Pipeline trench earthworks
Excavation of a trapezoidal trench, the soft bedding and padding around the pipe, the backfill with native soil and the spoil volume after bulking.
A(y) = b · y + m · y²; B = b + 2 · m · HV_exc = A(H) · L; V_pad = [A(h_b + D + h_p) − π · D² / 4] · LV_back = [A(H) − A(h_b + D + h_p)] · L; V_spoil = V_exc · K_rExcavation and backfill are in-place volumes, as in cost estimates; bulking is applied to the spoil only. Unshored slopes follow the construction safety rules (SNiP 12-04-2002, Table 1) for trenches up to 3 m deep; deeper than 5 m or in saturated soil the slopes are calculated. Bell holes for welding and widening at bends are not included.
Source: SNiP 12-04-2002 (construction safety, part 2), Table 1 (slopes); trapezoid geometry
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Cover to the top of the pipe (usually at least 0.8 m) + pipe diameter + bedding.
Usually D + 0.3 to 0.5 m and not less than the excavator bucket width.
0 for vertical shored walls. Unshored up to 3 m deep: sand 1, sandy loam 0.67, loam 0.5, clay 0.25.
Soft soil or sand, usually 0.1 m (required in rock and frozen ground); 0 for none.
Usually 0.2 m above the top of the pipe; 0 for none.
Sand 1.1–1.15, loam 1.15–1.25, clay 1.25–1.3.
Unit converter for this formulaLength · Liquid volume
- m1
- cm100
- mm1,000
- km0.001
- ft3.28084
- in39.3701
- 1/32 in1,259.84
- 1/64 in2,519.69
- mile0.000621371
- V_back — Backfill with native soil–
- V_pad — Soft bedding and padding–
- V_spoil — Spoil volume (bulked)–
- B — Top width–
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.