Aluminum hydraulic shoring guidance

The hydraulic cylinders must meet specific minimum safe working capacities as outlined in Appendix D to Subpart P.

• 2-inch cylinders must have a minimum 2-inch inside diameter and a safe working capacity of at least 18,000 pounds axial compressive load at maximum extension.
• 3-inch cylinders must have a minimum 3-inch inside diameter and a safe working capacity of at least 30,000 pounds axial compressive load at maximum extension.

The tables in Appendix D provide shoring specifications for different soil types, which must be determined using the classification method in Appendix A of the excavation standard.

• Tables D-1.1 and D-1.2 cover vertical shores for Type A and Type B soils.
• Tables D-1.3 and D-1.4 cover horizontal waler systems for Type B and Type C soils.

You must use the table that corresponds to the soil type identified in your excavation, as required by Appendix D of Subpart P.

For a 12-foot deep trench in Type A soil that is 10 feet wide, you must use 2-inch diameter cylinders with structural oversleeves. According to Table D-1.1 in Appendix D to Subpart P, the shores should be spaced a maximum of 8 feet apart horizontally and 4 feet apart vertically. The oversleeves are required because the trench width is over 8 feet but not more than 12 feet.

For an 18-foot deep, 12-foot wide trench in Type C soil, you have several options according to Table D-1.4 in Appendix D to Subpart P. One option is to use horizontal wales with a section modulus of 14.0, spaced 4 feet apart vertically. These would be paired with 3-inch diameter cylinders spaced at a maximum of 6 feet horizontally. Additionally, closely spaced 3x12 timber sheeting is required.

When using vertical shores as a protective system, you must install a minimum of three shores spaced equally and horizontally in a group. This requirement is specified in the footnotes to the tables in Appendix D to Subpart P.

Plywood used with vertical shores is intended only for preventing local raveling or sloughing of the trench face between the shores; it is not a structural member. According to Appendix D to Subpart P, the plywood must be either 1.125-inch thick softwood or 0.75-inch thick, 14-ply arctic white birch (Finland form).