Pullout resistance of single model nail in sand

• Main Authors: Wei-Chih Chen, 陳威志
• Other Authors: Cho-Sen Wu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/28000062776088297288

碩士 === 淡江大學 === 土木工程學系 === 92 === Pullout behavior of model nail in a sand box under various conditions was investigated through a series of laboratory tests. The conclusions from the result of laboratory experiment are summarized: (1)When D50 of the sand is smaller than the screw length, peak and residual apparent friction coefficients at the soil-nail interface are increased with the increase of screw length. When D50 of the sand is larger than the screw length, the peak apparent friction coefficient increases with the increase of screw length, and the residual apparent friction coefficient decreased and reaches a constant value. (2) The increase of sand particle creates greater value of the peak apparent friction coefficient. Apparent friction coefficient at residual varies with the particle size of the tested sand. (3) The residual pullout resistance for nail pulled out from No 9 silica and No. 315 sands decreased to 50-60% and 70-80% of peak values, respectively. The residual resistance of nail in No.313 Quartz sand reaches a constant value for all sizes of nails. According to the results of laboratory experiment, roughness was defined to evaluate the peak apparent friction coefficient from nail and soil properties. There are two formulas to calculate the peak average diameter of soil nail. Two formula are used for the D50 of sand is smaller and greater than screw length, respectively. The predicted values of silica sand are 13% greater than the values of laboratory experiment, while the No.315 Quartz sand and No. 313 quartz sand are 6.1% and 17.2% greater than the tested values.