas, a series of numerical simulations of supercavitation flows was performed. The water inflow flux of ramjets significantly influences the drag features of disk cavitators and the supercavity shape, but it has little influence on the slender ratio of supercavitaty. Furthermore, as the water inlet area increases, the drag coefficient of the cavitators' front face decreases, but this increase does not influence the diameter of the supercavity's maximum cross section and the drag coefficient of the entire cavitator significantly. In addition, with increasing waterflux of the ramjet, both the drag coefficient of cavitators and the maximum diameter of supercavities decrease stably. This research will be helpful for layout optimization and supercavitaty scheme design of HSSVs with water inflow for ramjets.
文摘Through a systematic observation of water level and temperature, and a comprehensive analysis of the data on major/trace elements, nitrite, hydrogen-oxygen isotopes, the conclusion has been drawn that there are two relatively independent groundwater systems (cool water and hot water), and the geochemical indicators of hot/cool waters are described. The cool water system is relatively enriched in Ca2+, Mg2+ and HCO3-. Its TDS is relatively low, about 1400–1800 mg/L. The hot water system is relatively enriched in K+, Na+, Cl- and SO42-. Its TDS is relatively high, about 2200–2300 mg/L. The cool water system is enriched in Ba, Ga, Cd, and the hot water system is enriched in B, Ti, Cr, Ni, Cu, Mo, Rb, and Cs, relatively. Especially, the contents of Rb and Cs in the hot water system are more than five times as high as those in the cool water system. The NO3- contents of cool water discharged from the gold mine are relatively high, and those of hot water are extremely low. The δD and δ18O values follow an increasing order of surface water>mine cool water>mine hot water. The cool water comes mainly from the lateral supply of phreatic water, while the hot water comes mainly from the vertical supply of deeply circulating structure-fracture water. The ratio of cool water over hot water was estimated to be about 1:1 by a water quality model..
基金supported by the National Natural Science Foundation of China(Grant Nos.41972300,41572301,and 42107201).
文摘Water sealing performance is important for underground water-sealed oil storage(UWSOS).The key issues concerning water sealing performance mainly include the permeability of fractured rock mass(FRM),water-sealed safety(WSS),water curtain performance,and prediction and control of water inflow.This paper reviews the progress of above four key issues on water sealing performances.First,the permeability of an FRM is the basis of water sealing performance,and several commonly used permeability test methods and spatial variation characteristics of permeability are outlined.Second,the current water sealing criteria are compared,and the evaluation methods of WSS are summarized.Third,the design parameters and efficiency evaluation of water curtain systems(WCSs)are introduced.The water inflow of oil storage caverns(OSCs)can reflect the water sealing effect,and the prediction methods and control measures of water inflow are also summarized.Finally,the advantages and disadvantages of the current research are discussed,and the potential research directions are pointed out,such as optimization of water sealing criteria and FRM model,quantitative evaluation of WCS efficiency,accurate prediction of water inflow,and improvement of grouting technology.
基金supported by the National Natural Science Foundation of China (Nos. 42027801, 42072284, and 42372297)the National Key Research and Development Program of China (Nos. 2023YFC3012102 and 2021YFC2902004)the Fundamental Research Funds for the Central Universities (No. 2023ZKPYSH01)
文摘The intricate interplay between rock mechanics and fracture-induced fluid flow during resource extrac-tion exerts profound effects on groundwater systems,posing a pivotal challenge for promoting green and safe development in underground engineering.To address this,a novel numerical model with an explicit coupling simulation strategy is presented.This model integrates distinct modules for individual physical mechanisms,ensuring second-order accuracy through shared time integration,thereby overcoming lim-itations in simulating mining-induced strata damage,water flow,and permeability dynamics.A novel mathematical model is incorporated into the mechanical simulation to characterize the abrupt increase in permeability resulting from rock fracture propagation.This increase is quantified by evaluating the plastic damage state of rocks and incorporating a damage coefficient that is intrinsically linked to rock strength.The mechanical model tracks permeability changes due to mining.The flow model simulates aquifer-mine water interactions by calculating hydraulic conductivity and using dynamic zoning,adapt-ing to mining progress.When applied to a case study of a complex mine,this approach significantly improved the accuracy of water inflow rate predictions by 57%.
基金sponsored by the Research Project on the Damage Mechanism and Performance Recovery of Carbon Phyllite in the Basement of HighSpeed Railway Tunnels in Cold Regions(51978668)the Key Technology of Green Construction of the Hongtu Extra Tunnel(DFH(201904)ys1-001)。
文摘Asymmetric blockage of drainage systems occasionally occurs,which seriously threatens the safety of tunnel operation.Based on theoretical analysis,a calculation expression of tunnel water inflow involving clogging parameters was derived.Degradation of the analytical solution was analysed with the Taylor equation and series expansion theorem,and a tunnel under construction was considered to conduct field tests to verify the rationality of the established model and correctness of the derived expression.Studies have demonstrated that with increasing drainage system blockage degree,the amount of water inflow in the nonblocked area slowly increases,and the total amount of water in the tunnel gradually decreases.The hydrodynamic pressure in the blocked area non-linearly decreased,and the water inrush velocity and hydraulic gradient in the non-blocked area gradually increased.When the drainage system was not blocked,the result of tunnel water inflow calculated by the formula derived in this paper was 8.3% higher than the measured value.When the drainage system was blocked,the theoretical water inflow was 10.5% higher than the measured value.The difference between the measured value and the theoretical value is small,which verifies the effectiveness of the calculation formula of water inflow deduced in this paper.
文摘This paper aims to quantitatively assess water losses of Badovc Lake-Kosovo based on both water balance of the lake and water hydrochemistry. This attempt was strongly prompt by both the importance of this lake for water supply of Prishtina city and the lack of water. According to lake water balance, a water loss of 3,738,905 m^3 and 1,722,552 m^3 for the hydrologic year 2014 and the period January-May （2015） was evaluated. These consistent data favour the opinion that a continuous groundwater outflow from the lake is present and it is conditioned by the intensively developed fracture system in the lake basement formations. This was also supported by the chemical data （chloride, sulphate, hardness and electric conductivity etc.） of the water. Water from the leakages on the right side of the dam shows the same chemical signature as the water from the lake. Whereas, water from the piezometer, monitoring well and the gallery of Hajvalia mine show similar values with those of the water from the lake. The calculations of the chloride mass balance showed that the fractions of lake and rainfall waters in the water mixture of Hajvalia mine were 67% and 33% respectively.
