Lythos MSEW

Retaining structures

Mechanically stabilised earth walls

External and internal stability per FHWA-NHI-10-024 and AASHTO LRFD 11.10: sliding, overturning, bearing, tensile, pullout, connection; steel strips and geosynthetics, corrosion, earthquake, ASD or LRFD.

$ pip install git+https://github.com/hdaltuntas/lythos-msew

Run

lythos-msew

Default port

8782

Python

3.10+

Version

0.1.0 · from GitHub

Licence

AGPL-3.0

See the examples →ReferenceSource ↗

Mechanically stabilised earth (MSE) walls — a facing, layers of steel strips, geogrids or geotextiles in a compacted fill, and the retained soil behind it — designed and checked the way FHWA-NHI-10-024 and AASHTO LRFD 11.10 do it, and the way the MSEW program made familiar.

What it computes

1. Earth pressure — Coulomb / Rankine K_a of the retained and the reinforced fill, with a battered face and a sloping backfill.
2. External stability — sliding on the base (through the fill, on the foundation soil, or along a geosynthetic), overturning about the toe, the eccentricity of the resultant.
3. Bearing capacity of the foundation under the effective width B′ = L − 2e by Terzaghi, Meyerhof, Brinch Hansen, Vesić and EN 1997-1, side by side (the factors are Lythos Bearing's); with the water table, the embedment, the load inclination and a slope in front of the toe.
4. Internal stability, layer by layer — the maximum tension by AASHTO's Simplified Method (K_r/K_a of 1.7 → 1.2 for strips, 1 for geosynthetics), then each layer's tensile, pullout (F*, α, L_e beyond the active zone), connection and sliding checks.
5. Reinforcement — the strips' width, thickness, yield strength and spacing (the section left after zinc and steel corrosion over the design life is worked out), or a geosynthetic's ultimate strength and reduction factors RF_ID·RF_CR·RF_D.
6. Earthquake — the pseudo-static method: A_m = (1.45 − A)·A, the dynamic thrust P_AE and the inertia P_IR externally, the inertia of the active zone shared among the layers internally.
7. ASD or LRFD — factors of safety, or load factors (EV, EH, ES, LS) and resistance factors φ.
8. The length the wall needs — the shortest uniform reinforcement length that satisfies the external and pullout checks, beside FHWA's minimum (0.7·H, 2.4 m).

On top of it, a height study runs the same design rule over a range of wall heights and shows where every check holds.

Screenshots

Results summary

Internal stability, layer by layer

Section — dark theme, Turkish

Bearing capacity by method

Height study

Checks against the reinforcement length

Reinforcement catalogue

Height study table

Quick start

Lythos MSEW is not on PyPI yet; install it from GitHub:

pip install git+https://github.com/hdaltuntas/lythos-msew
lythos-msew                                    # interface: http://127.0.0.1:8782/

lythos-msew example -o wall.msew
lythos-msew run wall.msew -o report.pdf
lythos-msew heights wall.msew -o heights.xlsx

Reinforcement catalogue

Typical market products are added to the type table in one click: ribbed galvanised steel strips (HA 40×4 to 60×5 in S355, 50×4 in Grade 65), polymer strips (PET core, PE sheath, 20–100 kN per strip), uniaxial HDPE and PET geogrids (35–200 kN/m), woven PET and PP geotextiles — with FHWA's typical reduction factors and pullout parameters.

WARNING

Catalogue values are generic starting values; check them against the datasheet of the product specified.

Not included

Global and compound stability, settlement and drainage are not included; check them separately — global stability with Lythos LE, settlement with Lythos Settle.