Based on the variational approach for pile groups embedded in soil modeled using a load-transfer curve method, a practical method was conducted to estimate the settlement of symmetric pile group supported embankments....Based on the variational approach for pile groups embedded in soil modeled using a load-transfer curve method, a practical method was conducted to estimate the settlement of symmetric pile group supported embankments. The working mechanism of composite foundations improved by rigid or semi-rigid columns is analyzed by this method. Under equivalent strain conditions, the pile-soil stress ratio approaches the pile-soil modulus ratio up to a limited value of pile stiffness （Rm〈10）; in the subsequent stages of high pile stiffness （Rm〉10）, a further increase in the pile-soil modulus ratio cannot lead to a significant increase of stress transferred to the columns in composite foundations. The major influencing factor of the stress concentration from soil to pile in a high pile-soil modulus ratio is the padding stiffness. For the composite foundation improved by cement mixing columns, the effective column length is about 15 to 20 m and it is a more economical and effective design when the column length is less than 15 m.展开更多
The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy f...The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy for the embankments of high moisture content, high void ratio and of the high compression nature to cause too much settlement and loss of stability. Embankment stability during construction and residual settlement of pavement during service period are two major challenges to be faced of the design and construction. This paper outlines the site investigation, laboratory tests and monitoring data in a few selected existing preloading areas, and presents the back-analysis results of the modified secondary compression indices of in-situ soft materials. It is found that the early monitoring data after primary settlement completion are a more reliable approach to estimate the residual settlements within a nominated duration.展开更多
文摘Based on the variational approach for pile groups embedded in soil modeled using a load-transfer curve method, a practical method was conducted to estimate the settlement of symmetric pile group supported embankments. The working mechanism of composite foundations improved by rigid or semi-rigid columns is analyzed by this method. Under equivalent strain conditions, the pile-soil stress ratio approaches the pile-soil modulus ratio up to a limited value of pile stiffness （Rm〈10）; in the subsequent stages of high pile stiffness （Rm〉10）, a further increase in the pile-soil modulus ratio cannot lead to a significant increase of stress transferred to the columns in composite foundations. The major influencing factor of the stress concentration from soil to pile in a high pile-soil modulus ratio is the padding stiffness. For the composite foundation improved by cement mixing columns, the effective column length is about 15 to 20 m and it is a more economical and effective design when the column length is less than 15 m.
文摘The construction of CKE road embankments is undertaken over soft soils, which include peats, organic soils, clays and sludge. The moisture content of peat is up to 700% and void ratio is up to 11.99. It＇s very easy for the embankments of high moisture content, high void ratio and of the high compression nature to cause too much settlement and loss of stability. Embankment stability during construction and residual settlement of pavement during service period are two major challenges to be faced of the design and construction. This paper outlines the site investigation, laboratory tests and monitoring data in a few selected existing preloading areas, and presents the back-analysis results of the modified secondary compression indices of in-situ soft materials. It is found that the early monitoring data after primary settlement completion are a more reliable approach to estimate the residual settlements within a nominated duration.
