Geotechnical Investigations for the Proposed Development of a 5-Storey Building in Roysambu, Nairobi (2018)
Introduction
In 2018, a comprehensive geotechnical investigation was conducted for the proposed development of a 5-storey building in Roysambu, Nairobi. The study aimed to assess the subsurface conditions and provide crucial geotechnical parameters to guide structural design and construction. The investigation involved borehole coring, Standard Penetration Tests (SPTs), water level checks, and detailed laboratory testing of soil and rock samples.
Site Investigation and Methodology
To establish the site’s geotechnical profile, several key procedures were undertaken. Borehole coring was performed to extract continuous rock samples for lithological identification and strength assessment. The cores provided insights into the depth, composition, and weathering profile of underlying geological formations. Standard Penetration Tests (SPTs) were carried out at regular depth intervals within the boreholes to evaluate soil and weak rock strength. The results were crucial in determining bearing capacity and settlement characteristics of the subsurface materials.
Water level checks were conducted to record groundwater table levels and assess potential challenges related to foundation stability and construction dewatering requirements. Seasonal fluctuations in groundwater levels were also considered to inform appropriate foundation design solutions. Soil and rock samples retrieved from the site underwent extensive laboratory testing, including Atterberg limits, particle size distribution, moisture content, shear strength, and unconfined compressive strength (UCS) of rock samples. The results provided vital geotechnical parameters for engineering design and material selection.
Findings and Recommendations
The investigation revealed a mix of clayey soils, lateritic deposits, and underlying weathered rock, which influenced the selection of suitable foundation options. SPT results indicated varying soil strengths, with recommendations for either reinforced shallow foundations or deep pile foundations based on localized soil strength variations. The water table was detected at moderate depths, necessitating waterproofing and appropriate drainage measures in the foundation design. The study provided crucial insights for site preparation, excavation support, and foundation reinforcement to ensure long-term structural stability.
Conclusion
The geotechnical investigation for the proposed 5-storey building in Roysambu played a vital role in ensuring safe and cost-effective construction. Through borehole coring, SPTs, groundwater assessments, and laboratory testing, the study provided essential data for structural engineers and contractors. Proper geotechnical assessments remain a cornerstone of successful construction projects, ensuring that foundation designs align with subsurface conditions and site-specific challenges.
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