Skip to main content
CalcStack

Soil Nail Wall Pullout & Tendon Sizing Calculator

Soil nailing is a top-down ground improvement technique reinforcing earth cuts with passively grouted steel tendons.

Diameter of the rotary or percussion drilled borehole (typically 100 to 200 mm).

Length of grouted nail extending past the potential planar slip surface.

Empirical interface bond strength (typically 100 to 450 kPa depending on soil classification).

Yield strength of steel bar (e.g. 420 MPa for Grade 60, 500 MPa for Grade 75).

Nominal diameter of steel reinforcing rebar (typically 25 to 36 mm).

Design factor of safety against pullout (typically 2.0 per FHWA specifications).

Calculated Result
169.3 kN

Allowable Nail Design Capacity

Allowable Nail Design Tension

169.3 kN (38.1 kips)

Ultimate Pullout Capacity (R_po)

565.5 kN

Allowable Ground Pullout (FS = 2)

282.7 kN

Bar Yield Capacity (T_y)

307.9 kN

Governing Failure Limit State

Bar Tensile Yield

Calculation Breakdown

  1. Grout-to-Ground Interface Pullout ResistanceR_po = π × d_hole × L_b × q_u = π × 0.150 m × 8 m × 150 kPa = 565.5 kN
  2. Allowable Ground Pullout LoadR_allow = R_po / FS = 565.5 kN / 2 = 282.7 kN
  3. Steel Tendon Yield CapacityT_y = A_s × f_y = [π × (28 mm)² / 4] × 500 MPa = 307.9 kN (Allowable: 169.3 kN)

Soil Nail Capacity Profile (kN)

Interactive visualization based on your current inputs

Force (kN)
0.0141283424566Ult. PulloutAllow. PulloutBar Yield TyAllow. TendonDesign CapacityCapacity ComponentForce (kN)

What Is the Soil Nail Wall Pullout & Tendon Sizing Calculator?

The Soil Nail Wall Pullout & Tendon Sizing Calculator evaluates the geotechnical bond and structural capacity of soil reinforcement nails.

How Does the Soil Nail Wall Pullout & Tendon Sizing Calculator Work?

It computes the circumferential grout-ground shearing area and determines whether the ground pullout or steel rebar yield governs design.

Soil Nail Wall Pullout & Tendon Sizing Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

R_{po} = \pi d_{hole} L_b q_u, \quad T_y = A_s f_y, \quad T_{allow} = \min\left(\frac{R_{po}}{FS}, 0.55 T_y\right)

FHWA GEC 7 limit state formulation balancing geotechnical cylindrical interface shear against structural steel yield.

How to Use the Soil Nail Wall Pullout & Tendon Sizing Calculator

  1. Input borehole drill diameter and bond embedment length.
  2. Specify ultimate grout-ground bond strength based on geotechnical bore logs.
  3. Enter rebar yield strength, bar diameter, and required safety factor.

Step-by-Step Example Calculation

8-Meter Highway Cut Soil Nail

Input Values:

drillHoleDiameterMm:150
bondLengthM:8
ultimateGroutBondStrengthKPa:150
rebarYieldStrengthMPa:500
rebarDiameterMm:28
pulloutSafetyFactor:2
Worked Steps: Generates 565.5 kN ultimate pullout capacity and 169.3 kN allowable tensile design capacity.

Understanding Your Result

Allowable Nail Design Capacity: Recommended working load per nail.

Ultimate Pullout: Total peak shear resistance along the bonded length.

Governing Failure Mode: Identifies whether geotechnical ground bond or steel rebar limits load.

Factors That Affect the Result

  • Coarse gravels and pressure-grouted holes exhibit significantly higher bond strength than soft clays.
  • Larger drill hole diameters linearly increase bond shear contact area.

When Should You Use This Calculator?

  • Highway widening cuts, railway slope stabilization, tunnel portal shoring, and basement excavations.

Assumptions & Limitations

  • Assumes uniform cylindrical grout column without necking and full encapsulation of the centralizer.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Adheres to FHWA Geotechnical Engineering Circular No. 7 (FHWA-NHI-14-007).

Related Calculators

Explore more tools and calculators in Math Calculators

Helical Screw Pile Ultimate Axial Capacity Calculator

Calculates ultimate and allowable compressive axial capacity of multi-helix screw anchors using individual plate bearing method in cohesive and frictional soils.

Culvert Outlet Riprap Apron Erosion Protection Calculator (HEC-14)

Calculates median stone size (D₅₀), apron length, downstream width, and blanket thickness for culvert outlet scour protection per FHWA HEC-14.

Dry Extended Detention Basin Drawdown Orifice Calculator

Calculates the required release orifice diameter, average discharge rate, and drawdown velocity for stormwater dry extended detention basins.

Broad-Crested Rectangular Weir Discharge Calculator (ISO 3846)

Calculates open channel discharge capacity, critical depth, crest flow velocity, and discharge coefficient for broad-crested rectangular weirs.

SWMM Urban Catchment Peak Runoff & Infiltration Calculator

Calculates peak stormwater runoff, Horton infiltration abstraction, depression storage losses, and composite runoff coefficients for urban subcatchments.

Flexible Pavement 18-kip ESAL Traffic Loading Calculator (AASHTO)

Calculates 20/30-year cumulative 18-kip Equivalent Single Axle Loads (W₁₈), compound traffic growth factors, and AASHTO design lane classifications.