Reaction System Verification (Kentledge, Reaction Piles, Beams)

Definition: Verify Reaction Systems guides site engineers to confirm kentledge, reaction piles, and beams meet capacity, stability, and instrumentation requirements before load testing, excluding any load application procedures.

Validate reaction capacity, stability, and geometry against approved design.
Confirm calibration and independence of load and displacement instrumentation.
Capture evidence: photos, readings, certificates, and signed approvals.
Interactive, commentable checklist with export and QR code sign-off.

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Checklist

Verify Reaction Systems is a focused checklist for confirming the capacity, stability, and instrumentation of kentledge, reaction piles, and reaction beams before any load is applied. It covers reaction system checks, kentledge verification, and anchor/reaction pile readiness without entering into load test execution. By systematically reviewing design capacity, bearing and bracing, alignment and clearances, and the entire data chain (jack, gauges, load cells, LVDTs, and logger), you reduce the risk of catastrophic instability, under-capacity, eccentric loading, or misleading measurements. The outcome is a stable, compliant, and traceably documented reaction arrangement that is ready for the separate load test procedure. This checklist is tailored to site engineers, QA/QC leads, and third-party inspectors working on static load test setups for foundations and structures. Use it to standardize evidence capture, accelerate approvals, and prevent costly rework. Start in interactive mode to tick items, add comments, attach photos and certificates, and export to PDF/Excel with a QR-secured record.

Ensure reaction systems are safe, stable, and capacity-compliant before any load application by verifying design calculations, materials, geometry, bracing, and bearing pressures with traceable field evidence and approvals.
Reduce measurement risk by confirming calibrated instrumentation, independent displacement references, correct channel mapping, and adequate data sampling rates, avoiding errors that can invalidate the subsequent load test.
Interactive online checklist with tick, comment, and export features secured by QR code.
Standardize communication among contractors, consultants, and authorities using photos, torque logs, calibration certificates, and stamped drawings, accelerating pre-test readiness reviews per approved project specifications and authority requirements.

Design Capacity Verification

1. Review approved drawings and reaction scheme; confirm required maximum jack force and reaction capacity match design.
2. Recalculate total kentledge mass or reaction pile/anchor capacity versus maximum expected jack force using a spreadsheet; upload calculation sheet demonstrating compliance per approved project specifications.
3. Check reaction beam bending, shear, and bearing stresses using section properties; verify fastener grades and spacing; acceptance: calculated demands ≤ capacities; evidence: annotated calc sheet and beam ID photo.
4. Verify jack capacity, stroke, and rated pressure exceed design requirements; evidence: manufacturer nameplate photo and data sheet confirming rating with margin per approved project specifications.

Stability and Geometry Checks

5. Confirm bearing pressure under kentledge grillage or cribbing ≤ allowable from the geotechnical report; evidence: area calculation and allowable bearing note, signed.
6. Measure levelness of grillage/reaction beam using a digital level; tolerance: ±3 mm/m; record readings and upload level screenshots/photos.
7. Verify alignment of jack centerline to test point; tolerance: within ±3 mm in plan; method: tape/laser; evidence: marked layout photo and measurement notes.
8. Check eccentricity of reaction load path; tolerance: resultant within 5 mm of reaction frame centroidal line; evidence: sketch with dimensions and sign-off.
9. Inspect lateral bracing, tie-downs, and anti-uplift measures installed as designed; acceptance: all connections tight, lock nuts engaged; evidence: photos of each bracing point.

Kentledge Stack and Supports

10. Count and identify all blocks; verify mass per block from certificates; acceptance: cumulative mass within ±2% of required; evidence: tally sheet and stack photo with IDs visible.
11. Check stacking pattern (staggered joints, interlocks, no rocking); overhang ≤ 50 mm; method: tape check; evidence: side-profile photos with dimensions.
12. Verify grillage/cribbing dimensions and timber/steel grade; bearing stress ≤ allowable; evidence: material tags, grade certificates, and calc snippet.
13. Confirm anti-topple restraints (chains/straps/stops) installed per design; acceptance: tensioners locked and tagged; evidence: photo of each restraint with tag numbers.

Reaction Piles/Anchors

14. Review installation logs for reaction piles/anchors (depth, diameter, tendon/strand data, grout volumes); acceptance: meets approved design; evidence: signed log extracts.
15. Verify grout/concrete strength test results meet required value before use; method: lab report; evidence: test certificates showing date, age, and strength.
16. Inspect head hardware (plates, nuts, couplers); torque nuts to manufacturer/approved spec using a calibrated wrench; acceptance: torque within ±10%; evidence: torque log and wrench serial.
17. Check pile/anchor alignment and inclination; tolerance: within design ±1°; method: inclinometer/plumbline; evidence: readings and head photos.

Reaction Beams and Frames

18. Confirm beam/box sections, stiffeners, and spreader plates match drawings; evidence: member ID photos and heat/grade certificates attached.
19. Examine welds and bearing seats; acceptance: no visible cracks, undercut, or distortion; method: visual inspection with good lighting; evidence: close-up photos and inspector initials.
20. Verify bolts/clamps grade and pretension; torque to approved values; acceptance: ±10% of target; evidence: torque log and bolt batch certificates.
21. Check hardened bearing plates under jack; flatness within 0.2 mm across bearing; method: straightedge/feeler gauge; evidence: measurement photo.

Instrumentation and Data Chain

22. Confirm hydraulic jack and pressure gauge/transducer calibration certificates current (e.g., within 12 months per approved project specifications); evidence: certificates and serial numbers.
23. Verify load cell capacity ≥ required and calibration traceability; perform zero check; acceptance: zero within ±0.5% FS; evidence: zero log and certificate.
24. Ensure displacement sensors (LVDTs) mount to independent reference frame, not the reaction system; evidence: photos showing mounting and gauge lengths.
25. Check data logger channel mapping, sampling rate ≥ 1 Hz, and time synchronization; evidence: configuration screenshot and saved setup file.

Documentation and Approvals

26. Verify approved method statement, drawings, and risk assessment cover the reaction system; evidence: approval stamps, revision numbers, and reviewer signatures.
27. Establish exclusion zone, barriers, and signage around the reaction system; acceptance: access controlled on all sides; evidence: site photos and permit-to-work.
28. Conduct multidisciplinary pre-use walkdown (contractor, consultant, QA); record actions closed; evidence: signed checklist and QR-secured sign-off.

Why reaction system verification prevents failures

Reaction systems must resist test forces safely and without unintended movement. Failures usually stem from under-estimated capacity, inadequate bearing, misalignment, or unsecured components. Before any load is applied, confirm the design basis, calculate real capacities for the assembled configuration, and compare against the maximum jack force. Field geometry matters: even small eccentricities can amplify bending in reaction beams and uplift on anchors. Levelness controls load distribution across grillage and blocks; lateral bracing prevents sway that can shift the jack. Document every check with traceable evidence—photos, measurements, serial numbers, and approvals—so that stakeholders share a single, auditable record. On real jobs, issues often include missing stiffeners, overhanging blocks beyond tolerance, or uncalibrated gauges. Catching these early prevents rework and protects personnel. Acceptance cues include capacity calculations matching approved specs, measured level within tolerance, locked restraints, and valid calibrations for all force and displacement devices.

Confirm capacities meet or exceed approved design requirements.
Keep levelness within ±3 mm/m across bearing surfaces.
Align jack centerline within ±3 mm to test point.
Lock all restraints; no looseness or rocking allowed.
Upload photos, readings, and certificates for traceability.

Kentledge, reaction piles, and beams: targeted checks

Kentledge stacks demand verified block masses, correct stacking patterns, and bearing checks to ensure allowable ground or grillage pressures are not exceeded. Reaction piles and anchors require compliant installation logs and sufficient grout/concrete strength before clamping. Head hardware must be torqued to specification and aligned to avoid bending. Reaction beams need confirmation of section grade, weld integrity, and proper bearing plates under the jack. Across all systems, maintain clear access and safe exclusion zones. Practical examples include reconfiguring stacks to reduce overhang, adding cribbing to distribute load, replacing undersized clamps, or installing stiffeners where design shows high flange stresses. Ensure all changes are reflected on marked-up drawings and rechecked. Acceptance is evidenced by updated calculations, torque logs within tolerance, block tallies within ±2% mass, and signed drawings matching the built condition.

Block mass total within ±2% of required.
Torque bolts/nuts within ±10% of target.
Inclination within ±1° for piles/anchors.
Use hardened, flat bearing plates under jacks.
Update and sign marked-up as-built drawings.

Instrumentation integrity and independent measurement

Reliable measurements need a calibrated force path and independent displacement references. Confirm jack, pressure gauge, and load cell calibrations are current and traceable. Perform zero checks before use and record serial numbers. Displacement sensors (LVDTs) must mount to a stable frame independent of the reaction system to avoid false readings from reaction movement. Validate data logger configuration: channel mapping, sampling rate, and time sync. Ensure secure cable routing, strain relief, and protected connectors to prevent intermittent signals. Provide power redundancy with a UPS to bridge outages during testing. On site, common issues include miswired channels, expired calibration certificates, and LVDTs fixed to the reaction beam. Correct these before the separate load test begins. Acceptance cues include valid certificates, zero within tolerance, confirmed independence of references, documented configuration, and a successful dry-run data capture without applying structural load.

Maintain valid calibration certificates for all sensors.
Mount LVDTs to independent references only.
Set sampling rate ≥ 1 Hz with synced time.
Secure cables with strain relief and labeling.
Record zero checks and channel mapping.

How to use this interactive reaction system verification checklist

Preparation: Gather approved drawings, method statement, geotechnical report, and calibration certificates. Bring measuring tapes/laser, digital level, torque wrench, feeler gauges, camera, laptop/tablet, and PPE. Ensure safe access and lighting.
Open the checklist on your device, enter project identifiers, select reaction system type (kentledge, piles/anchors, beams), and confirm the maximum required jack force from the approved documents.
Using the Interactive Checklist: Tick items as you verify, attach photos, enter measurements (mm, kN, MPa), and link certificates. Add comments to flag issues and assign actions with due dates.
Capture Evidence: Upload calculation sheets, torque logs, calibration records, and marked-up drawings. Use the device camera to document alignment, stacking patterns, labels, and cable routing.
Collaborate: Share the checklist with contractor, consultant, and QA reviewers. Use threaded comments to resolve findings and record approvals per approved project specifications and authority requirements.
Export: Generate an export as PDF/Excel for pre-test review meetings. Include photos, signatures, timestamps, and equipment serial numbers for traceability.
Sign-Off: Obtain digital signatures from responsible parties. Lock the record with a QR code for on-site verification and archive it in the project document control system.

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Chiara Bianchi Chiara Bianchi

Jan 24, 2026

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FAQ

Question: What is included in reaction system verification, and what is excluded?

Verification confirms capacity, stability, geometry, and instrumentation readiness of kentledge, reaction piles/anchors, and reaction beams. It includes document checks, calculations, alignment, torqueing, calibration, and evidence capture. It explicitly excludes load application, load increments, hold periods, and acceptance criteria associated with the actual load test procedure.

Question: How do I decide acceptable factors of safety for the reaction system?

Use the factors required by the approved project specifications and authority requirements. Compare the assembled system’s calculated capacities to the maximum jack force, document the margin, and obtain reviewer sign-off. Avoid adopting generic values without confirmation, especially when site conditions or component configurations differ from the design basis.

Question: Do I need a load cell if I already have a calibrated pressure gauge?

A calibrated pressure gauge can indicate jack force, but a load cell typically provides higher accuracy and independent verification. Follow the approved project specifications. If a load cell is required, ensure capacity, traceable calibration, correct wiring, zero checks, and data logging are all confirmed before the test day.

Question: When should verification be completed relative to the test date?

Complete verification after the reaction system is fully assembled and before the scheduled test day. Allow time to close actions such as re-torqueing, replacing expired certificates, or adjusting alignment. For grout or concrete strength-dependent components, confirm results meet requirements before declaring readiness.

Question: What evidence should I capture to satisfy third-party reviewers?

Provide annotated calculations, photos of IDs and assemblies, torque logs, calibration certificates with serial numbers, material certificates, marked-up drawings, and signed approvals. Ensure measurements show units (mm, kN, MPa), and export a consolidated PDF/Excel package with a QR-secured audit trail.