Geotechnical Assessment of Foundation Failures in Residential Buildings

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Foundation performance determines the safety and stability of any building. When a foundation fails, the entire structure becomes vulnerable to distress, cracking, differential settlement, or even collapse. Geotechnical conditions play a central role in foundation behaviour because soil is the primary support for structural loads. In many residential areas, weak or poorly understood soil conditions create risks for foundation performance. Poor site investigation, rapid urban development, and improper construction practices further increase this risk.

In developing countries such as Nigeria, foundation failures have become common in many residential communities. Several studies report that a significant number of building failures originate from geotechnical problems related to soil type, moisture variation, poor compaction, and inadequate bearing capacity (Ayeni & Adeleke, 2021). Lateritic soils dominate many regions of Nigeria, and although they can perform well when properly compacted, they become unstable under high moisture content. Expansive clays also pose serious challenges because they swell during the rainy season and shrink during the dry season. These changes place repeated stress on foundations, which leads to cracking and differential settlement.

Globally, geotechnical engineers emphasize the importance of detailed soil investigation. According to Das and Sivakugan (2018), understanding soil properties helps engineers design foundations that respond well to local conditions. When engineers ignore this step, foundations are placed on soils that cannot support structural loads. As buildings age, the problem becomes more severe. Because many residential buildings in Nigeria use shallow foundations, they are especially vulnerable to changes in soil moisture, poor drainage, and erosion.

Human activities worsen the situation. Unregulated developments, blocked drainage, and groundwater fluctuations all contribute to the weakening of soil beneath buildings. In many cases, homeowners expand structures without proper assessment of the existing foundation. This additional load increases the chance of failure. Consequently, geotechnical assessment of foundation failures has become an important research area that supports safer residential construction.

1.2 Statement of the Problem

Despite continuous construction activities in Nigeria, many residential buildings still experience foundation failure. Cracks on walls, uneven floors, and partial collapse have been reported across several states. These problems arise because soil conditions are often ignored during design and construction. Some developers rely on visual inspection alone without laboratory testing. Others use unsuitable foundation types for soil conditions. These practices expose buildings to long term structural problems.

Although several studies have discussed building collapse, fewer studies focus specifically on the geotechnical factors responsible for foundation failure in residential buildings. Without clear evidence, construction professionals may not fully understand the role of soil properties in structural performance. As a result, foundation problems continue to occur, and homeowners face unnecessary repair costs and safety risks. Therefore, a detailed geotechnical assessment is needed to identify the soil related factors contributing to foundation failure in residential areas.

1.3 Aim of the Study

The aim of this study is to conduct a geotechnical assessment of foundation failures in selected residential buildings.

1.4 Objectives of the Study

The study seeks to:

1. Identify the geotechnical factors contributing to foundation failures in residential buildings.

2. Assess the engineering properties of soil samples from affected sites.

3. Evaluate the relationship between soil conditions and observed structural defects.

4. Determine whether the foundation type used matches the bearing capacity of the soil.

5. Recommend geotechnical measures that can reduce foundation failures.

1.5 Research Questions

The research answers the following questions:

1. What geotechnical factors are responsible for foundation failures in residential buildings?

2. What properties do the soil samples from affected sites exhibit?

3. How do these soil properties relate to the structural defects observed?

4. Are the foundations designed appropriately for the soil conditions?

5. What geotechnical solutions can prevent future failures?

1.6 Research Hypothesis

The study tests the following hypothesis:

H0: Geotechnical factors do not significantly influence foundation failure in residential buildings.
H1: Geotechnical factors significantly influence foundation failure in residential buildings.

1.7 Significance of the Study

This study is important because it improves the understanding of how soil conditions contribute to foundation failure. First, it provides engineers with reliable evidence needed to design foundations that match site conditions. This reduces structural risks and improves building stability. Second, the research supports policymakers and regulatory agencies by offering insights that help them develop stricter building guidelines. These guidelines will encourage site investigation and discourage unregulated construction practices.

The study also benefits residents and homeowners. When foundations perform well, houses last longer, maintenance costs reduce, and safety improves. Academically, the study contributes to geotechnical engineering literature by providing data from the Nigerian context. This information supports future studies on soil behaviour, foundation design, and risk management. Finally, the study promotes sustainable construction, as preventing foundation failure reduces material waste and supports efficient land use.

1.8 Scope of the Study

The study focuses on residential buildings located in selected areas where signs of foundation failure are visible. It examines soil samples collected from these sites and evaluates their engineering properties through laboratory analysis. The study considers common foundation types such as strip foundations, pad foundations, and raft foundations. It does not examine high rise buildings or advanced foundation systems such as deep piles because these structures have different design requirements. The emphasis remains on typical residential buildings found in urban and peri urban communities.

1.9 Limitations of the Study

The study may face limitations related to access to affected buildings. Some homeowners may restrict access to their properties. Soil samples collected may represent only a small portion of the entire site, which can influence interpretation. In addition, seasonal variations in moisture content may affect test results. Time and resource constraints may also limit the number of sites assessed. Despite these limitations, the study provides reliable data and meaningful conclusions.

1.10 Operational Definition of Terms

Foundation Failure: A condition where the foundation does not adequately support the structure, leading to movement, cracking, or collapse.
Geotechnical Assessment: The process of evaluating soil properties and their influence on foundation performance.
Bearing Capacity: The maximum load that soil can safely support.
Differential Settlement: Uneven sinking of a building foundation caused by variations in soil strength or moisture.
Expansive Soil: Soil that expands when wet and shrinks when dry, causing pressure on foundations.

References 

Ayeni, D. A., & Adeleke, J. O. (2021). Assessment of geotechnical causes of building failure in southwestern Nigeria. Innovative Infrastructure Solutions, 6(3), 1–11.
Das, B. M., & Sivakugan, N. (2018). Principles of Geotechnical Engineering (9th ed.). Cengage Learning.