Ka
ka
Rankine active earth pressure coefficient Ka
Scores if within ±3% of the reference value.
Evaluates overturning stability of cantilever retaining walls by computing the factor of safety as the ratio of resisting to overturning moments about the wall toe. Uses Rankine active earth pressure (Ka) to determine lateral forces from backfill and surcharge, and sums stabilising moments from the self-weight of the stem, base slab, and backfill soil per AS 4678 and Eurocode 7.
with-tool: The model is given an executable Python calculator script.
Standards
One template produces many comparable benchmark tasks while keeping the scoring contract fixed.
01
The reusable contract shown on this page.
02
An archetype and site context are sampled.
03
Inputs may be hidden at harder tiers.
04
The model responds with the declared outputs.
Inputs the model receives, and the outputs it is scored on.
9 inputs
Included directly in every task prompt.
Wall height
wall_height_m
Height of the wall stem above the base slab
Base width
base_width_m
Total width of the base slab
Stem thickness
stem_thickness_m
Thickness of the wall stem
Base thickness
base_thickness_m
Thickness of the base slab
Concrete unit weight
concrete_unit_weight_kn_m3
Unit weight of the reinforced concrete
Sampled from the scenario and inferable from its description.
Backfill friction angle deg
backfill_friction_angle_deg
Effective friction angle of the backfill soil
Derived from the archetype scenario. Hidden at hard difficulty.
Backfill unit weight
backfill_unit_weight_kn_m3
Unit weight of the backfill soil
Derived from the archetype scenario. Hidden at hard difficulty.
Used only when the sampled task needs this part of the contract.
Surcharge
surcharge_kpa
Uniform surcharge load on the backfill surface
Optional input.
Water table depth
water_table_depth_m
Depth to water table from the top of the wall
Optional input.
5 outputs
ka
Rankine active earth pressure coefficient Ka
Scores if within ±3% of the reference value.
active_force_kn_m
Total active force per metre of wall Pa (kN/m)
Scores if within ±5% of the reference value.
overturning_moment_knm_m
Overturning moment about the toe Mo (kNm/m)
Scores if within ±5% of the reference value.
resisting_moment_knm_m
Resisting moment about the toe Mr (kNm/m)
Scores if within ±5% of the reference value.
factor_of_safety_overturning
Factor of safety against overturning FoS
Scores if within ±5% of the reference value.
Each template is sampled at three tiers. Harder tiers may hide inputs, forcing the model to infer them from the scenario description.
All inputs given
All parameters given, no surcharge, no water table
Surcharge restricted to: 0
Water table restricted to: False
All inputs given
All parameters given, surcharge and water table present
Water table restricted to: True
Some inputs hidden
Soil parameters hidden, surcharge and water table present
Hidden inputs
Prompt replacement text
The backfill soil is {{ archetype.description }} ({{ archetype.site_context }})
Water table restricted to: True
The exact instruction and parameter contract used to generate this task, pinned to the published library source.
/workspace
Teal lines show Jinja input conditions, not task visibility policy. A line renders only when that input or tool is visible.
1You are a senior geotechnical engineer specializing in retaining wall design.2 3## Problem4 5Check the stability of a cantilever retaining wall against overturning about the toe using Rankine active earth pressure theory.6 7## Given8 9| Parameter | Value | Unit |10|-----------|-------|------|11| Wall stem height (H) | {{ wall_height_m }} | m |12| Base slab width (B) | {{ base_width_m }} | m |13| Stem thickness (t_stem) | {{ stem_thickness_m }} | m |14| Base slab thickness (t_base) | {{ base_thickness_m }} | m |15{% if backfill_friction_angle_deg is defined %}16| Backfill friction angle (φ') | {{ backfill_friction_angle_deg }} | degrees |17{% endif %}18{% if backfill_unit_weight_kn_m3 is defined %}19| Backfill unit weight (γ_s) | {{ backfill_unit_weight_kn_m3 }} | kN/m³ |20{% endif %}21| Concrete unit weight (γ_c) | {{ concrete_unit_weight_kn_m3 }} | kN/m³ |22{% if surcharge_kpa is defined %}23| Surcharge load (q) | {{ surcharge_kpa }} | kPa |24{% endif %}25{% if water_table_depth_m is defined %}26| Water table depth from wall top | {{ water_table_depth_m }} | m |27{% endif %}28{% if archetype_description is defined %}29 30### Site Conditions31 32{{ archetype_description }}33{% endif %}34 35{% if tool_available %}36## Available Tool37 38A retaining wall overturning calculation tool is available at `/workspace/wall-overturning_calc.py`. Run it with:39 40```bash41python3 /workspace/wall-overturning_calc.py --help42```43 44You may use this tool to verify your calculations or compute values directly.45{% endif %}46 47## Required48 49Calculate the following:50 511. Rankine active earth pressure coefficient Ka522. Total active force per metre of wall Pa (kN/m)533. Overturning moment about the toe Mo (kNm/m)544. Resisting moment about the toe Mr (kNm/m)555. Factor of safety against overturning FoS56 57## Applicable Standards58 59- AS 4678 — Earth-retaining structures60- Eurocode 7 — Geotechnical design61 62## Constraints63 64- No internet access is available. Work from engineering knowledge and the provided tool.65- Use Rankine active earth pressure theory:66 - **Active coefficient:** Ka = (1 - sin φ') / (1 + sin φ')67 - **Active force (triangular):** Pa = 0.5 × Ka × γ_s × H_total²68 - where H_total = wall stem height + base slab thickness69- The active force resultant acts at H_total / 3 from the base.70- If a surcharge q is present, the additional lateral force is Ka × q × H_total, acting at H_total / 2.71- If the water table is within the wall height, add hydrostatic pressure: P_w = 0.5 × γ_w × h_w² (γ_w = 9.81 kN/m³, h_w = submerged height).72- Wall geometry (cantilever L-wall from toe to heel):73 - Toe length = B / 374 - Stem sits on the base starting at the toe length75 - Heel length = B - toe length - stem thickness76- Resisting moment about the toe includes:77 - Base slab self-weight (acting at B/2 from toe)78 - Stem self-weight (acting at toe_length + t_stem/2 from toe)79 - Backfill soil on the heel (acting at toe_length + t_stem + heel/2 from toe)80 - Vertical surcharge on the heel (if applicable)81- **Factor of safety against overturning:** FoS = Mr / Mo (minimum acceptable FoS = 2.0)82 83## Output Format84 85Show your step-by-step working in Markdown, including formulas and intermediate calculations. At the end of your solution, include a JSON block with your final answers in exactly this format:86 87```json88{89 "ka": <numeric_value>,90 "active_force_kn_m": <numeric_value>,91 "overturning_moment_knm_m": <numeric_value>,92 "resisting_moment_knm_m": <numeric_value>,93 "factor_of_safety_overturning": <numeric_value>94}95```96 97Write your complete solution to `/workspace/output.md`.98 Each generated task is drawn from one of these realistic scenario bands.
Site contexts ground each scenario in a real locale the model can use to infer hidden values.
loose_granular_fill
Loose granular fill
medium_dense_sand
Medium dense sand backfill
dense_gravel
Dense compacted gravel
stiff_clay_fill
Stiff clay fill
brisbane-alluvial-loose-granular-fill-preview — hard difficulty, some inputs hidden.
Loose granular fill. brisbane-alluvial. Required outputs: ka, active_force_kn_m, overturning_moment_knm_m, resisting_moment_knm_m, factor_of_safety_overturning
Scenario context and visible inputs.
Executable tool: wall-overturning_calc.py
Inputs withheld at this difficulty.
Backfill friction angle deg
backfill_friction_angle_deg
Backfill unit weight kn m3
backfill_unit_weight_kn_m3
Stand-in text in the prompt
The backfill soil is {{ archetype.description }} ({{ archetype.site_context }})
The scored JSON answer schema.
{
"ka": <number>,
"active_force_kn_m": <number>,
"overturning_moment_knm_m": <number>,
"resisting_moment_knm_m": <number>,
"factor_of_safety_overturning": <number>
}