Study Of Reinforcement And Improvement Of Embankment In Olympic Rowing-Cannoeing Park

The Project of Dynamic Water Area in Olympic Rowing-Cannoeing Park is to place a channel with a high-speed current on an embankment filled with sandy silt and fine sand, since the mechanical and hydraulic properties of them are very bad, improvement have to be carried out on them. In this paper, the study on densification, cementing and reinforcement of fine sand and silt is done through laboratory tests (including direct shearing and uniaxial compression tests of reinforced soil, pull-out tests and direct shearing tests of geogrid and soil), in-situ full-scale model tests (including tests of stratified backfill construction, loading and collapsibility tests, erosion tests, and tests of backfilling and measurements of reinforced earth wall), and analyses of stability, stress and deformation.In this paper, mechanical properties of the sandy silt and fine sand mixed with cement and fly ashes in different amounts after different ages curing are researched, and the effect of cementing is compared. Through pull-out tests and direct shearing tests of geogrid in various soil, the interface characteristics of between geogrid and soil are measured. The conclusions of the laboratory tests are as follows: after sandy silt is mixed with cement, its permeability coefficient reduces by magnitude, the modulus of compressibility and the strength increase obviously, the collapsibility is essentially eliminated; the frictional resistance of interface between geogrid and sandy silt or fine sand is quite low.In the in-situ full-scale model tests, the density, bearing capacity, homogeneity, capability against scouring and collapsibility of earth fill mixed with different amounts of cementing material and constructed in different ways are compared, and the limitation and advantage of various ways of construction are also concluded. In that way, the amounts of cementing material and the ways of construction adopted in the in-situ construction of the dynamic water area are determined. The strain of geogrid and the earthpressure are measured in the in-situ full-scale vertical geogrid reinforced retaining wall. The analysis of stability, numerical analysis of stress and strain of the reinforced steep slope and reinforced retaining wall are carried out by Program STAB95 and NMFRS. The computed results and the measured results are compared. The main conclusions are as follows: after soil is mixed with cement, its capability against erosion improves obviously; the key of the project of embankment in dynamic water area is not the bearing capacity; the distribution of horizontal earth pressure approaches to Rankine's earth pressure; in the vertical section, the strain of geogrid reaches to peak value in the lower part of the wall (about one half to one third of the height of wall); in normal state of the geogrid, its stress equals from 2.1 to 15.9 percent of the ultimate tensile strength of geogrid, and the safety coefficient of the retaining wall is quite high.