Help & Technical Documentation

This application contains two independent engineering models. They share pipe catalogues, units and reporting conventions, but they do not share the same mechanics or acceptance criterion. Select the model from the physical operation—not from the result you hope to obtain.

Valid / converged

The numerical checks required by that solver completed. This is not a physical-validity or code-compliance statement.

Criterion met / not met

The reported model stress is respectively at or below, or above, the selected strict threshold. There is no hidden mechanical margin.

Uncertain

The numerical uncertainty overlaps the threshold. It takes precedence over a pass/fail label.

Unresolved

A failed, uncertain, interrupted or unsampled region has not been classified and must not be treated as failing or impossible.

Numerical failure

The requested output could not be represented or solved reliably. The application does not substitute another model or a convenient mesh result.

Out of domain

A documented model-scope screen was exceeded. No result within this model is claimed.

Instability risk

The in-service initial effective compression reaches its Euler screen; the model stops without a post-buckling solution.

• The unit switch changes representation only; it does not restart a completed calculation.
• Editing a mechanical input invalidates results and export availability until the new request completes.
• Background calculations are isolated by request. Obsolete work is cancelled or ignored so it cannot overwrite a newer result.
• PDF exports use one coherent completed-request snapshot: inputs, derived values, result and displayed unit system belong together.
• A PDF records the model calculation; it is not a sealed design document or normative certificate.

The reference coordinate runs from the left clamp at x = 0 to the right clamp at x = L. Vertical elevation z is positive upward, lateral offset is y, and distributed weight q acts downward. Both end rotations are fixed; the right end is imposed at vertical offset hv and lateral offset hl.

All four modes support free or restrained axial behavior, with or without ground. The represented value controls the detailed plots and tables but does not rewrite the original input or prove that a search range is complete.

Free searches without ground retain their analytical regime paths. Ground and restrained searches share exploratory samplers and classifiers; Find L samples logarithmic length. Failed, uncertain and budget-limited regions remain unresolved.

• Mesh refinement and equilibrium/contact checks establish numerical acceptance only.
• Search budgets cover sampling and final verification; partial coverage remains visible when a budget ends.
• For restrained analyses, axial strain and transverse slope are indicators, not automatic physical certification thresholds.
• Pressure, temperature, plasticity, ovalization, local buckling, welds, defects, fatigue, dynamics and soil capacity are outside this model.
• Complex routing, bends, tees and local support/contact stresses require separate engineering analysis.

This module is independent from Pipe Lowering. It represents a straight, uniform, elastic steel pipe with ideal clamps at both buried ends. The full excavated length is twice the entered half-length. Pressure and temperature remain constant during construction; permanent mode adds explicit future operating cases.

Select Permanent maintained deviation for a separate direct calculation. The initial pipe remains the steel reference configuration: neither support adjustment nor backfill erases stress.

Quick setup pre-fills editable examples and offers uniform, successive-half or ends-first backfill layouts. Open a zone for its values and soil-response examples. Infobubbles explain units, signs, examples and limitations. Fill empty fields preserves existing entries; deliberate blanks stay blank until that action is used.

Flexible/intermediate/stiff soil examples are sensitivity cases, not material classifications. Stress and position verdicts remain not evaluated until starting values have been checked against project information. New operating cases initially copy construction conditions. Identity and applicability confirmations still require your input.

• Keep initial supports at their original height, or unload them under equipment control before moving the pipe. Loaded supports must be unloaded before reuse.
• Install symmetric vertical pairs at the calculated shape, without added preload, or enter common absolute heights for all scenarios. Common heights can create a calculated preload.
• Release equipment before or after backfill. Vertical supports allow lateral rebound and do not lock the imposed position.
• Enter documented axial, lateral, downward and uplift soil curves and separate backfill/construction loads. Zones activate in explicit stages; temporary pairs are lowered and removed in the specified order.
• Each future pressure/temperature case starts from the final loaded state. Enter its fluid density and confirm material properties at all temperatures.

Stress, final centre position and soil resistance limits have separate results. Position tolerances apply in controlled directions, including computed operating transitions. Convergence failures, missing data or soil limits prevent verified retention. Scenario-fitted support heights do not validate one common physical setting.

Pressure, temperature and additional wall force define the initial wall force. Subtracting the pressure-area term gives effective tension, which controls beam geometric stiffness. Unlike the Pipe Lowering restrained model, the initial effective force may be tensile or compressive.

1. Initially, soil support balances the pipe weight.
2. Weight is transferred uniformly to the pipe and installed temporary supports until the excavated state is reached.
3. The central actuator engages at the excavated midpoint and ramps controlled components to the target measured from the original axis.
4. The elastic, frictionless return retraces the sampled actuation path to the excavated state.
5. Uniform support restoration returns the model to its initial straight state.

A candidate passes only when every initial-state hypothesis produces a completed, decidable path below the custom threshold. Failed, uncertain, out-of-domain and budget-limited samples stay unresolved. Searches do not claim monotonicity or a global optimum.

The reported criterion is a conservative Von Mises beam bound. It combines the section maximum of pressure, wall-force and bending normal stress with a conservative transverse beam-shear bound. The normal and shear maxima may occur at different positions within an element.

• The strict custom threshold is applied only after numerical uncertainty is considered.
• Yield exceedance stops the elastic path; the module does not calculate plastic redistribution.
• Model-domain screens require full length / outside diameter ≥ 10 and maximum resultant slope ≤ 0.1.
• These scope screens are not code acceptance limits.

• Scenario comparison identifies the governing hypothesis and status.
• Detailed results show excavated and target profiles, governing phase, actuator forces, end reactions and moments, wall/effective force, critical element and separate normal/shear locations.
• With supports, select any sampled intervention stage to inspect its profile, reaction, gap and contact state; peak support and transverse loads remain available separately.
• Diagnostics expose refinement history, stress uncertainty, slope and axial residual rather than hiding incomplete paths.

• Steel only: no HDPE, plastic steel or material aging model.
• No plasticity, post-buckling, torsion, ovalization, local sling/contact stress, defects, weld concentration or fatigue assessment.
• No moving excavation front, support capacity, local bearing or evolving settlement check. The temporary branch excludes surrounding-soil interaction; the permanent branch uses the documented reversible soil laws described above.
• The temporary reverse path assumes elastic, frictionless behavior without impact, hysteresis or construction dynamics.
• Analytical benchmarks and automated regression tests support implementation evidence; no independent commercial FE benchmark or field calibration is claimed.
• Optional CSA Z662:2023 checks assess minimum nominal wall (4.3.11.2) and the anchored pressure/temperature design state (4.7.1), with the temperature factor from 4.3.9. Separate design inputs and scope confirmations are required. They do not assess lifting, bending/stability (4.7.2), or Annex C, and never govern searches. ASME and European checks and overall normative compliance verdicts are not implemented.