Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameter...Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.展开更多
A study was conducted in eight districts, viz., Faridkot, Moga, Ferozepur, Muktsar, Bathinda, Mansa, Barnala and Sangrur in south-western part of the Punjab, India to characterize aquifer strata by preparing a fence d...A study was conducted in eight districts, viz., Faridkot, Moga, Ferozepur, Muktsar, Bathinda, Mansa, Barnala and Sangrur in south-western part of the Punjab, India to characterize aquifer strata by preparing a fence diagram depicting sub-surface strata and distribution of groundwater quality. The sub-surface lithology drilled upto a depth of 60 m reveal the presence of top most layer of impervious strata comprising of clay upto the depth of 2 m to 5 m which impedes the percolation of surface runoff into the soil leading to surface flooding and water logging even in areas having saturated zone beyond the depth of 5 m. Thick pervious strata of 45 m to 50 m thickness is encountered in central and south-sentral part of the study area comprising of Bathinda, Muktsar and Mansa districts which at certain places are separated by one or two thin layers of impervious or semi-pervious strata comprising of clay and sand occasionally associated with ＂kankar＂ of thickness ranging between 2 m to 5 m. The northern, western and eastern parts, however, exhibit three to four layered pervious zones ranging in thickness from 5 m to 25 m separated by thin layers of impervious and semi pervious strata. The groundwater quality in about 6% of the study area in eight districts is fit, 18% is marginal and 76% is unfit for irrigation purpose.展开更多
Installation of impervious surface in urban area prevents the exchange of material and energy between soil and other environmental counterparts,thereby resulting in negative effects on soil function and urban environm...Installation of impervious surface in urban area prevents the exchange of material and energy between soil and other environmental counterparts,thereby resulting in negative effects on soil function and urban environment.Soil samples were collected at 0-20cm depth in Nanjing City,China,in which seven sites were selected for urban open soils,and fourteen sites with similar parent material were selected for the impervious-covered soils,to examine the effect of impervious surface on soil properties and microbial activities,and to determine the most important soil properties associated with soil organic carbon(SOC)transformation in the urban soils covered by impervious surfaces.Soil organic carbon and water-soluble organic carbon(WSOC)concentrations,potential carbon(C)and nitrogen(N)mineralization rates,basal respiration,and physicochemical properties with respect to C transformation were measured.Installation of impervious surface severely affected soil physicochemical properties and microbial activities,e.g.,it significantly decreased total N contents,potential C mineralization and basal respiration rate(P<0.01),while increased pH,clay and Olsen-P concentrations.Soil organic carbon in the sealed soils at 0-20 cm was 2.35 kg m^(-2),which was significantly lower than the value of 4.52 kg m^(-2)in the open soils(P<0.05).Canonical correlation analysis showed WSOC played a major role in determining SOC transformation in the impervious-covered soil,and it was highly correlated with total N content and potential C mineralization rate.These findings demonstrate that installation of impervious surface in urban area,which will result in decreases of SOC and total N concentrations and soil microbial activities,has certain negative consequences for soil fertility and long-term storage of SOC.展开更多
基金Project(kfj080205) supported by Key Laboratory of Road Structure and Material of Ministry of Transport of Changsha, China
文摘Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.
文摘A study was conducted in eight districts, viz., Faridkot, Moga, Ferozepur, Muktsar, Bathinda, Mansa, Barnala and Sangrur in south-western part of the Punjab, India to characterize aquifer strata by preparing a fence diagram depicting sub-surface strata and distribution of groundwater quality. The sub-surface lithology drilled upto a depth of 60 m reveal the presence of top most layer of impervious strata comprising of clay upto the depth of 2 m to 5 m which impedes the percolation of surface runoff into the soil leading to surface flooding and water logging even in areas having saturated zone beyond the depth of 5 m. Thick pervious strata of 45 m to 50 m thickness is encountered in central and south-sentral part of the study area comprising of Bathinda, Muktsar and Mansa districts which at certain places are separated by one or two thin layers of impervious or semi-pervious strata comprising of clay and sand occasionally associated with ＂kankar＂ of thickness ranging between 2 m to 5 m. The northern, western and eastern parts, however, exhibit three to four layered pervious zones ranging in thickness from 5 m to 25 m separated by thin layers of impervious and semi pervious strata. The groundwater quality in about 6% of the study area in eight districts is fit, 18% is marginal and 76% is unfit for irrigation purpose.
基金Surpported by the National Natural Science Foundation of China(No.41001047)
文摘Installation of impervious surface in urban area prevents the exchange of material and energy between soil and other environmental counterparts,thereby resulting in negative effects on soil function and urban environment.Soil samples were collected at 0-20cm depth in Nanjing City,China,in which seven sites were selected for urban open soils,and fourteen sites with similar parent material were selected for the impervious-covered soils,to examine the effect of impervious surface on soil properties and microbial activities,and to determine the most important soil properties associated with soil organic carbon(SOC)transformation in the urban soils covered by impervious surfaces.Soil organic carbon and water-soluble organic carbon(WSOC)concentrations,potential carbon(C)and nitrogen(N)mineralization rates,basal respiration,and physicochemical properties with respect to C transformation were measured.Installation of impervious surface severely affected soil physicochemical properties and microbial activities,e.g.,it significantly decreased total N contents,potential C mineralization and basal respiration rate(P<0.01),while increased pH,clay and Olsen-P concentrations.Soil organic carbon in the sealed soils at 0-20 cm was 2.35 kg m^(-2),which was significantly lower than the value of 4.52 kg m^(-2)in the open soils(P<0.05).Canonical correlation analysis showed WSOC played a major role in determining SOC transformation in the impervious-covered soil,and it was highly correlated with total N content and potential C mineralization rate.These findings demonstrate that installation of impervious surface in urban area,which will result in decreases of SOC and total N concentrations and soil microbial activities,has certain negative consequences for soil fertility and long-term storage of SOC.
