Pfc Brittle Rock Bpm

PFC Brittle Rock BPM

This skill turns Chapter 5.1-5.2 into a reusable guide for brittle-rock mechanics interpretation, standard BPM explanation, formula extraction, and figure planning.

When to use

Use this skill when the user wants to:

• summarize the three hallmark traits of brittle rock
• explain deep-rock brittle behavior, zonal failure, or rockburst context
• retain standard BPM assumptions and parallel-bond formulas
• compare standard BPM against laboratory brittle-rock behavior
• design figures for UCS/TS ratio, strength envelopes, or BPM mechanism sketches

First rules

1. Separate observed brittle-rock behavior from what the standard BPM can actually represent.
2. Keep the high-compression low-tension contrast explicit; the UCS/TS ratio is a primary signal.
3. When quoting formulas, define symbols and the failure condition, not only the final expression.
4. Treat the standard BPM as a baseline model with known deficiencies, not as the final answer for brittle rock.
5. For plots, state whether the figure is conceptual, laboratory-derived, or simulation-derived.

Default workflow

1. Frame the brittle-rock problem

Read references/theory.md to recover the chapter's three brittle-rock traits, three deep-rock mechanical phenomena, and the reason brittle rock is hard to represent with a simple bonded-particle model.

2. Retrieve the core formulas

Read references/formulas.md for the standard BPM parallel-bond stress expressions, geometric terms, and tension/shear failure criteria.

3. Plan the figures

Read references/plotting.md for the default figure families:

• UCS vs TS contrast
• linear vs nonlinear strength envelope comparison
• BPM force-displacement or constitutive sketch
• defect-to-figure mapping for standard BPM limitations

4. Trace back to the chapter

Read references/chapter-map.md when you need the exact section, figure, or formula provenance inside Chapter 5.1-5.2.

Read next

• references/theory.md
• references/formulas.md
• references/plotting.md
• references/chapter-map.md

Output contract

For a complete response or delivery, prefer these artifacts:

• a short statement of brittle-rock traits and deep-rock phenomena
• a formula block for BPM stress and failure criteria with symbol notes
• a figure list with axis definitions and input requirements
• a note that standard BPM underestimates brittle-rock compression-tension contrast and nonlinear envelope behavior

Required Inputs

Ask for these if missing:

• PFC version and 2D/3D target;
• specimen size, loading path, and boundary-control assumptions;
• BPM/contact model family and initial micro-parameter ranges;
• macro calibration targets such as UCS, modulus, peak strain, and fracture pattern;
• available scripts, references, or existing case files to audit.

Local Contents

• references/chapter-map.md: chapter-level routing and topic map.
• references/formulas.md: reusable formulas and parameter relationships.
• references/plotting.md: plotting expectations for brittle-rock BPM outputs.
• references/theory.md: theoretical background and modeling assumptions.