The investigation of the long-term performance of solidified/stabilized （S/S） contaminated soils was carried out in a trial site in southeast UK. The soils were exposed to the maximum natural weathering for four yea...The investigation of the long-term performance of solidified/stabilized （S/S） contaminated soils was carried out in a trial site in southeast UK. The soils were exposed to the maximum natural weathering for four years and sampled at various depths in a controlled manner. The chemical properties （e.g., degree of carbonation （DOC）, pH, electrical conductivity （EC）） and physical properties （e.g., moisture content （MC）, liquid limit CLL）, plastic limit （PL）, plasticity index （PI）） of the samples untreated and treated with the traditional and accelerated carbonated S/S processes were analyzed. Their variations on the depths of the soils were also studied. The result showed that the broad geotechnical properties of the soils, manifested in their PIs, were related to the concentration of the water soluble ions and in particular the free calcium ions. The samples treated with the accelerated carbonation technology （ACT）, and the untreated samples contained limited number of free calcium ions in solutions and consequently interacted with waters in a similar way. Compared with the traditional cement-based S/S technology, e.g., treatment with ordinary portland cement （OPC） or EnvirOceM, ACT caused the increase of the PI of the treated soil and made it more stable during long-term weathering. The PI values for the four soils ascended according to the order： the EnvirOceM soil, the OPC soil, the ACT soil, and the untreated soil while their pH and EC values descended according to the same order.展开更多
Determination of physical property of the soil helps in identification and classification of soil which includes analysis of particle size distribution, Atterberg limits, water content, specific gravity, phase determi...Determination of physical property of the soil helps in identification and classification of soil which includes analysis of particle size distribution, Atterberg limits, water content, specific gravity, phase determination and direct shear test. Water plays an important role in triggering landslides and slope failures. Increase of water content reduces the stability of slope. When the moisture content exceeds plastic limits, the slope begins to deform. Three soil samples are collected from the study area and the average bulk density, moisture content and specific gravity are 1.577, 37.032 and 2.434 respectively. Atterberg limit is the most distinctive properties of fine grained sediments and may be used to distinguish silts from clays. Plastic limits (WP), liquid limit (WL), shrinkage limit (WS) values of Nungbi Khunou are 26.236%, 48% and 9.4% respectively. Plasticity index (IP), consistency index (IC) and liquidity index (IL) value is 21.764%, 0.379%, and 60.623% respectively. From index properties value, the soil is highly plastic, stiff and semi-solid in nature. The soil sample falls under CI group in plasticity chart which indicates organic silt and clay soil with medium compressibility and plasticity. Phase determination and particle size distribution result in very high porosity and highly saturated soils which are well graded in nature. Slope and aspect map are prepared from DEM using ArcGIS. Slope is an important contributory factor to landslide, and slope reported from the sampling area indicates gentle slope. Aspect refers to the direction of the terrain faces which is influenced by component like vegetation, settlement, agriculture, precipitation, wind etc. Factor of safety (Fs) calculated from shear stress data is less than 1 indicating unstable slope. From the above finding, the study area may result in sudden and unpredictable failure due to volumetric changes in soil.展开更多
The present study is inscribed within the framework of the geotechnical characterization of the soils of the Santchou plain, their classification for employment as pavement subgrade, various identification tests were ...The present study is inscribed within the framework of the geotechnical characterization of the soils of the Santchou plain, their classification for employment as pavement subgrade, various identification tests were carried out on the samples. The results obtained showed that with a wide range of different grain sizes, the studied soils showed low content in clay grains and dominance of either sand grains or silt grains, this can be explaining how most of these soil are poorly graded. According to the USDA textural classification, the grain size distribution of these soils makes them to be classified as Silty Loam types to Sandy Loam types. Despite of their organic matter content which is less than 10%, according to their respective methylene blue values, the soils studied along the section should be mainly loamy soil of medium plasticity to clayed soil, therefore showing a sensibility of its behavior to variation of water content. That last one is confirmed by the consistency parameters of these soils which show intermediate plasticity to highly plastic. Also, the bearing capacity proposed by these soils at their respective optimum dry densities is relatively small, although most of these experimental CBR values of the studied soils are more important than the ones prescribed by the AASHTO Classification system for A5, A6, and A7 types, and the French Highway Earthworks Manual Classifications system (GTR) for the corresponding A2 and A3 types.展开更多
文摘The investigation of the long-term performance of solidified/stabilized （S/S） contaminated soils was carried out in a trial site in southeast UK. The soils were exposed to the maximum natural weathering for four years and sampled at various depths in a controlled manner. The chemical properties （e.g., degree of carbonation （DOC）, pH, electrical conductivity （EC）） and physical properties （e.g., moisture content （MC）, liquid limit CLL）, plastic limit （PL）, plasticity index （PI）） of the samples untreated and treated with the traditional and accelerated carbonated S/S processes were analyzed. Their variations on the depths of the soils were also studied. The result showed that the broad geotechnical properties of the soils, manifested in their PIs, were related to the concentration of the water soluble ions and in particular the free calcium ions. The samples treated with the accelerated carbonation technology （ACT）, and the untreated samples contained limited number of free calcium ions in solutions and consequently interacted with waters in a similar way. Compared with the traditional cement-based S/S technology, e.g., treatment with ordinary portland cement （OPC） or EnvirOceM, ACT caused the increase of the PI of the treated soil and made it more stable during long-term weathering. The PI values for the four soils ascended according to the order： the EnvirOceM soil, the OPC soil, the ACT soil, and the untreated soil while their pH and EC values descended according to the same order.
文摘Determination of physical property of the soil helps in identification and classification of soil which includes analysis of particle size distribution, Atterberg limits, water content, specific gravity, phase determination and direct shear test. Water plays an important role in triggering landslides and slope failures. Increase of water content reduces the stability of slope. When the moisture content exceeds plastic limits, the slope begins to deform. Three soil samples are collected from the study area and the average bulk density, moisture content and specific gravity are 1.577, 37.032 and 2.434 respectively. Atterberg limit is the most distinctive properties of fine grained sediments and may be used to distinguish silts from clays. Plastic limits (WP), liquid limit (WL), shrinkage limit (WS) values of Nungbi Khunou are 26.236%, 48% and 9.4% respectively. Plasticity index (IP), consistency index (IC) and liquidity index (IL) value is 21.764%, 0.379%, and 60.623% respectively. From index properties value, the soil is highly plastic, stiff and semi-solid in nature. The soil sample falls under CI group in plasticity chart which indicates organic silt and clay soil with medium compressibility and plasticity. Phase determination and particle size distribution result in very high porosity and highly saturated soils which are well graded in nature. Slope and aspect map are prepared from DEM using ArcGIS. Slope is an important contributory factor to landslide, and slope reported from the sampling area indicates gentle slope. Aspect refers to the direction of the terrain faces which is influenced by component like vegetation, settlement, agriculture, precipitation, wind etc. Factor of safety (Fs) calculated from shear stress data is less than 1 indicating unstable slope. From the above finding, the study area may result in sudden and unpredictable failure due to volumetric changes in soil.
文摘The present study is inscribed within the framework of the geotechnical characterization of the soils of the Santchou plain, their classification for employment as pavement subgrade, various identification tests were carried out on the samples. The results obtained showed that with a wide range of different grain sizes, the studied soils showed low content in clay grains and dominance of either sand grains or silt grains, this can be explaining how most of these soil are poorly graded. According to the USDA textural classification, the grain size distribution of these soils makes them to be classified as Silty Loam types to Sandy Loam types. Despite of their organic matter content which is less than 10%, according to their respective methylene blue values, the soils studied along the section should be mainly loamy soil of medium plasticity to clayed soil, therefore showing a sensibility of its behavior to variation of water content. That last one is confirmed by the consistency parameters of these soils which show intermediate plasticity to highly plastic. Also, the bearing capacity proposed by these soils at their respective optimum dry densities is relatively small, although most of these experimental CBR values of the studied soils are more important than the ones prescribed by the AASHTO Classification system for A5, A6, and A7 types, and the French Highway Earthworks Manual Classifications system (GTR) for the corresponding A2 and A3 types.
