Geotechnical Investigation

A comprehensive geotechnical investigation conducted at Adwemador to assess subsurface conditions and support the safe structural design of proposed classroom and administration blocks.

Project Overview

Jabez Projects Inc. commissioned a geotechnical investigation for a proposed development comprising three 5-storey classroom blocks and a 5-storey administration block at Adwemador.

The investigation examined the site geology, soil characteristics, bearing capacity, seismic considerations, excavation conditions, and foundation requirements. The findings provide technical guidance for the structural design and construction planning of the proposed development.

Scope of Investigation

Our study covered the following key areas:

Site Geology Assessment

Field & Laboratory Testing

Soil Analysis & Bearing Capacity

Seismic Risk Assessment

Excavation & Shoring Recommendations

Field Investigation

Dynamic Cone Penetration Testing (DCPT) was carried out at several test points across the proposed development area.

The tests measured the number of blows required for the cone to penetrate the ground at different depths. These values were converted into soil resistance and equivalent CBR values to support engineering analysis.

The field investigation concluded after the required penetration depth and resistance values were achieved, providing reliable data for foundation design.

Key Findings

Soil strength generally increases with depth across the test locations.
The site is underlain by rocks belonging to the Dahomeyan geological formation.
Allowable bearing capacity values were established using an appropriate engineering factor of safety.
Laboratory testing identified multiple soil layers, including silty sandy gravel, silty clay and lateritic silty sandy clay.

Foundation & Design Recommendations

Incorporate reinforced ground beams where conventional pad foundations are adopted.
Design the structure to account for potential ground movement using the recommended horizontal ground acceleration.
Final foundation dimensions and structural design should be confirmed by the project structural engineer.

Excavation & Site Safety

Upper near-surface soils are generally classified within Type A and Type B excavation categories.
For excavations up to 3 metres deep, the recommended maximum slope is approximately 45° (1H : 1V).
Where excavation slopes become unstable, suitable shoring or flatter slopes should be provided.
All excavation activities should comply with relevant construction safety standards and engineering supervision.