Specific gravity sr
specific_gravity_sr
Specific gravity of rock Sr = rho_r / rho_w
Scores if within ±3% of the reference value.
Determines the required median armor stone weight and nominal diameter for breakwater and revetment stability using Hudson's (1959) formula from the USACE Coastal Engineering Manual and CIRIA C683 Rock Manual. Accounts for design wave height, rock and water densities, structure slope, and the stability coefficient KD which depends on armor type and placement method.
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.
5 inputs
Included directly in every task prompt.
Design wave height
design_wave_height_m
Design wave height H
Slope angle deg
slope_angle_deg
Structure slope angle alpha from horizontal
Sampled from the scenario and inferable from its description.
Rock density
rock_density_kg_m3
Armor rock density rho_r
Derived from the archetype scenario. Hidden at hard difficulty.
Water density
water_density_kg_m3
Water density rho_w
Derived from the archetype scenario. Hidden at hard difficulty.
Stability coefficient kd
stability_coefficient_kd
Hudson stability coefficient KD
Derived from the archetype scenario. Hidden at hard difficulty.
3 outputs
specific_gravity_sr
Specific gravity of rock Sr = rho_r / rho_w
Scores if within ±3% of the reference value.
armor_weight_tonnes
Median armor unit weight W (tonnes)
Scores if within ±5% of the reference value.
nominal_diameter_m
Nominal armor diameter Dn50 (m)
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
Moderate wave height, all parameters given — straightforward Hudson formula
All inputs given
Larger wave height, steeper slopes — same formula, bigger numbers
Some inputs hidden
Rock density, water density, and KD hidden — agent must infer from site description
Hidden inputs
Prompt replacement text
The armor is {{ archetype.description }} ({{ archetype.site_context }})
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 coastal engineer specializing in breakwater and revetment design.2 3## Problem4 5Calculate the required median armor stone weight and nominal diameter for a rubble-mound breakwater using Hudson's equation.6 7## Given8 9| Parameter | Value | Unit |10|-----------|-------|------|11| Design wave height (H) | {{ design_wave_height_m }} | m |12{% if rock_density_kg_m3 is defined %}13| Rock density (ρ_r) | {{ rock_density_kg_m3 }} | kg/m³ |14{% endif %}15{% if water_density_kg_m3 is defined %}16| Water density (ρ_w) | {{ water_density_kg_m3 }} | kg/m³ |17{% endif %}18| Slope angle (α) | {{ slope_angle_deg }} | degrees |19{% if stability_coefficient_kd is defined %}20| Stability coefficient (KD) | {{ stability_coefficient_kd }} | - |21{% endif %}22{% if archetype_description is defined %}23 24### Site Conditions25 26{{ archetype_description }}27{% endif %}28 29{% if tool_available %}30## Available Tool31 32An armor sizing calculation tool is available at `/workspace/{{ meta.name }}_calc.py`. Run it with:33 34```bash35python3 /workspace/{{ meta.name }}_calc.py --help36```37 38You may use this tool to verify your calculations or compute values directly.39{% endif %}40 41## Required42 43Calculate the following:44 451. Specific gravity of the armor rock Sr = ρ_r / ρ_w462. Median armor unit weight W in tonnes473. Nominal armor diameter Dn50 in metres48 49## Applicable Standards50 51- USACE Coastal Engineering Manual (CEM)52- CIRIA C683 Rock Manual53 54## Constraints55 56- No internet access is available. Work from engineering knowledge and the provided tool.57- Use Hudson's equation:58 - W = (ρ_r × H³) / (KD × (Sr − 1)³ × cot(α))59 - where W is in kg, ρ_r is in kg/m³, H is in metres60 - Sr = ρ_r / ρ_w (specific gravity of rock)61 - cot(α) = cos(α) / sin(α) where α is the slope angle from horizontal62- Convert weight to tonnes: W (tonnes) = W (kg) / 100063- Nominal diameter: Dn50 = (W / ρ_r)^(1/3) where W is in kg and ρ_r is in kg/m³64 65## Output Format66 67Show your step-by-step working in Markdown. At the end of your solution, include a JSON block with your final answers in exactly this format:68 69```json70{71 "specific_gravity_sr": <numeric_value>,72 "armor_weight_tonnes": <numeric_value>,73 "nominal_diameter_m": <numeric_value>74}75```76 77Write your complete solution to `/workspace/output.md`.78 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.
rough_quarrystone_random
Rough angular quarrystone placed randomly on trunk section
rough_quarrystone_special
Rough angular quarrystone with special placement on trunk
basalt_armor_random
Dense basalt armor stone placed randomly
freshwater_quarrystone
Quarrystone armor for freshwater dam or lake revetment
concrete_unit_random
Concrete armor units (cubes) placed randomly
queensland-outer-reef-rough-quarrystone-random-preview — hard difficulty, some inputs hidden.
Rough angular quarrystone placed randomly on trunk section. queensland-outer-reef. Required outputs: specific_gravity_sr, armor_weight_tonnes, nominal_diameter_m
Scenario context and visible inputs.
Executable tool: hudson-armor-sizing_calc.py
Inputs withheld at this difficulty.
Stability coefficient kd
stability_coefficient_kd
Water density
water_density_kg_m3
Rock density
rock_density_kg_m3
Stand-in text in the prompt
The armor is {{ archetype.description }} ({{ archetype.site_context }})
The scored JSON answer schema.
{
"specific_gravity_sr": <number>,
"armor_weight_tonnes": <number>,
"nominal_diameter_m": <number>
}