Theoretical Foundation Engineering
Featuring an easy-to-understand format where detailed mathematical treatment is kept to a minimum, this in-depth book provides numerous charts, drawings, and illustrations to illuminate the problems and theory.
TABLE OF CONTENTS Theoretical Foundation Engineering
Chapter 3: Holding Capacity of Anchor Slabs and Helical Anchors
3.1 INTRODUCTION
In the construction of earth retaining structures such as sheet pile walls (Fig. 3.1a), it is necessary to use vertical anchor slabs. These anchors are usually made of reinforced concrete slabs and they are often arranged in a row as shown in Fig. 3.1b. In many instances, horizontal anchor slabs and also helical anchors (Fig. 3.1c and d) are used to ensure stability of foundations subjected to vertical uplifting forces. A typical example where such type of anchoring may be necessary is a transmission tower foundation. A relatively limited amount of research has been done so far to evaluate the holding capacity of anchors. The results of most of the related research work available at the present time will be summarized in this chapter.
3.2 ULTIMATE HOLDING CAPACITY OF SHALLOW VERTICAL ANCHOR SLABS IN SAND
Figure 3.2 shows an anchor slab with a height h and a width 3 measured at right angles to the cross section shown. The slab is embedded in a sand having a unit weight ? and angle of friction ?. P u is the ultimate load at which the soil in front of the slab will fail. At failure, the anchor will be subjected to a passive force derived from the soil located in front of the slab and an active force due to the soil located behind the slab. The directions of the active and passive forces are also shown in Fig. 3.2.
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