Quantity measurement of high-pressure jet grouting cut-off walls: holing by design pile length, grouting by design cross-section area times pile length in volume, cement dosage being a material consumption parameter only; overlaps, secant interlocking and re-jetting between piles are never measured twice

Topic Positioning

The quantity measurement position for high-pressure jet grouting cut-off walls (including jet grout water-stopping between retaining row piles): how holing and grouting are measured separately, the status of cement dosage in measurement, and the treatment of overlaps and interlocking between piles, covering the consumption standards of Beijing and other regions and the national standards.

Core Conclusions

1. Dual measurement: holing by length, grouting by volume - never by cement dosage

• Beijing DB11/T 2382-2024, building and decoration works, 4.3.19: "the holing quantities of high-pressure jet grout cement piles shall be computed by length on the design effective pile length plus the designed additional grouting length; the grouting shall be computed by volume on the pile cross-section area times the design pile length plus the designed additional grouting length."
• The same standard, urban rail transit works, 10.1.48: "the holing quantities of high-pressure jet grout cement piles shall be computed on the design pile length; the grouting quantities shall be computed by volume on the design pile cross-section area times the pile length."
• That is: holing in m, grouting in m3; cement dosage is not a quantity basis but a quota material consumption parameter. Corresponding Beijing Annex A table A.2.1-4 (grouting-pile composite foundation) items: A-2-14 pre-bored high-pressure rotary (swing) jet grout cement pile holing, cement dosage 18%, single-pipe method, unit m (all-in labour Grade II 0.0220 workday/m, geological drilling rig 0.0120 machine-shift/m); A-2-15 grouting, dosage 18%, single-pipe method, unit m3 (cement 42.5 consumed 330.48 kg/m3); A-2-57 grouting "cement dosage per 1% increase or decrease", single-pipe method, unit m (cement 42.5 18.36 kg). Where the design dosage differs from the item dosage, adjust the material consumption with the A-2-57 increase / decrease item; the quantity figures stay unchanged.

2. Companion compilation rules (Beijing 4.3.7, 4.3.9, 4.3.21)

• The construction consumption of high-pressure jet grout piles shall include re-jetting at joints and other work content (re-jetting takes no separate bill item);
• The construction consumption of high-pressure jet grout and swing-jet cement piles is preferably determined on the pre-bored method; where the drawings require the integrated drill-and-grout method, the labour and plant consumption of the corresponding pre-bored grouting items is multiplied by 1.10;
• Pile head treatment follows pile head cropping of cement piles: cropping quantities are computed by volume on the designed additional grouting length times the pile's design cross-section area; where the drawings do not state the additional length, cropping of 500 mm per pile is preferable.

3. Overlap and interlocking between retaining piles - never measured twice

• GB/T 50854-2024 (quantity take-off standard for building and decoration works) B.3.11: "re-driving and cross-section interlocking of the same pile type add no quantities."
• GB/T 50857-2024 (quantity take-off standard for municipal works) B.6.4: "the work content of cement mixing piles, powder-jet piles and high-pressure jet grouting piles already includes repetitive work such as overlapping and re-driving."
• Jiangsu 2024 consumption standard (2026 edition in the source data): jet grout pile drilling length is computed from the natural ground (or working level) to the design pile toe level; grouting quantities are computed by volume on the design reinforced pile cross-section area times the design pile length, without deducting overlaps between piles.
• Overlap width and interlocking amount are design and construction control requirements, not a measurement deduction basis: GB 51004-2015 clause 6.2.6 requires that where jet grouting serves as a local cut-off curtain, the bored piles are constructed first and the jet grout piles after; the re-jetting process shall be used, cement intake per cubic metre shall be not less than 450 kg, slurry down-and-up speeds preferably 50 mm/min to 150 mm/min; the overlap between jet grout piles shall be not less than 300 mm and the verticality deviation not more than 1/100. JGJ 120-2012 clause 7.2.9 sets the overlap width of soil-cement solidified bodies: not less than 150 mm at grout hole depths up to 10 m, not less than 250 mm at 10 m to 20 m, not less than 350 mm at 20 m to 30 m. DB11/T 2097-2023 clause 6.4.5 requires 100 mm to 200 mm interlocking between ultra-high-pressure jet grout piles, quincunx (staggered) multi-row layouts, and return-slurry consumption preferably controlled at 25% to 30%.

4. Regional position differences (pricing follows the project location's current standard)

• Beijing: the additional grouting length enters the holing and grouting quantities; pile head cropping is computed separately on the additional length (500 mm per pile where unstated).
• Jiangsu: drilling length runs from the natural ground to the design pile toe level.
• Hunan 2024 consumption standard (2025 edition in the source data): the high-pressure jet grouting items already comprehend re-jetting labour and materials at joints; where the design cement usage differs from the item usage it may be adjusted, wastage rate 2%; where the design has over-grouting, the over-grouted amount enters the quantities.

Applicability Boundaries

• Each clause must be used with the project location's current consumption standard / pricing basis; Beijing, Jiangsu, Hunan and elsewhere differ on the starting level and the treatment of additional / over-grouting - check the local standard before cross-region tendering.
• Cement dosage adjustment applies only where "the design dosage differs from the quota item dosage", adjusting materials with the per-1% item; the quantity figures do not change.
• This card addresses high-pressure jet grouting (swing-jet) cement piles; cement mixing piles and other pile types follow their own rules.
• Overlap width, re-jetting process and cement intake (e.g. the 450 kg/m3 or more required by GB 51004) are design and construction quality control parameters and form no basis for deducting or adding quantities.

Further Reading

• DB11/T 2382-2024 Construction Works Consumption Quota Standard, building and decoration works 4.3.7, 4.3.9, 4.3.19, 4.3.21; urban rail transit works 10.1.48; Annex A table A.2.1-4 (items A-2-14 holing, A-2-15 grouting, A-2-57 dosage adjustment)
• GB/T 50854-2024 Annex B ground treatment and excavation retention works, B.3.11; GB/T 50857-2024 Annex B road works, B.6.4
• GB 51004-2015 Code for Construction of Building Foundation Works, 6.2.6; JGJ 120-2012 Technical Specification for Excavation Retention of Building Foundations, 7.2.9; DB11/T 2097-2023 Technical Specification for Open-Cut Construction of Urban Rail Transit Works, 6.4.5
• Jiangsu 2024 consumption standard for building and decoration works and Hunan 2024 consumption standard for building and decoration works, relevant chapters