HomeJet-Grouting (High-Pressure Jet Grouting Pile) Construction Technology
Release time：Aug 13,2026
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Ⅰ. Process Overview
High-pressure jet grouting (jet-grouting method) employs a drilling rig to lower a grouting pipe with nozzles to the pre-determined soil depth. High-pressure equipment injects cement slurry through nozzles at 20-40 MPa to erode the in-situ soil mass. The high-velocity jet cuts and disturbs native soil, forcing cement slurry to mix with broken soil particles. While the grouting pipe rotates and lifts, the mixture hardens into continuous cylindrical consolidated bodies known as jet-grouting piles.
Three main jet-grouting variants are available:
1. Single-pipe jet grouting: Cement slurry jet only.
2. Double-pipe jet grouting: Co-axial injection of cement slurry and compressed air.
3. Triple-pipe jet grouting: High-pressure water, compressed air and cement slurry, delivering larger pile diameter.
Application Scope: Soft clay, muck, mucky soil, silty soil, sandy soil and fill soil. Widely used for ground improvement, foundation pit water-stop curtains, tunnel anti-seepage, dyke seepage control and remediation of existing building foundations.
Limitations: Not suitable for strata with dense large-size boulders or cobbles that cannot be easily eroded by high-pressure jets.
Ⅱ. Construction Principle
High-pressure fluid cuts and disintegrates soil → soil particles are stripped and churned → cement slurry blends with soil particles → slurry hydrates and hardens → cement-soil piles with favourable strength and anti-permeability are formed. Overlapping adjacent piles create monolithic water-stop curtains or composite ground.
Ⅲ. Main Construction Equipment
Drilling rig, high-pressure grouting pump, slurry mixing system (primary & secondary mixing tanks), grouting drill pipe, high-pressure nozzles, air compressor (for double-pipe / triple-pipe methods), cement slurry flowmeter, pressure gauge, crane.
Ⅳ. Standard Construction Process
Site levelling → surveying & pile layout → rig positioning → drilling & pipe lowering → trial jetting → high-pressure jetting with rotary lifting → re-jetting (if required) → completion of single pile → pipeline flushing → rig relocation to next pile position
4.1 Site Levelling & Pile Layout
Clear surface debris, level and compact the working site. Set-out pile centre-lines and mark individual pile points according to drawings. Verify pile spacing and positional deviations.
4.2 Rig Positioning
Move and align the drilling rig to the pile point. Level the rig frame and ensure verticality of drill pipe. Specification requirements: drill pipe verticality deviation ≤ 1.0%; pile positional deviation ≤ 50 mm (subject to design drawings).
4.3 Drilling & Grouting Pipe Lowering
Two construction approaches:
1. Direct jet-drilling: Drill down to designed base elevation using jet nozzles (for soft soil).
2. Pre-drilling: Pre-drill pilot holes for hard soil or interbedded hard layers, then lower the jet-grouting pipe.
Upon reaching designed pile base depth, maintain jet pressure for 30-60 seconds for base re-jetting to avoid mud inclusion and pile discontinuity at the pile toe.
4.4 Slurry Preparation (Key Quality Control Item)
- Binder: Ordinary Portland Cement P.O 42.5 (commonly adopted).
- Water-cement ratio: 0.8-1.2, subject to design documents.
- Mixing sequence: Add water first, then cement. Mix thoroughly. Filter mixed slurry to prevent nozzle blockage by cement lumps.
- Prepare slurry on demand. Do not reuse over-aged settled slurry. Record pressure and slurry volume via flowmeter and pressure gauge.
4.5 High-pressure Jetting & Rotary Lifting
Start high-pressure pump until design pressure is achieved. Rotate and lift drill pipe at constant speed with continuous slurry jet to erode surrounding soil.
Reference parameters (final values shall follow design and test piles):
- Jet pressure: 20-40 MPa
- Lifting speed: 8-25 cm/min
- Rotation speed: 10-20 r/min
- Grouting flow and cement consumption governed by design single-pile grouting volume.
Important note: Maintain steady lifting speed. Excessively fast lifting causes necking and insufficient pile strength; excessively slow lifting leads to material waste.
4.6 Pile-top Termination Treatment
Stop jetting when the grouting pipe is lifted 0.5-1.0 m above the designed pile top elevation. The over-jet section shall be chiselled off later to guarantee quality of the effective pile top, because near-surface soil features low confining stress and high slurry loss risk.
4.7 Pipeline Flushing
Upon completion of each pile, flush drill pipes and high-pressure pipelines with clean water immediately to prevent cement slurry solidification and blockage.
4.8 Rig Relocation
Move the rig to the next pile position for continuous construction.
Ⅴ. Key Quality Control Measures
1. Pile discontinuity & mud inclusion prevention: When jetting is interrupted by shutdown or equipment failure, resume jetting with an overlap re-jet segment ≥ 0.5 m. Pull out drill pipe for full cleaning after long-time shutdown.
2. Insufficient pile diameter: Strictly control jet pressure and lifting speed. Reduce lifting speed and increase cement dosage for sandy strata with high porosity.
3. Slurry return (bleed-off): Minor slurry return is normal. For continuous heavy slurry return: moderately reduce jet pressure, slow lifting speed, or adopt intermittent grouting.
4. Verticality control: Calibrate rig level before each pile. Inclined strata or alternating soft-hard soil may induce pile deviation.
Ⅵ. Inspection & Testing Methods
1. In-process monitoring: Keep construction records including pressure, lifting speed, cement consumption and water-cement ratio.
2. Post-construction testing
- Excavation inspection: Visual check of pile shape and lap joints (widely used for shallow water-stop curtains).
- Core-drilling test: Verify pile continuity, cement-soil compactness and unconfined compressive strength.
- Water injection / pumping test: Measure permeability coefficient for water-stop curtain projects.
- Plate load test: Evaluate bearing capacity for composite ground improvement works.
Ⅶ. Advantages & Limitations
Advantages
1. Compact equipment footprint; feasible for confined working space and construction adjacent to existing buildings.
2. Applicable to vertical, inclined and horizontal jet-grouting installation.
3. Delivers both ground improvement and anti-seepage performance.
4. Good adaptability to various soft soil strata.
Limitations
1. Poor pile forming performance in cobble or large boulder strata.
2. Slurry may spread laterally; monitoring is required where underground utilities are nearby.
3. High consumption of water and cement.
4. Construction generates waste mud requiring dedicated mud disposal measures.
Ⅷ. Typical Engineering Applications
1. Foundation pit works: Jet-grouting water-stop curtains combined with soldier piles or diaphragm walls for cut-off.
2. Composite ground improvement for soft-soil roadbeds, storage yards and logistics parks.
3. Seepage prevention and leakage remediation for dykes and river channels.
4. Ground improvement and seepage control around underground pipelines and tunnels.
5. Settlement remediation and foundation underpinning for existing buildings.
Source: Guangzhou Sunzo Foundation Engineering Co., Ltd.
If you have ground improvement requirements for your project, please contact SUNZO. We will deliver customized solutions tailored to your project conditions to support safe and efficient project delivery.
