The main aspects that require attention in tunnel design in terms of safety and economy are the precise estimation of probable ground conditions and ground behavior during construction. The variation in rock mass beha...The main aspects that require attention in tunnel design in terms of safety and economy are the precise estimation of probable ground conditions and ground behavior during construction. The variation in rock mass behavior due to tunnel excavation sequence plays an important role during the construction stage.The purpose of this research is to numerically evaluate the effect of excavation sequence on the ground behavior for the Lowari tunnel project, Pakistan. For the tunnel stability, the ground behavior observed during the actual partial face excavation sequence is compared with the top heading and bench excavation sequence. For this purpose, the intact rock parameters are used along with the characterization of rock mass joints related parameters to provide input for numerical modelling via FLAC 2D. The in-situ stresses for the numerical modelling are obtained using empirical equations. From the comparison of the two excavation sequences, it was observed that the actual excavation sequence used for Lowari tunnel construction utilized more support than the top heading and bench method. However, the actual excavation sequence provided good results in terms of stability.展开更多
This paper proposes homogenization scheme for estimating the effective thermal conductivity of fully saturated soils. This approach is based on the random checkerboard-like microstructure. Two modeling scales and two ...This paper proposes homogenization scheme for estimating the effective thermal conductivity of fully saturated soils. This approach is based on the random checkerboard-like microstructure. Two modeling scales and two modeling approaches are distinguished and used, i.e. microscale and mesoscale and 1-step and 2-step homogenizations, respectively. The 2-step homogenization involves sequential averaging procedure, i.e. first, at microscale, a mineralogical composition of soil skeleton is considered and averaging process results in estimation of the skeleton effective thermal conductivity, and then, at mesoscale, a random spatial packing of solid skeleton and pores via random checkerboard microstructure is modeled and leads to evaluation of the soil overall thermal conductivity. The 1-step homogenization starts directly at the mesoscale and homogenization procedure yields evaluation of the overall soil thermal conductivity. At the mesoscale, the distinct nature of soil skeleton, as composed of soil separates,is considered and random variability of soil is modeled via enriched random checkerboard-like structure.Both approaches, i.e. 1-step and 2-step homogenizations, interrelate mineralogical composition with the soil texture characterized by the volume fractions of soil separates, i.e. sand, silt and clay. The probability density functions(PDFs) of thermal conductivity are assumed for each of the separates. The soil texture PDF of thermal conductivity is derived taking into consideration the aforementioned functions. Whenever the random checkerboard-like structure is used in averaging process, the Monte Carlo procedure is applied for estimation of homogenized thermal conductivity. Finally, the proposed methodology is tested against the laboratory data from our measurements as well as those available from literature.展开更多
The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and en...The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.展开更多
Coal extraction in Huainan area is basically characterized by one of typical multi-seam mining conditions observed in China, where coal is mined in soft seams characterized by high gas content, high stress, low permea...Coal extraction in Huainan area is basically characterized by one of typical multi-seam mining conditions observed in China, where coal is mined in soft seams characterized by high gas content, high stress, low permeability and difficult geological conditions. The average mining depth in Huainan area is 875 m and continues to increase by 15-25 m annually. The rise in mining depth increases the risk of coal and gas outbursts and makes it more difficult to control outburst risk in Huainan coalmines. This paper reviews the main achievements（e.g. theories, technologies and equipment） in outburst control in Huainan, and tries to analyze some key challenging issues, and to present associated strategies to address these issues.It suggests that the outburst control in Huainan must take a combination approach of both regional and localized control in which the former plays a dominant role. Other outburst prevention principles include（1） non-outburst seams protecting outburst seams,（2） less outburst-prone seams protecting strong outburst-prone seams,（3） stress-releasing mining, and（4） the combination of ground and underground gas drainage（the model is dubbed as ＂walking on two legs＂）. The paper concludes that we should conduct fundamental researches on outburst mechanism, and develop outburst control technologies and equipment to ensure safe and efficient coal mining of deep coal resources in Huainan area.展开更多
The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the tha...The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the thawing degree of permafrost soils,frost heaving of clays,and groundwater flooding require careful engineering and geological surveying.The paper describes the unique,long-standing experience of the university scientists connected with maintaining the Russian EastSiberian and Trans-Baikal Railways'facilities.Specific features of and requirements for the surveying,depending on the geological and climatic conditions,are identified.展开更多
Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to inves...Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry(PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands,then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy.展开更多
Thin-walled spread foundations are used in coastal projects where the soil strength is relatively low. Developing a predictive model of bearing capacity for this kind of foundation is of interest due to the fact that ...Thin-walled spread foundations are used in coastal projects where the soil strength is relatively low. Developing a predictive model of bearing capacity for this kind of foundation is of interest due to the fact that the famous bearing capacity equations are proposed for conventional footings. Many studies underlined the applicability of artificial neural networks （ANNs） in predicting the bearing capacity of foundations. However, the majority of these models are built using conventional ANNs, which suffer from slow rate of learning as well as getting trapped in local minima. Moreover, they are mainly developed for conventional footings. The prime objective of this study is to propose an improved ANN-based predictive model of bearing capacity for thin-walled shallow foundations. In this regard, a relatively large dataset comprising 145 recorded cases of related footing load tests was compiled from the literature. The dataset includes bearing capacity （Qu）, friction angle, unit weight of sand, footing width, and thin-wall length to footing width ratio （Lw/B）. Apart from Qu, other parameters were set as model inputs. To enhance the diversity of the data, four more related laboratory footing load tests were conducted on the Johor Bahru sand, and results were added to the dataset. Experimental findings suggest an almost 0.5 times increase in the bearing capacity in loose and dense sands when LJB is increased from 0.5 to 1.12. Overall, findings show the feasibility of the ANN-based predictive model improved with particle swarm optimization （PSO）. The correlation coefficient was 0.98 for testing data, suggesting that the model serves as a reliable tool in predicting the bearing capacity.展开更多
Vibratory driving is the most efficient method of sheet pile installation. The elimination or at least reduction of harmful consequences of sheet pile vibratory driving becomes an increasingly important and often the ...Vibratory driving is the most efficient method of sheet pile installation. The elimination or at least reduction of harmful consequences of sheet pile vibratory driving becomes an increasingly important and often the decisive factor in the selection of the excavation protection technology. In difficult soil conditions with strength soil parameters, pressure water jetting precedes sheet pile driving. This technique changes the soil properties, destroying its existing structure near the installed sheet pile. Unfortunately, the results and achievements of contractors using this technique are very often held confidential or simply remain in the records and it is difficult to find papers on this subject. This article features a detailed description of jet-assisted sheet pile driving, including a prefabrication description for the sheet pile toe used to jet water through, water pressure and quantity data and the results with regard to reduce vibrations and noise, as well as to the increase in sheet pile vibratory driving performance.展开更多
In this paper, the effects of the stiffness of circular, square and strip foundation structures and bonding effects were analyzed. Presented analysis was oriented on the influence of stiffness system ＂foundation--sub...In this paper, the effects of the stiffness of circular, square and strip foundation structures and bonding effects were analyzed. Presented analysis was oriented on the influence of stiffness system ＂foundation--subsoil＂ and bonds （bi-directional bond and one-directional bond with and without friction）. The results of numerical calculations have proved that the relative stiffness of system ＂foundation--subsoil＂ affect considerably the value and the distribution of contact stresses （vertical normal and shear stresses） in the foundation gap and value of the displacements （settlement, deflection and relative deformations） of foundation. From the numerical point of view, this problem was solved by deformation variant of the FEM （finite element method）. The numerically obtained results were presented in the graphical and tabular forms. Obtained results were qualitative and quantitative compared with one another. From the calculation results it is obvious that relative stiffness of the system ＂foundation structure--subsoil＂ substantially affects distribution of contact stresses in the foundation subsoil and displacements （settlement, deflection and relative deformations, flexibility） of foundation. In the case of flexible foundations, the bond on the contact surfaces must be considered during the calculation. On the other hand, the effects of friction on the contact surface between the foundation and subsoil affect the distribution of contact stresses and deformations only to smaller extent.展开更多
Based on the concepts of social inclusion, universal design and accessibility, this paper aims to describe the stages of the development and implementation of a Web GIS （geographic information system for the internet...Based on the concepts of social inclusion, universal design and accessibility, this paper aims to describe the stages of the development and implementation of a Web GIS （geographic information system for the internet） based on OS （open source） software The Web GIS developed is called ＂accessibility to Campinas tourist attractions＂, which provides information about cultural and natural attractions in Campinas/SP-Brazil, especially for people with disabilities or reduced mobility that prevents access these sites via public and private transportation. The verification of the existence or lack of accessibility equipment at bus stops and parking areas close to tourist attractions relies on current legislation （NBR 9050/1994） that establishes the right to accessibility for disabled people to transportation, local culture and leisure. An application that facilitates this recognition with low operating costs and high performance was developed using the OS software Quantum GIS 1.0.2, Apache 2.2.4, Mapserver 5.0.2, I3GEO 4.0, PostgreSQL 8.3 and PostGIS 1.3.5. This software is able to integrate the management of tourist areas and the advertisement of tourist information regarding accessibility devices at sights recognized as tourist attractions by Campinas city hall.展开更多
This study aims to analyze the quality of positioning orthophoto generated through the technique of direct georeferencing using metric digital camera system coupled to the laser system,and both systems were aided iner...This study aims to analyze the quality of positioning orthophoto generated through the technique of direct georeferencing using metric digital camera system coupled to the laser system,and both systems were aided inertial navigation platform.For this,we compared the coordinates obtained in 16 control points collected in the field with dual-frequency GNSS(global navigation satellite system)receiver with those obtained in the orthophoto,flight conducted in June 2009 on the campus of the State University of Campinas--UNICAMP,using a medium format digital camera and laser system,with which we obtained images with a spatial resolution of 0.15 m.Taking into account the pattern accuracy cartographic used in Brazil,it is concluded that the products produced have a standard accuracy"A"to 1:2,000 scale,which represents the best quality level,both for planimetric as for altimetry,and that the procedure reached results consistent with cartographic products in 1:2,000 scale,representing a reduction of steps in the mapping process,necessary for the preparation of cartographic databases with reduction of time for preparation of design basis large civil engineering projects,such as roads,railways,studies of urban road systems,power plants and other infrastructure systems needed to develop the country.展开更多
This study was conducted to assess the performance of modified asphalt binders and engineering properties of mixtures prepared with incorporation 3 vol%and 6 vol%of calcium carbonate(CaCO3),linear low-density polyethy...This study was conducted to assess the performance of modified asphalt binders and engineering properties of mixtures prepared with incorporation 3 vol%and 6 vol%of calcium carbonate(CaCO3),linear low-density polyethylene(LLDPE),and combinations of CaCO3 and LLDPE.The rheological properties of control and modified asphalt binders were evaluated using a series of testing such as rotational viscometer(RV),multiple stress creep recovery(MSCR)and bending beam rheometer(BBR)tests.Meanwhile,four-point beam fatigue test,the dynamic modulus(E*)test and tensile strength ratio(TSR)test were conducted to assess the engineering properties of asphalt mixtures.Based on the findings,the RV and MSCR test result shows that all modified asphalt binders have improved performance in comparison to the neat asphalt binders in terms of higher viscosity and improved permanent deformation resistance.A higher amount of CaCO3 and LLDPE have led modified asphalt binders to better recovery percentage,except the asphalt binders modified using a combination of CaCO3 and LLDPE.However,the inclusion of LLDPE into asphalt binder has lowered the thermal cracking resistance.The incorporation of CaCO3 in asphalt mixtures was found beneficial,especially in improving the ability to resist fatigue cracking of asphalt mixture.In contrast,asphalt mixtures show better moisture sensitivity through the addition of LLDPE.The addition of LLDPE has significantly enhanced the indirect tensile strength values and tensile strength ratio of asphalt mixtures.展开更多
The aim of this study is to characterize soil/reinforcement interaction in reinforced earth structures. The study showed that the internal behavior of this type of structure depends on a number of factors, including t...The aim of this study is to characterize soil/reinforcement interaction in reinforced earth structures. The study showed that the internal behavior of this type of structure depends on a number of factors, including the engineering backfill, the reinforcement and the soil/reinforcement interaction. The study also showed that the soil-reinforcement interaction phenomenon is a fairly complex mechanism that depends on the applied load, the geometry of the structure, the characteristics of the soil and a set of parameters characterizing the nailing: density, number and length of reinforcements, inclination of the reinforcements in relation to the sliding surface, mechanical characteristics of the reinforcements and, in particular, the relative stiffness of the reinforcements and the soil. The results showed that the tensile forces developed in the reinforcement are not entirely reversible, and that the soil at the interface undergoes permanent deformation, leading to the appearance of irreversible tensile forces in the reinforcement.展开更多
Among the natural hazards, destructive earthquakes are the most common cause of casualties and financial losses and human deaths several times more in developing countries than developed countries. By increasing urban...Among the natural hazards, destructive earthquakes are the most common cause of casualties and financial losses and human deaths several times more in developing countries than developed countries. By increasing urbanization and construction process, construction activities and because Behbahan is a new city and is located near active faults, earthquake risk is increasing and will have disastrous results. Historical data also indicate destructive earthquakes in 1052 and 1085 with the magnitudes of 8.6 and 8.5 on the Richter scale which destroyed Arjan and killed many people. Due to frequent earthquakes in Behbahan as well as numerous small and large faults around it, the city has high seismic potential. So locating new developments and constructions should be more accurate.展开更多
IGCP Project 641(Mechanisms,Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation–M3EF3)held its second international workshop from November 2 to 6,2016,in Puerto ...IGCP Project 641(Mechanisms,Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation–M3EF3)held its second international workshop from November 2 to 6,2016,in Puerto Vallarta and included a two-day field trip to Guadalajara and Jocotepec in the Mexican state of Jalisco(Fig.1a).M3EF3 is aimed at i)understanding the mechanisms that cause the formation of“ground ruptures”,as a response to changes in the stress state in the subsoil,ii)monitoring their occurrence,and iii)developing appropriate approaches to model their formation and growth.Notice that many times it is difficult to discern whether a particular instance of a“ruptured”land surface is due to an earth fissure with a surface manifestation or a surface failure associated with the activation of a pre-existing fault,especially where a fault has not been mapped and where there is no obvious scarp.Therefore,in M3EF3 we preferred to use the term“ground rupture”,to refer to both such occurrences.展开更多
基金supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2019R1A2C2003636)
文摘The main aspects that require attention in tunnel design in terms of safety and economy are the precise estimation of probable ground conditions and ground behavior during construction. The variation in rock mass behavior due to tunnel excavation sequence plays an important role during the construction stage.The purpose of this research is to numerically evaluate the effect of excavation sequence on the ground behavior for the Lowari tunnel project, Pakistan. For the tunnel stability, the ground behavior observed during the actual partial face excavation sequence is compared with the top heading and bench excavation sequence. For this purpose, the intact rock parameters are used along with the characterization of rock mass joints related parameters to provide input for numerical modelling via FLAC 2D. The in-situ stresses for the numerical modelling are obtained using empirical equations. From the comparison of the two excavation sequences, it was observed that the actual excavation sequence used for Lowari tunnel construction utilized more support than the top heading and bench method. However, the actual excavation sequence provided good results in terms of stability.
文摘This paper proposes homogenization scheme for estimating the effective thermal conductivity of fully saturated soils. This approach is based on the random checkerboard-like microstructure. Two modeling scales and two modeling approaches are distinguished and used, i.e. microscale and mesoscale and 1-step and 2-step homogenizations, respectively. The 2-step homogenization involves sequential averaging procedure, i.e. first, at microscale, a mineralogical composition of soil skeleton is considered and averaging process results in estimation of the skeleton effective thermal conductivity, and then, at mesoscale, a random spatial packing of solid skeleton and pores via random checkerboard microstructure is modeled and leads to evaluation of the soil overall thermal conductivity. The 1-step homogenization starts directly at the mesoscale and homogenization procedure yields evaluation of the overall soil thermal conductivity. At the mesoscale, the distinct nature of soil skeleton, as composed of soil separates,is considered and random variability of soil is modeled via enriched random checkerboard-like structure.Both approaches, i.e. 1-step and 2-step homogenizations, interrelate mineralogical composition with the soil texture characterized by the volume fractions of soil separates, i.e. sand, silt and clay. The probability density functions(PDFs) of thermal conductivity are assumed for each of the separates. The soil texture PDF of thermal conductivity is derived taking into consideration the aforementioned functions. Whenever the random checkerboard-like structure is used in averaging process, the Monte Carlo procedure is applied for estimation of homogenized thermal conductivity. Finally, the proposed methodology is tested against the laboratory data from our measurements as well as those available from literature.
文摘The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.
基金the Ministry of Education, Malaysia for the MTCP scholarship awarded to the first author
文摘Coal extraction in Huainan area is basically characterized by one of typical multi-seam mining conditions observed in China, where coal is mined in soft seams characterized by high gas content, high stress, low permeability and difficult geological conditions. The average mining depth in Huainan area is 875 m and continues to increase by 15-25 m annually. The rise in mining depth increases the risk of coal and gas outbursts and makes it more difficult to control outburst risk in Huainan coalmines. This paper reviews the main achievements（e.g. theories, technologies and equipment） in outburst control in Huainan, and tries to analyze some key challenging issues, and to present associated strategies to address these issues.It suggests that the outburst control in Huainan must take a combination approach of both regional and localized control in which the former plays a dominant role. Other outburst prevention principles include（1） non-outburst seams protecting outburst seams,（2） less outburst-prone seams protecting strong outburst-prone seams,（3） stress-releasing mining, and（4） the combination of ground and underground gas drainage（the model is dubbed as ＂walking on two legs＂）. The paper concludes that we should conduct fundamental researches on outburst mechanism, and develop outburst control technologies and equipment to ensure safe and efficient coal mining of deep coal resources in Huainan area.
文摘The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the thawing degree of permafrost soils,frost heaving of clays,and groundwater flooding require careful engineering and geological surveying.The paper describes the unique,long-standing experience of the university scientists connected with maintaining the Russian EastSiberian and Trans-Baikal Railways'facilities.Specific features of and requirements for the surveying,depending on the geological and climatic conditions,are identified.
文摘Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry(PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands,then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy.
基金Project supported by the Science Fund of Malaysian Ministry of Science,Technology and Innovation(No.#4S077)
文摘Thin-walled spread foundations are used in coastal projects where the soil strength is relatively low. Developing a predictive model of bearing capacity for this kind of foundation is of interest due to the fact that the famous bearing capacity equations are proposed for conventional footings. Many studies underlined the applicability of artificial neural networks （ANNs） in predicting the bearing capacity of foundations. However, the majority of these models are built using conventional ANNs, which suffer from slow rate of learning as well as getting trapped in local minima. Moreover, they are mainly developed for conventional footings. The prime objective of this study is to propose an improved ANN-based predictive model of bearing capacity for thin-walled shallow foundations. In this regard, a relatively large dataset comprising 145 recorded cases of related footing load tests was compiled from the literature. The dataset includes bearing capacity （Qu）, friction angle, unit weight of sand, footing width, and thin-wall length to footing width ratio （Lw/B）. Apart from Qu, other parameters were set as model inputs. To enhance the diversity of the data, four more related laboratory footing load tests were conducted on the Johor Bahru sand, and results were added to the dataset. Experimental findings suggest an almost 0.5 times increase in the bearing capacity in loose and dense sands when LJB is increased from 0.5 to 1.12. Overall, findings show the feasibility of the ANN-based predictive model improved with particle swarm optimization （PSO）. The correlation coefficient was 0.98 for testing data, suggesting that the model serves as a reliable tool in predicting the bearing capacity.
文摘Vibratory driving is the most efficient method of sheet pile installation. The elimination or at least reduction of harmful consequences of sheet pile vibratory driving becomes an increasingly important and often the decisive factor in the selection of the excavation protection technology. In difficult soil conditions with strength soil parameters, pressure water jetting precedes sheet pile driving. This technique changes the soil properties, destroying its existing structure near the installed sheet pile. Unfortunately, the results and achievements of contractors using this technique are very often held confidential or simply remain in the records and it is difficult to find papers on this subject. This article features a detailed description of jet-assisted sheet pile driving, including a prefabrication description for the sheet pile toe used to jet water through, water pressure and quantity data and the results with regard to reduce vibrations and noise, as well as to the increase in sheet pile vibratory driving performance.
文摘In this paper, the effects of the stiffness of circular, square and strip foundation structures and bonding effects were analyzed. Presented analysis was oriented on the influence of stiffness system ＂foundation--subsoil＂ and bonds （bi-directional bond and one-directional bond with and without friction）. The results of numerical calculations have proved that the relative stiffness of system ＂foundation--subsoil＂ affect considerably the value and the distribution of contact stresses （vertical normal and shear stresses） in the foundation gap and value of the displacements （settlement, deflection and relative deformations） of foundation. From the numerical point of view, this problem was solved by deformation variant of the FEM （finite element method）. The numerically obtained results were presented in the graphical and tabular forms. Obtained results were qualitative and quantitative compared with one another. From the calculation results it is obvious that relative stiffness of the system ＂foundation structure--subsoil＂ substantially affects distribution of contact stresses in the foundation subsoil and displacements （settlement, deflection and relative deformations, flexibility） of foundation. In the case of flexible foundations, the bond on the contact surfaces must be considered during the calculation. On the other hand, the effects of friction on the contact surface between the foundation and subsoil affect the distribution of contact stresses and deformations only to smaller extent.
文摘Based on the concepts of social inclusion, universal design and accessibility, this paper aims to describe the stages of the development and implementation of a Web GIS （geographic information system for the internet） based on OS （open source） software The Web GIS developed is called ＂accessibility to Campinas tourist attractions＂, which provides information about cultural and natural attractions in Campinas/SP-Brazil, especially for people with disabilities or reduced mobility that prevents access these sites via public and private transportation. The verification of the existence or lack of accessibility equipment at bus stops and parking areas close to tourist attractions relies on current legislation （NBR 9050/1994） that establishes the right to accessibility for disabled people to transportation, local culture and leisure. An application that facilitates this recognition with low operating costs and high performance was developed using the OS software Quantum GIS 1.0.2, Apache 2.2.4, Mapserver 5.0.2, I3GEO 4.0, PostgreSQL 8.3 and PostGIS 1.3.5. This software is able to integrate the management of tourist areas and the advertisement of tourist information regarding accessibility devices at sights recognized as tourist attractions by Campinas city hall.
文摘This study aims to analyze the quality of positioning orthophoto generated through the technique of direct georeferencing using metric digital camera system coupled to the laser system,and both systems were aided inertial navigation platform.For this,we compared the coordinates obtained in 16 control points collected in the field with dual-frequency GNSS(global navigation satellite system)receiver with those obtained in the orthophoto,flight conducted in June 2009 on the campus of the State University of Campinas--UNICAMP,using a medium format digital camera and laser system,with which we obtained images with a spatial resolution of 0.15 m.Taking into account the pattern accuracy cartographic used in Brazil,it is concluded that the products produced have a standard accuracy"A"to 1:2,000 scale,which represents the best quality level,both for planimetric as for altimetry,and that the procedure reached results consistent with cartographic products in 1:2,000 scale,representing a reduction of steps in the mapping process,necessary for the preparation of cartographic databases with reduction of time for preparation of design basis large civil engineering projects,such as roads,railways,studies of urban road systems,power plants and other infrastructure systems needed to develop the country.
基金The authors grateful to express their appreciation to Specialty Minerals Inc.(Bethlehem,PA,USA),Payne&Dolan Inc.(Waukesha,WI,USA),and Dow Chemical Company(Midland,MI,USA)for donating test materials.The authors would like to acknowledge the research assistantships to Mohd Rosli Mohd Hasan,Mohd Khairul Idham Mohd Satar,Muhammad Naqiuddin Mohd Warid,and Nurul Hidayah Mohd Kamaruddin.The authors also want to acknowledge Julia A.King from the Department of Chemical Engineering of Michigan Technological University for her significant contributions in materials preparation,test design,and paper revision.It is impossible for the authors to complete the work without her effort.Any opinions,findings and conclusions expressed in this paper are those of the authors’and do not necessarily reflect the views of the official views and policies of any institution or company.
文摘This study was conducted to assess the performance of modified asphalt binders and engineering properties of mixtures prepared with incorporation 3 vol%and 6 vol%of calcium carbonate(CaCO3),linear low-density polyethylene(LLDPE),and combinations of CaCO3 and LLDPE.The rheological properties of control and modified asphalt binders were evaluated using a series of testing such as rotational viscometer(RV),multiple stress creep recovery(MSCR)and bending beam rheometer(BBR)tests.Meanwhile,four-point beam fatigue test,the dynamic modulus(E*)test and tensile strength ratio(TSR)test were conducted to assess the engineering properties of asphalt mixtures.Based on the findings,the RV and MSCR test result shows that all modified asphalt binders have improved performance in comparison to the neat asphalt binders in terms of higher viscosity and improved permanent deformation resistance.A higher amount of CaCO3 and LLDPE have led modified asphalt binders to better recovery percentage,except the asphalt binders modified using a combination of CaCO3 and LLDPE.However,the inclusion of LLDPE into asphalt binder has lowered the thermal cracking resistance.The incorporation of CaCO3 in asphalt mixtures was found beneficial,especially in improving the ability to resist fatigue cracking of asphalt mixture.In contrast,asphalt mixtures show better moisture sensitivity through the addition of LLDPE.The addition of LLDPE has significantly enhanced the indirect tensile strength values and tensile strength ratio of asphalt mixtures.
文摘The aim of this study is to characterize soil/reinforcement interaction in reinforced earth structures. The study showed that the internal behavior of this type of structure depends on a number of factors, including the engineering backfill, the reinforcement and the soil/reinforcement interaction. The study also showed that the soil-reinforcement interaction phenomenon is a fairly complex mechanism that depends on the applied load, the geometry of the structure, the characteristics of the soil and a set of parameters characterizing the nailing: density, number and length of reinforcements, inclination of the reinforcements in relation to the sliding surface, mechanical characteristics of the reinforcements and, in particular, the relative stiffness of the reinforcements and the soil. The results showed that the tensile forces developed in the reinforcement are not entirely reversible, and that the soil at the interface undergoes permanent deformation, leading to the appearance of irreversible tensile forces in the reinforcement.
文摘Among the natural hazards, destructive earthquakes are the most common cause of casualties and financial losses and human deaths several times more in developing countries than developed countries. By increasing urbanization and construction process, construction activities and because Behbahan is a new city and is located near active faults, earthquake risk is increasing and will have disastrous results. Historical data also indicate destructive earthquakes in 1052 and 1085 with the magnitudes of 8.6 and 8.5 on the Richter scale which destroyed Arjan and killed many people. Due to frequent earthquakes in Behbahan as well as numerous small and large faults around it, the city has high seismic potential. So locating new developments and constructions should be more accurate.
基金contribution of IGCP project 641 sponsored by UNESCO-IUGS.
文摘IGCP Project 641(Mechanisms,Monitoring and Modeling Earth Fissure generation and Fault activation due to subsurface Fluid exploitation–M3EF3)held its second international workshop from November 2 to 6,2016,in Puerto Vallarta and included a two-day field trip to Guadalajara and Jocotepec in the Mexican state of Jalisco(Fig.1a).M3EF3 is aimed at i)understanding the mechanisms that cause the formation of“ground ruptures”,as a response to changes in the stress state in the subsoil,ii)monitoring their occurrence,and iii)developing appropriate approaches to model their formation and growth.Notice that many times it is difficult to discern whether a particular instance of a“ruptured”land surface is due to an earth fissure with a surface manifestation or a surface failure associated with the activation of a pre-existing fault,especially where a fault has not been mapped and where there is no obvious scarp.Therefore,in M3EF3 we preferred to use the term“ground rupture”,to refer to both such occurrences.
