TABLE OF CONTENTS When selecting the type of shoring for a particular project, it is important that a rational appraisal of its ultimate usage be made. The design intent can have a great influence on the type of shoring chosen and can affect even the engineering method and factors of safety used in its design. Once a shoring method is chosen, it is sometimes difficult to change to another system. Some systems, if selected, might be adaptable to a change of usage while others simply cannot be revised. A change in use might result in the abandonment of the initial shoring in order to construct a system compatible with the revised intent. The following are the types of uses and their constraints.
Temporary shoring systems are just that-temporary. This is not to say that they are flimsy or unsafe, but they are designed with the understanding that they will be in place and load bearing for a finite period of time. The period envisioned may be as short as a number of hours in the case of trench boxes (see Chapter 3.2) or as long as two years for deep building excavations. The PTI Manual for Soil and Rock Anchors specifies that any exposure longer than 24 months should be considered permanent, at least in terms of corrosion protection for the anchor components of the wall system. Exposures to particularly aggressive soil conditions may require corrosion protection for even shorter periods of time. See the bibliography in this text for...
