When the tunnel underpasses through the building,it will cause deformation and even damage to the buildings above,and the deformation of building foundation is the key to building safety.Based on the engineering case,...When the tunnel underpasses through the building,it will cause deformation and even damage to the buildings above,and the deformation of building foundation is the key to building safety.Based on the engineering case,the theoretical analysis was employed to evaluate the influence of shield tunnel underpass construction on the stability of the building,and the optimal tunneling parameters in the field construction have been obtained through the verified theoretical model and parameter analysis.First,the strip foundation of the building was simplified to the Timoshenko beam,which was taken into account the shear effect,and then the deformation displacement of the soil at the same place of strip foundation was applied to the simplified Timoshenko beam.Finally,the numerical solution of the displacement of the strip foundation was obtained by using the finite element method and verified its reliability using Euler-Bernoulli beam theoretical model,field monitoring data,and numerical simulation.Parameters analysis for the deformation and internal force of strip foundation under different types of shield machine tunneling parameters showed that the influence of the pressure of shield excavation chamber,thrust of shield,and driving speed played an important role in the deformation of the building’s strip foundation and internal force.展开更多
Foundation is considered as one of the main parts of any structure. The type of foundation used is highly dependent on the type and properties of soil. The design of foundations requires many factors that should be de...Foundation is considered as one of the main parts of any structure. The type of foundation used is highly dependent on the type and properties of soil. The design of foundations requires many factors that should be defined. There are number of differences in the geological and soil conditions in Iraq. As a consequence, these differences are reflected on the type of foundation to be used. Despite these differences, same materials and style of buildings are used all over Iraq. The main problems of Iraqi soil are high gypsum content, salinity and shallow water table depth. These factors that influence the foundations are the soil properties and the amount of loads that transmitted by the superstructure. The situation has been analysed through a case study which illustrated the link between soil and foundation types in three different parts of Iraq (Mosul, Baghdad and Basra). One building was analysed using "STAAD (structural analysis and design). Pro" software in these regions. It is evident that Iraqi designers and engineers require local code to define all the loads, materials and design of the foundation to be used. The use of local materials might be very effective from both engineering and economic perspectives.展开更多
The effect of geosynthetic reinforcing on bearing capacity of a strip footing resting on georeinforced clayey slopes was investigated.The results of a series of numerical study using finite element analyses on strip f...The effect of geosynthetic reinforcing on bearing capacity of a strip footing resting on georeinforced clayey slopes was investigated.The results of a series of numerical study using finite element analyses on strip footing upon both reinforced and unreinforced clayey slopes were presented.The objectives of this work are to:1) determine the influence of reinforcement on the bearing-capacity of the strip footings adjacent slopes,2) suggest an optimum number of reinforcement and 3) survey the effect of friction angle in clayey soils reinforced by geogrids.The investigations were carried out by varying the edge distance of the footing from slope.Also different numbers of geosynthetic layers were applied to obtaining the maximum bearing capacity and minimum settlement.To achieve the third objective,two different friction angles were used.The results show that the load?settlement behavior and ultimate bearing capacity of footing can be considerably improved by the inclusion of reinforcing layer.But using more than one layer reinforcement,the ultimate bearing capacity does not change considerably.It is also shown that for both reinforced and unreinforced slopes,the bearing capacity increases with an increase in edge distance.In addition,as the soil friction angle is increased,the efficiency of reinforcing reduces.展开更多
A considerable amount of tunnelling has been going on in India for various projects such as hydroelectric power, irrigation, roads and railways. Most of these projects are located in Himalayas, far away from the urban...A considerable amount of tunnelling has been going on in India for various projects such as hydroelectric power, irrigation, roads and railways. Most of these projects are located in Himalayas, far away from the urban areas. Tunnelling through weak and jointed rock masses such as the one in the Himalayas is a challenging task for the planners, designers, engineers and geologists because of high overburden, thickly vegetated surface, weak, poor and fragile rocks and highly varying geology with the presence of numerous small and big shear zones, faults, etc. Due to these reasons, various tunnelling problems have been faced in the past and are still being encountered. Failures and the problems may be regarded as challenges and opportunities for generating new knowledge base and thereby increasing self-reliance in tunnelling. The experiences of Himalayan tunnelling through weak and fragile rocks covering varying and mixed geology, understanding on tunnelling in squeezing ground conditions and applicability of TBM in Himalayas are presented. It has also been highlighted that the probe holes planning, drilling and monitoring shall be followed seriously to reduce the geological surprises.展开更多
A footing may get an eccentric load caused by earthquake or wind, thus the bearing capacity of footing subjected to eccentric load become a fundamental geotechnical problem. The conventional limit equilibrium method u...A footing may get an eccentric load caused by earthquake or wind, thus the bearing capacity of footing subjected to eccentric load become a fundamental geotechnical problem. The conventional limit equilibrium method used for this problem usually evaluates the material properties only by its final strength. But the classical finite element method(FEM) does not necessarily provide a clear collapse mechanism associated with the yield condition of elements. To overcome these defects, a numerical procedure is proposed to create an explicit collapse mode combining a modified smeared shear band approach with a modified initial stress method. To understand the practical performance of sand foundation and verify the performance of the proposed procedure applied to the practical problems, the computing results were compared with the laboratory model tests results and some conventional solutions. Furthermore, because the proposed numerical procedure employs a simple elasto-plastic model which requires a small number of soil parameters, it may be applied directly to practical design works.展开更多
This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The re...This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.展开更多
At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line...At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line. It is proved that geotechnical materials do not abide by the associated flow rule. It is impossible for the stress characteristic line to conform to the velocity line. Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle, so that the velocity line must be studied by non-associated flow rule. According to limit analysis theory, the theory of slip line field is put forward in this paper, and then the ultimate beating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow nile individually. These two results are identical since the ultimate bearing capacity is independent of flow role. On the contrary, the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associat- ed flow rule is incorrect.展开更多
Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional...Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional development. Thus, focusing on material wealth, regional development can be evaluated from resources and perspective of resources conversion. Taking the infrastructural level, transportation accessibility and economic development level into full account, the concept of "material-based development" was presented and the material-based development index (MDI) model was established. By using the MDI model, geographic information system technology and mathematic methods, this article then calculated MDI of each county and province of China in 2005 and systematically evaluated the material-based development of China at county and provincial scales, so as to bring some scientific references and policy-making supports to the population development function oriented zoning and population spatial distribution planning of China. The result showed that: (1) At county scale, the material-based development of counties within China in 2005 was significantly different, in which there were 1876 counties belonging to the mid-level material-based development and accounted for 78.10% of the total. The numbers of high-level and low-level counties were 144 and 382 and accounted for 6.00% and 15.90% respectively, demonstrating a spindle shape in general. The spatial distribution of material-based development was unbalanced, and it was much better in southeastern part of the line of "Daxinganling–Yinshan-Liupanshan–southeast edge of Qinghai–Tibet Plateau" than that of northwestern. Furthermore, there were also differences of the sub-index between different material-based development levels. Therefore, for different regions, key issues and measures adaptable to local condition should be prioritized and taken in order to realize regional balance development. (2) At provincial scale, there was also significant difference between each province and the spatial distribution of it was "high in the east, low in the west" in general. It meant that the capacity of natural resources attraction and conversion of east China was better than that of west China. The infrastructure level was the main factor ac- counting for the differences of material-based development levelsamong provinces. As a result, our government should make great efforts to improve infrastructure condition, especially the western part of China, so as to narrow the gap between the western part and the eastern part to realize the coordinated development within different regions and rapidly socio-economic development of China.展开更多
The roof system of social housing in Brazil generally consists of components made out of native forest lumber of high market value. Taking into account the increasing number of planted forests and the need to develop ...The roof system of social housing in Brazil generally consists of components made out of native forest lumber of high market value. Taking into account the increasing number of planted forests and the need to develop new products and to add value to this timber, this work deals with the development and structural analysis of a roof system using yellow pine plantation wood (Pinus spp), a sustainable material which however presents many defects. The NLT (laminated nailed timber) technology was chosen as it allows the use of shorter length and smaller cross section pieces, eliminating major defects. Seven samples of structural trussed rafters in NLT were tested; six made out of graded timber and one ungraded in order to verify the impact of the wood grading in the structural performance of the model. The results showed that the trussed rafter system in NLT meets the necessary structural performance requiring poor conditions of infrastructure for manufacture process, and that the graded wood samples showed better performance than the ungraded one.展开更多
The background of research was conditions of settlement in slum area at Tallo which are most apprehensive; lack of facilities, the houses made of flammable materials, and some criminal action occurred in the density s...The background of research was conditions of settlement in slum area at Tallo which are most apprehensive; lack of facilities, the houses made of flammable materials, and some criminal action occurred in the density settlement. Upgrading Programs has been twice implemented in this area. However, those have the same aim, to improve street and drainage condition around the area. The different between of them is the using of material which are the first program used asphalt as street cover material and the second one used paving blok. Although the upgrading programs had done, the condition of the settlement did not improve significantly. The problems in settlement were not only leak in infrastructure condition and needs, but also lake of community welfare, unemployment, housing conditions, and the existence of the warehouses in the settlement. The flood problems also appeared in this area which closed with the water channel to the city disposal channel so when rainy season, the area is always flooded and enter into the entrance of the houses. The objective of this research was to find the root of the problems and find good solutions for the environment and how to meet the major needs of the settlement upgrading program into the local community point of view. Field research and questioners was conducted as research method to the research objectivities in the needs of community for good environment. Furthermore, the data from the field research was analyzed by making synchronization with the theory of environmental sustainability. Results from this research showed the comparison study between first and the last condition of the settlement area which had the upgrading program implementation. These findings could provide a new guideline for the government in policy related to slum upgrading.展开更多
From a financial point of view,urbanization frequently enforces the clients to construct superstructures near the slopes,giving rise to increasing the risk of building instability.By conducting a series of small-scale...From a financial point of view,urbanization frequently enforces the clients to construct superstructures near the slopes,giving rise to increasing the risk of building instability.By conducting a series of small-scale plate load tests,this work aims to investigate the effects of installing geotextile reinforcement layers in sandy slope and reducing the apex angle of triangular shell strip footings.The results show considerable effect of using geotextile-reinforced layers and decreasing the apex angle on the ultimate bearing capacity of shell foundations.With increasing foundation distance from the slope,the adverse effect of the slope is reduced.However,as the distance decreases,the effect of reinforcement and apex angle is increased.For practical applications,empirical equations are also presented for determining the ultimate bearing capacity of the footings and scale effect as well.Finally,3D numerical simulations are executed and compared with the experimental results.展开更多
基金Projects(41807265,41972286,42072309)supported by the National Natural Science Foundation of ChinaProjects(HKLBEF202001,HKLBEF202002)supported by the Hubei Key Laboratory of Blasting Engineering Foundation,China。
文摘When the tunnel underpasses through the building,it will cause deformation and even damage to the buildings above,and the deformation of building foundation is the key to building safety.Based on the engineering case,the theoretical analysis was employed to evaluate the influence of shield tunnel underpass construction on the stability of the building,and the optimal tunneling parameters in the field construction have been obtained through the verified theoretical model and parameter analysis.First,the strip foundation of the building was simplified to the Timoshenko beam,which was taken into account the shear effect,and then the deformation displacement of the soil at the same place of strip foundation was applied to the simplified Timoshenko beam.Finally,the numerical solution of the displacement of the strip foundation was obtained by using the finite element method and verified its reliability using Euler-Bernoulli beam theoretical model,field monitoring data,and numerical simulation.Parameters analysis for the deformation and internal force of strip foundation under different types of shield machine tunneling parameters showed that the influence of the pressure of shield excavation chamber,thrust of shield,and driving speed played an important role in the deformation of the building’s strip foundation and internal force.
文摘Foundation is considered as one of the main parts of any structure. The type of foundation used is highly dependent on the type and properties of soil. The design of foundations requires many factors that should be defined. There are number of differences in the geological and soil conditions in Iraq. As a consequence, these differences are reflected on the type of foundation to be used. Despite these differences, same materials and style of buildings are used all over Iraq. The main problems of Iraqi soil are high gypsum content, salinity and shallow water table depth. These factors that influence the foundations are the soil properties and the amount of loads that transmitted by the superstructure. The situation has been analysed through a case study which illustrated the link between soil and foundation types in three different parts of Iraq (Mosul, Baghdad and Basra). One building was analysed using "STAAD (structural analysis and design). Pro" software in these regions. It is evident that Iraqi designers and engineers require local code to define all the loads, materials and design of the foundation to be used. The use of local materials might be very effective from both engineering and economic perspectives.
文摘The effect of geosynthetic reinforcing on bearing capacity of a strip footing resting on georeinforced clayey slopes was investigated.The results of a series of numerical study using finite element analyses on strip footing upon both reinforced and unreinforced clayey slopes were presented.The objectives of this work are to:1) determine the influence of reinforcement on the bearing-capacity of the strip footings adjacent slopes,2) suggest an optimum number of reinforcement and 3) survey the effect of friction angle in clayey soils reinforced by geogrids.The investigations were carried out by varying the edge distance of the footing from slope.Also different numbers of geosynthetic layers were applied to obtaining the maximum bearing capacity and minimum settlement.To achieve the third objective,two different friction angles were used.The results show that the load?settlement behavior and ultimate bearing capacity of footing can be considerably improved by the inclusion of reinforcing layer.But using more than one layer reinforcement,the ultimate bearing capacity does not change considerably.It is also shown that for both reinforced and unreinforced slopes,the bearing capacity increases with an increase in edge distance.In addition,as the soil friction angle is increased,the efficiency of reinforcing reduces.
文摘A considerable amount of tunnelling has been going on in India for various projects such as hydroelectric power, irrigation, roads and railways. Most of these projects are located in Himalayas, far away from the urban areas. Tunnelling through weak and jointed rock masses such as the one in the Himalayas is a challenging task for the planners, designers, engineers and geologists because of high overburden, thickly vegetated surface, weak, poor and fragile rocks and highly varying geology with the presence of numerous small and big shear zones, faults, etc. Due to these reasons, various tunnelling problems have been faced in the past and are still being encountered. Failures and the problems may be regarded as challenges and opportunities for generating new knowledge base and thereby increasing self-reliance in tunnelling. The experiences of Himalayan tunnelling through weak and fragile rocks covering varying and mixed geology, understanding on tunnelling in squeezing ground conditions and applicability of TBM in Himalayas are presented. It has also been highlighted that the probe holes planning, drilling and monitoring shall be followed seriously to reduce the geological surprises.
基金Projects(cstc2012jjA0510,cstc2013jcyjA30014)supported by Chongqing Natural Science Foundation in ChinaProject(CDJZR12200011)supported by the Fundamental Research Funds for the Central Universities in China+1 种基金Project(KJTD201305)supported by the Innovation Team Building Programs of Chongqing Universities in ChinaProject supported by the Scientific Research Foundation for the Returned Oversea Chinese Scholars
文摘A footing may get an eccentric load caused by earthquake or wind, thus the bearing capacity of footing subjected to eccentric load become a fundamental geotechnical problem. The conventional limit equilibrium method used for this problem usually evaluates the material properties only by its final strength. But the classical finite element method(FEM) does not necessarily provide a clear collapse mechanism associated with the yield condition of elements. To overcome these defects, a numerical procedure is proposed to create an explicit collapse mode combining a modified smeared shear band approach with a modified initial stress method. To understand the practical performance of sand foundation and verify the performance of the proposed procedure applied to the practical problems, the computing results were compared with the laboratory model tests results and some conventional solutions. Furthermore, because the proposed numerical procedure employs a simple elasto-plastic model which requires a small number of soil parameters, it may be applied directly to practical design works.
文摘This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.
文摘At present, associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials. So the stress characteristic line conforms to the velocity line. It is proved that geotechnical materials do not abide by the associated flow rule. It is impossible for the stress characteristic line to conform to the velocity line. Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle, so that the velocity line must be studied by non-associated flow rule. According to limit analysis theory, the theory of slip line field is put forward in this paper, and then the ultimate beating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow nile individually. These two results are identical since the ultimate bearing capacity is independent of flow role. On the contrary, the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associat- ed flow rule is incorrect.
基金supported by the project of Chinese Academy of Sciences (Grant no. KZCX2-YW-323)the Nation-al Population Development Strategy of China (Development Planning 2008-5)
文摘Regional development is a course of accumulation based on many factors, which is directly related to resources utilization and conversion. And material wealth production and accumulation embody the outcome of regional development. Thus, focusing on material wealth, regional development can be evaluated from resources and perspective of resources conversion. Taking the infrastructural level, transportation accessibility and economic development level into full account, the concept of "material-based development" was presented and the material-based development index (MDI) model was established. By using the MDI model, geographic information system technology and mathematic methods, this article then calculated MDI of each county and province of China in 2005 and systematically evaluated the material-based development of China at county and provincial scales, so as to bring some scientific references and policy-making supports to the population development function oriented zoning and population spatial distribution planning of China. The result showed that: (1) At county scale, the material-based development of counties within China in 2005 was significantly different, in which there were 1876 counties belonging to the mid-level material-based development and accounted for 78.10% of the total. The numbers of high-level and low-level counties were 144 and 382 and accounted for 6.00% and 15.90% respectively, demonstrating a spindle shape in general. The spatial distribution of material-based development was unbalanced, and it was much better in southeastern part of the line of "Daxinganling–Yinshan-Liupanshan–southeast edge of Qinghai–Tibet Plateau" than that of northwestern. Furthermore, there were also differences of the sub-index between different material-based development levels. Therefore, for different regions, key issues and measures adaptable to local condition should be prioritized and taken in order to realize regional balance development. (2) At provincial scale, there was also significant difference between each province and the spatial distribution of it was "high in the east, low in the west" in general. It meant that the capacity of natural resources attraction and conversion of east China was better than that of west China. The infrastructure level was the main factor ac- counting for the differences of material-based development levelsamong provinces. As a result, our government should make great efforts to improve infrastructure condition, especially the western part of China, so as to narrow the gap between the western part and the eastern part to realize the coordinated development within different regions and rapidly socio-economic development of China.
文摘The roof system of social housing in Brazil generally consists of components made out of native forest lumber of high market value. Taking into account the increasing number of planted forests and the need to develop new products and to add value to this timber, this work deals with the development and structural analysis of a roof system using yellow pine plantation wood (Pinus spp), a sustainable material which however presents many defects. The NLT (laminated nailed timber) technology was chosen as it allows the use of shorter length and smaller cross section pieces, eliminating major defects. Seven samples of structural trussed rafters in NLT were tested; six made out of graded timber and one ungraded in order to verify the impact of the wood grading in the structural performance of the model. The results showed that the trussed rafter system in NLT meets the necessary structural performance requiring poor conditions of infrastructure for manufacture process, and that the graded wood samples showed better performance than the ungraded one.
文摘The background of research was conditions of settlement in slum area at Tallo which are most apprehensive; lack of facilities, the houses made of flammable materials, and some criminal action occurred in the density settlement. Upgrading Programs has been twice implemented in this area. However, those have the same aim, to improve street and drainage condition around the area. The different between of them is the using of material which are the first program used asphalt as street cover material and the second one used paving blok. Although the upgrading programs had done, the condition of the settlement did not improve significantly. The problems in settlement were not only leak in infrastructure condition and needs, but also lake of community welfare, unemployment, housing conditions, and the existence of the warehouses in the settlement. The flood problems also appeared in this area which closed with the water channel to the city disposal channel so when rainy season, the area is always flooded and enter into the entrance of the houses. The objective of this research was to find the root of the problems and find good solutions for the environment and how to meet the major needs of the settlement upgrading program into the local community point of view. Field research and questioners was conducted as research method to the research objectivities in the needs of community for good environment. Furthermore, the data from the field research was analyzed by making synchronization with the theory of environmental sustainability. Results from this research showed the comparison study between first and the last condition of the settlement area which had the upgrading program implementation. These findings could provide a new guideline for the government in policy related to slum upgrading.
文摘From a financial point of view,urbanization frequently enforces the clients to construct superstructures near the slopes,giving rise to increasing the risk of building instability.By conducting a series of small-scale plate load tests,this work aims to investigate the effects of installing geotextile reinforcement layers in sandy slope and reducing the apex angle of triangular shell strip footings.The results show considerable effect of using geotextile-reinforced layers and decreasing the apex angle on the ultimate bearing capacity of shell foundations.With increasing foundation distance from the slope,the adverse effect of the slope is reduced.However,as the distance decreases,the effect of reinforcement and apex angle is increased.For practical applications,empirical equations are also presented for determining the ultimate bearing capacity of the footings and scale effect as well.Finally,3D numerical simulations are executed and compared with the experimental results.