To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core （MPSC）, which is formed by inserting a precast reinforced concrete pile （PRCP）, in-situ tests involving MPSCs with differen...To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core （MPSC）, which is formed by inserting a precast reinforced concrete pile （PRCP）, in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out. Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained. The load transfer between cement soil and PRCP was analyzed by finite element method （FEM）. Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil. The length and the section area on PRCP of an MPSC both have an optimum value. Adopting MPSC is effective in improving the bearing capacity of soft soil ground.展开更多
This study was conducted in Mgbede, River State, Nigeria, hosting up to, or even more than 100 oil wells. It examined the relationship between the bearing capacity of crude oil contaminated soil and the percentage con...This study was conducted in Mgbede, River State, Nigeria, hosting up to, or even more than 100 oil wells. It examined the relationship between the bearing capacity of crude oil contaminated soil and the percentage contamination. Four uncontaminated soil samples were randomly collected at 1.5 m depth within the oil field with hand auger and analyzed for the load bearing properties limited to cohesion, angle of internal friction and bulk density. With these parameters, the bearing capacity was determined for each sample. Crude oil, collected from one of the oil wells with viscosity 0.02611 poises at 40~C and specific gravity 0.8227 g/cm3, was used as the contaminant. This was mixed with the soil sample at 5%, 10%, 15% and 20% concentrations. The mean values of the bearing capacity were 582.458 KN/m2, 495.35 KN/m2 for square and strip footings respectively at 0% contamination, 240.735 KN/m2 and 204.753 KN/m2 at 5%, 321.683 KN/m2 and 274.593 KN/m2 at 10%, 127.003 KN/m2 and 109.12 KN/m2 at 15%, 105.28 KN/m2 and 90.758 KN/m2 at 20% for square and strip footings, respectively. The results showed a consistent decrease in the load bearing values as the crude oil content increased. The result of the null hypothesis established a strong and significant relationship between the bearing capacity of crude oil contaminated soil and the percentage contamination.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
文摘以恢复年限分别为14、36、50 a的落叶松人工林及相邻耕地表层土壤（0～10 cm）为研究对象,采用快速固结试验法,对土壤孔隙比、压缩指数、先期固结压力等指标进行测试,分析植被恢复对典型黑土表层土壤压缩性、承载能力的影响。结果表明：土壤孔隙比、压缩指数、先期固结压力,均随恢复年限的增加而增加,压缩指数、先期固结压力变化范围分别为0.231～0.399、4.2～100.0 k Pa。落叶松林地土壤压缩指数、先期固结压力,均显著高于耕地土壤（p〈0.05）;随植被恢复年限的增加,典型黑土表层土壤压缩性、承载能力逐渐提高,耕性有所增强。土壤力学性质指标与理化性质之间,表现出显著的相关性（p〈0.05）;压缩指数与土壤黏粒比例、有机质质量分数之间关系更为紧密（p〈0.01）;先期固结压力与土壤黏粒比例呈极显著负相关（p〈0.01）。植被恢复导致土壤有机质质量分数的增加;土壤密度和黏粒比例的降低,是黑土表层土壤压缩性增加、土壤承载能力增强的重要原因。
基金Supported by National Natural Science Foundation of China( No. 59978028).
文摘To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core （MPSC）, which is formed by inserting a precast reinforced concrete pile （PRCP）, in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out. Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained. The load transfer between cement soil and PRCP was analyzed by finite element method （FEM）. Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil. The length and the section area on PRCP of an MPSC both have an optimum value. Adopting MPSC is effective in improving the bearing capacity of soft soil ground.
文摘This study was conducted in Mgbede, River State, Nigeria, hosting up to, or even more than 100 oil wells. It examined the relationship between the bearing capacity of crude oil contaminated soil and the percentage contamination. Four uncontaminated soil samples were randomly collected at 1.5 m depth within the oil field with hand auger and analyzed for the load bearing properties limited to cohesion, angle of internal friction and bulk density. With these parameters, the bearing capacity was determined for each sample. Crude oil, collected from one of the oil wells with viscosity 0.02611 poises at 40~C and specific gravity 0.8227 g/cm3, was used as the contaminant. This was mixed with the soil sample at 5%, 10%, 15% and 20% concentrations. The mean values of the bearing capacity were 582.458 KN/m2, 495.35 KN/m2 for square and strip footings respectively at 0% contamination, 240.735 KN/m2 and 204.753 KN/m2 at 5%, 321.683 KN/m2 and 274.593 KN/m2 at 10%, 127.003 KN/m2 and 109.12 KN/m2 at 15%, 105.28 KN/m2 and 90.758 KN/m2 at 20% for square and strip footings, respectively. The results showed a consistent decrease in the load bearing values as the crude oil content increased. The result of the null hypothesis established a strong and significant relationship between the bearing capacity of crude oil contaminated soil and the percentage contamination.
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.
