Phillip Katuve,a landlord who owns a six-storey apartment complex in Kileleshwa,an upmarket Nairobi suburb,embraced green roofing two years ago.His building now boasts a vibrant rooftop garden with integrated solar pa...Phillip Katuve,a landlord who owns a six-storey apartment complex in Kileleshwa,an upmarket Nairobi suburb,embraced green roofing two years ago.His building now boasts a vibrant rooftop garden with integrated solar panels,supplying energy to all 24 units.“Initially,the idea sounded expensive,but the long-term benefits have been remarkable,”said Katuve.展开更多
The Iberian Peninsula is,nowadays,the main producer of roofing slate of the world.Most of the outcrops are located in the NW of the Iberian Peninsula,in the regions of Galicia,Leon,and in Portugal.The technique of wor...The Iberian Peninsula is,nowadays,the main producer of roofing slate of the world.Most of the outcrops are located in the NW of the Iberian Peninsula,in the regions of Galicia,Leon,and in Portugal.The technique of working and roofing with slate was brought from Flanders by King Felipe II by the second half of the XVI century.The most representative building from this period is the Monastery of El Escorial,N Madrid.However,the Spanish slate industry remained incipient until the 1960s,when Galicia and Leon suffered an accelerated industrialization process which greatly enhanced the volume of production.Additionally,the Portuguese slate industry was well developed by the second half of the XIX century.Most of the Portuguese production was exported,mainly to the United Kingdom.By the second half of the XX century,the Spanish,and in a lesser extent,the Portuguese roofing slate spread all over Europe,forcing most of the existing European quarries to close.Nowadays,different varieties of roofing slates are quarried,mainly in Spain,being used indistinctly in new residential construction and for restoration of historical buildings.The main importing countries are France,Germany and the United Kingdom.This work presents an overview of the history and main varieties of the Iberian roofing slate,in order to propose its inclusion as a Global Heritage Stone Province.展开更多
In the construction of civil engineering projects, the application of roofing waterproof technology is a key construction content that should be paid attention to based on the safety and convenience of the application...In the construction of civil engineering projects, the application of roofing waterproof technology is a key construction content that should be paid attention to based on the safety and convenience of the application of building construction after the completion of the basic frame construction of the building entity and the core project of the entity part construction. In the concrete implementation of roofing waterproof construction, professional technology needs to be applied, and the application of waterproof technology should be assisted to achieve good waterproof effect in combination with the construction technology requirements of each link of roofing. Specifically, in civil engineering projects, the application of roofing waterproof technology needs to find targeted waterproof technology in combination with different building entity areas. In addition, the quality control of raw materials in waterproof construction, construction of waterproof layer, design and construction of drainage system may affect the application effect of waterproof construction technology. Based on this, it is necessary for construction personnel and management personnel to guarantee the effective application of waterproof technology from the aspects of raw material construction technology and construction management.展开更多
The mining space of large mining height coal face is large,the range of movement and caving of rock strata is large and the stability of supports at coal face is low and damage rate of supports is high,which significa...The mining space of large mining height coal face is large,the range of movement and caving of rock strata is large and the stability of supports at coal face is low and damage rate of supports is high,which significantly affects the safe and efficient production of coal mines.By similar simulation experiment and theoretical analysis,the mode of fractured roofing structure of large mining height coal face and the method of determination of reasonable support resistance of the support was evaluated.Analysis shows that the structural mode of "combined cantilever beam – non-hinged roofing – hinged roofing" of the large mining height coal face appears at the roofing of large mining height coal face.The supporting factor of caved gangue at the gob is introduced,the calculating equations of the fractured step distance of roofing were derived and conventional calculating method of caved height of roofing was corrected and the method of determination of the length and height of each structural area of the roofing was provided.With reference to the excavating conditions at Jinhuagong coal mine in Datong minefield,the dimensions of structural areas of the roofing of the coal face were determined and analyzed,and reasonable support resistance of the height coal face was acquired.By selecting Model ZZ13000/28/60 support and with procedures of advanced pre-cracking blasting,the safe production of large mining height coal face was assured.展开更多
This work focused on characterizing and improving the thermal behavior of metal sheet roofing.To decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change ma...This work focused on characterizing and improving the thermal behavior of metal sheet roofing.To decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change materials,with different melting points:PCMІ,PCM II,PCM III and PCM IV,when used in conjunction with a sheet metal roof.The exterior metal roofing surface temperature was held constant at 50℃,60℃,70℃and 80℃,using a thermal source(halogen lights)for 360 min to investigate and compare the thermal performance of the metal sheet roofing with and without phase change materials for each condition.The thermal behaviors of the phase change materials were analyzed by differential scanning calorimeter(DSC).The results showed the melting points of PCMІ,PCM II,PCM III and PCM IV were around 45℃,50℃,55℃and 59℃,respectively.The integration of PCM IV into the metal roofing sheet increased the thermal performance by reducing the room temperature up to 2.8%,1.4%,1.0%and 0.7%when compared with the normal metal roof sheet,at the controlled temperatures of 50℃,60℃,70℃and 80℃,respectively.The thermal absorption of the phase change materials also caused a time delay in the model room reaching a steady temperature.The integration of phase change materials with metal roofing sheets resulted in better thermal performance and conservation of electrical energy by reducing the demand for cooling.展开更多
In architecture, in the past, different materials were used for covering of the buildings. The selection of the type of roofing depended on the purpose and size of the building; thus all the churches, administrative b...In architecture, in the past, different materials were used for covering of the buildings. The selection of the type of roofing depended on the purpose and size of the building; thus all the churches, administrative buildings and important medieval buildings were originally covered with stone or lead slabs as the final roofing material. The tendency of return of stone as an authentic roofing in the reconstruction of medieval buildings and churches, as well as the introduction of stone as a roofing on the new buildings in protected historic cores, is possible only if fulfilled modem principles and requirements of the physics of construction. The application of modem principles of double ventilated roofs and the use of stone as a roofing enables the restoration and preservation of the original appearance of medieval buildings, as well as the preservation and conservation of existing frescoes that have been present for centuries in these facilities. It also enables a successful reconstruction of a large number of medieval buildings. In this way it has been given a contribution to the preservation of old medieval buildings as the improvement of world cultural heritage.展开更多
This paper mainly focuses on the establishment of an effective static estimation method for the extreme wind-induced force for clips between purlins and metal panels of the standing-seam metal roofing system(hereinaft...This paper mainly focuses on the establishment of an effective static estimation method for the extreme wind-induced force for clips between purlins and metal panels of the standing-seam metal roofing system(hereinafter referred to as SMRS)of typical double-slope light-weight steel portal frame structure considering dynamic characteristics of wind and structure.First,simultaneous pressure measurement with rigid gable roof models was conducted mainly considering the length-span ratio in the boundary layer wind tunnel of Tokyo Polytechnic University,Japan.Then,finite element modeling for SMRS according to the wind load path in the roofing system was carried out to check the actual wind load of the clips based on the traditional calculation method provided in design codes,and the spatial correlation of fluctuating wind pressure on the roof surface,as well as the dynamic effect of the roof structure itself,had been considered.According to the related Chinese,American,and Japanese codes,a magnification coefficient based on the traditional method of static wind-induced force for the clips was calculated and compared.Finally,a simplified estimation method of effective wind-induced force for the clips in typical zones on the roof surface considering dynamic characteristics was proposed.展开更多
The pipe roofing method is widely used in tunnel construction because it can realize a flexible section shape and a large section area of the tunnel,especially under good ground conditions.However,the pipe roofing met...The pipe roofing method is widely used in tunnel construction because it can realize a flexible section shape and a large section area of the tunnel,especially under good ground conditions.However,the pipe roofing method has rarely been applied in soft ground,where the prediction and control of the ground settlement play important roles.This study proposes a sliced-soil-beam(SSB)model to predict the settlement of ground due to tunnelling using the pipe roofing method in soft ground.The model comprises a sliced-soil module based on the virtual work principle and a beam module based on structural mechanics.As part of this work,the Peck formula was modified for a square-section tunnel and adopted to construct a deformation mechanism of soft ground.The pipe roofing system was simplified to a threedimensional Winkler beam to consider the interaction between the soil and pipe roofing.The model was verified in a case study conducted in Shanghai,China,in which it provided the efficient and accurate prediction of settlement.Finally,the parameters affecting the ground settlement were analyzed.It was clarified that the stiffness of the excavated soil and the steel support are the key factors in reducing ground settlement.展开更多
Increase of indoor temperature compared with outdoor temperature is a major concern in modern house design. Occupants suffer from this uncomfortable condition because of overheating indoor temperature. Poor passive de...Increase of indoor temperature compared with outdoor temperature is a major concern in modern house design. Occupants suffer from this uncomfortable condition because of overheating indoor temperature. Poor passive design causes heat to be trapped, which influences the rise in indoor temperature. The upper part, which covers the area of the roof, is the most critical part of the house that is exposed to heat caused by high solar radiation and high emissivity levels. During daytime, the roof accumulates heat, which increases the indoor temperature and affects the comfort level of the occupants. To maintain the indoor temperature within the comfort level, most house designs usually depend on mechanical means by using fans or air conditioning systems. The dependence on a mechanical ventilation system could lead to additional costs for its installation, operation, and maintenance. Thus, this study concentrates on reviews on passive design and suggests recommendations for future developments. New proposals or strategies are proposed to improve the current passive design through ventilated and cool roof systems. It is possible to achieve the comfort level inside a house throughout the day by reducing the transmitted heat into the indoor environment and eliminating the internal hot air. These recommendations could become attractive strategies in providing a comfortable indoor temperature to the occupants as well as in minimizing energy consumption.展开更多
Green roof technology and implementation are taking root in North America at an accelerating pace.Growing recogni-tion of the benefits of green roofs and increasing interest in green infrastructure are leading to expa...Green roof technology and implementation are taking root in North America at an accelerating pace.Growing recogni-tion of the benefits of green roofs and increasing interest in green infrastructure are leading to expansion of green roof tech-nologies that have been in use for decades in Europe and elsewhere.While some regions have adopted the use of green roofs on a large scale,other areas are warming up to the concept more slowly.Large-scale implementation of green roofs has not yet occurred in Indiana,but a number of exemplary projects have been constructed,and there are signs that interest in the technology is increasing in the state.The purpose of this article is to provide an overview of green roof technology,analyze selected green roofs in Indiana,explore trends in the state,and address issues for future development of green roof technol-ogy in the region.A variety of green roofs were investigated throughout the state.Discussions were held with individuals involved in each project to obtain technical and logistical details of green roof design,installation,and performance.展开更多
Design frequently involves making tradeoffs to obtain the“optimal”solution to a design problem,often using intuition or past experience as a guide.Since vegetated roofing is a relatively complex and comparatively ne...Design frequently involves making tradeoffs to obtain the“optimal”solution to a design problem,often using intuition or past experience as a guide.Since vegetated roofing is a relatively complex and comparatively new technology to many practitioners,a rational,explicit method to help organize and rank the tradeoffs made during the design process is needed.This research comprises the creation of a framework diagramming the decision process involved in the selection of vegetated roofi ng systems.Through literature review,case studies and interviews with experts,the available knowledge is captured and organized to determine the critical parameters affecting design decisions.Six important evaluative categories are identifi ed and parameters within these categories are addressed in the context of a decision support system for green roof designers.A summation of the total importance of the advantages represented by each alternative is used to determine the most feasible green roof system for a particular project.The framework is demonstrated and compared with green roof designers’decision-making processes and conclusions are drawn regarding its effectiveness.展开更多
The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains lar...The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.展开更多
To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the consi...To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.展开更多
The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated...The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.展开更多
This study analyzes the energy impact of applying green roofs on flat roofs of existing buildings,assessing their potential to reduce the demand for non-renewable primary energy for heating and cooling.Through dynamic...This study analyzes the energy impact of applying green roofs on flat roofs of existing buildings,assessing their potential to reduce the demand for non-renewable primary energy for heating and cooling.Through dynamic numerical simulations conducted on two real buildings located near Florence,Italy,and modeled in 130 different European locations,with a particular focus on the Mediterranean climate,it was possible to quantify the energy benefits derived from the application of green roofs on existing structures.The results show that,while the effect on heating is limited,with an average reduction in energy demand of only a few percentage points,the impact on cooling is significantly more pronounced,with average savings of 20%in non-renewable primary energy,particularly in Mediterranean climates with high CDD(cooling degree days)values.The study confirms that green roofs can be an effective solution to improve the energy efficiency of existing buildings with flat roofs in the Mediterranean climate,in line with European goals for reducing CO_(2) emissions and promoting renewable energy.展开更多
Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formati...Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.展开更多
The effectiveness of horizontal well multi-stage and multi-cluster fracturing in the fractured soft coal seam roof for coalbed methane(CBM) extraction has been demonstrated.This study focuses on the geological charact...The effectiveness of horizontal well multi-stage and multi-cluster fracturing in the fractured soft coal seam roof for coalbed methane(CBM) extraction has been demonstrated.This study focuses on the geological characteristics of the No.5 and No.11 coal seams in the Hancheng Block,Ordos Basin,China.A multi-functional,variable-size rock sample mold capable of securing the wellbore was developed to simulate layered formations comprising strata of varying lithology and thicknesses.A novel segmented fracturing simulation method based on an expandable pipe plugging technique is proposed.Large-scale true triaxial experiments were conducted to investigate the effects of horizontal wellbore location,perforation strategy,roof lithology,and vertical stress difference on fracture propagation,hydraulic energy variation,and the stimulated reservoir volume in horizontal wells targeting the soft coal seam roof.The results indicate that bilateral downward perforation with a phase angle of 120° optimizes hydraulic energy conservation,reduces operational costs,enhances fracture formation,and prevents fracturing failure caused by coal powder generation and migration.This perforation mode is thus considered optimal for coal seam roof fracturing.When the roof consists of sandstone,each perforation cluster tends to initiate a single dominant fracture with a regular geometry.In contrast,hydraulic fractures formed in mudstone roofs display diverse morphology.Due to its high strength,the sandstone roof requires significantly higher pressure for crack initiation and propagation,whereas the mudstone roof,with its strong water sensitivity,exhibits lower fracturing pressures.To mitigate inter-cluster interference,cluster spacing in mudstone roofs should be greater than that in sandstone roofs.Horizontal wellbore placement critically influences fracturing effectiveness.For indirect fracturing in sandstone roofs,an optimal position is 25 mm away from the lithological interface.In contrast,the optimal location for indirect fracturing in mudstone roofs is directly at the lithological interface with the coal seam.Higher vertical stress coefficients lead to increased fractu ring pressures and promote vertical,layer-penetrating fractures.A coefficient of 0.5 is identified as optimal for achieving effective indirect fracturing.This study provides valuable insights for the design and optimization of staged fracturing in horizontal wells targeting crushed soft coal seam roofs.展开更多
As complex and diverse ecosystems,cities encounter numerous challenges posed by both nature and humanity.Architecture,serving as the framework and texture of the city,has undoubtedly emerged as a crucial guide in addr...As complex and diverse ecosystems,cities encounter numerous challenges posed by both nature and humanity.Architecture,serving as the framework and texture of the city,has undoubtedly emerged as a crucial guide in addressing urban resilience issues.Roof greening and vertical greening of buildings,as ecofriendly urban green infrastructures,hold significant potential for mitigating these challenges.This paper explores the methods and strategies for implementing roof greening and vertical greening as solutions to enhance urban resilience.The objective is to offer valuable insights for sustainable urban development,encourage the widespread adoption of these greening techniques in urban construction,and ultimately strengthen urban resilience.展开更多
Gas explosions in coal mine goafs are associated with the roof rock fracturing.An experimental system was established to investigate the potential for electrical ignition induced by sandstone fracturing.The electrical...Gas explosions in coal mine goafs are associated with the roof rock fracturing.An experimental system was established to investigate the potential for electrical ignition induced by sandstone fracturing.The electrical responses,luminescent emissions,and ignition characteristics during tensile and compressive failure of sandstones were analyzed in methane/air premixed gas environments.Results indicate that the application of mechanical loading induces the emergence of electrical signals on rock surfaces and in the surrounding atmosphere.This phenomenon is attributed to the generation,accumulation,and subsequent release of free charges during the deformation and fracture within the sandstone.Compressive failure proved to be more conducive to free charge generation than tensile failure,owing to more crack connections.Furthermore,a precipitous increase in surface and external voltages was observed during complete fracturing,a consequence of electron emission from crack tips within the rock structure.Moreover,the ionization induces luminous emissions owing to the collision of energetic electrons released from gas molecules in methane/air mixtures.A strong positive correlation(R2=0.9429)was identified between luminescence intensity and the magnitude of electrical discharge resulting from rock fracture.Notably,such discharge by rock fracturing can be capable of igniting the premixed gas,particularly when the quartz content exceeds 61%.Piezoelectric effects and crack propagation are crucial mechanisms in the causal chain of the charge generation,discharge,and ionization triggered by rock fractures.Based on the above laboratory results,electric ignition of the transient roof fracturing caused by stress mutations can serve as a new potential ignition source for gas explosions in the goaf.These results offer new insights into the prevention and control of gas explosions.展开更多
With an average elevation of over 4,500 meters and spanning 2.5 million square km,the Qinghai-Xizang Plateau is the highest and largest plateau on Earth,earning it the title the"roof of the world".Un surpris...With an average elevation of over 4,500 meters and spanning 2.5 million square km,the Qinghai-Xizang Plateau is the highest and largest plateau on Earth,earning it the title the"roof of the world".Un surprisingly,the plateau is home to exceptional biodiversity,making it one of the most biologically rich geographical regions in the world.展开更多
文摘Phillip Katuve,a landlord who owns a six-storey apartment complex in Kileleshwa,an upmarket Nairobi suburb,embraced green roofing two years ago.His building now boasts a vibrant rooftop garden with integrated solar panels,supplying energy to all 24 units.“Initially,the idea sounded expensive,but the long-term benefits have been remarkable,”said Katuve.
基金grateful to the Foundation for the Scientific Research(FWO)from the Flanders Government,Belgium,for his Pegasus Marie Curie Fellowship.
文摘The Iberian Peninsula is,nowadays,the main producer of roofing slate of the world.Most of the outcrops are located in the NW of the Iberian Peninsula,in the regions of Galicia,Leon,and in Portugal.The technique of working and roofing with slate was brought from Flanders by King Felipe II by the second half of the XVI century.The most representative building from this period is the Monastery of El Escorial,N Madrid.However,the Spanish slate industry remained incipient until the 1960s,when Galicia and Leon suffered an accelerated industrialization process which greatly enhanced the volume of production.Additionally,the Portuguese slate industry was well developed by the second half of the XIX century.Most of the Portuguese production was exported,mainly to the United Kingdom.By the second half of the XX century,the Spanish,and in a lesser extent,the Portuguese roofing slate spread all over Europe,forcing most of the existing European quarries to close.Nowadays,different varieties of roofing slates are quarried,mainly in Spain,being used indistinctly in new residential construction and for restoration of historical buildings.The main importing countries are France,Germany and the United Kingdom.This work presents an overview of the history and main varieties of the Iberian roofing slate,in order to propose its inclusion as a Global Heritage Stone Province.
文摘In the construction of civil engineering projects, the application of roofing waterproof technology is a key construction content that should be paid attention to based on the safety and convenience of the application of building construction after the completion of the basic frame construction of the building entity and the core project of the entity part construction. In the concrete implementation of roofing waterproof construction, professional technology needs to be applied, and the application of waterproof technology should be assisted to achieve good waterproof effect in combination with the construction technology requirements of each link of roofing. Specifically, in civil engineering projects, the application of roofing waterproof technology needs to find targeted waterproof technology in combination with different building entity areas. In addition, the quality control of raw materials in waterproof construction, construction of waterproof layer, design and construction of drainage system may affect the application effect of waterproof construction technology. Based on this, it is necessary for construction personnel and management personnel to guarantee the effective application of waterproof technology from the aspects of raw material construction technology and construction management.
基金Project(51174192)supported by the National Natural Science Foundation of ChinaProject(BRA2010024)supported by "333" Training Foundation of Jiangsu Province,China+2 种基金Projects(2011QNB03,2014ZDPY21,2014QNB30)supported by the Fundamental Research Funds for the Central Universities,ChinaProject Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,ChinaProject(2015M581896)supported by China Postdoctoral Science Foundation
文摘The mining space of large mining height coal face is large,the range of movement and caving of rock strata is large and the stability of supports at coal face is low and damage rate of supports is high,which significantly affects the safe and efficient production of coal mines.By similar simulation experiment and theoretical analysis,the mode of fractured roofing structure of large mining height coal face and the method of determination of reasonable support resistance of the support was evaluated.Analysis shows that the structural mode of "combined cantilever beam – non-hinged roofing – hinged roofing" of the large mining height coal face appears at the roofing of large mining height coal face.The supporting factor of caved gangue at the gob is introduced,the calculating equations of the fractured step distance of roofing were derived and conventional calculating method of caved height of roofing was corrected and the method of determination of the length and height of each structural area of the roofing was provided.With reference to the excavating conditions at Jinhuagong coal mine in Datong minefield,the dimensions of structural areas of the roofing of the coal face were determined and analyzed,and reasonable support resistance of the height coal face was acquired.By selecting Model ZZ13000/28/60 support and with procedures of advanced pre-cracking blasting,the safe production of large mining height coal face was assured.
基金The authors would like to thank the Thailand Science Research and Innovation(TSRI),Faculty of Science,Naresuan University for providing financial support to this research work,and our research center.
文摘This work focused on characterizing and improving the thermal behavior of metal sheet roofing.To decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change materials,with different melting points:PCMІ,PCM II,PCM III and PCM IV,when used in conjunction with a sheet metal roof.The exterior metal roofing surface temperature was held constant at 50℃,60℃,70℃and 80℃,using a thermal source(halogen lights)for 360 min to investigate and compare the thermal performance of the metal sheet roofing with and without phase change materials for each condition.The thermal behaviors of the phase change materials were analyzed by differential scanning calorimeter(DSC).The results showed the melting points of PCMІ,PCM II,PCM III and PCM IV were around 45℃,50℃,55℃and 59℃,respectively.The integration of PCM IV into the metal roofing sheet increased the thermal performance by reducing the room temperature up to 2.8%,1.4%,1.0%and 0.7%when compared with the normal metal roof sheet,at the controlled temperatures of 50℃,60℃,70℃and 80℃,respectively.The thermal absorption of the phase change materials also caused a time delay in the model room reaching a steady temperature.The integration of phase change materials with metal roofing sheets resulted in better thermal performance and conservation of electrical energy by reducing the demand for cooling.
文摘In architecture, in the past, different materials were used for covering of the buildings. The selection of the type of roofing depended on the purpose and size of the building; thus all the churches, administrative buildings and important medieval buildings were originally covered with stone or lead slabs as the final roofing material. The tendency of return of stone as an authentic roofing in the reconstruction of medieval buildings and churches, as well as the introduction of stone as a roofing on the new buildings in protected historic cores, is possible only if fulfilled modem principles and requirements of the physics of construction. The application of modem principles of double ventilated roofs and the use of stone as a roofing enables the restoration and preservation of the original appearance of medieval buildings, as well as the preservation and conservation of existing frescoes that have been present for centuries in these facilities. It also enables a successful reconstruction of a large number of medieval buildings. In this way it has been given a contribution to the preservation of old medieval buildings as the improvement of world cultural heritage.
基金financial support of the National Key Research and Development Program of China(No.2017YFC0703803)the Joint Usage/Research Center(JURC)project“Wind-induced Load Estimation for Clips of Standing-seam Roofing System Considering Dynamic Characteristics”from Tokyo Polytechnic University(2018 FY)the National Natural Science Foundation of China(Grant No.51978500).
文摘This paper mainly focuses on the establishment of an effective static estimation method for the extreme wind-induced force for clips between purlins and metal panels of the standing-seam metal roofing system(hereinafter referred to as SMRS)of typical double-slope light-weight steel portal frame structure considering dynamic characteristics of wind and structure.First,simultaneous pressure measurement with rigid gable roof models was conducted mainly considering the length-span ratio in the boundary layer wind tunnel of Tokyo Polytechnic University,Japan.Then,finite element modeling for SMRS according to the wind load path in the roofing system was carried out to check the actual wind load of the clips based on the traditional calculation method provided in design codes,and the spatial correlation of fluctuating wind pressure on the roof surface,as well as the dynamic effect of the roof structure itself,had been considered.According to the related Chinese,American,and Japanese codes,a magnification coefficient based on the traditional method of static wind-induced force for the clips was calculated and compared.Finally,a simplified estimation method of effective wind-induced force for the clips in typical zones on the roof surface considering dynamic characteristics was proposed.
基金supported by the National Natural Science Foundation of China(Grant No.52178342)the Tianjin Natural Science Foundation(No.21JCZDJC00590)the Shanghai Excellent Academic/Technical Leader Program(No.20XD1432500).
文摘The pipe roofing method is widely used in tunnel construction because it can realize a flexible section shape and a large section area of the tunnel,especially under good ground conditions.However,the pipe roofing method has rarely been applied in soft ground,where the prediction and control of the ground settlement play important roles.This study proposes a sliced-soil-beam(SSB)model to predict the settlement of ground due to tunnelling using the pipe roofing method in soft ground.The model comprises a sliced-soil module based on the virtual work principle and a beam module based on structural mechanics.As part of this work,the Peck formula was modified for a square-section tunnel and adopted to construct a deformation mechanism of soft ground.The pipe roofing system was simplified to a threedimensional Winkler beam to consider the interaction between the soil and pipe roofing.The model was verified in a case study conducted in Shanghai,China,in which it provided the efficient and accurate prediction of settlement.Finally,the parameters affecting the ground settlement were analyzed.It was clarified that the stiffness of the excavated soil and the steel support are the key factors in reducing ground settlement.
文摘Increase of indoor temperature compared with outdoor temperature is a major concern in modern house design. Occupants suffer from this uncomfortable condition because of overheating indoor temperature. Poor passive design causes heat to be trapped, which influences the rise in indoor temperature. The upper part, which covers the area of the roof, is the most critical part of the house that is exposed to heat caused by high solar radiation and high emissivity levels. During daytime, the roof accumulates heat, which increases the indoor temperature and affects the comfort level of the occupants. To maintain the indoor temperature within the comfort level, most house designs usually depend on mechanical means by using fans or air conditioning systems. The dependence on a mechanical ventilation system could lead to additional costs for its installation, operation, and maintenance. Thus, this study concentrates on reviews on passive design and suggests recommendations for future developments. New proposals or strategies are proposed to improve the current passive design through ventilated and cool roof systems. It is possible to achieve the comfort level inside a house throughout the day by reducing the transmitted heat into the indoor environment and eliminating the internal hot air. These recommendations could become attractive strategies in providing a comfortable indoor temperature to the occupants as well as in minimizing energy consumption.
文摘Green roof technology and implementation are taking root in North America at an accelerating pace.Growing recogni-tion of the benefits of green roofs and increasing interest in green infrastructure are leading to expansion of green roof tech-nologies that have been in use for decades in Europe and elsewhere.While some regions have adopted the use of green roofs on a large scale,other areas are warming up to the concept more slowly.Large-scale implementation of green roofs has not yet occurred in Indiana,but a number of exemplary projects have been constructed,and there are signs that interest in the technology is increasing in the state.The purpose of this article is to provide an overview of green roof technology,analyze selected green roofs in Indiana,explore trends in the state,and address issues for future development of green roof technol-ogy in the region.A variety of green roofs were investigated throughout the state.Discussions were held with individuals involved in each project to obtain technical and logistical details of green roof design,installation,and performance.
文摘Design frequently involves making tradeoffs to obtain the“optimal”solution to a design problem,often using intuition or past experience as a guide.Since vegetated roofing is a relatively complex and comparatively new technology to many practitioners,a rational,explicit method to help organize and rank the tradeoffs made during the design process is needed.This research comprises the creation of a framework diagramming the decision process involved in the selection of vegetated roofi ng systems.Through literature review,case studies and interviews with experts,the available knowledge is captured and organized to determine the critical parameters affecting design decisions.Six important evaluative categories are identifi ed and parameters within these categories are addressed in the context of a decision support system for green roof designers.A summation of the total importance of the advantages represented by each alternative is used to determine the most feasible green roof system for a particular project.The framework is demonstrated and compared with green roof designers’decision-making processes and conclusions are drawn regarding its effectiveness.
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20242059)the Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province(PCMGH-2023-02)the opening fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105827-FW202209)are gratefully acknowledged.
文摘The stability and fracture behavior of a goaf roof beneath an open-pit bench are critical concerns,especially under impact loading.However,the effect of the thickness-to-span ratio on dynamic failure modes remains largely unexplored,as existing research focuses mainly on static stability.Energy dissipation and instability evolution under impact loading require further study.To address this gap,this study conducts drop-weight impact experiments on specimens with circular perforations,complemented by numerical simulations.By integrating dimensional analysis,cusp catastrophe theory,and strength reduction techniques,the dynamic instability mechanism of goaf roofs with varying thickness-to-span ratios is revealed.Results show that the thickness-to-span ratio significantly influences energy accumulation and dissipation during roof failure.A higher ratio increases both the magnitude and rate of energy dissipation,particularly during crack initiation and stable propagation,while its impact diminishes in the final failure stage.Optimizing the thickness-to-span ratio within a critical range enhances structural stability,improving the safety factor by up to 83%.However,beyond a certain threshold,additional thickness yields diminishing benefits.This study provides new insights into the energy-based instability mechanism of goaf roofs under impact loads,establishing a theoretical foundation for early warning systems and optimized safety design.
基金Project(52204164) supported by the National Natural Science Foundation of ChinaProject(2023ZKPYSB01) supported by the Fundamental Research Funds for the Central Universities,China。
文摘To enhance the recuperation rate of the mine and comply with the stipulations of green mining technology, it is vital to expeditiously recuperate the coal pillar resources in the final stage, thus preventing the considerable squandering of resources. The coal pillar resource of the main roadway and its branch roadway constitutes a significant recovery subject. Its coal pillar shape is regular and possesses a considerable strike distance, facilitating the arrangement of the coal pillar recovery working face (CPRWF) for mining operations. However, for the remaining coal pillars with a thick and hard roof (THF) and multiple tectonic zones, CPRWF encounters challenges in selecting an appropriate layout, managing excessive roof pressure, and predicting mining stress. Aiming at the roadway coal pillar group with THF and multi-structural areas in specific projects, a method of constructing multi-stage CPRWF by one side gob-side entry driving (GSED) and one side roadway reusing is proposed. Through theoretical calculation of roof fracture and numerical simulation verification, combined with field engineering experience and economic analysis, the width of the narrow coal pillar (NCP) in the GSED is determined to be 10 m and the length of the CPRWF is 65 m. Concurrently, the potential safety hazard that the roof will fall asymmetrically and THF is difficult to break during CPRWF mining after GSED is analyzed and verified. Then, a control method involving the pre-cutting of the roof in the reused roadway before mining is proposed. This method has been shown to facilitate the complete collapse of THF, reduce the degree of mine pressure, and facilitate the symmetrical breaking of the roof. Accordingly, a roof-cutting scheme based on a directional drilling rig, bidirectional shaped polyvinyl chloride (PVC) pipe, and emulsion explosive was devised, and the pre-splitting of 8.2 m THF was accomplished. Field observations indicate that directional cracks are evident in the roof, the coal wall is flat during CPRWF mining, and the overall level of mining pressure is within the control range. Therefore, the combined application of GSED and roof-cutting technology for coal pillar recovery has been successfully implemented, thereby providing new insights and engineering references for the construction and pressure relief mining of CPRWF.
基金financially supported by the National Natural Science Foundation of China(Nos.52374094 and 52274086)the Climbling Project of Taishan Scholar in Shandong Province(No.tspd20210313)the Shandong Provincial Youth Innovation and Technology Support Program(No.2024KJH069)。
文摘The accumulation and release of deformation energy within the rock mass of a roadway are primary contributors to the occurrence of rock bursts.This study introduces a calculation model for the kinetic energy generated during roadway excavation,which is based on the fracture and energy states of the rock mass.The relationships among the mining depth,width of the plastic zone,rebound range of the roof and floor,stress concentration factor,and the induced kinetic energy are systematically explored.Furthermore,a rock burst risk evaluation method is proposed.The findings indicate that the energy evolution of the rock mass can be categorized into four stages:energy accumulation due to in-situ stress,energy accumulation resulting from coal compression,energy dissipation through coal plastic deformation,and energy consumption due to coal failure.The energy release from the rock mass is influenced by several factors,including mining depth,stress concentration factor,the width of the plastic zone,and the rebound range of the roof and floor.Within the plastic zone of coal,the energy released per unit volume of coal and the induced kinetic energy exhibit a nonlinear increase with mining depth and stress concentration factor,while they decrease linearly as the width of the plastic zone increases.Similarly,the driving energy per unit volume of the roof and floor shows a nonlinear increase with mining depth and stress concentration factor,a linear increase with the rebound range of the roof and floor,and a linear decrease with the width of the plastic zone.A rock burst risk evaluation method is developed based on the kinetic energy model.Field observations demonstrate that this method aligns with the drilling cuttings rock burst risk assessment method,thereby confirming its validity.
文摘This study analyzes the energy impact of applying green roofs on flat roofs of existing buildings,assessing their potential to reduce the demand for non-renewable primary energy for heating and cooling.Through dynamic numerical simulations conducted on two real buildings located near Florence,Italy,and modeled in 130 different European locations,with a particular focus on the Mediterranean climate,it was possible to quantify the energy benefits derived from the application of green roofs on existing structures.The results show that,while the effect on heating is limited,with an average reduction in energy demand of only a few percentage points,the impact on cooling is significantly more pronounced,with average savings of 20%in non-renewable primary energy,particularly in Mediterranean climates with high CDD(cooling degree days)values.The study confirms that green roofs can be an effective solution to improve the energy efficiency of existing buildings with flat roofs in the Mediterranean climate,in line with European goals for reducing CO_(2) emissions and promoting renewable energy.
基金Project(2022XDHZ12)supported by the Lvliang Technology Project,ChinaProjects(8232056,2232080)supported by the Beijing Natural Science Foundation,ChinaProject([2020]3008)supported by the Science and Technology Projects in Guizhou Province,China。
文摘Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.
基金support from China National Natural Science Foundation (11672333)。
文摘The effectiveness of horizontal well multi-stage and multi-cluster fracturing in the fractured soft coal seam roof for coalbed methane(CBM) extraction has been demonstrated.This study focuses on the geological characteristics of the No.5 and No.11 coal seams in the Hancheng Block,Ordos Basin,China.A multi-functional,variable-size rock sample mold capable of securing the wellbore was developed to simulate layered formations comprising strata of varying lithology and thicknesses.A novel segmented fracturing simulation method based on an expandable pipe plugging technique is proposed.Large-scale true triaxial experiments were conducted to investigate the effects of horizontal wellbore location,perforation strategy,roof lithology,and vertical stress difference on fracture propagation,hydraulic energy variation,and the stimulated reservoir volume in horizontal wells targeting the soft coal seam roof.The results indicate that bilateral downward perforation with a phase angle of 120° optimizes hydraulic energy conservation,reduces operational costs,enhances fracture formation,and prevents fracturing failure caused by coal powder generation and migration.This perforation mode is thus considered optimal for coal seam roof fracturing.When the roof consists of sandstone,each perforation cluster tends to initiate a single dominant fracture with a regular geometry.In contrast,hydraulic fractures formed in mudstone roofs display diverse morphology.Due to its high strength,the sandstone roof requires significantly higher pressure for crack initiation and propagation,whereas the mudstone roof,with its strong water sensitivity,exhibits lower fracturing pressures.To mitigate inter-cluster interference,cluster spacing in mudstone roofs should be greater than that in sandstone roofs.Horizontal wellbore placement critically influences fracturing effectiveness.For indirect fracturing in sandstone roofs,an optimal position is 25 mm away from the lithological interface.In contrast,the optimal location for indirect fracturing in mudstone roofs is directly at the lithological interface with the coal seam.Higher vertical stress coefficients lead to increased fractu ring pressures and promote vertical,layer-penetrating fractures.A coefficient of 0.5 is identified as optimal for achieving effective indirect fracturing.This study provides valuable insights for the design and optimization of staged fracturing in horizontal wells targeting crushed soft coal seam roofs.
文摘As complex and diverse ecosystems,cities encounter numerous challenges posed by both nature and humanity.Architecture,serving as the framework and texture of the city,has undoubtedly emerged as a crucial guide in addressing urban resilience issues.Roof greening and vertical greening of buildings,as ecofriendly urban green infrastructures,hold significant potential for mitigating these challenges.This paper explores the methods and strategies for implementing roof greening and vertical greening as solutions to enhance urban resilience.The objective is to offer valuable insights for sustainable urban development,encourage the widespread adoption of these greening techniques in urban construction,and ultimately strengthen urban resilience.
基金supported by the National Natural Science Foundation of China(Nos.52130411,52174219 and 52174220)the Natural Science Foundation of Jiangsu Province(No.BK20240104)the Fundamental Research Funds for the Central Universities(No.2024-11044).
文摘Gas explosions in coal mine goafs are associated with the roof rock fracturing.An experimental system was established to investigate the potential for electrical ignition induced by sandstone fracturing.The electrical responses,luminescent emissions,and ignition characteristics during tensile and compressive failure of sandstones were analyzed in methane/air premixed gas environments.Results indicate that the application of mechanical loading induces the emergence of electrical signals on rock surfaces and in the surrounding atmosphere.This phenomenon is attributed to the generation,accumulation,and subsequent release of free charges during the deformation and fracture within the sandstone.Compressive failure proved to be more conducive to free charge generation than tensile failure,owing to more crack connections.Furthermore,a precipitous increase in surface and external voltages was observed during complete fracturing,a consequence of electron emission from crack tips within the rock structure.Moreover,the ionization induces luminous emissions owing to the collision of energetic electrons released from gas molecules in methane/air mixtures.A strong positive correlation(R2=0.9429)was identified between luminescence intensity and the magnitude of electrical discharge resulting from rock fracture.Notably,such discharge by rock fracturing can be capable of igniting the premixed gas,particularly when the quartz content exceeds 61%.Piezoelectric effects and crack propagation are crucial mechanisms in the causal chain of the charge generation,discharge,and ionization triggered by rock fractures.Based on the above laboratory results,electric ignition of the transient roof fracturing caused by stress mutations can serve as a new potential ignition source for gas explosions in the goaf.These results offer new insights into the prevention and control of gas explosions.
文摘With an average elevation of over 4,500 meters and spanning 2.5 million square km,the Qinghai-Xizang Plateau is the highest and largest plateau on Earth,earning it the title the"roof of the world".Un surprisingly,the plateau is home to exceptional biodiversity,making it one of the most biologically rich geographical regions in the world.
