Anchorage Behavior of Vertical Anchors in Gravel Formation

• Main Authors: Hsiao-ping Huang, 黃曉屏
• Other Authors: Shih-Tsung Hsu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/a223ey

碩士 === 朝陽科技大學 === 營建工程系碩士班 === 92 === To evaluate the uplift behavior of cylindrical anchors installed in gravel formation, a series of triaxial test results were used to obtain the parameters needed for a strain hardening-softening and volume dilation model named “SHSE”. Using this model, a numerical study was carried out to analyze the behavior of vertically pulled out anchors in gravel formation. A field test program was conducted to verify the applicability of the numerical program. Finally, parametric studies on the factors affecting the anchorage behavior were performed as well. The numerical results indicate that the load-displacement of anchors calculated from this numerical model was almost in close agreement with those of field tests. When overburden depth, fixed length or diameter of an anchor increased, the anchorage capacity also increased. Increasing fixed length should be the optimum method to increase the anchorage capacity. No peak value of end resistance can be found from a depth anchor. According to the definition of yielding end-resistance, the yielding end-resistance of a depth anchor develops anchor displacement about 55%D. The coefficient of lateral earth pressure Kf decreases with fixed length and overburden depth of an anchor in gravel formation, however it is greater than the lateral earth pressure coefficient Kf of an anchor in sand. Based on the development of end resistance coefficient Nq, it can be defined as a shallow anchor when overburden-diameter ratio Z/D<11, Z/D=11~21 of an anchor is classified to a transited anchor, Z/D>21 is belong to a depth anchor. For tension anchor, the load transfers from the top to the bottom of fixed end; however, the load of a compression anchor transfers from the bottom to the top of fixed end. For a short anchor, a rectangular shaped distribution of friction stress along fixed end can be found except the top and bottom of fixed end. However, the friction stress along the fixed anchor end shows progressive yielding when the fixed length is greater than 3m.