Construct Secant Pile Wall—Guide Wall Sequence Checklist

Definition: Construct secant pile wall—guide wall and sequence checklist for site engineers to verify primary/secondary offsets, guide wall accuracy, and drilling tolerances, ensuring consistent sequencing and records while explicitly excluding diaphragm wall methods.

Validate offsets, guide wall geometry, and drilling verticality tolerances.
Standardize primary–secondary sequencing to achieve reliable pile interlock.
Capture survey, photos, and logs for traceable quality evidence.
Interactive, commentable checklist with export and QR code verification.

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Checklist

Construct secant pile wall—guide wall and sequence is the focus of this practical, job-ready checklist for site engineers and inspectors. It covers secant bored piles with clear emphasis on guide wall construction, primary and secondary pile offsets, and drilling tolerance control. You will verify alignment using total stations and templates, manage drilling verticality, and sequence primaries then secondaries to achieve the designed overlap. This checklist deliberately excludes diaphragm walls to keep the scope precise and avoid method confusion. Following it helps prevent misaligned guides, inadequate interlock, overbreak, and costly rework while delivering a watertight, dimensionally accurate wall ready for excavation support. Each step calls for tools, acceptance criteria, and evidence such as photos, batch tickets, and survey files. Use the interactive features to tick items, add field comments, and export your records to PDF/Excel with a secure QR for authentication.

Ensure guide wall accuracy, pile set-out, and drilling tolerances are controlled from day one. The sequence mandates primaries before secondaries, protecting interlock and water cut-off, with survey checks, template verification, and documented acceptance at each hold point.
Improve construction reliability by validating primary/secondary offsets with total station data and drilling logs. Capture concrete placement evidence, verify verticality, and compare placed volumes to theoretical values to flag anomalies early and reduce rework and delays.
Interactive online checklist with tick, comment, and export features secured by QR code.
Produce defensible, audit-ready records. Photos, batch tickets, survey files, and signed inspections demonstrate conformance per approved project specifications and authority requirements, de-risking approvals and enabling confident handover before excavation.

Survey & Controls

1. Verify site control points and benchmarks with total station and digital level; positional error ≤ ±5 mm and elevation ≤ ±5 mm. Upload survey report, instrument calibration certificates, and georeferenced photos.
2. Set out pile centerline and stationing on the guide wall footprint; transverse offset ≤ ±3 mm, chainage ≤ ±5 mm. Record as-built coordinates and attach layout sketches with station references.
3. Scan for underground utilities using GPR and verify clearances; mark no-drill zones. Evidence: utility permits, GPR map, and signed clearance form per approved project specifications and authority requirements.

Guide Wall Construction

4. Construct guide wall to drawings; top elevation within ±5 mm and thickness within −0/+10 mm. Verify reinforcement and cover with bar schedules and photos before casting. Record concrete delivery tickets and pour times.
5. Check guide wall alignment parallel to design line using total station; straightness deviation ≤ 5 mm over 10 m. Document with alignment shots at 5 m intervals and a signed inspection sheet.
6. Install steel drilling templates/sleeves fixed to the guide wall; hole centers within ±2 mm of set-out and plumbness ≤ 1:500. Upload template survey, plumb gauge readings, and fixation details.

Pile Layout & Offsets

7. Confirm design diameters and center-to-center spacing for secant interlock; acceptance: spacing within ±5 mm of approved drawings. Evidence: layout table, total station shots, and CAD overlay check.
8. Mark primary pile locations in one color and secondary in another on the guide; include chainage tags. Photo-document color coding and station references at every 10 m.
9. Before drilling secondaries, re-verify offsets from as-built primaries; acceptance: center shift of secondaries ≤ ±5 mm from design and overlap per approved design. Upload comparison report.

Drilling (Primary Piles)

10. Drill primary piles through guide sleeves to design toe level using CFA/rotary tools; verticality tolerance ≤ 1:100. Capture rig inclinometer logs and depth records; photo of kelly scale at toe depth.
11. Maintain bore within guide opening; top-of-hole deviation ≤ ±2 mm at guide elevation. Evidence: feeler gauge check at sleeve, total station shot of bore center, and supervisor sign-off.
12. Clean bore base; residual sediment thickness ≤ 50 mm or stricter per specifications. Verify with weighted tape or slurry sampler; upload measurement photos and timestamps.

Concreting & Reinforcement

13. Place primary pile concrete by tremie from toe upward; maintain concrete head ≥ 1 m above groundwater. Record start/finish times and batch tickets; acceptance: continuous pour without interruption.
14. Confirm primary concrete achieves minimum handling strength prior to adjacent drilling as specified. Evidence: field cube/cylinder results or maturity log and authorization to proceed.

Drilling (Secondary Piles)

15. Re-survey guide sleeves and set-out for secondaries; acceptance: center deviation ≤ ±3 mm at guide. Attach re-survey file and sleeve condition photos.
16. Drill secondary piles cutting into primaries to achieve designed overlap; verify verticality ≤ 1:100. Evidence: drilling logs, torque trends, and visual confirmation of primary material in cuttings.

Concreting & Reinforcement

17. Inspect secondary pile reinforcement cage: diameter, splice, and centralizers at ≤ 3 m spacing; concrete cover ≥ design. Upload cage checklist, heat numbers, and photos showing spacers.
18. Tremie concrete secondary piles in one continuous operation; acceptance: placed volume within −5%/+10% of theoretical unless justified. Record tremie embedment and concrete head; attach batch tickets.

Verification & Records

19. Survey as-built pile centers at guide level after each shift; acceptance: wall alignment within ±15 mm cumulative over 25 m. Upload CSV coordinates and comparison plot to design.
20. Verify designed overlap indirectly from spacing and verticality; acceptance: overlap meets or exceeds design per approved project specifications. Provide calculation sheet and engineer approval.
21. Perform integrity testing on selected secondary piles per ITP (e.g., low-strain PIT). Acceptance: no major defects indicated. Upload test reports and mark tested piles on plan.
22. Protect and trim piles to cut-off; acceptance: cut-off elevation within ±10 mm and no damage to interlock. Evidence: photos with staff gauge and supervisor sign-off.

Guide Wall Accuracy Drives the Entire Secant Wall

The guide wall is the physical reference that controls pile spacing, alignment, and verticality at the ground surface. Achieving a top elevation within ±5 mm keeps drilling tools correctly seated and prevents entry angle errors that magnify with depth. Survey the guide alignment with a total station at 5–10 m intervals and fix steel templates or sleeves whose hole centers sit within ±2 mm of set-out and remain plumb to ≤ 1:500. Record reinforcement placement and concrete pours with batch tickets and photos. On busy city sites, small temperature-driven expansion or traffic vibrations can shift unsecured templates; positive fixation and a re-check before each drilling shift prevent those drifts. A short field example: after a midday temperature swing, a re-shot caught a 3 mm lateral creep in sleeves; tightening dowels restored compliance before drilling resumed, avoiding misaligned bores and lost interlock.

Top of guide wall elevation within ±5 mm.
Template hole centers within ±2 mm of set-out.
Template plumbness tolerance ≤ 1:500.
Alignment deviation ≤ 5 mm over 10 m.

Primary–Secondary Sequence and Drilling Tolerances

Install primary piles first, then secondary piles with reinforcement to cut into primaries and form the designed overlap. Control verticality to ≤ 1:100 using rig inclinometers and periodic checks from a digital inclinometer or caliper shoes at the guide. Keep the bore clean; residual sediment should not exceed 50 mm or the more stringent project requirement. During concreting, keep tremie pipes embedded and maintain a concrete head above groundwater to prevent segregation and contamination. Before drilling secondaries, confirm the primaries have reached the required handling strength, and re-verify offsets. Monitor cuttings during secondary drilling for fragments of primary concrete, a practical confirmation of interlock engagement. Compare placed concrete volumes to theoretical values to flag overbreak, obstructions, or voids, and document any corrective actions immediately.

Verticality tolerance: ≤ 1:100.
Residual sediment: ≤ 50 mm or stricter per specs.
Maintain tremie embedment and concrete head.
Verify primary strength before drilling secondaries.

Offsets, Overlap Assurance, and Documentation

Offsets determine whether secant piles will interlock as designed. Use total station set-out to place centers within ±5 mm, and re-check before secondary drilling using as-built primary coordinates. Since direct overlap measurement is difficult, demonstrate compliance indirectly by verifying spacing, verticality, and consistent engagement with primaries during secondary drilling. Document everything: survey CSVs, drilling logs, inclinometer outputs, batch tickets, and integrity testing reports where specified. Good records accelerate approvals and enable objective troubleshooting. Produce daily as-built plots comparing actual positions to design; highlight any outliers and obtain engineer acceptance for mitigations. An organized record set, including tagged photos at chainages and elevations, supports confident handover and protects the schedule when excavation begins against the secant wall.

Center spacing tolerance: ±5 mm.
Daily as-built plots against design line.
Indirect overlap proof via spacing and verticality.
Attach tagged photos and survey CSVs.

How to Use This Interactive Secant Pile Guide Wall Checklist

Preparation: Gather total station, digital level, drilling templates, plumb gauges, inclinometers, tremie gear, cleaning buckets, GPR, PPE, and the approved drawings/specifications. Confirm ITP hold points, concrete supply, and access/permits.
Start Interactive Mode: Open the checklist on your device, select the work area, and enable tick and comment features. Attach photos, logs, and survey files directly at each item in real time.
Collaborate and Capture: Assign items to team members, add comments, and tag issues. Validate tolerances with instrument readings, then store approvals and evidence to build a traceable record automatically.
Sign-Off and Archive: Capture digital signatures from contractor, consultant, and client. Export the commentable record as PDF/Excel with an embedded QR code for authentication and archive it per project protocol.

Construct secant pile wall—guide wall sequence checklist

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Secant Pile Wall Guide Wall & Sequence Inspection

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Javier Rama SeismoJavi

Nov 26, 2025

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FAQ

Question: What tolerances should I hold for guide wall and drilling when building a secant pile wall?

For guide walls, hold top elevation around ±5 mm and template hole centers within a few millimetres, with plumbness near 1:500. For drilling, target verticality around 1:100 and maintain bore cleanliness with minimal sediment, or any stricter limits per approved project specifications and authority requirements.

Question: How do I verify overlap between primary and secondary secant piles on site?

Use indirect evidence: confirm center spacing within tolerance, verticality within limit, and observe primary concrete fragments in secondary cuttings. Correlate with drilling logs and as-built survey. Where required, perform integrity tests and submit calculations confirming the designed overlap per approved project specifications.

Question: When can I start drilling secondary piles after casting primaries?

Begin only after primary concrete reaches the specified handling or minimum strength, confirmed by field cylinders, maturity data, or engineer approval. Also re-check offsets at the guide, verify template stability, and ensure access and permits are current before commencing secondary drilling.

Question: What documentation is essential for approvals before excavation against the wall?

Provide survey CSVs and plots, drilling and inclinometer logs, concrete batch tickets, integrity test reports (if specified), photos with chainage/elevation tags, and signed inspection sheets. Export the complete, commentable record as PDF/Excel with QR authentication for streamlined review and traceable approvals.

Question: Does this checklist apply to diaphragm walls?

No. This checklist is exclusive to secant bored pile walls focusing on guide walls, primary/secondary sequencing, offsets, and drilling tolerances. For diaphragm walls, use a method-specific checklist aligned to slurry panels, cages, joints, and panel tolerances.