This study aims to investigate the effect of mica content on the mechanical properties of clays.Commercially available ground mica was blended with a locally available clayey soil,at varying mica contents by mass of 5...This study aims to investigate the effect of mica content on the mechanical properties of clays.Commercially available ground mica was blended with a locally available clayey soil,at varying mica contents by mass of 5%,10%,15%,20%,25%and 30%,to artificially prepare various micaceous clay blends.The preliminary testing phase included consistency limits and standard Proctor compaction tests.The primary testing program consisted of unconfined compression(UC),direct shear(DS)and scanning electron microscopy(SEM)tests.The test results showed that the liquid and plastic limits exhibited a linear,monotonically increasing trend with increase in mica content.The rate of increase in the plastic limit,however,was found to be greater than that of the liquid limit,thereby leading to a gradual transition towards a non-plastic,cohesionless character.The soft,spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica content.Under low confinement conditions,i.e.the UC test and the DS test at low normal stresses,the shear strength was adversely affected by mica.However,the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface,thus leading to improved strength resistance.展开更多
Clay minerals, as e.g. montmorillonite, abundantly exist in the slip zones such as earthquake faults and landslides. Water contents are an important factor for controlling slip behavior, since montmorillonite contains...Clay minerals, as e.g. montmorillonite, abundantly exist in the slip zones such as earthquake faults and landslides. Water contents are an important factor for controlling slip behavior, since montmorillonite contains a considerable amount of water molecules compared with other clay minerals. Here, a series of mechanochemical milling experiments were conducted for montmorillonite at the water contents ranging from 0% to 800%. Decomposition occurs at the water contents below 25% and above 600%, which are well correlated with the consistency limits of montmorillonite reported so far, i.e. shrinkage/plastic and liquid limits, respectively. Montmorillonite is found to be effectively decomposed into amorphous materials at the water contents below the shrinkage/plastic limit. In the region of water content between shrinkage/plastic and liquid limits, decomposition cannot be achieved solely by the mechanochemical treatment. At the water contents higher than the liquid limit, decomposition is again started. The present work demonstrates that the degree of decomposition can be of usefulness for speculating how the water molecules behave in the slip zones in nature.展开更多
The California bearing ratio (CBR) test is the most widely spread method of determining the bearing strength of the pavement material and is fundamental to pavement design practice in most countries. This test is expe...The California bearing ratio (CBR) test is the most widely spread method of determining the bearing strength of the pavement material and is fundamental to pavement design practice in most countries. This test is expensive, laborious and time consuming, and to overcome this, Quasi static cone penetrometer machine was fabricated and used to measure the consistency limits (liquid limit-LL, Plastic limit-PL and Plasticity index-PI), which were used to develop an empirical equation to determine CBR. Soil samples were collected and unsoaked CBR, PL, LL and PI were determined according to BS 1377 part 9 and BS 1377-2;1990. Quasi static penetration forces at 20 mm depth of penetration were also determined at consistency limits. It was found that the force of 1020 gf and 60 gf was achieved at a depth of 20 mm at PI and LL respectively. The correlation and regression analysis between consistency limits, and the experimental CBR obtained showed coefficient of determination, R<sup>2</sup> = 0.907 between CBR and all the parameters using multiple linear regression analysis (MLRA). The regression equation developed was used together with the relationship developed between the Quasi static Penetration force at consistency limits and the tested consistency limits to come up with the General Empirical Equation. Verification of the formula showed that the correlation can be used accurately to determine the un soaked CBR.展开更多
Some soil properties were studied in relation soil aggregate along a climatologically region and different crop land use in the Northeast of Sulaimani City/Kurdistan Region of Iraq. Five locations were selected along ...Some soil properties were studied in relation soil aggregate along a climatologically region and different crop land use in the Northeast of Sulaimani City/Kurdistan Region of Iraq. Five locations were selected along these regions ranging from semiarid to sub-humid climatologically conditions. The soil physical, chemical properties, aggregate stability and size distribution were analyzed. A mean-weight-diameter (MWD) value was determined on 5 soils, which was the sum of the percentage of soil on each sieve (6, 3, 1.5, 0.75, 0.375 and 0.125 mm). The results of the measurements could evaluated with linear correlation coefficients for the relationships between aggregate stability (MWD) and soil physical and chemical properties of the different crop land use. The correlation coefficient for the relationship between aggregate stability and organic matter was highly significant (P < 0.0l%) which is in agreement with the findings of [1]. Generally large aggregates (large 6, 3, 3 - 1.5 mm) were present in highest proportions in the most semiarid of the studied areas. Aggregates 0.75 - 0.125 mm were positively correlated to fine, very fine sand and silt fractions and to organic matter. Stability of aggregates showed a positive correlation with clay content and organic matter content, while the carbonate content was strongly correlated with aggregate stability. The land use history affecting soil overlaps the pattern of climatological situations and cultivated crop lands and has to be taken into account. Aggregate size distribution and stability can be used as indicator of soil conservation and productivity.展开更多
基金made possible through the provision of an Australian Government Research Training Program Scholarship
文摘This study aims to investigate the effect of mica content on the mechanical properties of clays.Commercially available ground mica was blended with a locally available clayey soil,at varying mica contents by mass of 5%,10%,15%,20%,25%and 30%,to artificially prepare various micaceous clay blends.The preliminary testing phase included consistency limits and standard Proctor compaction tests.The primary testing program consisted of unconfined compression(UC),direct shear(DS)and scanning electron microscopy(SEM)tests.The test results showed that the liquid and plastic limits exhibited a linear,monotonically increasing trend with increase in mica content.The rate of increase in the plastic limit,however,was found to be greater than that of the liquid limit,thereby leading to a gradual transition towards a non-plastic,cohesionless character.The soft,spongy fabric and high water demand of the mica mineral led to higher optimum water contents and lower maximum dry unit weights with increasing mica content.Under low confinement conditions,i.e.the UC test and the DS test at low normal stresses,the shear strength was adversely affected by mica.However,the closer packing of the clay and mica components in the matrix under high confinement conditions offsets the adverse effects of mica by inducing frictional resistance at the shearing interface,thus leading to improved strength resistance.
文摘Clay minerals, as e.g. montmorillonite, abundantly exist in the slip zones such as earthquake faults and landslides. Water contents are an important factor for controlling slip behavior, since montmorillonite contains a considerable amount of water molecules compared with other clay minerals. Here, a series of mechanochemical milling experiments were conducted for montmorillonite at the water contents ranging from 0% to 800%. Decomposition occurs at the water contents below 25% and above 600%, which are well correlated with the consistency limits of montmorillonite reported so far, i.e. shrinkage/plastic and liquid limits, respectively. Montmorillonite is found to be effectively decomposed into amorphous materials at the water contents below the shrinkage/plastic limit. In the region of water content between shrinkage/plastic and liquid limits, decomposition cannot be achieved solely by the mechanochemical treatment. At the water contents higher than the liquid limit, decomposition is again started. The present work demonstrates that the degree of decomposition can be of usefulness for speculating how the water molecules behave in the slip zones in nature.
文摘The California bearing ratio (CBR) test is the most widely spread method of determining the bearing strength of the pavement material and is fundamental to pavement design practice in most countries. This test is expensive, laborious and time consuming, and to overcome this, Quasi static cone penetrometer machine was fabricated and used to measure the consistency limits (liquid limit-LL, Plastic limit-PL and Plasticity index-PI), which were used to develop an empirical equation to determine CBR. Soil samples were collected and unsoaked CBR, PL, LL and PI were determined according to BS 1377 part 9 and BS 1377-2;1990. Quasi static penetration forces at 20 mm depth of penetration were also determined at consistency limits. It was found that the force of 1020 gf and 60 gf was achieved at a depth of 20 mm at PI and LL respectively. The correlation and regression analysis between consistency limits, and the experimental CBR obtained showed coefficient of determination, R<sup>2</sup> = 0.907 between CBR and all the parameters using multiple linear regression analysis (MLRA). The regression equation developed was used together with the relationship developed between the Quasi static Penetration force at consistency limits and the tested consistency limits to come up with the General Empirical Equation. Verification of the formula showed that the correlation can be used accurately to determine the un soaked CBR.
文摘Some soil properties were studied in relation soil aggregate along a climatologically region and different crop land use in the Northeast of Sulaimani City/Kurdistan Region of Iraq. Five locations were selected along these regions ranging from semiarid to sub-humid climatologically conditions. The soil physical, chemical properties, aggregate stability and size distribution were analyzed. A mean-weight-diameter (MWD) value was determined on 5 soils, which was the sum of the percentage of soil on each sieve (6, 3, 1.5, 0.75, 0.375 and 0.125 mm). The results of the measurements could evaluated with linear correlation coefficients for the relationships between aggregate stability (MWD) and soil physical and chemical properties of the different crop land use. The correlation coefficient for the relationship between aggregate stability and organic matter was highly significant (P < 0.0l%) which is in agreement with the findings of [1]. Generally large aggregates (large 6, 3, 3 - 1.5 mm) were present in highest proportions in the most semiarid of the studied areas. Aggregates 0.75 - 0.125 mm were positively correlated to fine, very fine sand and silt fractions and to organic matter. Stability of aggregates showed a positive correlation with clay content and organic matter content, while the carbonate content was strongly correlated with aggregate stability. The land use history affecting soil overlaps the pattern of climatological situations and cultivated crop lands and has to be taken into account. Aggregate size distribution and stability can be used as indicator of soil conservation and productivity.
