The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has ...The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has emerged as a critical issue that restricts their development.While scholars have focused on the safety of LRC under multiphysics field coupling,few have noticed the inevitable damage sustained by the primary load-bearing components—the surrounding rock and concrete lining—under high internal pressure,compromising their strength and permeation resistance.This study investigates the impact of damage to the surrounding rock and lining concrete on the stability and airtightness of the CAES cavern.First,a damagepermeability evolution model was established by analyzing cyclic loading and unloading test data on concrete samples.Then,a thermo-hydro-mechanical damage(THM-D)coupling model for the CAES cavern was developed and validated against operational data from the Huntorf plant.The coupling responses of both the surrounding rock and lining were compared and analyzed under three different schemes of the first charging and discharging operation.The results revealed the correlation between the air temperature in the cavern and the injection rate and the uneven damage evolution of the surrounding rock and lining caused by the geostress distribution coupled with the heat transfer process.Through the analysis,a higher air injection rate causes more lining damage and air leakage,posing greater risks to engineering safety and airtightness.However,the reduction of inflation time will weaken this effect to some extent.These findings offer valuable insights into the design,construction,and safe operation of LRC compressed air energy storage systems.展开更多
The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass ...The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur.Analytical and numerical models can be used to estimate the rock mass response to high internal pressure;however,the fitness of these models under different in situ stress conditions and cavern shapes has not been studied.In this paper,the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied.The analytical model is derived in detail and finite element(FE)models considering both two-dimensional(2D)and three-dimensional(3D)geometries are presented.These models are verified with field measurements from the LRC in Skallen,southwestern Sweden.The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights.For the case of anisotropic horizontal in situ stresses,as the conditions in Skallen,the 3D FE model is the best approach.展开更多
In order to reduce the risk associated with water seepage in an underground rock cavern project inSingapore, a reliable hydro-geological model should be established based on the in situ investigationdata. The key chal...In order to reduce the risk associated with water seepage in an underground rock cavern project inSingapore, a reliable hydro-geological model should be established based on the in situ investigationdata. The key challenging issue in the hydro-geological model building is how to integrate limitedgeological and hydro-geological data to determine the hydraulic conductivity of the fractured rockmasses. Based on the data obtained from different stages （feasibility investigation stage, constructionstage, and post-construction stage）, suitable models and methods are proposed to determine the hydraulicconductivities at different locations and depths, which will be used at other locations in thefuture. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
This paper presents a comprehensive summary of data,analyses and findings from the investigations over the past twelve years about the relics of large Longyou rock caverns carved about 2000 years ago at shallow depths...This paper presents a comprehensive summary of data,analyses and findings from the investigations over the past twelve years about the relics of large Longyou rock caverns carved about 2000 years ago at shallow depths in argillaceous siltstone.The paper presents the typical features associated with the rock caverns.They include structures,large spans,portals,extreme shallow-buried depths,imprints,drainages,inclined ceiling,inclined sidewalls,slender rock pillars,rock staircases,site and strata selections,caving lighting,carving method,and underground construction surveying.They are used to reconstruct and highlight the design and construction methods adopted by the ancients.The paper further demonstrates that the relics of the complete large rock caverns are a consequence of coincidental combinations of ancient human effort and natural factors.The full occupation of water with weak acidity in the large rock caverns with the soft surrounding rocks of weak alkalinity is found to be the main factor ensuring and preserving the caverns to have been stable and integral over 2000 years.However,the five unwatered complete rock cavern relics have been experiencing various deteriorations and small failures including cracks,seepage,small rock falls and delaminating ceiling rocks.Although these deteriorations have been repaired and stabilized effectively,the paper demonstrates that an entire roof collapse failure is highly possible in the near future to each of the five unwatered rock cavern relics.The findings presented in this paper are also invaluable both to the long-term protection and preservation of the large rock cavern relics of national and international interests and importance,and to extend and enrich our experience and knowledge on the long-term stability and integrity of man-made underground rock cavern engineering projects.展开更多
A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetrat...A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetration projectiles exploding adjacent to the cavern/tunnel. The resulting problem necessitates the solution of the dynamics of a beam loaded by a transient pressure uniformly distributed over the span. According to mechanical characteristics of the system with rock bolt and shotcrete, a dynamic support design method based on equivalent single degree of freedom （SDOF） was put forward. The SDOF method was applied to obtaining the maximum displacement at the mid-span of the beam, which is often the controlling factor in the blast-resistant design. In the formulation of the problem, the proposed method combines the phenomena of spalling and structural dynamics theory. An example is provided to demonstrate the applicability of this simplified method.展开更多
Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to comp...Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.展开更多
The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,con...The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,concentrating strains in the lining.The structural interaction between the LRC componentsmust be able to reduce the strain concentration in the sealing steel lining;however,this interaction iscomplex and difficult to predict with analytical methods.In this paper,the strain concentration in LRCsfrom the opening of rock joints is studied using finite element(FE)analyses,where the large-and small-scale deformation behaviors of the LRC are coupled.The model also includes concrete crack initiation anddevelopment with increasing gas pressure and rock joint width.The interaction between the jointed rockmass and the reinforced concrete,the sliding layer,and the steel lining is demonstrated.The results showthat the rock mass quality and the spacing of the rock joints have the greatest influence on the straindistributions in the steel lining.The largest effect of rock joints on the maximum strains in the steellining was observed for geological conditions of“good”quality rock masses.展开更多
This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage ...This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage with high internal pressure,e.g.compressed air energy storage(CAES)underground caverns or hydrogen storage caverns.Initially,the stress paths of the surrounding rock during the excavation,pressurization,and depressurization processes are delineated.Analytical expressions for the stress and deformation of the surrounding rock are derived based on the MohreCoulomb criterion.These expressions are then employed to evaluate the displacement of cavern walls under varying qualities of surrounding rock,the contact pressure between the steel lining and the surrounding rock subject to different gas storage pressures,the load-bearing ratio of the surrounding rock,and the impact of lining thickness on the critical gas pressure.Furthermore,the deformation paths of the surrounding rock are evaluated,along with the effects of tunnel depth and diameter on residual deformation of the surrounding rock,and the critical minimum gas pressure at which the surrounding rock and the lining do not detach.The results indicate that residual deformation of the surrounding rock occurs after depressurization under higher internal pressure for higher-quality rock masses,leading to detachment between the surrounding rock and the steel lining.The findings indicate that thicker linings correspond to higher critical minimum gas pressures.However,for lower-quality surrounding rock,thicker linings correspond to lower critical minimum gas pressures.These findings will provide invaluable insights for the design of LRCs for underground energy storage caverns.展开更多
In this paper,we develop a two-dimensional(2D)numerical model based on the finite element method to analyse the impact of fracture networks on the behaviour of pressurised lined rock caverns(LRCs).We use the discrete ...In this paper,we develop a two-dimensional(2D)numerical model based on the finite element method to analyse the impact of fracture networks on the behaviour of pressurised lined rock caverns(LRCs).We use the discrete fracture network approach to represent the fracture system in rock obeying a power law length distribution.The LRC consisting of an inner steel lining and an outer reinforced concrete is situated within the rock mass characterised by spatially distributed and intersected fractures.An elasto-brittle constitutive relationship is adopted to characterise the deformation/failure of intact rocks,while the classical Mazars damage model is used to simulate the cracking of concrete linings.For pre-existing fractures in rock,a non-linear stress-displacement formulation is implemented to capture their normal and shear deformations.The 2D model,representing the horizontal cross-section of an LRC with its surrounding rock mass,is subject to a prescribed in situ stress condition.We explore various fracture network scenarios associated with different values of power law length exponent and fracture intensity.We analyse the damage evolution in rock/concrete and tangential strain in the concrete/steel linings.It is found that the damage within the rock mass mainly evolves in the form of wing cracks that emanate from the tips of pre-existing fractures.For damage development in the concrete lining,it is primarily induced by tensile cracking under cavern pressurisation.The damage emerges in the lining sections where pre-existing fractures are located in the tensile region around the cavern and either intersect with the cavern wall or could reach the cavern wall by promoting wing crack propagation.The results and insights obtained from our study have significant implications for the design optimisation and performance assessment of LRCs for sustainable hydrogen storage.展开更多
Large underground caverns are commonly used in variety of applications. In many cases, because of the geomechanical limitations of dimensions and requirement of high volume, several parallel caverns are used. Plastic ...Large underground caverns are commonly used in variety of applications. In many cases, because of the geomechanical limitations of dimensions and requirement of high volume, several parallel caverns are used. Plastic zone integration requires a larger rock pillar distance of theses adjacent caverns while eco- nomic and access reasons require smaller distance. In lran many underground projects are located in West and South West, Asmari formation covers a large part of these regions. The stability of underground spaces that are constructed or will be constructed in this formation has been investigated. A proper cross section based on plastic analysis and a stability criterion has been proposed for each region. Finally, in each case, allowable rock pillar between adjacent caverns with similar dimension was determined with two methods （numerical analysis and fire service law）. Results show that Fire Service Law uses a very con- servative safety factor and it was proposed to use a correction factor for allowable distance based on application of underground space.展开更多
For better rock mass characterization and support design, 3D engineering geological mapping was carried for the heading portion of the under construction 200.00 m long, 68.75 m high and 20.20 m wide underground additi...For better rock mass characterization and support design, 3D engineering geological mapping was carried for the heading portion of the under construction 200.00 m long, 68.75 m high and 20.20 m wide underground additional surge pool cavern of a Pranahitha-Chevella Sujala Sravanthi lift irrigation scheme package 8, India. To study cavern behavior, 3D geologic mapping of heading portion is very important for large cavern for predicting geologic conditions in benching down up to invert level, planning support system, selecting inclination for best location of supplemental rock bolt and choosing strategic locations for various types of instrumentation. The assessment of Tunnel Quality Index “Q” and Geomechanics classification for the granitic rock mass was done based on the information available of the rock joints and their nature and 3D geological logging. Hoek-Brown parameters were also determined by the statistical analysis of the results of a set of triaxial tests on core samples. On basis of geological characteristics and NMT Q-system chart, support system is recommended which includes rock bolt, steel fibre reinforced shotcrete and grouting. To evaluate the efficacy of the proposed support system, the capacity of support system is determined.展开更多
在高内压循环作用下地下储气库衬砌易产生裂缝与渗透通道,密封层受力与裂缝控制问题尤为关键。基于有限-离散元方法(finite-discrete element method,简称FDEM),建立了连续-非连续的围岩-衬砌-密封层整体模型,系统研究了平钢板与波拱两...在高内压循环作用下地下储气库衬砌易产生裂缝与渗透通道,密封层受力与裂缝控制问题尤为关键。基于有限-离散元方法(finite-discrete element method,简称FDEM),建立了连续-非连续的围岩-衬砌-密封层整体模型,系统研究了平钢板与波拱两类钢衬及预设缝设计参数对衬砌裂缝演化与密封性能的影响。结果表明,平钢板型密封层应力水平和裂缝数量较高,整体性差,预设缝改善衬砌开裂与密封结构受力作用有限;波拱型结构能显著降低峰值应力并改变裂缝分布,使得裂缝多集中在波拱底部,整体裂缝数量减少,但波拱处的裂缝开裂宽度更大。采用波拱+预设缝相结合的方案可进一步均匀化开裂,减少密封钢衬应力。随着波拱和预设缝数量增加,应力分布趋于均匀,裂缝扩展受控,但最大裂缝宽度呈先减后增趋势,钢衬应力模式由拉应力向弯-剪应力转变。当缝设于拱底时,裂缝可沿预设路径均匀扩展,并可结合防排水措施降低渗透风险。总体而言,波拱+预设缝复合设计在引导裂缝、释放应变和提升密封渗透性能方面具有显著优势,为储气库密封-衬砌协同优化设计提供参考。展开更多
Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different ...Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different types of underground storages require different geological and hydrogeological conditions and are associated with different rock engineering problems.However,the common issue is to ensure the gas-and oil-tightness of storage caverns.In other words,the stored oil and gas must not escape from the storage caverns.This may be realized by different means according to the types of storages and the sites geological conditions.There are basically two approaches of gas leakage control,i.e.permeability control and hydrodynamic containment.The latter involves the use of a water curtain system in many cases,which creates an artificial hydraulic boundary condition and helps to establish the required groundwater condition when needed.In addition to the common problems,the underground storage of liquefied petroleum gas(LPG) requires special attentions to the opening of rock joints,which result from the tensile thermal stress induced by the low storage temperature.Great care must be taken in choosing abandoned mines for oil and gas-storage since it is quite rare that the natural site conditions can meet the usual requirements,in particular for the gas tightness.The paper provides a general description of the gas leakage control for underground oil and gas storage projects,and addresses various rock engineering problems associated with selected types of storages in detail.展开更多
Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a ...Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:U23B20147Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS),Grant/Award Number:ZDBS-LY-DQC022+1 种基金Hubei Provincial Natural Science Foundation of China,Grant/Award Number:2023AFB346Knowledge Innovation Program of Wuhan-Shuguang Project,Grant/Award Number:2023010201020278。
文摘The lined rock cavern(LRC)compressed air energy storage(CAES)system is currently regarded as one of the most promising methods for large-scale energy storage.However,the safety of LRC under high internal pressure has emerged as a critical issue that restricts their development.While scholars have focused on the safety of LRC under multiphysics field coupling,few have noticed the inevitable damage sustained by the primary load-bearing components—the surrounding rock and concrete lining—under high internal pressure,compromising their strength and permeation resistance.This study investigates the impact of damage to the surrounding rock and lining concrete on the stability and airtightness of the CAES cavern.First,a damagepermeability evolution model was established by analyzing cyclic loading and unloading test data on concrete samples.Then,a thermo-hydro-mechanical damage(THM-D)coupling model for the CAES cavern was developed and validated against operational data from the Huntorf plant.The coupling responses of both the surrounding rock and lining were compared and analyzed under three different schemes of the first charging and discharging operation.The results revealed the correlation between the air temperature in the cavern and the injection rate and the uneven damage evolution of the surrounding rock and lining caused by the geostress distribution coupled with the heat transfer process.Through the analysis,a higher air injection rate causes more lining damage and air leakage,posing greater risks to engineering safety and airtightness.However,the reduction of inflation time will weaken this effect to some extent.These findings offer valuable insights into the design,construction,and safe operation of LRC compressed air energy storage systems.
基金This work has been conducted as part of the HYBRIT research project RP-1.This research was financially supported by the Swedish Energy Agency(Grant No.42684e2).
文摘The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur.Analytical and numerical models can be used to estimate the rock mass response to high internal pressure;however,the fitness of these models under different in situ stress conditions and cavern shapes has not been studied.In this paper,the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied.The analytical model is derived in detail and finite element(FE)models considering both two-dimensional(2D)and three-dimensional(3D)geometries are presented.These models are verified with field measurements from the LRC in Skallen,southwestern Sweden.The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights.For the case of anisotropic horizontal in situ stresses,as the conditions in Skallen,the 3D FE model is the best approach.
文摘In order to reduce the risk associated with water seepage in an underground rock cavern project inSingapore, a reliable hydro-geological model should be established based on the in situ investigationdata. The key challenging issue in the hydro-geological model building is how to integrate limitedgeological and hydro-geological data to determine the hydraulic conductivity of the fractured rockmasses. Based on the data obtained from different stages （feasibility investigation stage, constructionstage, and post-construction stage）, suitable models and methods are proposed to determine the hydraulicconductivities at different locations and depths, which will be used at other locations in thefuture. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
基金Supported by the National Natural Science Foundation of China(40902088 and 40672190)the Key Project of Zhejiang Province Science and Technology(2007C23093)
文摘This paper presents a comprehensive summary of data,analyses and findings from the investigations over the past twelve years about the relics of large Longyou rock caverns carved about 2000 years ago at shallow depths in argillaceous siltstone.The paper presents the typical features associated with the rock caverns.They include structures,large spans,portals,extreme shallow-buried depths,imprints,drainages,inclined ceiling,inclined sidewalls,slender rock pillars,rock staircases,site and strata selections,caving lighting,carving method,and underground construction surveying.They are used to reconstruct and highlight the design and construction methods adopted by the ancients.The paper further demonstrates that the relics of the complete large rock caverns are a consequence of coincidental combinations of ancient human effort and natural factors.The full occupation of water with weak acidity in the large rock caverns with the soft surrounding rocks of weak alkalinity is found to be the main factor ensuring and preserving the caverns to have been stable and integral over 2000 years.However,the five unwatered complete rock cavern relics have been experiencing various deteriorations and small failures including cracks,seepage,small rock falls and delaminating ceiling rocks.Although these deteriorations have been repaired and stabilized effectively,the paper demonstrates that an entire roof collapse failure is highly possible in the near future to each of the five unwatered rock cavern relics.The findings presented in this paper are also invaluable both to the long-term protection and preservation of the large rock cavern relics of national and international interests and importance,and to extend and enrich our experience and knowledge on the long-term stability and integrity of man-made underground rock cavern engineering projects.
基金Projects（50934006, 50904079） supported by the National Natural Science Foundation of China Project（2010CB732004） supported by the National Basic Research Program of China
文摘A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetration projectiles exploding adjacent to the cavern/tunnel. The resulting problem necessitates the solution of the dynamics of a beam loaded by a transient pressure uniformly distributed over the span. According to mechanical characteristics of the system with rock bolt and shotcrete, a dynamic support design method based on equivalent single degree of freedom （SDOF） was put forward. The SDOF method was applied to obtaining the maximum displacement at the mid-span of the beam, which is often the controlling factor in the blast-resistant design. In the formulation of the problem, the proposed method combines the phenomena of spalling and structural dynamics theory. An example is provided to demonstrate the applicability of this simplified method.
基金the financial support from the Natural Science Foundation of China (Nos.52179118,52209151 and 42307238)the Science and Technology Project of Jiangsu Provincial Department of Science and Technology-Carbon Emissions Peak and Carbon Neutrality Science and Technology Innovation Specia Fund Project (No.BK20220025)+3 种基金the Excellent Postdoctoral Program of Jiangsu Province (No.2023ZB602)the China Postdoctora Science Foundation (Nos.2023M733773 and 2023M733772)Xuzhou City Science and Technology Innovation Special Basic Research Plan (KC23045)State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining&Technology (No SKLGDUEK1916)。
文摘Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.
基金supported by the Swedish Energy Agency(Grant Nos.42684-2,P2022-00209).
文摘The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,concentrating strains in the lining.The structural interaction between the LRC componentsmust be able to reduce the strain concentration in the sealing steel lining;however,this interaction iscomplex and difficult to predict with analytical methods.In this paper,the strain concentration in LRCsfrom the opening of rock joints is studied using finite element(FE)analyses,where the large-and small-scale deformation behaviors of the LRC are coupled.The model also includes concrete crack initiation anddevelopment with increasing gas pressure and rock joint width.The interaction between the jointed rockmass and the reinforced concrete,the sliding layer,and the steel lining is demonstrated.The results showthat the rock mass quality and the spacing of the rock joints have the greatest influence on the straindistributions in the steel lining.The largest effect of rock joints on the maximum strains in the steellining was observed for geological conditions of“good”quality rock masses.
基金supported by the State Key Laboratory of Disaster Reduction in Civil Engineering(Grant No.SLDRCE23-02)Ningbo PublicWelfare Fund Project(Grant No.2023S100)the National Key Research and Development Program of China(Grant No.2024YFE0105800).
文摘This study investigates the mechanical response of an underground cavern subjected to cyclic high gas pressure,aiming to establish a theoretical foundation for the design of lined rock caverns(LRCs)for energy storage with high internal pressure,e.g.compressed air energy storage(CAES)underground caverns or hydrogen storage caverns.Initially,the stress paths of the surrounding rock during the excavation,pressurization,and depressurization processes are delineated.Analytical expressions for the stress and deformation of the surrounding rock are derived based on the MohreCoulomb criterion.These expressions are then employed to evaluate the displacement of cavern walls under varying qualities of surrounding rock,the contact pressure between the steel lining and the surrounding rock subject to different gas storage pressures,the load-bearing ratio of the surrounding rock,and the impact of lining thickness on the critical gas pressure.Furthermore,the deformation paths of the surrounding rock are evaluated,along with the effects of tunnel depth and diameter on residual deformation of the surrounding rock,and the critical minimum gas pressure at which the surrounding rock and the lining do not detach.The results indicate that residual deformation of the surrounding rock occurs after depressurization under higher internal pressure for higher-quality rock masses,leading to detachment between the surrounding rock and the steel lining.The findings indicate that thicker linings correspond to higher critical minimum gas pressures.However,for lower-quality surrounding rock,thicker linings correspond to lower critical minimum gas pressures.These findings will provide invaluable insights for the design of LRCs for underground energy storage caverns.
基金support from the Nordic Energy Research(Grant No.187658)Zixin Zhang thanks for the support from the National Natural Science Foundation of China(Grant No.42377146).
文摘In this paper,we develop a two-dimensional(2D)numerical model based on the finite element method to analyse the impact of fracture networks on the behaviour of pressurised lined rock caverns(LRCs).We use the discrete fracture network approach to represent the fracture system in rock obeying a power law length distribution.The LRC consisting of an inner steel lining and an outer reinforced concrete is situated within the rock mass characterised by spatially distributed and intersected fractures.An elasto-brittle constitutive relationship is adopted to characterise the deformation/failure of intact rocks,while the classical Mazars damage model is used to simulate the cracking of concrete linings.For pre-existing fractures in rock,a non-linear stress-displacement formulation is implemented to capture their normal and shear deformations.The 2D model,representing the horizontal cross-section of an LRC with its surrounding rock mass,is subject to a prescribed in situ stress condition.We explore various fracture network scenarios associated with different values of power law length exponent and fracture intensity.We analyse the damage evolution in rock/concrete and tangential strain in the concrete/steel linings.It is found that the damage within the rock mass mainly evolves in the form of wing cracks that emanate from the tips of pre-existing fractures.For damage development in the concrete lining,it is primarily induced by tensile cracking under cavern pressurisation.The damage emerges in the lining sections where pre-existing fractures are located in the tensile region around the cavern and either intersect with the cavern wall or could reach the cavern wall by promoting wing crack propagation.The results and insights obtained from our study have significant implications for the design optimisation and performance assessment of LRCs for sustainable hydrogen storage.
文摘Large underground caverns are commonly used in variety of applications. In many cases, because of the geomechanical limitations of dimensions and requirement of high volume, several parallel caverns are used. Plastic zone integration requires a larger rock pillar distance of theses adjacent caverns while eco- nomic and access reasons require smaller distance. In lran many underground projects are located in West and South West, Asmari formation covers a large part of these regions. The stability of underground spaces that are constructed or will be constructed in this formation has been investigated. A proper cross section based on plastic analysis and a stability criterion has been proposed for each region. Finally, in each case, allowable rock pillar between adjacent caverns with similar dimension was determined with two methods （numerical analysis and fire service law）. Results show that Fire Service Law uses a very con- servative safety factor and it was proposed to use a correction factor for allowable distance based on application of underground space.
文摘For better rock mass characterization and support design, 3D engineering geological mapping was carried for the heading portion of the under construction 200.00 m long, 68.75 m high and 20.20 m wide underground additional surge pool cavern of a Pranahitha-Chevella Sujala Sravanthi lift irrigation scheme package 8, India. To study cavern behavior, 3D geologic mapping of heading portion is very important for large cavern for predicting geologic conditions in benching down up to invert level, planning support system, selecting inclination for best location of supplemental rock bolt and choosing strategic locations for various types of instrumentation. The assessment of Tunnel Quality Index “Q” and Geomechanics classification for the granitic rock mass was done based on the information available of the rock joints and their nature and 3D geological logging. Hoek-Brown parameters were also determined by the statistical analysis of the results of a set of triaxial tests on core samples. On basis of geological characteristics and NMT Q-system chart, support system is recommended which includes rock bolt, steel fibre reinforced shotcrete and grouting. To evaluate the efficacy of the proposed support system, the capacity of support system is determined.
文摘在高内压循环作用下地下储气库衬砌易产生裂缝与渗透通道,密封层受力与裂缝控制问题尤为关键。基于有限-离散元方法(finite-discrete element method,简称FDEM),建立了连续-非连续的围岩-衬砌-密封层整体模型,系统研究了平钢板与波拱两类钢衬及预设缝设计参数对衬砌裂缝演化与密封性能的影响。结果表明,平钢板型密封层应力水平和裂缝数量较高,整体性差,预设缝改善衬砌开裂与密封结构受力作用有限;波拱型结构能显著降低峰值应力并改变裂缝分布,使得裂缝多集中在波拱底部,整体裂缝数量减少,但波拱处的裂缝开裂宽度更大。采用波拱+预设缝相结合的方案可进一步均匀化开裂,减少密封钢衬应力。随着波拱和预设缝数量增加,应力分布趋于均匀,裂缝扩展受控,但最大裂缝宽度呈先减后增趋势,钢衬应力模式由拉应力向弯-剪应力转变。当缝设于拱底时,裂缝可沿预设路径均匀扩展,并可结合防排水措施降低渗透风险。总体而言,波拱+预设缝复合设计在引导裂缝、释放应变和提升密封渗透性能方面具有显著优势,为储气库密封-衬砌协同优化设计提供参考。
文摘Oil and gas can be stored underground by a variety of means,such as in depleted oil and gas fields,in aquifers,in rock salt caverns,in unlined mined rock caverns,in lined shallow caverns and abandoned mines.Different types of underground storages require different geological and hydrogeological conditions and are associated with different rock engineering problems.However,the common issue is to ensure the gas-and oil-tightness of storage caverns.In other words,the stored oil and gas must not escape from the storage caverns.This may be realized by different means according to the types of storages and the sites geological conditions.There are basically two approaches of gas leakage control,i.e.permeability control and hydrodynamic containment.The latter involves the use of a water curtain system in many cases,which creates an artificial hydraulic boundary condition and helps to establish the required groundwater condition when needed.In addition to the common problems,the underground storage of liquefied petroleum gas(LPG) requires special attentions to the opening of rock joints,which result from the tensile thermal stress induced by the low storage temperature.Great care must be taken in choosing abandoned mines for oil and gas-storage since it is quite rare that the natural site conditions can meet the usual requirements,in particular for the gas tightness.The paper provides a general description of the gas leakage control for underground oil and gas storage projects,and addresses various rock engineering problems associated with selected types of storages in detail.
基金supported by the National Natural Science Foundation of China(No.42272321)Hubei Provincial Key Research Projects(Nos.2022BAA093 and 2022BAD163)+1 种基金Major Scientific and Technological Special Project of Jiangxi Province(No.2023ACG01004)WSGRI Engineering&Surveying Incorporation Limited(No.6120230256)。
文摘Enhancing cavern sealing is crucial for improving the efficiency of compressed air energy storage(CAES)in hard rock formations.This study introduced a novel approach using a nano-grade organosilicon polymer(NOSP)as a sealant,coupled with an air seepage evaluation model that incorporates Knudsen diffusion.Moreover,the initial coating application methods were outlined,and the advantages of using NOSP compared to other sealing materials,particularly regarding cost and construction techniques,were also examined and discussed.Experimental results indicated a significant reduction in permeability of rock specimens coated with a 7–10μm thick NOSP layer.Specifically,under a 0.5 MPa pulse pressure,the permeability decreased to less than 1 n D,and under a 4 MPa pulse pressure,it ranged between4.5×10^(-6)–5.5×10^(-6)m D,marking a 75%–80%decrease in granite permeability.The sealing efficacy of NOSP surpasses concrete and is comparable to rubber materials.The optimal viscosity for application lies between 95 and 105 KU,and the coating thickness should ideally range from 7 to 10μm,applied to substrates with less than 3%porosity.This study provides new insights into air transport and sealing mechanisms at the pore level,proposing NOSP as a cost-effective and simplified solution for CAES applications.
