31/03/2026
𝗣𝗚𝗔𝗧𝗘𝗖𝗛𝗫𝗣𝗢 𝟮𝟬𝟮𝟲 𝗦𝗽𝗲𝗮𝗸𝗲𝗿 𝗛𝗶𝗴𝗵𝗹𝗶𝗴𝗵𝘁
Speaker: Engr. Jashwin Benedict Ullal
Topic: Experience with Jet Grouting in Soft Alluvial Soils of Metro Manila.
Engr. Ullal presented the subsurface conditions of Central Manila and how jet grouting can be effectively applied as a ground improvement solution for challenging alluvial soils. His talk began with a detailed overview of the typical soil profile in the area, characterized by shallow groundwater, loose silty sands prone to liquefaction, highly compressible clays, and deeper competent layers where foundations are usually supported. He emphasized the risks associated with these conditions, including excessive settlement and liquefaction, especially for structures founded on shallow systems.
He then discussed the importance of proper site investigation and laboratory testing to establish reliable design parameters. The session highlighted key tests such as sieve analysis, Atterberg limits, consolidation tests, and strength assessments, which are essential in identifying soil behavior, compressibility, and liquefaction susceptibility. The comparison of sampling methods, including SPT and CPT, was also presented to ensure accurate subsurface characterization.
The presentation focused on the application of jet grouting, particularly the use of Jumbo Special Piles (JSP), as a ground improvement technique. He explained the step-by-step construction process, where high-pressure cement slurry is injected into the soil to break, mix, and solidify it into “soilcrete” columns. These columns act as structural elements that improve bearing capacity, reduce settlement, and mitigate liquefaction by creating a stiffer composite ground.
He also discussed key design considerations, such as ensuring that jet grouted columns pe*****te through liquefiable layers and terminate in competent strata. Concepts such as area replacement ratio, spacing of columns, and composite bearing capacity were emphasized, showing how proper configuration can significantly enhance soil performance and meet structural load requirements.
The session further highlighted how jet grouting contributes to settlement control and liquefaction mitigation by redistributing stresses within the soil matrix. By increasing stiffness and reducing shear stress in surrounding soils, the improved ground achieves higher factors of safety against failure.
To ensure performance, he emphasized strict quality assurance and quality control measures, including monitoring spoil density, maintaining proper grouting pressure, verifying column diameter, conducting coring and compressive strength tests, and performing post-grouting SPT validation. These procedures confirm that the constructed columns meet design specifications and perform as intended.
He concluded by stressing that while jet grouting is a highly effective solution for Central Manila’s complex soil conditions, its success depends on thorough investigation, careful design, and rigorous QA/QC. A holistic and site-specific approach is essential to minimize geotechnical risks and deliver safe, reliable, and long-term ground improvement solutions.
