EASIER FASTER STRONGER
Retaining Wall Calculator
Designed with reference to AS 4678 & AS 1170.0
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Sleeper length is linked to Post Spacing
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LOAD TYPE PRESSURE
(kPa)		 THRUST (HL)
(kN/m)		 THRUST (HL*)
(kN/m)		 LEVER ARM
(mm)		 MW
(kN.m/m)		 MW*
(kN.m/m)		 NOTES
Soil = Ka*γs*hs - - - - - - Max. pressure at base
Surcharge = Ka*s - - - - - - Uniform pressure dist.
Total (at wall base) - - - - - -
mm
Set the number of sleepers per layer below. Multiple sleepers share the lateral load, reducing stress per sleeper.
Layer - Ha
(mm)		 Sleeper M*(a)
/ØMrd		 δ(dl)
SLS · J7.1.1 (long-term, fixed)		 δ(dl+Ψl.ll)
SLS · J4(b)(iii) (long-term, fixed)
Deflection columns δ(dl) and δ(dl+ψl·ll) use SLS pressures (Φuc = Φuo = 1.0 per AS4678 J7.1.1). Bending check M*/φMrd uses ULS factored values.
Note: Pressure and load values below use the ULS material reduction factors (Φuc, Φuo per AS4678) and the active load-combination factors. Serviceability deflection is checked separately on an SLS basis (AS4678 J7.1.1).
LAYER - Ha
(mm)		 Ka.S
(kPa)		 Ka.γs.Ha
(kPa)		 TOTAL
(kPa)		 Wdl
(kN/m)		 Wll
(kN/m)		 W*
(1.25G + 1.5Q)
(kN/m)		 M*
(1.25G + 1.5Q)
(kN.m)		 ØMrd RATIO
Pressure values calculated at the central horizontal plane of the sleeper (values in brackets)
Section Classification (AS4100 Table 5.2)
?
Flange: ?
Web: ?
Yield Stress, fy
?
Effective Section Modulus, Ze
?
Section Capacity, Ms = fy x Ze
?
Capacity Factor, φ
0.90
Design Moment Capacity
φMs = ?
Applied Moment, M*
?
Utilisation Ratio (M*/φMs)
?
Web Depth, d
?
Web Thickness, tw
?
Shear Area, Aw = d x tw
?
Web Yield Stress, fyw
?
Shear Yield Capacity (Cl 5.11.4)
Vw = 0.6 x fyw x Aw
Shear Yield Capacity, Vw
?
Nominal Shear, φVv (pure)
?
Design Shear Capacity
φVv = ?
Applied Shear, V*
?
Utilisation Ratio (V*/φVv)
?
AS4100 Cl 5.11.2: dp/tw <= 82/sqrt(fy/250) → Vv=Vw. Cl 5.11.5: αv=[82/((dp/tw)sqrt(fy/250))]². Cl 5.12.3: If M*>0.75φMs: Vvm=Vv[2.2-1.6M*/φMs]
SLS Basis (AS4678 J7.1.1)
Φuc = Φuo = ?
Ka = ?
φ* = ?
Acting depth h = ?
σsoil,max = ?
σsurcharge = ?
Cantilever Length, L
?
Second Moment of Area, Ix
?
Elastic Modulus, E
200,000 MPa
DL — Soil Pressure (VDL)
?
LL — Surcharge (UDL)
?
Acting Depth, h
?
Calculated Deflection
δ = ?
Deflection Limit (H/100)
?
Deflection Ratio (δ / Limit)
?
SLS deflection per AS4678 J4(b)(iii) and J7.1.1: G + ψl Q with Φuc = Φuo = 1.0. Wind effects excluded (long-term load combination).
Analysis Method
Layer φ (°) c (kPa) γ (kN/m³) Φuc Φuo
LSD: φ* = atan(Φuo·tan(φ)), c* = Φuc·c
Ka = ? (using φ = ?°)
Thrust, HL*
?
Moment, MW*
?
Post Spacing
?
H* = HL* x Spacing
?
M* = MW* x Spacing
?
e = M / H
?
Values include load factors (LSD) or unfactored (ASD)
Pile Diameter, B
?
Embedment Depth, L
?
Edit pile geometry in the Pile Properties section on the left panel
Demand / Capacity
?
Hu (Ultimate Capacity)
?
Rotation Point, x
?
LSD: Ratio = H* / Hu (must be < 1.0)
Ultimate Applied Load (HL*)
Pile forces for factored applied load H* from wall design
Node z (m) z/B qz (kPa) Kqz Kcz pz (kPa) Δz (m) Fz (kN) Lever (m) M (kNm)
POSTS
M*/φMs = N/A
V*/φVv = N/A
δ/δlim = N/A
SLEEPERS
M*/φMrd = N/A
V*/φVrd = N/A
δ/δlim = N/A
PILE
H*/Hu = N/A
P-Y Curve Analysis (API Sand)
Parameters taken from main input. Edit in Geometry and Soil tabs.
Pile Diameter, B—
Embedment Depth, L—
Pile EI (Post)—
Applied H*—
Applied M*—
Layer φ' (°) γ (kN/m³) kh (kN/m³)
Head Deflection
—
Max Bending Moment
—
Max Shear Force
—
Results at Depth
Depth z (m) Deflection y (mm) Moment M (kNm) Shear V (kN) Soil Rxn p (kN/m)
Run analysis to populate

TABLE D4 - SOIL CLASSIFICATION

Soil group Typical soils in group φ' (degrees)
Poor Soft and firm clay of medium to high plasticity, silty clays, loose variable clayey fill, loose sandy silts 17 to 25
Average Stiff sandy clays, gravelly clays, compact clayey sands and sandy silts, compacted clay fill (Class II) 26 to 32
Good Gravelly sands, compacted sands, controlled crushed sandstone and gravel fills (Class I), dense well-graded sands 32 to 37
Very good Weak weathered rock, controlled fills (Class I) of roadbase, gravel and recycled concrete 36 to 43
This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

TABLE D4 - SOIL CLASSIFICATION

Soil group Typical soils in group c' (kPa)
Poor Soft and firm clay of medium to high plasticity, silty clays, loose variable clayey fill, loose sandy silts 0 to 5
Average Stiff sandy clays, gravelly clays, compact clayey sands and sandy silts, compacted clay fill (Class II) 0 to 10
Good Gravelly sands, compacted sands, controlled crushed sandstone and gravel fills (Class I), dense well-graded sands 0 to 5
Very good Weak weathered rock, controlled fills (Class I) of roadbase, gravel and recycled concrete 0 to 25
This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

Deflection Calculation

Bending deflection calculated via classical beam theory while adopting Timoshenko correction for shear deformation.

δtotal = δbending + δshear

TABLE 5.1(A) - MATERIAL STRENGTH AND SERVICEABILITY UNCERTAINTY FACTORS FOR SOIL

(based on peak values of c' and φ')

Soil or material uncertainty factor Soil or fill conditions
Class I Class II Uncontrolled fill In situ material
Strength
Strength Φuφ 0.95 0.90 0.75 0.85
Φuc 0.90 0.75 0.50 0.70
Serviceability
Serviceability Φuφ 1.0 0.95 0.90 1.00
Φuc 1.0 0.85 0.65 0.85

TABLE 5.1(B) - MATERIAL STRENGTH AND SERVICEABILITY UNCERTAINTY FACTORS FOR SOILS

(based on cu and Φu)

Soil or material uncertainty factor Soil or fill conditions
Controlled fill Uncontrolled fill In situ material
Class I Class II
Strength Φuφ 0.0 0.0 0.0 0.0
Φuc 0.6 0.5 0.3 0.5
Serviceability Φuφ 0.0 0.0 0.0 0.0
Φuc 0.9 0.8 0.5 0.75
This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

TABLE D1 - UNIT WEIGHTS OF SOILS (AND SIMILAR MATERIALS)

Material γm: moist bulk weight
(kN/m³)		 γs: saturated bulk weight
(kN/m³)
Loose Dense Loose Dense
A - Granular
Gravel16.018.020.021.0
Well-graded sand and gravel19.021.021.523.0
Coarse or medium sand16.518.520.021.5
Well-graded sand18.021.020.522.5
Fine or silty sand17.019.020.021.5
Rock fill15.017.519.521.0
Brick hardcore13.017.516.519.0
Slag fill12.015.018.020.0
Ash fill6.510.013.015.0
B - Cohesive
Peat (very variable)12.012.0
Organic clay15.015.0
Soft clay17.017.0
Firm clay18.018.0
Stiff clay19.019.0
Hard clay20.020.0
Stiff or hard glacial clay21.021.0
This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

TABLE 1.1 - STRUCTURE CLASSIFICATION

Classification Examples of structures
C Where failure would result in significant damage or risk to life
B Where failure would result in moderate damage and loss of services
A Where failure would result in minimal damage and loss of access

NOTES:

1  Classification B includes structures not covered by Classifications A or C

2  For more information on structure classification, see Appendix A.

This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

TABLE 5.2 - STRUCTURE CLASSIFICATION DESIGN FACTOR (φn)

Structure classification Design factor, (φn)
Ultimate limit state Serviceability limit state
C 0.9 1.0
B 1.0 1.0
A 1.1 1.0
This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

APPENDIX A - STRUCTURE CLASSIFICATION

TABLE A1 - EXAMPLES OF STRUCTURE CLASSIFICATION

Classification Description Examples
A Low consequence for loss of human life, or small or moderate economic, social or environmental consequences Where failure would result in minimal damage and loss of access:

Walls in areas rarely visited by people
Walls on private property supporting gardens, fences, etc.
B Medium consequence for loss of human life, or considerable economic, social or environmental consequences Where failure would result in moderate damage and loss of services:

Walls not included in classifications A or C
Walls supporting or above normal structures
Walls supporting minor roads
Walls above public spaces
Walls with height >=1.5 m
C High consequence for loss of human life, or very great economic, social or environmental consequences Where failure would result in significant damage or risk to life:

Walls supporting structures identified for post-disaster recovery
Walls supporting or above access or services to structures identified for post-disaster recovery

TABLE A2 - GENERAL METHOD FOR STRUCTURE CLASSIFICATION

Public impact
(economic, social or environmental)		 Risk to life
Low Medium High
Low A B B
Medium B B C
High B C C
These tables have been recreated from AS4678 Appendix A. Seek professional advice to confirm appropriate classification for your specific project.

TABLE 4.1 - LIVE LOAD kPa

Classification Backfill slope (horizontal/vertical)
Steeper than 4:1 4:1 or flatter
B, C 2.5 5
A 1.5 2.5

Minimum live loads as per AS4678

This table has been recreated from AS4678. Seek professional advice to confirm appropriate values for your specific site conditions.

ACTIVE EARTH PRESSURE COEFFICIENT (Ka)

Horizontal backfill (β = 0°):
Ka = tan²(45° − φ*/2)
Ka = (1 − sin φ*) / (1 + sin φ*)
Inclined backfill (β > 0°):
Ka = cos β x [cos β − sqrt(cos²β − cos²φ*)] / [cos β + sqrt(cos²β − cos²φ*)]
Valid when β < φ* (incline less than design friction angle)

Where:

β = crest incline angle from horizontal

φ* = design friction angle (reduced)

φ* = tan⁻¹(Φuφ x tan φ)

Φuφ = material uncertainty factor for friction angle (AS4678)

Rankine's theory for active earth pressure (vertical wall, AS4678 Cl 4.2)