Every analysis. Every test.No black boxes.
213 code-checked analyses and 47 lab-test workflows — each one carries its governing standard in the output and is covered by the golden test suite (4,569+ automated engine tests, green on every build). 149 of those suites benchmark results value-by-value against published worked examples, and we are extending that engine by engine. This is exactly what you get, the day you sign up.
Not a drawer of lookup calculators — real solvers.
Most of the catalogue is a standards calc. But a handful are full numerical engines we wrote ourselves — finite-element solvers, a double-hardening constitutive model, rigorous limit analysis — the work that usually costs a separate five-figure specialist seat. Each is validated against its published benchmark.
Full 2-D finite-element suite
Our own solvers — bearing capacity & load–settlement (Prandtl-validated), slope strength-reduction (critical FoS, no assumed surface), seepage flow-nets, consolidation and 2-D deformation. Not a wrapper: the element assembly, Newton solve and yield return-mapping are ours, benchmarked against the published cases.
Hardening-Soil constitutive model
The double-hardening Hardening-Soil model on a stress point (calibrate against your lab curves) AND in a boundary-value problem — stress-dependent stiffness, shear + cap hardening, K₀ⁿᶜ and OCR. It drives the nonlinear confined & layered settlement engines.
Rigorous limit analysis
Two-sided bounds on the collapse load by linear programming — a statically-admissible lower bound (always safe) AND a kinematically-admissible upper bound — so the true failure load is provably bracketed. Immune to the stress singularity that trips displacement FE at a footing edge.
Laterally-loaded piles (p-y)
The p-y finite-difference solver for a single pile (deflection, moment, shear down the shaft), t-z / q-w axial load-transfer, group p-multipliers, and the pile-head stiffness matrix — plus RC M–φ and P–M interaction for the section itself.
Mechanistic-empirical pavements
Multilayer layered-elastic response (Burmister), a rigid-slab plate-on-Winkler FE with Westergaard stresses, time-stepping M-E distress (fatigue, rutting, IRI, JPCP cracking/faulting) and FAARFIELD-style airfield CDF — the mechanistic core, not a nomograph.
Nonlinear seismic site response
Time-domain nonlinear 1-D response with Masing hysteresis (the strain / stress / G-Gmax profiles down the column) and a 2-D FE site-response solver for basins and ridges — the amplification a 1-D column analysis misses.
213 analyses, every result cites its clause.
Don’t take our word for it. Each analysis is pinned to a published worked example and re-checked on every build. Download the validation traceability matrix — source, inputs, textbook value, our computed value, and the measured deviation, for a PE to audit line by line.
Shallow foundations & settlement
42Bearing, settlement and raft systems on soil.
Bearing capacityTerzaghi-Vesic-Hansen · EC7 · IS 6403
Strip 2 m, Df 1.5 m, c′ 10 kPa, φ′ 30°, γ 18 kN/m³
q_ult ≈ 1,210 kPa → q_safe ≈ 400 kPa (FoS 3), every N-factor cited
Settlement (elastic + consolidation)Schmertmann · EC7 · IS 8009
q 150 kPa, B 2 m, Es 25 MPa, 4 m NC clay
Immediate 8 mm + consolidation 22 mm = 30 mm
Differential settlement & angular distortionSkempton-MacDonald 1956 · Bjerrum 1963 · IS 1904
Footings 30 / 12 / 22 / 8 mm on a 6 × 6 m grid
Governing β = 1/333, tilt 1/520, within framed 1/300 ✓
Schmertmann CPT settlementSchmertmann 1978 · CFEM
q 120 kPa over a qc profile, B 2.5 m, 30-yr
s ≈ 19 mm with depth + creep correction
Consolidation time-rateTerzaghi 1-D · IS 8009
Cv 3 m²/yr, H_dr 2 m, U 90 %
t ≈ 1.1 yr (Tv 0.848)
Degree of consolidation (U ↔ Tv)Terzaghi 1-D · IS 8009
Tv 0.2; target U 90 %
U 50.5 % at Tv 0.2; Tv 0.848 needed for U 90 %
Finite-strain (large-strain) consolidation — GibsonGibson, England & Hussey 1967 · CONDES-class · soft soil / slurry / tailings
Phosphate-clay slurry H₀ 9.6 m, e₀ 14.8, power-law e-σ′ / k-e (Townsend-McVay 1990)
Ultimate settlement 5.32 m by the nonlinear PDE — within 2.2% of the published CONDES/FSConsol symposium result (5.44 m); log-linear or power-law constitutive
Finite-strain consolidation — layered (multi-material)Gibson 1967 · per-layer C_c / C_k / e₀ / k₀ · σ′-continuous interface
Soft slurry (C_c 2.4, e₀ 5) over stiffer clay (C_c 0.8, e₀ 3), H₀ 6 m
Interface flux in the continuous σ′ gradient (harmonic-mean k) — e jumps at the boundary, σ′ continuous; reduces exactly to the single-material engine within a layer
Coupled consolidation (Biot u–p)Biot 1941 / Terzaghi 1943
E 5 MPa, ν 0.3, k 1e-4 m/day, 5 m layer double-drained, σ 100 kPa
Settlement 74 mm (σ·H/E_oed), c_v ≈ 0.069 m²/day derived from k & E_oed, t₉₀ ≈ 77 days — coupled poroelastic solve, U–Tv matches Terzaghi
Consolidation under a footing — 3-D coupled Biot FEBiot 1941 · Zienkiewicz §3.2 u–p · 20-node hex Q2–Q1 · Terzaghi + Skempton-Bjerrum cross-check
6×6 m loaded area, q 100 kPa, 10 m clay, E′ 5 MPa, ν′ 0.3, k 1e-8 m/s, top drainage
Final 93.3 mm (62.0 immediate + 31.3 consolidation); computed Skempton-Bjerrum μ 0.41; t₅₀ 3.1 days against 33.2 by 1-D Terzaghi — 10.7× faster because water escapes sideways. Collapses to q·H/E_oed exactly when the far field is set to 0
Combined footingBowles §9 · Das §4
2 columns 800 + 1200 kN at 4 m, qa 150 kPa
L 6.4 m, resultant centred (e 0), B 2.1 m
Raft sizingACI 336.2R · EC7 · IS 2950
Σ load 24 MN, qa 150 kPa
Raft 13 × 13 m, q 142 kPa < qa ✓
Raft on Winkler springsACI 336.2R · Bowles §9 · IS 2950
k 30 MN/m³, 0.5 m slab, 8 columns
Max settlement 18 mm, M_max 420 kN·m/m
Beam on elastic foundationHetényi 1946
EI, k 20 MN/m³, point load 200 kN
λ 0.62 /m, y_max 4.1 mm, M_max 81 kN·m
Subgrade reaction (soil springs)Bowles · Vesić · IS 2950
B 2 m, Es 20 MPa, ν 0.3
k_s ≈ 11.8 MN/m³ (Vesić) for the STAAD / ETABS hand-off
Plate load testASTM D1195 / D1196 · IS 1888
0.3 m plate, 12 mm settlement at 220 kPa
Safe BP 147 kPa, scaled to the footing width
Machine foundation (block dynamics)ACI 351 · DIN 4024 · Richart · IS 2974
A 6 m², 20 t block, Cu 4×10⁴ kN/m³, 25 Hz
f_n 17.4 Hz, ratio 1.43 — clear of resonance ✓
Foundation analysis (SPT → SBC table)AASHTO · EC7 · IS 6403/8009
SPT profile, Df 2 m, silty sand, B = 1 → 3 m
Allowable pressure per size = min(shear, settlement), governing mode flagged
Probabilistic bearing capacityMonte-Carlo · Eurocode 7 · IS 6403
N 21, φ′ COV 0.12, B 2 m, Df 8 m, demand 250 kPa
Characteristic SBC (P05), reliability 96 %, β 1.8
Two-layer bearing capacityMeyerhof-Hanna 1978 · Das §4
Dense sand φ 40° (1.5 m) over soft clay c_u 30, B 1.5 m
q_ult 459 kPa by punching shear (q₂/q₁ 0.11, Ks 2.5)
Footing on / near a slopeMeyerhof 1957 · Vesić-Hansen
B 2 m, Df 1 m, φ′ 30°, slope 20° at the crest
q_ult 529 kPa — 51 % of level-ground capacity retained
Settlement on sand (Burland-Burbidge)Burland & Burbidge 1985 · BS 8004
q′ 100 kPa, B 3 m, average SPT N̄ 12, normal sand
Immediate 11.4 mm, with creep 14.8 mm (z_I 2.28 m)
Immediate (elastic) settlementBowles · Steinbrenner
q 150 kPa, 3 m square, Es 20 MPa, ν 0.3, H 6 m
Centre 17.6 mm (Steinbrenner I_s 0.43, F1/F2 closed-form)
Vertical stress increase (Boussinesq / Westergaard)Newmark · Westergaard
q 100 kPa, 1 × 1 m, z 1 m, centre, ν 0
Δσ_z 33.6 kPa (Boussinesq) vs 21.6 kPa (Westergaard, layered)
Stress under a circular areaBoussinesq · tank / silo
q 100 kPa, R 2 m, z 3 m (centre)
I 0.424 → Δσ_z 42.4 kPa
Stress under a strip loadBoussinesq · wall footing / road
q 100 kPa, B 2 m, z 1 m (centreline)
I 0.818 → Δσ_z 81.8 kPa (vs 66.7 by 2:1)
Stress under a line loadBoussinesq 2-D · wall / rail
Q 100 kN/m, x 0, z 2 m
Δσ_z 31.8 kPa (I 0.637); σ_x = τ = 0 on the centreline
Secondary compression (creep)Mesri · Cα/Cc
Cα 0.04, e_p 1.0, H 4 m, t₁ 2 yr → t₂ 50 yr
Cαε 0.02 → creep S_s 112 mm over 1.4 log-cycles
Skempton-Bjerrum settlement correctionSkempton-Bjerrum 1957 · Scott
S_oed 100 mm, A 0.7, α 0.7, S_imm 15 mm
μ 0.91 → field S_c 91 mm, total 106 mm
Eccentric footing pressure (kern)Meyerhof 1953 · IS 1904
Q 1000 kN, M 100 kN·m, 2 × 2 m
e 0.1 m < B/6 → q 325 / 175 kPa, no uplift, B′ 1.8 m
Layered elastic settlement (IS 8009)Newmark · Fox · EC7 · IS 8009
22.4 × 4.5 m raft, p 140, soil 0.5 m Es 49.5 + rock 8.5 m Es 248.7
σz = 4·p·I_B per layer → 3.9 mm total (rigidity × depth corrected)
Flotation / uplift checkEN 1997-1 UPL · buoyancy
Basement 20 × 30 m, base 5 m, water table 1 m
Uplift 23,544 kN, FoS 2.55, EN 1997-1 UPL util 0.44
Compensated (floating) foundationBowles · Skempton-Bjerrum · EC7 · IS 2950
q_gross 200 kPa, Df 5 m, γ 18 kN/m³
relief 90 kPa → net 110 kPa, 45 % compensated (settlement governs)
Overlay design (Benkelman / IRC 81)Add-onIRC 81:1997 · BBD
Deflections 1.2/1.4/1.0/1.6/1.3 mm, major road
x̄ 1.30, σ 0.224 → Dc 1.747 mm (read overlay off the IRC 81 curve)
FE bearing capacity & load–settlementAdd-onPrandtl 1921 · viscoplastic Mohr–Coulomb FE
Strip 2 m, sᵤ 20 kPa, φ 0 (undrained)
q_ult = 102.9 kPa (Prandtl 5.14·sᵤ to 0.1%) + the full load–settlement curve & collapse mechanism
Limit-analysis bearing bracket (lower + upper bound)Sloan 1988/1995 · FE limit analysis (LP)
Strip 2 m, cᵤ 50 kPa, φ 0 (undrained)
Rigorous two-sided bound 4.07·cᵤ ≤ q_exact ≤ 6.00·cᵤ, bracketing the exact Prandtl 5.14·cᵤ — singularity-immune
Footing bearing capacity — 2-D elasto-plastic FE (HS/MC)Prandtl 1921 · Vesić 1973 · Hardening-Soil (Schanz-Vermeer-Bonnier 1999) · B-bar FE
Strip B 2 m, c′ 10, φ 25°, E_ref 30 MPa, m 0.5
Full load–settlement curve + q_ult from a meshed plane-strain continuum (general-stress Mohr-Coulomb strength + HS stress-dependent stiffness, B-bar anti-locking), cross-checked live against the closed-form Vesić N-factors — a PLAXIS/RS2-class footing BVP
Footing bearing capacity — 3-D elasto-plastic continuum FESkempton 1951 · Vesić 1973 · viscoplastic Mohr-Coulomb · 20-node hex FE
Square B 2 m, sᵤ 50 kPa, φ 0 (undrained)
q_ult + full load–settlement curve from a true 3-D continuum (quarter-symmetry, 20-node serendipity hexahedra, viscoplastic Mohr-Coulomb) capturing the square/circular shape effect (s_c≈1.2) a 2-D model cannot — cross-checked live against Skempton/Vesić; heavy solve on Modal — a PLAXIS-3D/RS3-class footing BVP
Hardening-Soil footing — load–settlement (2-D double-hardening FE)Schanz-Vermeer-Bonnier 1999 · Vesić 1973 / Prandtl 1921 · B-bar FE
Strip B 2 m, D_f 1 m, c′ 10, φ′ 30°, E₅₀ʳᵉᶠ 30 MPa, m 0.5
The FULL load–settlement curve from the true HS constitutive law integrated at every Gauss point (hyperbolic pre-failure response, stress-dependent E(σ₃), per-point plastic shear hardening γ^p) + q_ult cross-checked live against the Vesić closed form — 28 cited literature anchors: Prandtl 5.14·sᵤ reproduced from above with q_ult/sᵤ constant to 0.7 % over an 8× strength range, Vesić c·N_c + q₀·N_q matched to ~2–5 % over a 20× surcharge range, and monotone mesh convergence to the exact limit
Hardening-Soil model — SoilTest (triaxial + oedometer)Schanz-Vermeer-Bonnier 1999 · Duncan-Chang
E₅₀ʳᵉᶠ 30 MPa, m 0.5, c′ 1, φ 35°, σ₃ 100 kPa
Stress-dependent E₅₀/E_ur, hyperbolic q–ε₁ to q_f 273 kPa (secant = E₅₀ exactly at half-strength) + oedometer E_oed — calibrate HS parameters against your lab curves
Hardening-Soil confined (1-D) nonlinear settlementHardening-Soil oedometer · Schanz-Vermeer-Bonnier 1999
5 m NC clay, Δq 100 kPa, σ′v0 50 kPa, E_oedʳᵉᶠ 4 MPa, m 0.9, φ 25°
Nonlinear settlement 135 mm with stress-dependent stiffness (secant E_oed 3.8 MPa) — vs 233 mm from a fixed initial modulus; OCR 2 halves it (stiff E_ur reload)
Hardening-Soil layered (multilayer) settlementHardening-Soil per layer · Terzaghi sub-layer summation
3-layer profile (soft 3 m / firm 4 m / stiff 5 m), Δq 120 kPa, WT 2 m
Total 253 mm; each sub-layer an oedometer at its own σ′v0 + HS params + OCR, auto sub-discretised (discretisation-independent) — soft shallow layer contributes 189 mm (the dominant stratum for ground improvement)
Deep foundations — piles & wells
24Bored, driven and well foundations, capacity to load test.
Pile capacity (bored / driven) + upliftAASHTO LRFD · EC7 · IS 2911
600 mm bored, 15 m, c_u 50 kPa
Q_ult ≈ 1,850 kN → Q_safe 740 kN (FoS 2.5); tension T_safe from shaft + self-weight
RC moment–curvature (M–φ) sectionAdd-onHognestad 1951 · ACI 318 §22.2 · IS 456
1 m bored pile, M30, 8000 mm² steel
M_n, M_cr, M_y + the COMPUTED cracked-EI (not a 0.35–0.7 guess) for the p-y solver
RC axial–moment (P–M) interactionAdd-onACI 318 §22.4 · IS 456 cl.39 · fibre integration
1 m bored pile, M30, 8000 mm² steel
Full P–M failure envelope: squash 19,860 kN, balance, pure-bending M_n — check any (M, P) demand
Rigid pile-cap group (V-H-M)Add-onPoulos-Davis · Hrennikoff
3×3 group, s 2 m, V 300 kN, M 1200 kN·m
Per-pile axial 133 kN (leeward) to −67 kN (uplift), cap stiffness — statics-validated
Helical (screw) pileICC-ES AC358 · Hoyt-Clemence · Perko
3 helices 0.3 m at 5/4/3 m, φ 32°, γ′ 10
Σ plate bearing 197 kN + shaft → Q_ult 214 kN; torque-checked
Drilled shaft (bored pile) axialFHWA GEC-10 · O'Neill-Reese 1999
1 m × 15 m, c_u 100 kPa (α-method)
Side 2180 kN + base 707 kN → Q_ult 2884 kN
Micropile (Types A-D)FHWA-NHI-05-039
0.2 m bond, 8 m, α 150 kPa, 3000 mm² steel
Bond allow 302 kN vs structural 957 kN → 302 kN governs
Wave-equation drivabilitySmith 1960 · FHWA GEC-12
20 m steel pile, 50 kN ram, 100 kJ, Rᵤ 1500 kN
Set 24 mm → 41 blows/m, σ_c 253 MPa (bearing graph)
Pile-cap / footing punching shearACI 318 · EC2 · IS 456
P 1500 kN, 0.4 m column, d 0.5 m, M25, q 240 kPa
τv 0.73 MPa ≤ τc 1.25 MPa → util 0.58 ✓
Pile-group settlement (interaction)Poulos-Davis · Randolph-Wroth
3×3 group, d 0.5 m, L 15 m, s 1.5 m, w_single 8 mm
r_m 26 m → Rs 5.6 → group settlement 45 mm
Pile group efficiencyConverse-Labarre · Feld · IS 2911
9 piles, 3 d c/c spacing
η 0.74 (Converse-Labarre) → group 12.3 MN
Lateral pile (p-y curves)Reese-Matlock · API RP 2GEO
600 mm, soft clay ε50 0.02, 150 kN head
Groundline 5.5 mm, M_max −258 kN·m (FDM)
Lateral pile capacity (Broms ULS)Broms 1964 · Tomlinson
0.5 m pile, e 1 m, My 200 kN·m, clay cu 50 kPa
Hu 101 kN, hinge at 1.2 m (long-pile yield-governed)
Driven pile dynamics (Hiley)Tomlinson · IS 2911-1 App B
30 kN ram, 1.2 m drop, 5 mm/blow set
R_u 1,731 kN → safe 692 kN
Pile downdrag (negative friction)FHWA NHI-05-039 · EC7 · IS 2911
Fill over soft clay, neutral plane 9 m
Drag load 380 kN added at the neutral plane
Pile-raft (Poulos PDR)Poulos 1991/2001
Raft + 16 piles, 30 MN
α_pr 0.7, settlement 24 mm, 62 % carried by piles
Pile load test (Davisson)ASTM D1143 · Davisson · IS 2911-4
500 mm × 15 m, maintained-load curve
Safe 1,333 kN (IS ⅔ @ 12 mm), Davisson ult 2,209 kN
Well foundationIRC 45:1972 · IRC 78
6 m well, 6 m grip, H 1,500 kN, M 9,000 kN·m
K_p 6.11, elastic demand 98 > capacity 64 → revise
Pile-group settlement (equivalent raft)Tomlinson · Terzaghi-Peck
Group 3 × 3 m, 12 m friction piles, Q 4 MN, m_v 0.2
Settlement 133 mm (raft at 8 m, 2:1 spread Δσ′ 111 kPa)
Single-pile settlement (Vesić)Vesić 1977 · FHWA · Das §9
Q 500 kN (40 % point), 15 m × 0.5 m, q_p 4 MPa
Head settlement 5.7 mm = 1.4 (elastic) + 4.0 (point) + 0.4 (shaft)
Axial pile load–settlement (t-z/q-w)Add-onCoyle-Reese 1966 · API RP 2GEO · Reese-O’Neill
0.6 m × 15 m bored pile, clay s_u 60 kPa, 900 kN working
Q_ult 2,150 kN (shaft 72 %), 7.4 mm at working load
Lateral pile group (p-multiplier)Add-onReese & Van Impe Ch 8 · AASHTO §10.7.2.4 · Mokwa-Duncan
3×2 group of 0.6 m piles at 3D in sand, 1,200 kN cap load
9.8 mm cap deflection, Gₑ 0.66; leading row governs at 468 kN·m
Pile-head stiffness matrix (K22/K23/K33)Add-onp-y beam-column (Reese) · Maxwell-Betti
0.6 m × 15 m free-head pile in sand, 200 kN operating shear
K22 3.1×10⁴ kN/m, K33 1.4×10⁵ kN·m/rad, coupling K23; symmetric to <1%
Steel pile section M–φ (pipe / solid)Add-onAISC 360 §F · Timoshenko · fibre integration
Ø600 pipe, 20 mm wall, fy 355 MPa
My 1,816 kN·m, Mp 2,389 kN·m (= fy·Z), shape factor 1.32
Slopes & embankments
25Soil and rock slope stability, seismic displacement.
Slope stability (Bishop · Spencer · M-P)Duncan & Wright · Bishop/Spencer · IS 7894
12 m slope, 1.5:1, c′ 15 kPa, φ′ 28°, r_u 0.3
FoS 1.38 (Spencer), critical circle located
Infinite slopeDuncan-Wright · EM 1110-2-1902
β 20°, z 2 m, c′ 5 kPa, φ′ 30°, full seepage
FoS 1.12 (parallel seepage)
Rock slope stability (planar / wedge / toppling)Wyllie & Mah · Markland · Goodman-Bray
30 m face 60°, joint dips 35°, c 50 kPa, φ 30°
FoS 1.28 dry → 0.88 with water + seismic
Rockfall trajectory + catchmentRitchie 1963 · Pierson/ODOT-FHWA · lumped-mass / RocFall
30 m face 60°, 1000 kg block, μ 0.40, Rₙ 0.35, Rₜ 0.85
runout 16.9 m, max bounce 2.1 m, 227 kJ at the toe; Ritchie ditch 8.7 m × 1.8 m
Rapid (sudden) drawdown — upstream slopeDuncan-Wright-Wong 3-stage · USACE EM 1110-2-1902 App. G
15 m dam, 1:2.5 upstream, c' 5 kPa, φ' 28°, R-env φR 20°, pool 13 m → 0
FoS drops from the full-reservoir value to the after-drawdown value (3rd/undrained stage governs); Duncan-Wright-Wong τff interpolation
Barton-Bandis rock-joint strengthBarton & Choubey 1977 · Barton-Bandis 1990
JRC 10, JCS 50 MPa, φr 30°, σn′ 500 kPa
φpeak 50° (i = 20° dilation), τ = 596 kPa — nonlinear envelope
Duncan-Chang hyperbolic modelDuncan & Chang 1970 · Duncan et al. 1980
K 300, n 0.5, c′ 10, φ′ 30°, Rf 0.9, σ₃ 100 kPa
(σ₁−σ₃)f 234.6 kPa, Ei 30.2 MPa, hyperbolic q(ε) → qult 260.7 kPa
Modified Cam-Clay (NC undrained)Roscoe-Burland 1968 · Muir Wood · Wroth 1984
φcs 25.4° (M 1.0), λ 0.16, κ 0.03, p′₀ 200 kPa
su 57.0 kPa (su/p′₀ 0.285), critical state p′ 114, q 114 kPa
HS-Small small-strain stiffnessBenz 2007 · Hardin-Drnevich
G₀ 100 MPa, γ₀.₇ 2e-4, Gur 25 MPa
Gs = 72.2 MPa (0.722·G₀) at γ₀.₇; decays G₀→Gur with strain
Drucker-Prager coneDrucker-Prager 1952 · de Souza Neto §8.3
c' 10, φ' 30°, σ₃ 100 kPa
triaxial failure 234.6 kPa (= Mohr-Coulomb), α 0.231, k 12.0 kPa
von Mises (J2) yieldvon Mises 1913 · Simo & Hughes
σ 200/100/100 kPa, σy 150 kPa
q = 100 kPa (√3J₂) < σy → elastic, FoS 1.50
NGI-ADP anisotropic undrainedGrimstad-Andresen-Jostad 2012
suA 60, suP/suA 0.4, suDSS/suA 0.6
suA 60, suP 24, suDSS 36 kPa; isotropic q = 2suA = 120 kPa
Soft-Soil-Creep parametersVermeer & Neher 1999
Cc 0.3, Cs 0.05, Cα 0.01, e₀ 1.0, φcv 25°
λ* 0.065, κ* 0.022, μ* 0.00217, M 0.984, creep 0.5%/decade
Seismic slope displacementBray & Travasarou 2007 · Newmark
ky 0.1 g, Ts 0.3 s, Sa 0.5 g, Mw 7.5
D₅₀ 18.5 cm (16–84%: 9.6–35.8 cm)
Probabilistic slope (reliability)Duncan 2000 · FOSM + Monte-Carlo · USACE
β 25°, c′ 10±30%, φ′ 28±10%, γ 19
μ_FoS 1.60, reliability index β, Pf (FOSM ≈ Monte-Carlo)
Multi-layer site response (SHAKE)Kramer Ch.7 · Schnabel-Lysmer-Seed
30 m soil column over Vs 600 rock
Transfer function → T₀ + peak amplification (eq-linear)
Seismic design spectrumASCE 7-16 · EC8 · IS 1893
Zone IV, medium soil, T 0.5 s, R 5
Sa/g 2.50 → Ah 0.06 (ZPA 0.12 g)
Seismic design spectrum (code-based)ASCE/SEI 7-16 · EN 1998-1 (EC8) · IS 1893
ASCE 7-16, site B, Sₛ 1.5, S₁ 0.6, Vs30 800
SDS 0.90 g (Sa @ 0.2 s), SD1 0.32 g (Sa @ 1.0 s) — pick any code (IS / ASCE / EC8), no region gate
Field-vane correction (Bjerrum μ)Bjerrum 1973 · IS 2720-30
s_u,vane 50 kPa, PI 40 %
μ 0.835 → design s_u 41.7 kPa
Embankment basal stabilityIRC:75 · Ladd · Terzaghi
6 m fill on soft clay c_u 20 kPa
FoS 1.31 (Ladd) — sets the stage-construction band
Embankment benchingIRC:75 · MoRTH
Side-hill fill, 1 m benches
Interface FoS 1.45
Newmark seismic displacementNewmark · Jibson 2007
PGA 0.24 g, yield k_y 0.12 g
Permanent slip 4.6 cm
FE slope stability (strength reduction)Add-onZienkiewicz SRM · Griffiths & Lane 1999
10 m slope 2:1, c′ 15 kPa, φ′ 25°, γ 19
FoS by φ-c reduction on a finite-element mesh (no assumed slip surface)
3-D FE slope stability (strength reduction)Griffiths & Marquez 2007 · 20-node hex viscoplastic
10 m slope 2:1, c′ 10 kPa, φ′ 20°, γ 20, finite width B/H = 1
F₃D by 3-D φ-c reduction — the failure mechanism emerges (no assumed slip surface); end restraint gives F₃D ≈ 1.15·F₂D, converging to the 2-D value as the slide widens
3-D DEM slope stability (Scoops3D)USGS Scoops3D TM 14-A1 · Bishop/Ordinary column method
A real terrain grid (DEM), multi-material soil, thousands of spherical trial surfaces
the 3-D-critical failure mass anywhere on the terrain — F₃D, the sphere, its volume/area/footprint — reproducing the parametric slope-3d circle on a planar slope (validated to within the 3-D end-restraint credit)
Retaining & excavation
16Walls, cuts and embedded support systems.
Earth pressure (active / passive / seismic)Rankine · Coulomb · Mononobe-Okabe · IS 14458 · EN 1997-1 · AS 4678
5 m wall, φ′ 32°, kh 0.1
Ka 0.31, Pa 56 kN/m; Kae 0.41 (Mononobe-Okabe)
Earth pressure at rest (K0)Jaky · Mayne-Kulhawy (OCR)
φ′ 30°, OCR 4, γ 18, H 5 m
K0 1.00 (vs 0.50 NC), at-rest thrust 225 kN/m
Retaining wallBowles · IS 14458 · AS 4678
5 m cantilever, 10 kPa surcharge
FoS overturn 2.4, slide 1.7, resultant in kern ✓
Sheet pile wallCIRIA C580 · BS 8002 · Bowles §14 · AS 4678
Cantilever 6 m retained, φ′ 30°
Embedment 4.2 m, M_max 185 kN·m/m
Braced excavationTerzaghi-Peck · Peck 1969
8 m cut in soft clay
Strut loads from apparent pressure; base-heave FoS 1.4
Basal heave (excavation)Bjerrum & Eide 1956 · Terzaghi 1943 · Skempton Nc
10 m cut, 15×30 m, s_u 40 kPa, γ 18, q 10
N_c 6.41 → FoS 1.35 (Bjerrum-Eide) — deepen toe / improve clay
Excavation-induced settlementClough & O'Rourke 1990 · Hsieh-Ou 1998
He 10 m, δh,max 30 mm (sand), building at 5 m
δv,max 30 mm, trough to 20 m, 22.5 mm at building (1/667)
Ground anchor / tiebackBS 8081 · PTI · Littlejohn
0.15 m hole, 8 m bond, c_u 100 kPa, α 0.4
τ 40 kPa → T_ult 151 kN, allowable 75 kN (FoS 2)
Embedded wall — soil-structure interactionAdd-onBeam on elastic foundation · CIRIA C760 · Padfield-Mair
6 m propped wall, prop at 1.5 m
Deflection 13 mm, M_max 156 kN·m/m, prop 80 kN/m, passive 38% mobilised
Staged embedded retaining wallEN 1997-1 (EC7) · CIRIA C760 · subgrade reaction
6 m dig, Ø600 diaphragm wall, 6 m embedment, prop at 1.5 m
Deflection 4 mm, M_max 132 kN·m/m, prop 88 kN/m, passive 40% mobilised; LEM cross-check agrees (≥ 3.58 m)
Contiguous pile wallCIRIA C760 · IS 14458 · IS 456
9 m retained, 600 mm piles
Embedment 5.1 m, M 420 kN·m, deflection 22 mm
Secant pile wallCIRIA C760 · DIN 4126
10 m, 750 mm secant
Embedment 5.6 m, water cut-off achieved ✓
MSE wallFHWA NHI-10-024 · BS 8006 · IS 14458 · AS 4678
8 m, geogrid at 0.6 m spacing
T_max 24 kN/m, pullout FoS 1.6, sliding 1.8
Soil nail wallFHWA-IF-03-017 (GEC-7)
9 m cut, nails on a 1.5 m grid
Global FoS 1.5, nail tension 95 kN
Soil-structure interface (Goodman joint)Goodman-Taylor-Brekke 1968 · R_inter reduction · Potyondy 1961
φ 35°, R_inter 0.67 (concrete/sand), σ′_n 100 kPa
δ 25.1°, τ_max 46.9 kPa — only 67% of the soil strength; the reduced wall/shaft friction to design with
Staged excavation — FE heave & basal stabilityK0 staged FE · Smith-Griffiths §6 · Terzaghi/Bjerrum-Eide basal heave
Wide cut, cᵤ 30 kPa, γ 18, excavate to 8 m in 6 lifts
Base heave builds 18→62 mm per lift then basal-heave collapse near 6.7 m (N≈4.8, conservative vs Prandtl 5.14) — the staged deformation a closed-form check can’t give
Seepage & dewatering
13Flow nets, FE seepage, drains and dam seepage.
Seepage & dewateringFlow net · Thiem · Terzaghi
Δh 6 m, 4-well system
Q 1,150 m³/day (Thiem), drawdown to formation
FE seepage (2-D)Add-onFinite element · Laplace
Zoned dam, k profile
Phreatic line + exit gradient 0.42 < critical
FE unconfined seepage (phreatic surface)Add-onFree-surface FE · Dupuit-Charny
L 30 m, h₁ 12 m, h₂ 3 m, k 10⁻⁵
Phreatic line + q within ~5 % of the exact Dupuit q, seepage face located
Earth-dam seepageCasagrande · EM 1110-2-1901
Homogeneous 20 m dam
Casagrande line, q 1.8×10⁻⁵ m³/s per m
In-situ permeabilityHvorslev · BS 5930 · IS 5529
Falling-head in cased borehole
k 3.2×10⁻⁶ m/s (Hvorslev)
Percolation testUSEPA · IS 2470
30 min for a 25 mm drop
Perc rate → soak-field sizing
Vertical drains (PVD)Barron · Hansbo · Carrillo
PVD 1 m grid, Cv 2 m²/yr
90 % consolidation in ~4 months (Hansbo)
Vacuum preloadingKjellman · Indraratna · Hansbo PVD
70 kPa vacuum, 8 m clay, PVD 1.5 m, 0.5 yr
63 kPa eff. (replaces 3.5 m fill) → 657 mm primary, U 74 %
Multi-layer consolidationTerzaghi 1-D · IS 8009-1
2-layer NC profile, Δσ 40/30, cv 1.5/2.0
Total 190 mm; U 95.6 % at 2 yr (settlement-weighted)
Asaoka settlement predictionAsaoka 1978 · observational
Plate readings 100…433 mm at equal Δt
Final 500 mm, U 86.6 %, 67 mm remaining
Seepage under structures (Lane & Bligh)Lane 1935 · Bligh · creep theory
Head 2 m, ΣL_v 14 m, ΣL_h 30 m, fine sand
Lane C_w 12 ≥ 7 ✓, Bligh C_B 22 ≥ 15 ✓ — safe against piping
Permeability from grain sizeHazen 1892 · Kozeny-Carman
D10 0.2 mm, void ratio 0.7, 20 °C
k 4×10⁻⁴ m/s (Hazen), 4.3×10⁻⁴ m/s (Kozeny-Carman)
Quick condition / hydraulic heaveTerzaghi · critical gradient
Gs 2.65, e 0.65, Δh 3 m over L 6 m
i_cr 1.00, i_e 0.50 → FoS 2.0 against boiling (γ′ 9.81)
Seismic & liquefaction
44Triggering, settlement and lateral spread.
Seismic site classificationASCE 7-16 · EC8 · IS 1893
Vs30 / SPT profile to 30 m
Site class D → design response spectrum
Seismic site responseKramer Ch.7 · 1-D SH wave · IS 1893 · EC8
H 30 m, Vs 200 m/s, ξ 5 %, rock Vs 760
T₀ 0.60 s, peak amplification ×3.6, surface PGA from rock
Nonlinear time-domain site responseDEEPSOIL-class · Masing hysteresis · Newmark integration · Kramer Ch.7
H 30 m, Vs 200 m/s, τ_max 80 kPa, rock PGA 0.02 → 0.4 g
Weak motion amplifies ×1.8; strong motion DE-amplifies to ×0.8 (soil softens + hysteretic damping) — the nonlinearity equivalent-linear misses
2-D site response — basin amplification (SH-wave FE)QUAD4M-class · antiplane SH FE · Lysmer absorbing base · Bard & Bouchon 1985
Sediment basin, H 30 m, soil Vs 200 / rock Vs 760 m/s, ξ 5%
2-D basin focusing amplifies the surface ×1.8 MORE than a 1-D column (Mexico City / Kobe effect) — validated to 2-D/1-D = 1.00 on a flat profile
2-D topographic amplification — ridge crest (SH-wave FE)Trifunac 1973 · Eurocode 8 Part 5 Annex A (S_T) · homogeneous SH FE
Ridge H 20 m, half-width 50 m (slope ~22°), Vs 500 m/s
Crest topographic factor S_T ≈ 1.4 — the hilltop shakes 40% harder than flat ground, purely from geometry (validated flat S_T = 1.00, bounded < Trifunac 2)
Coupled effective-stress liquefaction — 1-D site responseDobry 1985 / Matasovic-Vucetic 1993 · DEEPSOIL v7 Eq. 4.10 + 4.30/4.31 · Carlton 2014
H 15 m, Vs 140 m/s, WT 1 m, FC 5 %, bedrock PGA 0.30 g, 2 Hz, 12 s, v = 1
Liquefaction at t = 3.37 s, peak r_u 0.992. AFTER triggering the surface peak collapses to 0.024 g against the 0.156 g a total-stress solve on identical inputs gives (−84.8 %), the late-window RMS to 3.5 %, and the site period lengthens 1.23× — the recorded Port Island / Wildlife Array de-amplification signature that a total-stress site response plus a separate triggering check structurally CANNOT produce. Before triggering the two runs agree, so the coupling is shown to act only where the physics says it should; both are reported side by side
Liquefaction triggeringBoulanger-Idriss 2014 · NCEER · IS 1893
N 15, FC 5 %, σ′v 66 kPa, PGA 0.24 g, M 7.5
CRR 0.186, CSR 0.257 → FoS 0.72 → liquefiable
CPT liquefaction triggering (Boulanger-Idriss)B-I 2014 · UCD/CGM-14-01
qc 5 MPa, FC 10 %, σ′v 60 kPa, z 5 m, amax 0.3 g, Mw 7.0
qc1Ncs 73, CRR 0.134, CSR 0.307 → FoS 0.47 (liquefies)
Vs liquefaction triggering (Andrus-Stokoe)Andrus-Stokoe 2000 · Youd 2001
Vs 180 m/s, FC 10 %, σ′v 80 kPa, z 5 m, amax 0.3 g, Mw 7.0
Vs1 190, CRR 0.193, CSR 0.234 → FoS 0.98 (marginal)
Tunnel settlement trough (Peck)Peck 1969 · O’Reilly-New
D 6 m, axis 15 m, volume loss 1 %, K 0.5 (clay)
i 7.5 m, Smax 15.0 mm, 6.2 mm at 10 m offset, slope 1.2 mm/m
Slope stability number (Taylor)Taylor 1937 · friction-circle
Ns 0.18, c 20 kPa, γ 18 kN/m³, H 6 m
c_d 19.4 kPa → FoS 1.03, critical height 6.2 m
Dam seismic deformation (Makdisi-Seed)Makdisi-Seed 1978 · Kramer
H 30 m, Vs 250 m/s, ky 0.1 g, kmax 0.2 g, norm 0.05 s
T0 0.31 s, ky/kmax 0.5 → crest displacement 31 mm
Cement / lime stabilisation (IRC SP:89)IRC SP:89 · MoRTH §400
4 % cement, γd 2000 kg/m³, 7-day UCS 5.0 MPa, CTB
binder 80 kg/m³, target 4.5–7.0 MPa → accepted
Rural road pavement (IRC SP:72)Add-onIRC SP:72-2015
CVPD 100, CBR 5 %, total 350 mm (curve C)
curve C → base 225 mm + sub-base 125 mm, bituminous surfacing
Airfield strength (ACN-PCN)Add-onICAO Annex 14 · Doc 9157
Aircraft ACN 45, pavement PCN 50, flexible
ratio 0.90 ≤ 1 → unrestricted operations
Airfield thickness design (FAA closed-form)Add-onFAA AC 150/5320-6D · Corps CBR / Westergaard
Flexible: ESWL 30000 lb, p 100 psi, CBR 8, 5000 coverages
Corps CBR → 19.2 in cover (α 1.001); rigid slab via Westergaard edge
MEPDG fatigue cracking (flexible)Add-onAASHTO MEPDG · NCHRP 1-37A
εt 70 µε, E 500 ksi, Hac 6 in, Va 7 %, Vbe 11 %, N 1e7
C 0.415, Nf 1.01e9 → damage 0.99 % → 0.59 % area cracking
Layered-elastic pavement response (Burmister)Add-onBurmister 1945 · Huang 2e · KENLAYER/WESLEA-class
3-layer AC/base/subgrade, E 500/25/7.5 ksi, h 4/8 in, q 100 psi, a 5 in
εt 346 µε (fatigue) · εv 942 µε (rutting) · deflection 0.71 mm — exact-Boussinesq-validated
Asphalt Institute M-E flexible design checkAdd-onAsphalt Institute MS-1 · Burmister strains
3-layer section, εt 346 µε, εc 942 µε, E 500 ksi, 1e5 ESALs
Nf 2.65e5 (fatigue) · Nr 4.82e4 (rutting govern) → rutting CDF 2.07 — thicken
Aircraft landing-gear pavement response (multi-wheel)Add-onFAA AC 150/5320-6E · Burmister LET
3-layer section, dual wheel at 20 in spacing, q 100 psi, a 5 in
single-wheel 942 µε → dual-gear 1132 µε subgrade strain (1.20× amplification)
FAARFIELD subgrade CDF design checkAdd-onFAA AC 150/5320-6E · DOT-57714 failure model
dual gear 150 kN/wheel, 1.4 MPa, 125 mm AC / 400 mm base, 1200 dep/yr × 20 yr
subgrade strain → coverages-to-failure (verified Bleasdale) → CDF vs 1.0 adequacy
FAARFIELD aircraft-mix CDF design checkAdd-onFAA AC 150/5320-6E · cumulative damage (mix)
narrow-body (130 kN, 3000 dep/yr) + wide-body (250 kN dual-tandem, 400 dep/yr), 20 yr
Σ-aircraft CDF; the heavy wide-body governs despite fewer departures
FAARFIELD HMA fatigue CDF (RDEC)Add-onCarpenter-Shen RDEC · FAA HMA CDF
125 mm AC, εt from Burmister, S 3447 MPa, Va 7 %, Vb 11 %, 1200 dep/yr × 20 yr
PV → Nf (0.4801·PV⁻⁰·⁹⁰⁰⁷) → HMA CDF vs 1.0 (secondary to the governing subgrade CDF)
MEPDG IRI (ride quality / smoothness)Add-onAASHTO MEPDG Eq. 5-15a
IRI₀ 63, RD 0.3 in, FC 5 %, TC 200 ft/mi, age 10 yr, wet frost-prone subgrade
site factor 368 → IRI 84 in/mi (1.33 m/km) — good ride
JPCP transverse cracking (rigid)Add-onAASHTO MEPDG Eq. 5-16/17 · Westergaard
250 mm slab, MR 4.5 MPa, k 30 MPa/m, 9 kip wheel, 5e7 reps
Westergaard edge stress → σ/MR → Nf → ~20 % slabs cracked
Rigid slab structural response (FE + Westergaard)Add-onPlate-on-Winkler FE · Westergaard (1926/48) · Ioannides 1985
250 mm slab, E 28 GPa, k 30 MPa/m, 40 kN wheel @ 0.7 MPa, edge load, MR 4.5
ℓ 1056 mm · σ_edge 1.44 MPa (FoS 3.1) · FE deflection 0.64 mm · corner 0.38 mm
Climate-zone EICM inputs (MEPDG)Köppen-Geiger · AASHTO MEPDG §3
Cold continental (Dfa) zone, Northern hemisphere
Monthly temps −9→21 °C, precip 600 mm, freezing index 450 °C·days — feeds the distress drivers
JPCP cracking time-stepping (rigid MEPDG)Add-onAASHTO MEPDG §5 · monthly Miner · Bradbury curling
280 mm slab, MR 4.5, k 40, 5×10⁷ reps, 20 yr
Month-by-month load + curling → 6.6 % slabs cracked (within terminal); ΔT=0 matches the single-pass check
Airfield thickness design (FAARFIELD, CDF=1)Add-onFAA AC 150/5320-6 · iterate to CDF=1
3-aircraft mix (B737/A320/B777), 20 yr, 60 MPa subgrade
Required AC 335 mm; B777-300 governs (heaviest gear dominates the subgrade CDF)
FAARFIELD flexible design (full LEAF)FAA AC 150/5320-6G · FAAModulus + Bleasdale · Appendix H
4" P-401 / 8" P-403 / 12" P-209 / design P-154, CBR 5, 4-aircraft mix (B737-800/A321/EMB195/CRJ700), 20 yr
FAAModulus sublayer moduli + Bleasdale failure → P-154 = 10.6 in (FAARFIELD 10.1); A321-200 governs
FAARFIELD rigid design (PCC slab)FAA AC 150/5320-6G Ch.4 · Westergaard edge + Rollings SCI · Appendix H
P-501 R=600 psi, k=100 pci, 4-aircraft mix, 20 yr
Westergaard edge stress + Rollings SCI failure → slab = 17.9 in (FAARFIELD FE 17.14); A321-200 governs
Axle-load spectra (NALS → ESALs)Add-onAASHTO fourth-power · MEPDG §3
Single-axle spectrum 40–120 kN, 1M axles
Truck factor 1.54 → 1.54M ESALs; heavy tail dominates
Pavement-ME performance (time-stepping)Add-onAASHTO Pavement-ME / MEPDG · monthly EICM
150 mm AC / 300 mm base / 60 MPa subgrade, 1e6 axles/yr, 20 yr, moderate climate
month-by-month → total rut 21 mm (AC 15 + subgrade 5), fatigue 22 %, IRI 1.66 m/km (NCDOT-validated band)
JPCP IRI (rigid ride quality)Add-onAASHTO MEPDG Eq. 5-32a
IRI₀ 63, 10 % cracked, 5 % spalled, 2 in/mi faulting, age 20 yr
site factor + distress → IRI 79 in/mi (good ride)
JPCP joint spalling (rigid)Add-onAASHTO MEPDG Eq. 5-33a
age 20 yr, 6 % air, f'c 28 MPa, 50 freeze-thaw/yr, 250 mm slab, w/c 0.45
durability scaling factor → ~5 % joints spalled (feeds JPCP IRI)
JPCP joint load transfer & faulting potentialAdd-onAASHTO MEPDG Eq. 5-20d/22/23a · Westergaard
250 mm slab, aggregate base, undowelled, erodibility 3, curling 0.024 in
joint LTE 52 % · DE 0.079 lb/in · curling faulting potential 0.126 in
CRCP punchouts (rigid)Add-onAASHTO MEPDG Eq. 5-26
accumulated transverse fatigue damage DIPO = 1, crack spacing 48 in
PO = 216.8421/(1+33.158·1^-0.589) → 6.4 punchouts/mi
MEPDG thermal cracking (TCMODEL)Add-onAASHTO MEPDG Eq. 5-11 · Paris law
mild climate ΔT 25 °C vs cold ΔT 60 °C, 150 mm AC
mild ~6 ft/mi (negligible) → cold ~200 ft/mi (severe) low-temp cracking
MEPDG asphalt rutting (climate-integrated)Add-onAASHTO MEPDG Eq. 5-1a · EICM-lite
150 mm AC, hot climate (mean 20 °C ± 18), 1e7 reps, β1r 0.5
monthly-incremental asphalt rut ~0.6 in — realistic (single-shot gives absurd 0.5 in/sublayer)
MEPDG subgrade rutting (Tseng-Lytton)Add-onAASHTO MEPDG Eq. 5-2a · FHWA NHI-05-037
fine subgrade MR 60 MPa, Wc 15 %, 1e7 reps over 1.5 m compressible depth
εo/εr 71, depth-integrated subgrade rut ~0.2 in (wetter subgrade → more)
Concrete durability (IS 456 exposure)EN 206 · ACI 318 · IS 456
SO3 0.6 %, SO4 1.5 g/L, Cl 500 mg/L, pH 6.5
Class 3 (Severe) → SRPC, 330 kg/m³, w/c 0.50, cover 50 mm
Liquefaction settlementTokimatsu-Seed · Ishihara-Yoshimine
FoS profile, Dr 50 %
Post-liquefaction settlement 92 mm
Lateral spreadYoud-Hansen-Bartlett 2002
Free-face 5 m, T15 3 m
Ground displacement 0.9 m
Post-liquefaction residual strengthOlson-Stark 2002 · Seed-Harder
(N1)60cs 8, σ′v0 100 kPa, driving shear 12 kPa
Sr/σ′v0 0.09 → Sr 9 kPa, flow-slide FoS 0.75 < 1 (mitigate)
Ground improvement
3Stone columns, vibro and deep mixing.
Stone columnsPriebe 1995 · IS 15284-1 · FHWA NHI-08-082
0.8 m columns, 2 m grid, a_s 0.13
n 2.8 (Priebe) → settlement reduced to 38 %
Vibro-compactionMitchell 1981 · Brown 1977
Loose sand Dr 45 %
Dr → 75 % at 2.6 m probe spacing
Deep soil mixingFHWA-RD-99-138 · Bruce 2000
0.8 m columns, a_s 0.25
Composite stiffness → settlement to 45 %
Pavements
5Flexible and rigid pavement design.
Flexible pavement (IRC 37)Add-onIRC 37:2018 · IITPAVE
50 msa, subgrade CBR 8 %, 90 % reliability
BC 50 + DBM 130 + 553 granular = 733 mm; ε checked
Rigid pavement (IRC 58)Add-onIRC 58:2015 · Westergaard
30 MSA, 98-pctile axle stress
Slab 280 mm, fatigue + erosion < 100 %
Flexible pavement (AASHTO 93)Add-onAASHTO 1993 Part II
W18 5×10⁶, MR 10 ksi
SN 4.2 → layer thicknesses
Rigid pavement (AASHTO 93)Add-onAASHTO 1993 Part III · Eq 3.1
W18 30×10⁶, S′c 4.5 MPa, k 40 MPa/m, J 3.2, R 90 %
PCC slab D ≈ 302 mm (serviceability ΔPSI 2.0)
DCP subgrade strengthASTM D6951 · IRC SP-72
8 mm/blow penetration rate
CBR ≈ 14 % → subgrade acceptance band
In-situ investigation
36CPT, DMT, pressuremeter and field tests.
Site investigation planASTM D420 · BS 5930 · EC7-2 · IS 1892
Building footprint, 8 m grid
12 boreholes, depths to 1.5 × B below founding
Phase relations (weight-volume)Index · γ, e, n, Sr
Gs 2.70, γd 16 kN/m³, w 12 %
e 0.655, n 0.396, Sr 49 %, γ 17.9 / γsat 19.9 / γ′ 10.1 kN/m³
Soil classification (USCS / IS / AASHTO)ASTM D2487 · IS 1498 · Casagrande
70 % fines, LL 45, PL 22 (PI 23)
USCS CL (lean clay), AASHTO A-7-6, above the A-line
Consistency & activity (Atterberg)Skempton · IS 2720-5
w 30, LL 45, PL 22, clay 30 %
PI 23, I_L 0.35 (medium/firm), activity 0.77 (normal)
Stress path invariants (p-q / s-t)MIT s-t · Cambridge p-q
σ1 150, σ3 50 kPa, c′ 0, φ′ 30°
p 83.3, q 100, s 100, t 50, η = M = 1.2 — at failure
Layered-soil permeability (k_h, k_v)Parallel / series · anisotropy
3 layers: 2 m@1e-5, 3 m@1e-7, 1 m@1e-6 m/s
k_h 3.6×10⁻⁶, k_v 1.9×10⁻⁷ m/s, anisotropy 18.5×
Flow-net seepage quantityCasagrande · q = k·H·N_f/N_d
k 1e-5 m/s, H 4 m, N_f 4, N_d 12, 50 m wide
q 1.33×10⁻⁵ m³/s/m → 57.6 m³/day total, exit gradient 0.22
Construction dewatering (well system)Equivalent-well · Sichardt · Thiem / Dupuit
40 × 20 m pit, k 1e-4 m/s, drawdown 5 m, H 12 m, 10 wells
r_e 16 m, R 150 m → 1,151 m³/day total (115 per well), drawdown cone plotted
Pumping test (Cooper-Jacob)Cooper-Jacob 1946 · ASTM D4105
Q 1000 m³/day, r 30 m, Δs 0.5 m/cycle, t₀ 0.01 day, b 10 m
T 367 m²/day, S 0.0092, k 36.6 m/day
Granular filter design (Terzaghi)Terzaghi / USACE EM 1110-2-1901
Base D15/D85 0.05/0.5 mm, filter D15/D50/D85 0.6/2/8 mm
Retention 1.2 ≤ 4 ✓, permeability 12 ≥ 4 ✓ → filter acceptable
Gradation indices (Cu, Cc)ASTM D2487 · well / poorly graded
D10 0.1, D30 0.3, D60 0.6 mm (sand)
C_u 6.0, C_c 1.5 → well graded
Capillary rise & suctionHazen · Terzaghi · h_c = C/(e·D10)
D10 0.2 mm, e 0.6, C 0.3 cm²
h_c 0.25 m (25 cm), suction 2.45 kPa
Darcy flow & seepage velocityDarcy 1856 · v = k·i
k 1e-5 m/s, Δh 3 m over L 10 m, n 0.4, A 2 m²
i 0.30, v 3×10⁻⁶, v_s 7.5×10⁻⁶ m/s, Q 6×10⁻⁶ m³/s
Effective stress at depthTerzaghi · σ′ = σ − u
z 5 m, WT 2 m, γ 18 / γ_sat 20 kN/m³
σ_v 96, u 29.4, σ′_v 66.6 kPa (full profile plotted)
Mohr-Coulomb failureCoulomb · Mohr circle
σ3 50 kPa, c 10 kPa, φ 30°
σ1f 184.6 kPa, q_u 34.6, plane 60°, circle tangent to envelope
Pore-pressure parameters (A, B)Skempton 1954 · Bishop-Henkel
Δσ₁ 200, Δσ₃ 50 kPa, A 0.5, B 1.0
Δu 125 kPa (contractive), Ā 0.5, Δσ′₁ 75 / Δσ′₃ −75 kPa
CPT interpretationRobertson 1990 · IS 4968
qc / fs depth profile
SBT zones, φ′ 36° (Kulhawy-Mayne), Dr, su
CPTu dissipation → chTeh & Houlsby 1991
t50 100 s, 10 cm² cone, Ir 100, u2
ch 246 m²/yr (T50* 0.245); kh from mv
Critical State Line (triaxial p'-q)Schofield-Wroth · BS 1377-8
3 CD tests σ'3 100/200/300, σ'1 3× σ'3
M 1.20 → φ' 30°, c' 0 (R² 1.0)
CPT soil behaviour type index IcRobertson 2009 · SBTn
z 5 m, qt 5 MPa, fs 50 kPa, γ 20, GWT 0
iterated n 0.64 → Ic 2.01 (SBT 6, sand-like)
Embankment load stress (Osterberg)Osterberg 1957 · trapezoidal fill
H 5 m, γ 20, crest a 5 m, 2H:1V, z 10 m
q 100 kPa, I 0.395 → Δσv 79 kPa (centreline)
Deadman (tie-rod) anchor capacityTeng 1962 · passive block
γ 18, φ 30°, surface deadman h 2 m, T 40 kN/m
Kp−Ka 2.67 → T_ult 96 kN/m, FoS 2.4 (OK)
PVD spacing designer (preload)Hansbo · invert radial U
ch 2 m²/yr, U 90% in 6 mo, dw 66 mm, s 2, kh/ks 2
required triangular spacing ≈ 1.05 m (n ≈ 17)
Strut / waler buckling checkPerry-Robertson · AISC · IS 800
KL/r 100, fy 250, class b, Ae 6000 mm²
χ 0.52 → fcd 118 MPa → Nd 709 kN
RC section design (IS 456 flexure)ACI 318 · EC2 · IS 456
Mu 225 kN·m, b 300, d 500, M25, Fe415
Mu,lim 259 → Ast 1495 mm² (singly OK)
Pile buckling + P-δDavisson-Robinson 1965
N 1000 kN, Lu 3 m, EI 40 MN·m², clay kh 10 MN/m³
zf 1.98 m → Pcr 3982 kN → δ 1.34 (FoS 4.0)
SPT N correctionASTM D1586 · IS 2131:2025
Field N 19/23/33, σ′v 144–198 kPa, Peck Cn
Design N 17/19/26 with overburden + dilatancy + N60
SPT correlations (multi-method)Stroud · Schultze · Bowles · IS 6403
Corrected N 21, silty sand, σ′v 160 kPa
φ′, cu, Es, Dr, γ, qc — min/mean/max envelope + recommended
Flat dilatometer (DMT)Marchetti · ISSMGE TC16 (2001)
p0 300, p1 800, u0 50, σ′v 100 kPa
ID 2.0 (sand), KD 2.5, M 20.9 MPa, φ′ 33.5°
Ménard pressuremeter (PMT)NF P94-261 Annexes D + H
ple* 1.0 MPa, EM 10 MPa, 2 m square in sand
kp 1.28, q_net 1,285 kPa, settlement 7.5 mm
Field densityASTM D1556/D6938 · IS 2720-28/29
Sand-replacement on a compacted layer
γ_d 17.8 kN/m³ → 96 % of MDD ✓
Resistivity (ERT)ASTM G57 · NACE · AWWA · IS 3043
Wenner array, 4 spacings
ρ 22 Ω·m → soil corrosivity class
Compression index (Cc, Cr)Skempton · Terzaghi-Peck · Nagaraj
LL 50, w_n 35, e0 0.95, Gs 2.70
Cc 0.29 (mean of 5 correlations), Cr 0.06
Frost penetration depthStefan · Modified Berggren
k 1.5 W/m·°C, ρd 1700, w 15 %, F 600 °C·days
Frost line 1.22 m (Modified Berggren, λ 0.9)
Coefficient of consolidation (oedometer)Casagrande · Taylor · IS 2720-15
t₅₀ 10 min, H_dr 10 mm, m_v 0.2 (Casagrande)
c_v 1.04 m²/yr (3.3×10⁻⁸ m²/s), k 6.4×10⁻¹¹ m/s
Preconsolidation σ′p / OCRBecker work method · Casagrande · IS 2720-15
e–log σ′ curve, break at 100 kPa, σ′v0 50
σ′p 100 kPa, OCR 2.0, Cc 0.25, Cr 0.05
Rock & tunnelling
2Rock-mass classification and tunnel support.
Rock mass classificationRMR89 · Q · GSI · Hoek-Brown 2002
σci 50 MPa, mi 10, GSI 45, RQD 70
RMR 62 (class II), Q 8.3, mb 1.40, s 0.0022
Tunnel ground reaction (convergence-confinement)Duncan Fama · Hoek
r0 5 m, p0 10 MPa, c 1 MPa, φ 30°, unsupported
p_cr 4.13 MPa, plastic radius 9.2 m, convergence 77 mm
Problem soils
3Expansive and collapsible ground.
Expansive soil (swell)ASTM D4546 · IS 1498 · IS 2720-40/41
FSI 80 %, PI 45, swell pressure 220 kPa
Severity high → under-reamed piles / CNS layer
Expansive heave magnitudeASTM D4546 · IS 9214
2 m active zone, Cs 0.08, p_s 200 kPa, σ'_final 50
ΔH 50.7 mm (high) — surcharge 200 kPa to suppress
Collapse potentialASTM D5333 · Jennings & Knight
h0 20 mm, 19 → 17.5 mm on wetting at 200 kPa
I_c 7.5 % → moderately severe collapse
47 lab workflows, signed and chained.
Classification & index
8Water contentIS 2720-2 / ASTM D2216
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Atterberg limitsIS 2720-5 / ASTM D4318
Casagrande LL + rolled PL
LL 42, PL 20 → PI 22, USCS CL
Sieve analysisIS 2720-4 / ASTM D6913
Mass retained per sieve
Cu 8, Cc 1.2 → well-graded sand (SW)
HydrometerASTM D7928 / IS 2720-4
Hydrometer readings vs time
18 % clay, 22 % silt fraction
Specific gravityASTM D854 / IS 2720-3
4-mass pycnometer
G 2.67 at 27 °C
Particle shape (D4791)ASTM D4791
Flakiness + elongation gauges
Flakiness 28 %, elongation 22 %
Shrinkage limitASTM D4943 / IS 2720-6
Mercury displacement
SL 14 %, shrinkage ratio 1.8
Linear ShrinkageIS 2720-20 / BS 1377-2
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Compaction & strength
10Proctor compactionIS 2720-7 / ASTM D698
Compaction at 5 moisture points
OMC 14 %, MDD 1.82 g/cc
California Bearing RatioASTM D1883 / IS 2720-16
Soaked 4-day, 2.5 / 5.0 mm
CBR 8 % (governs at 2.5 mm)
Relative densityASTM D4254 / IS 2720-14
e_max / e_min, field e
Dr 65 % → medium dense
Unconfined compressionASTM D2166 / IS 2720-10
Single specimen to failure
qu 110 kPa → su 55 kPa, sensitivity 3
Triaxial UUASTM D2850 / IS 2720-11
3 cells, undrained
c_u 48 kPa, φ_u 0°
Triaxial CUASTM D4767 / IS 2720-12
3 cells, CU + pore pressure
c′ 8 kPa, φ′ 29°, A_f 0.6
Triaxial CDASTM D7181 / IS 2720-12
3 cells, drained
c′ 5 kPa, φ′ 32°
Direct shearASTM D3080 / IS 2720-13
3 normal stresses
c′ 6 kPa, φ′ 31°
Vane shear (lab)ASTM D4648 / IS 2720-30
Peak + remoulded torque
su 52 → 17 kPa, sensitivity 3.1
Ring shear (residual)ASTM D6467
3 stages to large displacement
φ′r 27.5°, c′r 0 (residual)
Consolidation & permeability
3Oedometer / 1-D consolidationASTM D2435 / IS 2720-15
e-log p loading
Cc 0.32, Cv 2.4 m²/yr, pc′ 120 kPa
CRS consolidationASTM D4186
Constant rate of strain
Cv(σ′) curve + mv, continuous
PermeabilityASTM D2434 / IS 2720-17
Falling-head
k 3×10⁻⁷ m/s
Dynamic
2Cyclic triaxialASTM D5311 / D3999
CSR vs cycles to liquefaction
Liquefies in 14 cycles at CSR 0.2
Resonant columnASTM D4015
Torsional resonance
Gmax 95 MPa, damping 1.8 %
Rock laboratory
5Rock UCS (uniaxial compression)IS 9143 / ASTM D7012
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Brazilian Tensile StrengthIS 10082 / ASTM D3967
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Rock Density / Porosity / AbsorptionIS 13030 / ISRM
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Point load indexIS 8764 / ISRM
Diametral on core
Is(50) 3.2 MPa → UCS ≈ 77 MPa
Slake durabilityIS 10050 / ISRM
2-cycle wet-dry
Id2 96 % → durable rock
Swell, chemical & special
5Free swell indexASTM D4546 / IS 2720-40
Free-swell index
FSI 80 % → high expansivity
Swell pressureASTM D4546 / IS 2720-41
Constant-volume oedometer
Swell pressure 220 kPa
Chemical aggressivity batteryIS 2720-21/22/26/27
pH · sulphate · chloride · organic
pH 7.8, SO₄ 1,200 ppm → moderate exposure
Organic content (LOI)ASTM D2974 / BS 1377-3
Loss on ignition at 440 °C
OC 20 % → organic soil
Pinhole dispersionASTM D4647
Flow at 50 mm head, dark effluent
Class D1 → highly dispersive
Aggregates (IS 2386)
8Aggregate Impact Value (AIV)IS 2386-4 / BS 812-112
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Aggregate Crushing Value (ACV)IS 2386-4 / BS 812-110
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Los Angeles Abrasion (LAA)IS 2386-4 / ASTM C131
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Ten Percent Fines Value (TFV)IS 2386-4 / BS 812-111
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Flakiness & Elongation IndexIS 2386-1 / BS 812-105
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Aggregate Specific Gravity & AbsorptionIS 2386-3 / ASTM C127
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Aggregate Soundness (sulphate)IS 2386-5 / ASTM C88
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Stripping Value (bitumen adhesion)IS 6241 · ASTM D3625
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Bitumen & bituminous mix (IS 1201–1220)
6Penetration of BitumenIS 1203:1978 / ASTM D5
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Softening Point (Ring & Ball)IS 1205:1978 / ASTM D36
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Ductility of BitumenIS 1208:1978 / ASTM D113
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Penetration Index (susceptibility)Pfeiffer & Van Doormaal
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Specific Gravity of BitumenIS 1202:1978 / ASTM D70
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Marshall Stability & VolumetricsASTM D6927 / MS-2
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One platform. From the rig to a signed report.
Code-checked to IS, Eurocode 7, NF P94-261, BS, AASHTO, ASTM and IRC — the same platform answers an Indian highway, a French foundation and a US bridge. 1-month free trial.