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Excavation Shoring Lateral Active Soil Pressure Calculator (Rankine)

Estimate the lateral active earth pressure a shoring wall or trench box must resist, using the classical Rankine theory for cohesionless soil.

Computed in your browser — nothing you enter is uploaded. Figures are presented in United States units and terminology, and each formula’s basis is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
10 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Total active lateral force per linear meter of wall

28 kN/m

Low confidence

This is a preliminary Rankine active-pressure estimate for COHESIONLESS soil under simplified conditions (no water table, no surcharge, vertical smooth wall) — a screening/educational estimate, NOT a stamped design. Cohesive soils, groundwater, surcharge loads (equipment, spoil piles, adjacent structures), sloped ground, braced/strutted multi-level systems (which use Peck's empirical apparent-pressure diagrams instead), and seismic loading all require different methods not captured here. Per OSHA 29 CFR 1926 Subpart P, the actual excavation protective system must be selected by a competent person using the Subpart P tables or designed by a registered professional engineer using site-specific geotechnical data — this calculator is not a substitute for that process.

Peak lateral pressure at base of cut
2.65 psi
Active pressure coefficient Ka
0.33 (dimensionless)

With the figures above, the total active lateral force per linear meter of wall comes to 27.9 kN/m. Treat this one cautiously — the confidence rating is low, so verify it against a merchant quote or a trade opinion first. This is presented for United States. Building in another market? Change the selector above and the units and terminology follow.

Add the equipment this sizes

This result is a specification — 28 kN/m — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.

Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Regulatory standards & verification citations

  • Rankine active earth pressure theory for a cohesionless soil, vertical smooth wall, horizontal ground surface, no surcharge, no water table: Ka = tan²(45° − φ/2); peak pressure at base p_max = γ×H×Ka; total active force per unit length of wall Pa = 0.5×γ×H²×Ka. This is the standard textbook formula (used in the Caltrans Trenching and Shoring Manual and standard geotechnical references). OSHA 29 CFR 1926 Subpart P classifies soil by Type A/B/C using field tests (unconfined compressive strength), NOT by friction angle or Ka — the actual protective system must be selected per Subpart P's prescriptive tables or designed by a registered professional engineer (1926.652(b)/(c)); this formula is not itself an OSHA-published method.

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Frequently asked questions

Does this account for OSHA's soil classification (Type A/B/C)?
No. OSHA 29 CFR 1926 Subpart P classifies soil by Type A/B/C using field tests such as unconfined compressive strength — not by friction angle or the Rankine active pressure coefficient (Ka). The actual protective system for an excavation must be selected using Subpart P's prescriptive tables or designed by a registered professional engineer per 1926.652(b)/(c); this formula is not itself an OSHA-published method.
What conditions does this Rankine formula assume, and when does it not apply?
It assumes cohesionless soil, a vertical smooth wall, a horizontal ground surface, no surcharge, and no water table. Cohesive soils, groundwater, surcharge loads (equipment, spoil piles, adjacent structures), sloped ground, braced/strutted multi-level systems (which instead use Peck's empirical apparent-pressure diagrams), and seismic loading all require different methods this calculator does not capture.
Is this enough to design a shoring system?
No — this is a preliminary screening/educational estimate only, not a stamped design. Per OSHA 29 CFR 1926 Subpart P, the excavation protective system must be selected by a competent person using the Subpart P tables or designed by a registered professional engineer using site-specific geotechnical data.