APPENDIX B 



AWPI Technical Guidelines 



For Preisure Treated Wood 



S2 



1970 



Bulkheads: Design and Construction— Part I 



SUMMARY 



This bulletin describes several variations of bulkhead 

 construction, including two principal types of anchor- 

 age systems- The reader is given summaries of both 

 the proper construction sequence and the design 

 procedures- The step-by-step descriptions will be dis- 

 cussed in Parts Ih and III and will assist the designer 

 in completing the design and specification of treated 

 timber bulkheads. 



INTRODUCTION 



There are many approaches to bulkhead design and 

 construction- Three typical systems are shown in Figs 

 1. 2 and 3 These systems illustrate the differences 

 that may be expected under varying site conditions, 

 particularly with respect to variations in water levelS- 

 An engineer or architect who is not experienced in 

 the design of bulkheads may want to rely upon con- 

 sultants tor the design of critical bulkheads and sea- 

 walls, the latter being a bulkhead exposed to more 

 severe forces 



The principal difference between a bulkhead and a 

 retaining or crib wall is that a bulkhead is built near 

 water, adding an additional design factor. In designing 

 bulkheads, the architect and engineer can utilize their 

 experiences with design of similar earth-retaining 

 structures The mam question that may arise is how to 

 cope with the presence ol water. Therelore, the pur- 

 pose of this bulletin is to show where inlormation about 

 the effects of water can be lound and to express, in 

 concise terms, the procedures that bulkhead designers 

 have consistently used. 



The designs in this bulletin are relatively conserva- 

 tive Where existing soil conditions are superior to 

 those assumed m these design procedures, the thick- 

 nesses of sheet pilings and the sizes and spacings of 

 tie rods and anchor systems can be reduced. Yet, 

 precisely because these procedures are somewhat 

 conservative, they may be used with conlidence, 



TYPICAL TIMBER BULKHEADS 



Figure 1 shows a conservatively-designed, low bulk- 

 head for installation where the existing grade along 

 the sheet piles is somewhat higher than the low-water 

 level. Figure 2 shows an intermediate bulkhead suit- 

 able for retaining till at the site of a marina or lor 

 providing a finished waterfront in a housing develop- 



ment. If these bulkheads are located further in shore, 

 or if the outside water level variations are less than 

 shown in the figures, the heights of bulkheads and 

 lengths ol sheet piles may be reduced, 



The anchorage systems shown m these two figures 

 depend upon the passive resistance of a mound of 

 earth immediately around the anchor post and wales- 

 The theoretical mound required to develop this pas- 

 sive resistance is shown by a dotted line If backfill 

 were placed directly against the sheet piles before 

 this mound of earth is compacted around the anchor 

 system, the resulting forces would displace the bulk- 

 head or even push it over, resulting in a costly and 

 disastrous failure After earth is compacted over the 

 anchorage system, backlill can be deposited against 

 the sheet piles by a drag line, truck dumping, hydraulic 

 pipe line, or other suitable method 



Figure 3 shows a bulkhead suitable for the deep- 

 water portions ol marinas, or lor locations where the 

 existing water depths are 6 to 8 leet and extensive 

 land tills are desirable. The anchorage system is a 

 self-supporting A-lrame that does not depend on pas- 

 sive earth resistance- The anchor system is particu- 

 larly adaptable to filling by the hydraulic method 

 because the backfill can be raised behind the sheet 

 piles without regard lor the placement of backlill at 

 the anchorage location 



To install the A-lrame anchdrage. a pile-driving rig 

 is required to drive the piles to specilied bearing 

 capacity At locations with less water-level variation 

 than the 4 leet. shown, the height ol linished grade 

 may be lowered proportionally. For an increase in 

 water-level variation, a similar increase in height ol 

 finished grade can be made with a corresponding 

 reduction in water depth. The 5-foot vertical distance 

 from finished grade to tie rod level should be main- 

 tained- 



CONSTRUCTION PROCEDURES 



The proper sequence for bulkhead construction is: 



1. Drive all round timber piles, both vertical and 

 battered: set or drive all posts, 



2. Using bolts, attach the horizontal wales lor the 

 sheet piles and the anchorage system. 



3. Drive sheet piling, 



4 Complete all bolted connections and install tie 

 rods. 



© 1969 AMERICAN WOOD PRESERVERS INSTITUTE 



308 



