A Flood-Resilient Amphibious Foundation for a Small House: Buoyancy, Guide-Post Loads and Failure Limits

An amphibious foundation lets a small house sit at ground level in dry weather and rise with flood water on vertical guide posts. This paper designs such a foundation for a single-storey house of 38,000 kg on a watertight buoyant base 10.0 m by 8.0 m and 1.40 m deep, and computes its full float and load budget from one set of inputs. The house lifts off at a flood depth of 0.50 m, floats with a draft of 0.475 m and a freeboard of 0.925 m, and rises 2.525 m at the design flood of 3.0 m. In a current of 2.0 m/s the design lateral load, including a debris-damming allowance, is 17.10 kN; the most heavily loaded of six steel guide posts reaches 89.4 MPa against an allowable stress of 165.1 MPa (margin 1.85), and the current at which the posts reach the allowable stress is 2.72 m/s. A 500 kg floating debris impact at design speed is carried with a margin of 1.97, with a computed maximum debris mass of 987 kg. A stated uneven-loading case heels the floating house 1.80 degrees and leaves 0.799 m of freeboard on the low side. The failure cases are printed at full size: a guide bracket jammed after 1.00 m of rise is overloaded to a margin of 0.13 by the design flood and reaches its stated capacity at a flood depth of 1.679 m; a house prevented from rising is overtopped at 1.40 m; and post engagement falls to its stated minimum at a flood depth of 3.475 m. All results are simulated, not measured; nothing has been built or load-tested, the figures are computed values under stated assumptions, and they are not a safety certification. The computation is reproducible from the deposited compute.py and results.json.