Ground Improvement by Controlled Modulus Columns – A San Pedro Case Study-PPT Presentation

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The San Pedro project involved a bulk-material terminal, buildings, pavements, and quay and revetment works. Confirmatory geotechnical investigations revealed soft clay and peat layers, including weak strata missed by tender-stage boreholes. These compressible soils raised concerns about settlement and slope or shear instability, prompting extensive ground improvement.<br /><br />The project used several approaches, including densification and preloading, with Controlled Modulus Columns (CMCs) selected for multiple zones. CMCs are semi-rigid soil-reinforcement columns that reduce ground deformability and improve support capacity. Loads are transferred through the columns and surrounding soil, with a load-transfer platform between the column heads and the pavement or structure. Column lengths were determined using site-specific geotechnical data.<br /><br />Quality assurance included load tests in the treated zones. Tests were conducted at loads corresponding to the design column loads; measured settlements were below the stated permissible limits. The design anticipated about 14 mm settlement under the serviceability load.<br /><br />The case study concludes that CMC installation was a rapid and economical solution for stabilizing soft, layered ground, particularly where compressible layers exceeded 5 m. Compared with methods such as deep soil mixing and stone columns, CMC construction was reported to progress faster and involve relatively few quality issues. The San Pedro experience also suggests the technique is suitable for Indian ground conditions.

Keywords

San Pedro project

bulk-material terminal

Controlled Modulus Columns

ground improvement

soft clay

peat layers

settlement control

geotechnical investigation

load-transfer platform

soil stabilization