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
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
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 CO₂emissions 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
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
The present paper investigates the methods for estimating the maximum(positive)and the minimum(negative)peak wind force coefficients on domed free roofs based on the quasi-steady theory and the peak factor method,in w...The present paper investigates the methods for estimating the maximum(positive)and the minimum(negative)peak wind force coefficients on domed free roofs based on the quasi-steady theory and the peak factor method,in which the experimental results obtained from our previous studies(2019,2025)are used.Focus is on the distributions of the peak wind force coefficients along the centerline parallel to the wind direction considering that domed free roof is an axisymmetric body.Empirical formulas are provided to the distributions of mean wind force coefficient,RMS(root mean square)fluctuating wind force coefficient and peak factors as a function of the rise/span ratio of the roof and the turbulence intensity of the approach flow in the along-wind direction at the mean roof height.The proposed methods are validated by the experimental results for the peak wind force coefficients.The methods would provide useful information to structural engineers when estimating the design wind loads on cladding/components of domed free roofs.展开更多
This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utiliz...This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utilizing an engineering case from a gold mine in Dandong, China, a laboratory-based similar test is conducted to extract the actual roof characteristic curve. This test continues until the mining stope collapses due to a U-shaped failure. Concurrently, a semi-theoretical method for obtaining the roof characteristic curve is proposed and verified against the actual curve. The semi-theoretical method calculated that the support force and vertical displacement at the demarcation point between the elastic and plastic zones of the roof characteristic curve are 5.0 MPa and 8.20 mm, respectively, corroborating well with the laboratory-based similar test results of 0.22 MPa and 0.730 mm. The weakening factor for the plastic zone in the roof characteristic curve was semi-theoretically estimated to be 0.75. The intersection between the actual roof characteristic curve and the support characteristic curves of expandable props, natural pillars, and concrete props indicates that the expandable prop is the most effective “yielding support” for the stope roof in room-and-pillar mining. That is, the deformation and failure of the stope roof can be effectively controlled with proper release of roof stress. This study provides practical insights for optimizing support strategies in room-and-pillar mining, enhancing the safety and efficiency of mining operations.展开更多
The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying t...The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.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
Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large de...Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large deformation and roof collapse.Four-point bending tests were conducted on anchored double-layer rock beams with different pre tightening force and upper/lower rock strength ratios(Ⅰ/Ⅱ)based on the digital speckle correlation method(DSCM).The research results indicate that the instability process of anchored roof can be divided into stages of elastic deformation,crack propagation,alternating fracture,and failure collapse.The proportion of crack propagation and alternating fracture processes increased with the increase of pre-tightening force and Ⅰ/Ⅱ.The pre-tightening force can suppress the sliding of the upper/lower rock interface,and delay the initiation and propagation of cracks.As Ⅰ/Ⅱ increases,the failure mode changes from tensile failure steel strip to shear failure anchor rod.Steel strip can improve the continued bearing effect of anchored roof during crack propagation and alternating fracture processes.展开更多
Considering the characteristics of deep thick top coal roadway,in which the high ground stress,coal seam with low strength,and a large range of surrounding rock fragmentation,the pressure relief anchor box beam suppor...Considering the characteristics of deep thick top coal roadway,in which the high ground stress,coal seam with low strength,and a large range of surrounding rock fragmentation,the pressure relief anchor box beam support system with high strength is developed.The high-strength bearing characteristics and coupling yielding support mechanism of this support system are studied by the mechanical tests of composite members and the combined support system.The test results show that under the coupling effect of support members,the peak stress of the box-shaped support beam in the anchor box beam is reduced by 21.9%,and the average deformation is increased by 135.0%.The ultimate bending bearing capacity of the box-shaped support beam is 3.5 times that of traditional channel beam.The effective compressive stress zone applied by the high prestressed cable is expanded by 26.4%.On this basis,the field support comparison test by the anchor channel beam,the anchor I-shaped beam and the anchor box beam are carried out.Compared with those of the previous two,the surrounding rock convergence of the latter is decreased by 41.2%and 22.2%,respectively.The field test verifies the effectiveness of the anchor box beam support system.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.
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.
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 CO₂emissions 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.
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.
文摘The present paper investigates the methods for estimating the maximum(positive)and the minimum(negative)peak wind force coefficients on domed free roofs based on the quasi-steady theory and the peak factor method,in which the experimental results obtained from our previous studies(2019,2025)are used.Focus is on the distributions of the peak wind force coefficients along the centerline parallel to the wind direction considering that domed free roof is an axisymmetric body.Empirical formulas are provided to the distributions of mean wind force coefficient,RMS(root mean square)fluctuating wind force coefficient and peak factors as a function of the rise/span ratio of the roof and the turbulence intensity of the approach flow in the along-wind direction at the mean roof height.The proposed methods are validated by the experimental results for the peak wind force coefficients.The methods would provide useful information to structural engineers when estimating the design wind loads on cladding/components of domed free roofs.
基金Project(2022YFC2903801) supported by the National Key Research and Development Program of ChinaProjects(52374117, 52274115) supported by the National Natural Science Foundation of China。
文摘This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utilizing an engineering case from a gold mine in Dandong, China, a laboratory-based similar test is conducted to extract the actual roof characteristic curve. This test continues until the mining stope collapses due to a U-shaped failure. Concurrently, a semi-theoretical method for obtaining the roof characteristic curve is proposed and verified against the actual curve. The semi-theoretical method calculated that the support force and vertical displacement at the demarcation point between the elastic and plastic zones of the roof characteristic curve are 5.0 MPa and 8.20 mm, respectively, corroborating well with the laboratory-based similar test results of 0.22 MPa and 0.730 mm. The weakening factor for the plastic zone in the roof characteristic curve was semi-theoretically estimated to be 0.75. The intersection between the actual roof characteristic curve and the support characteristic curves of expandable props, natural pillars, and concrete props indicates that the expandable prop is the most effective “yielding support” for the stope roof in room-and-pillar mining. That is, the deformation and failure of the stope roof can be effectively controlled with proper release of roof stress. This study provides practical insights for optimizing support strategies in room-and-pillar mining, enhancing the safety and efficiency of mining operations.
基金Project(52204164)supported by the National Natural Science Foundation of ChinaProject(2021QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.
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Project(SDAST2024QT060)supported by the Young Talent of Lifting Engineering for Science and Technology in Shandong,ChinaProjects(52304136,52304149,52204093)supported by the National Natural Science Foundation of China+1 种基金Project(ZR2022ME165)supported by the Shandong Provincial Natural Science Foundation,ChinaProject(2023YD02)supported by the Key Project of Research and Development in Liaocheng,China。
文摘Affected by the geological characteristics of coal bearing strata in western mining areas of China,the double soft composite roof has low strength and poor integrity,which is prone to induce disasters such as large deformation and roof collapse.Four-point bending tests were conducted on anchored double-layer rock beams with different pre tightening force and upper/lower rock strength ratios(Ⅰ/Ⅱ)based on the digital speckle correlation method(DSCM).The research results indicate that the instability process of anchored roof can be divided into stages of elastic deformation,crack propagation,alternating fracture,and failure collapse.The proportion of crack propagation and alternating fracture processes increased with the increase of pre-tightening force and Ⅰ/Ⅱ.The pre-tightening force can suppress the sliding of the upper/lower rock interface,and delay the initiation and propagation of cracks.As Ⅰ/Ⅱ increases,the failure mode changes from tensile failure steel strip to shear failure anchor rod.Steel strip can improve the continued bearing effect of anchored roof during crack propagation and alternating fracture processes.
基金Project(2023YFC2907600)supported by the National Key Research and Development Program of ChinaProjects(42277174,42477166)supported by the National Natural Science Foundation of China+1 种基金Project(2024JCCXSB01)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(KFJJ24-01M)supported by the State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology,China。
文摘Considering the characteristics of deep thick top coal roadway,in which the high ground stress,coal seam with low strength,and a large range of surrounding rock fragmentation,the pressure relief anchor box beam support system with high strength is developed.The high-strength bearing characteristics and coupling yielding support mechanism of this support system are studied by the mechanical tests of composite members and the combined support system.The test results show that under the coupling effect of support members,the peak stress of the box-shaped support beam in the anchor box beam is reduced by 21.9%,and the average deformation is increased by 135.0%.The ultimate bending bearing capacity of the box-shaped support beam is 3.5 times that of traditional channel beam.The effective compressive stress zone applied by the high prestressed cable is expanded by 26.4%.On this basis,the field support comparison test by the anchor channel beam,the anchor I-shaped beam and the anchor box beam are carried out.Compared with those of the previous two,the surrounding rock convergence of the latter is decreased by 41.2%and 22.2%,respectively.The field test verifies the effectiveness of the anchor box beam support system.
