阳茂高速改扩建工程的软基路段,软土赋存状况主要为淤泥、淤泥质粉质粘土、淤泥质细砂等,软土埋深最大为 11.5 m,对于埋深超过 4 m 的深层软基,旧路软基处理采用袋装砂井排水固结法,扩建时此部分段落比较难控制的是扩建填土引起老路的...阳茂高速改扩建工程的软基路段,软土赋存状况主要为淤泥、淤泥质粉质粘土、淤泥质细砂等,软土埋深最大为 11.5 m,对于埋深超过 4 m 的深层软基,旧路软基处理采用袋装砂井排水固结法,扩建时此部分段落比较难控制的是扩建填土引起老路的附加荷载,从而导致老路发生新的沉降。因此,合理确定旧路软基处理采用袋装砂井排水固结法的拼宽路段拼宽软基处理进入旧路边坡的范围,避免老路发生新沉降导致老路路面开裂,成为本项目改扩建工程成败的关键点之一。通过研究,深层软基路段拼宽软基处理采用管桩,新旧路基结合部分采用剩余未被管桩覆盖部分的水平填土宽度控制在 4 m 进行处理,避免了旧路的新沉降过大导致的旧路面开裂,有效的保持了旧路的稳定性,提高了拼宽软土地基处治的工程质量。展开更多
Through the shear tests on composite specimens using four different kinds of tack coat material （epoxy resin, SBS modified emulsified asphalt, SBS modified asphalt and H# bridge waterproof material）, the bond condit...Through the shear tests on composite specimens using four different kinds of tack coat material （epoxy resin, SBS modified emulsified asphalt, SBS modified asphalt and H# bridge waterproof material）, the bond condition between layers of porous asphalt pavement under traffic load, temperature variation and moisture situation is evaluated. The test results show that the bond strength decreases with the rise in temperature, and the relationship between shear strength and temperature can be expressed by a logarithm curve at a high reliability. Under the action of traffic load, the value of shear strength of the mixture right under the centre of the wheel track is smaller than that of other parts of the pavement. It is also found that some effects concerning moisture have comparative effects on the bonding of the two layers. Given all the results achieved during the study, it will be quite rewarding to make rational comparisons during selecting the sound type of tack coat.展开更多
In order to study the water flow in the drainage layer of highway under steady-state condition, one-dimensional （1D） Boussinesq equation-based model with Dupuit-Forchheimer assumption was established and the semi-an...In order to study the water flow in the drainage layer of highway under steady-state condition, one-dimensional （1D） Boussinesq equation-based model with Dupuit-Forchheimer assumption was established and the semi-analytical solutions to predict the water-table height were presented. In order to validate the model, a two-dimensional （2D） saturated flow model based on the Laplace equation was applied for the purpose of the model comparison. The water-table elevations predicted by ID Boussinesq equation-based model and 2D Laplace equation-based model match each other well, which indicates that the horizontal flow in drainage layer is dominated. Also, it validates the 1D Boussinesq equation-based model which can be applied to predict the water-table elevation in drainage layer. Further, the analysis was conducted to examine the effect of infiltration rate, hydraulic conductivity and slope of drainage layer on the water-table elevation. The results show that water-table falls down as the ratio of Is to K decreases and the slope increases. If the aquifer becomes confined by the top of drainage layer due to the larger ratio of Is to K or smaller slope, the solution presented in this work can also be applied to approximate the water-table elevation in unconfined sub-section as well as hydraulic head in the confined sub-section.展开更多
To investigate the dynamic characteristics of total suspended solids (TSS) and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rain...To investigate the dynamic characteristics of total suspended solids (TSS) and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash off behavior of TSS under varying runoff rate condition can be explained by different antecedent dry weather period (ADWP). Contribution of fine fraction (<45 μm) to TSS was generally higher than that of coarse fraction (>45 μm). When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.展开更多
Bridges are structures being used to cross rivers, lakes or any other obstacles which involve water. These instruments are commonly used in cities like Recife, which consists of several islands. However, it is common ...Bridges are structures being used to cross rivers, lakes or any other obstacles which involve water. These instruments are commonly used in cities like Recife, which consists of several islands. However, it is common in this city to observe the fast deterioration of these structures that have been built for decades and are subjected to structural recoveries only when they present a possible imminent collapse. The maintenance of these constructions, often used as tourist spots, is essential because of the economic importance, while these structures are responsible for transporting people and cargo, and also play a key role in the city＇s roads. This paper aims to present and assess the conservation status of these bridges through the study of possible pathologies found at Princesa Isabel Bridge, Government Agamenon Bridge, Ponte Giratória Bridge and Paulo Guerra Bridge. The methodology for its inspection will be prescribed by ABNT NBR-9452/86, which provides for ＂Surveys of Concrete Bridges/Viaducts＂. After analysis, it was found that most bridges problems were caused by the presence of moisture that accumulates in bridges due to the absence or malfunction of drainage systems.展开更多
Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry betw...Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.展开更多
文摘阳茂高速改扩建工程的软基路段,软土赋存状况主要为淤泥、淤泥质粉质粘土、淤泥质细砂等,软土埋深最大为 11.5 m,对于埋深超过 4 m 的深层软基,旧路软基处理采用袋装砂井排水固结法,扩建时此部分段落比较难控制的是扩建填土引起老路的附加荷载,从而导致老路发生新的沉降。因此,合理确定旧路软基处理采用袋装砂井排水固结法的拼宽路段拼宽软基处理进入旧路边坡的范围,避免老路发生新沉降导致老路路面开裂,成为本项目改扩建工程成败的关键点之一。通过研究,深层软基路段拼宽软基处理采用管桩,新旧路基结合部分采用剩余未被管桩覆盖部分的水平填土宽度控制在 4 m 进行处理,避免了旧路的新沉降过大导致的旧路面开裂,有效的保持了旧路的稳定性,提高了拼宽软土地基处治的工程质量。
文摘Through the shear tests on composite specimens using four different kinds of tack coat material （epoxy resin, SBS modified emulsified asphalt, SBS modified asphalt and H# bridge waterproof material）, the bond condition between layers of porous asphalt pavement under traffic load, temperature variation and moisture situation is evaluated. The test results show that the bond strength decreases with the rise in temperature, and the relationship between shear strength and temperature can be expressed by a logarithm curve at a high reliability. Under the action of traffic load, the value of shear strength of the mixture right under the centre of the wheel track is smaller than that of other parts of the pavement. It is also found that some effects concerning moisture have comparative effects on the bonding of the two layers. Given all the results achieved during the study, it will be quite rewarding to make rational comparisons during selecting the sound type of tack coat.
基金Project(511114) supported by the Natural Science Foundation of Hainan Province, ChinaProject(2009YBFZ05) supported by Postgraduate Award of Central South University, China+1 种基金Project(200731) supported by Traffic Technology Fund of Hunan Province, ChinaProject(2008BAG10B01) supported by the National Key Technology R&D Program, China
文摘In order to study the water flow in the drainage layer of highway under steady-state condition, one-dimensional （1D） Boussinesq equation-based model with Dupuit-Forchheimer assumption was established and the semi-analytical solutions to predict the water-table height were presented. In order to validate the model, a two-dimensional （2D） saturated flow model based on the Laplace equation was applied for the purpose of the model comparison. The water-table elevations predicted by ID Boussinesq equation-based model and 2D Laplace equation-based model match each other well, which indicates that the horizontal flow in drainage layer is dominated. Also, it validates the 1D Boussinesq equation-based model which can be applied to predict the water-table elevation in drainage layer. Further, the analysis was conducted to examine the effect of infiltration rate, hydraulic conductivity and slope of drainage layer on the water-table elevation. The results show that water-table falls down as the ratio of Is to K decreases and the slope increases. If the aquifer becomes confined by the top of drainage layer due to the larger ratio of Is to K or smaller slope, the solution presented in this work can also be applied to approximate the water-table elevation in unconfined sub-section as well as hydraulic head in the confined sub-section.
基金Project supported by the National Key Technology R&D Program of China (No. 2006BAK13B04)the Expo Shanghai Sci-Tech Program of Science and Technology Commission of Shanghai (No.06dz05808)the Natural Science Foundation of Jiangxi Province(No. 2007GZH839), China
文摘To investigate the dynamic characteristics of total suspended solids (TSS) and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash off behavior of TSS under varying runoff rate condition can be explained by different antecedent dry weather period (ADWP). Contribution of fine fraction (<45 μm) to TSS was generally higher than that of coarse fraction (>45 μm). When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.
文摘Bridges are structures being used to cross rivers, lakes or any other obstacles which involve water. These instruments are commonly used in cities like Recife, which consists of several islands. However, it is common in this city to observe the fast deterioration of these structures that have been built for decades and are subjected to structural recoveries only when they present a possible imminent collapse. The maintenance of these constructions, often used as tourist spots, is essential because of the economic importance, while these structures are responsible for transporting people and cargo, and also play a key role in the city＇s roads. This paper aims to present and assess the conservation status of these bridges through the study of possible pathologies found at Princesa Isabel Bridge, Government Agamenon Bridge, Ponte Giratória Bridge and Paulo Guerra Bridge. The methodology for its inspection will be prescribed by ABNT NBR-9452/86, which provides for ＂Surveys of Concrete Bridges/Viaducts＂. After analysis, it was found that most bridges problems were caused by the presence of moisture that accumulates in bridges due to the absence or malfunction of drainage systems.
基金supported by the National Natural Science Foundation of China project (Grant Nos. 41201130, 41101361, and 41371183)
文摘Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.
