Papers by Keyword: Superposition Effect

Abstract: In this paper, through theoretical analysis and finite element of numerical calculation method, superimposed influence effect in the process of typical complex foundation pit group excavation was analysis and research. Put forward hazard prevention methods aim at the superposition effect in the process of construction, at the same time, the information construction means monitoring is conducted to be verified. Results show that, the relevant control measures was effectively control the displacement of deep foundation pit and surrounding environment.

Abstract: During turning open-pit into underground mining, the state of slope stability is related to the relative space positional relationship between open-pit mining and underground mining. The toe area of slope is the most unfavorable area to slope stability and the outer region of slope is the most favorable area, while the central area of the slope has the most complicated effect on slope stability so that the mechanism of its influence can be understood only by the means of calculation. The slope stability coefficient decreases with the augment of underground mining geometric dimension. But it remains constant when the underground mining area is fully extracted. With the increase of mining depth, its range of influence on slope stability increases, which results in the decrease of slope stability coefficient. However, the slope stability coefficient tends to unchanged when the mining depth increases to some certain value.

Abstract: Performing the superposition effect of multi-elements mineral admixtures, high performance concrete (HPC) with 3% of silicon fume, 20% of fly ash and 40% of ground granulated blast-furnace slag (GGBS) was prepared, and its physical and mechanical properties and durability were studied systematically. The compressive strength and tensile strength of HPC are better than those of ordinary concrete. HPC has high compactness with smaller gas diffusion coefficient and relative permeability coefficient. Adding volume stabilizer and controlling the contents of SO3 in the GGBS and volume stabilizer at 3%, can reduce dry shrinkages effectively. Large mount of mineral admixture was used to make the concentrations of K+ and Na+ in the pore solution and the expansion caused by alkali-silica reaction depress greatly. So the alkali-silica reaction gets controlled markedly. The effective diffusion coefficient of chloride ion is 1.96×10-12 m2/s, which means HPC has a favorable chloride ion penetration resistance. After 15 times of wet-dry cycle, the rates of the rust area and quality loss of the reinforcing steel bars in HPC are only 4.1% and 0.05% respectively, so HPC has better performance of steel protection. The mortar bar did not expand in corrosive sodium sulfate solution, and it means HPC has better performance of sulfate resistance. The performances of frost resistance and carbonation resistance of HPC are also favorable. It’s proved in tests that the superposition effect of multi-elements mineral admixtures can enhance the physical and mechanical properties and durability of concrete greatly.