Foundation failures occur when the foundation or soil on which the foundation is to rest cannot sustain the structural weight imposed on it, cracks form, the foundation tilts or even collapses. Depending on the severity of the foundation failure, the end result may be minor cracks in walls and floors up to major structural damage that must be fixed at a high cost.
Getting to know 7 Foundation Failures
The most important part of a building that guarantees stability and longevity of the structure is its base. Nevertheless, most constructions are being affected by foundational failures that cause structural damages, loss of money and even dangerous situations.
Civil engineers, architects, and builders should understand what causes foundations to fail and what preventive measures should be taken to stop such a failure. This paper identifies the general causes of foundation failure (such as soil settlement, expansive soils, and construction flaws), and how they can be prevented.
The foundation failure may be either abrupt or gradual. Although sudden failures are normally disastrous and uncommon, progressive failures as a result of soil settlement or poor design are more typical. It is important to identify the early signs of danger like small cracks, uneven floors, and doors that will not close easily to avoid serious structural destruction.
Usual Foundation Failure Causes
Responsible parties Foundation failure may be caused by several factors which are usually coupled. The primary causes include:
1.Soil Settlement:
Settlement of the soil is defined as the vertical movement of the ground as a result of compression of the layers of the soil on the pressure exerted by the foundation. Settlement may be homogeneous or not.
Uniform Settlement: This happens when the soil is compressing in an even manner so that the whole building settles without damage to its structure. Although not as problematic, it may result in cosmetic problems in the form of minor cracks.
Differential Settlement: It is more perilous, and takes place when the foundation does not settle evenly. Largely, major building cracks, tilting and structural failures are often related to differential settlement.
Soil settlement causes include:
- Lack of compaction of the soil prior to construction.
- Vegetation: loose or organic soils.
- High water table, or alterations of moisture content.
- Excessive loading of the foundation to the soil bearing capacity.
2.Expansive Soil Issues
Expansive soils swell when wet and contract when dry e.g. clayey soils. Such cyclic expansion and contraction lead to a lot of movement below the foundation, cracking walls, uneven floors and in worst cases, collapse.
Significant problems of expansive soils:
Cyclic expansion and contraction are caused by seasonal shocks in moisture content.
Unstable buildings which lack deep foundation or adequate soil stabilization are very susceptible.
Structural damage may be increased by unequal movement caused by an uneven distribution of moisture.
3.Shoddily Built Construction
Under ideal soil conditions, the failure of foundations may be caused by poor construction practices. Common issues include:
Application of inferior concrete or reinforcing material.
- Poor curing of concrete.
- Poor design, disregarding of the nature of soil and loading distribution.
- Excavation depth mistakes or alignment mistakes of foundation.
4.Water and Drainage Problems
The presence of excess water around the foundation is the major cause of foundation failures and soil instability. Poor drainage can result in:
- Soil erosion under the base.
- Raised soil settlement as a result of water infiltration.
- Creation of voids under the foundation with the result of unequal support.
5.Good Building Practices
- High construction standards will ensure that the failures caused by human error are avoided:
- Install concrete and reinforcement of high quality as per design.
- Carefully cure concrete to gain the intended strength.
- Avoid overloading the foundations in the process of construction and after construction.
- Correct alignment and leveling in excavation and foundation.
6.Regular Checking and servicing
Even the well-structured foundations can have certain problems with time. Problems can be identified at the earliest stage:
- Periodically check cracks in walls, floors and ceilings.
- Check against signs of uneven settlement which include slanted floors or doors that stick.
- Keep drainage systems in good order to offer protection against soil issues relating to water.
- Conduct routine soil tests on soil prone to changes in moisture.
7.Tips to avoid expansive soils
Expansive soils involve special consideration in design and in construction:
Shallow foundations are to be avoided, deep piers or pile foundations are desirable.
When possible, substitute expansive soil with engineered fill.
Make sure that there is the right management of moisture based on landscaping, irrigation and drainage.
Put soil barriers to avoid movement of moisture towards foundation.
Case Studies of Foundation Failures.
It is more effective to realize the value of preventative measures through real-life examples:
Case Study 1: Differential Settlement in Residential Building.
Diagonal cracks on the walls in a storey building in an urban setting were witnessed in the fifth year after its construction. It was found out that there has been an uneven soil compaction on the area below the various parts of the foundation. The corrective activities consisted of underpinning the affected areas and enhancing soil compaction to be used in construction in future.
Case Study 2: Impact of expansive Clay Soil.
A commercial building erected on clay soil formed more than three floor cracks and uneven settlement in three years. It was shallow and it failed to consider seasonal changes in moisture. The remedy entailed the reintegration of the foundation by installing deep piles and placing moisture barriers in the vicinity of the building.
Case Study 3: Settlement due to Water Infiltration.
The settlement of foundations of a school building that was located close to a river occurred because of the continued water infiltration. The foundation soil was eroded leading to a partial collapse. Use of a complete drainage system and soil stabilization prevented further mitigation.
The examples demonstrate the role of geotechnical studies, appropriate design, and precautions in the prevention of foundation failures.
Conclusion:
It is important to note that foundation failures in the construction industry are known to incur expensive repairs and put the lives of persons in danger. The major factors are settlement of soils, expansive soils, improper construction methods and water mismanagement. Of particular harm are the differential settlement and expansive soil movements that lead to cracks in the building, tilting, and structural instability.
A combination of geotechnical studies, adequate foundation design, soil stabilization, good construction practices, and good management of water prevent foundation failure. Frequent inspection and maintenance keep the possibility of structural damage low as well. Engineers and builders can make sure structures have a long and safe life by knowing the reasons, and taking prophylactic action.
The costs associated with investing in preventive strategies today will save a lot in terms of money and avoid disastrous failures in the future. Good foundations are the pillars of safe, stable and robust structures