7 Geotechnical Engineering Specialisations that You Need to Know!
Geotechnical engineering is a branch of civil engineering, where it focuses more on earth materials. Usually, their expertise is required at the beginning of the construction project to create a stable base for roads and railways to retaining walls and building foundations. However, every condition will require specific geotechnical engineering specialisations.
When you are building a structure on soil, it is different from rock. They are adjusted to the needs based on the surface conditions to eliminate risks and avoid construction failures or project delays that can be costly.
Therefore, geotechnical engineering specialisations can help to solve those issues based on their understanding and experiences. If you want to know more about those specific roles in groundwork projects, this article provides the information that you might need.
What are the different types of geotechnical engineering?
There are seven different roles in the discipline, which are geotechnical investigation, foundation design, ground improvement, slope stabilisation, slope stability analysis, geosynthetics, and offshore. Each geotechnical engineering specialisation requires different skill sets to solve a particular issue. Nonetheless, they serve the same purpose, which is ensuring infrastructures can stand safe and strong.
Depending on the situation, they often work together to solve an issue. For example, if the project is to build a structure above a rocky surface with a slope, they might require experts from geotechnical investigation, foundation design, ground improvement, slope stabilisation, and slope stability analysis. To give you a clearer picture of each specialisation, here is the explanation of each role.
Geotechnical investigation
It is the role that conducts ground assessment to ascertain the physical properties of soil and rock at a specific site. Their purpose is to determine if the surface is suitable for various construction projects, such as landscaping, site development, renovation and extensions or new builds and constructions. Here are variables that they have to check for every building project:
- Soil and rock: This role is responsible for checking types of soil and rock that are present. They determine the ground’s strength, permeability, and distribution, ensuring its suitability for engineering projects.
- Groundwater conditions: It is vital to investigate the presence, depth, and quality of groundwater under the surface of the site because it could impact the foundation design and stability.
- Site stability: This geotech engineering specialisation also focuses on finding potential landslides, subsidence, and other ground movements.
- Construction planning: Their expertise is essential to evaluate potential challenges or constraints throughout the project lifecycle.
Foundation design
One of the geotechnical engineering roles is foundation design. They analyse the load characteristics of the structure and the properties of the soils and bedrock at the site. The purpose is to control bearing failure, settlement, lateral movement, uplift, and construction risk. To achieve it, here are some key steps that are required in the process:
- Site testing: Drilling boreholes and testing soil strengths.
- Load check: Adding the weight of the building and outside forces like wind or quakes.
- Capacity check: Ensuring the soil can hold the structure without failing.
- Settlement check: Calculating how long the ground will sink over time.
Those testings are crucial to determine which type of foundation they will use for the entire project. In general, there are two main bases that you can find in a building; they are
- Shallow foundations: Optimal for strong top soil (e.g., spread footings, strip footings, and large mat/raft slabs)
- Deep foundations: Optimal for weak top soil (e.g., driven piles, bored piles, and drilled shafts that reach hard rock or dense layers)
Ground improvement
Not every ground is ideal for building structures; however, that doesn’t mean that it cannot be used. Sometimes, all it needs to do is to do ground improvement to stabilise or improve the condition of an area of ground before construction work takes place. The geotechnical engineer specialist in this role will improve or modify the ground shear strength, stiffness, permeability, and others. They usually use these methods:
- Grouting: Injecting pumpable materials into soil or rock, thus changing the physical characteristics.
- Soil mixing: Adding high moisture content to soft clays, peats, and other weak soils to create soilcrete.
- Soil compaction: Increasing soil density while decreasing air volume while maintaining the water content.
- Vibro-replacement: Constructing stone columns through weak soils by using a crane-suspended downhole vibrator.
- Geotextiles: Applying synthetic fibres to create a flexible and porous fabric that is capable of providing strength and stability.
- Cement/lime stabilisation: Adding a binder product like hydrated lime or quicklime to soil to reduce moisture and improve stability.
Slope stability analysis
The primary focus of this geotechnical engineering role is to create an estimation of the risk of slope failure in natural or designed slopes. Experts will review and decide if the condition of the ground is currently safe, marginally stable, or at risk of collapse. The analysis process involves:
- Calculating the factor of safety (FoS), the ratio of available shear strength to mobilised shear stress.
- Identifying critical slip surfaces, such as circular or planar failure planes.
- Modelling soil and rock behaviour under different conditions like heavy rainfall, quakes, loading, and excavation.
- Using numerical software like limit equilibrium methods or finite element analysis to simulate stress distributions and groundwater pore pressures.
Slope stabilisation
The other geotechnical engineering specialisation is slope stabilisation, where engineers will design and improve slope stability using engineering methods after analysing it. For proper stability, it needs the balance of shear stress and shear strength. What you have to realise is a previously steady slope can become unstable when exposed to various factors. The stabilisation process usually involves:
- Grading and reshaping: Reducing angle and redistributing soil mass to create a more stable formation.
- Drainage control: Managing water infiltration into the slope to decrease pore water pressure to increase soil strength.
- Vegetation and erosion control: Binding soil with vegetation and their root systems to protect the surface from erosion.
- Retaining structures: Building rigid structures to hold back soil to provide lateral support to unstable slopes.
- Soil nailing: Planting steel bars into the slope with a regular interval to provide internal reinforcement.
- Geosynthetics: Applying geotextiles, geogrids, and geomembranes to improve soil stability.
- Rock bolting and anchoring: Similar to soil nailing, but this involves inserting steel rods into rock masses to stabilise them and prevent rockfalls.
- Gabions and riprap: Gabions are wire mesh baskets filled with stones, while riprap is placing loose rock on the slope to provide erosion control.
Geosynthetics
This is a sub-discipline from geotechnical engineering specialisations. Here, professionals are tasked with creating synthetic polymers to improve the ground stability by using geotextiles, geogrids, geomembranes, geocells, and geocomposites. Due to the nature of the products, they are suitable for ground improvements where high levels of durability are required.
Offshore
The majority of human activities are on land; however, it is not rare that they have to go over the water to get some essential resources. This type of geotechnical engineering specialisation focuses on creating human-made structures away from the coastline, such as oil platforms, artificial islands, and submarine pipelines. Those structures are exposed to geohazards, such as wind, waves, and currents. They will affect the integrity of the structure, reducing the operational lifespan.
For this geotech engineer, they are facing different challenges. The seabed materials are composed of rock or mineral particles and water. Depending on the ideal situation, they have to decide whether it is better to create a fixed place in the seabed or compromise a floating structure that remains roughly relative to its geotechnical anchor point.
Interested in more information about geotechnical engineering specialisations? Learn more at the CCM!
From afar, all groundwork can look the same. Now, you have learnt that geotechnical engineering specialisations consist of various expertise, ensuring the structure will be stable and sustainable. If you have any interest in building a career in this pathway, you have the chance to become an expert at one of the roles or more.
The Postgraduate Professional Diploma in Geotechnical Engineering can help you to provide the “foundation” for you to step up and thrive in this career. The College of Contract Management also offers various courses and CPDs that can help develop your professional progression. Let’s enrol in the CCM right now!
FAQs
What does a geotechnical site investigation involve before construction?
They are evaluating the physical properties of the soil and bedrock at a project site, ensuring and analysing soil strength, permeability, and groundwater conditions.
What is the difference between shallow and deep foundations?
The shallow bases are used when topsoil is strong enough to support the building, while deep foundations are when the soils are weak.
How do ground improvement techniques stabilise weak soil for construction?
Engineers are using ground improvement methods to modify soil shear strength, density, and permeability on soft clay, peat, or loose ground.
What is the difference between slope stability analysis and slope stabilisation?
Slope stability analysis is the evaluation process that models soil and rock behaviour under stress, while slope stabilisation focuses on the physical engineering to prevent collapse.