Geotechnical

Site Characterisation

Site characterization is the first step in design of any geotechnical system. The objective of a site characterization program is to explore, sample and test geological materials and monitor groundwater conditions in order to develop an understanding of the site conditions, predict soil behavior in response to construction works, and to quantify project risks. While the techniques for investigation are diverse, TREK can select the most appropriate drilling, coring and sampling techniques, as well as in-situ and laboratory tests to provide cost-effective information sufficient for geotechnical design.

Our services specific to site characterization include:

• Supervising sub-surface investigations and in-situ testing
• Classification of soil and groundwater conditions
• Core logging and geological classification of bedrock
• Laboratory testing of soil and rock index properties
• Advanced laboratory testing (oedometer, triaxial, and permeability tests)
• Geotechnical instrumentation including slope inclinometers, piezometers, thermistors and settlement plates
• Mapping of sub-surface data using GIS systems
• Permafrost Characterization
• Terrain Analysis

Foundation Engineering

The design of foundations for structures involves an assessment of sub-surface conditions and the capacity of geological materials to support gravity and dynamic loads transferred from the structure. Foundation engineering involves a broad knowledge of geology, soil and rock mechanics, as well as soil-structure interaction in order to predict how the engineered and natural materials will interact. Where geotechnical conditions are unfavorable, alternatives that involve ground improvement such as rockfill columns, deep soil mixing, or grouting can be employed to strengthen the subgrade and increase foundation capacity.

Our services specific to foundation engineering include:

• Geotechnical site characterization
• Limit States Design and Working Stress Design
• Design and construction of shallow foundations (footings, thickened-edge slabs, rafts, mats)
• Design and construction of deep foundations (driven piles, cast-in-place, helical, rock-socketed piles)
• Load-displacement evaluation, finite-element analysis and down-drag assessment
• Numerical pile analyses (lateral loading, load-displacement, drivability)
• High-strain dynamic load testing (PDA testing and CAPWAP analysis)
• Design of static load testing programs
• Design for ad-freezing, permafrost, and frost protection
• Forensic evaluations
• Foundation construction observation
• Foundations in Permafrost (adfreeze piles, thermosyphons)

Riverbanks and Erosion

Natural slopes along rivers and lakes are continuously subjected to environmental conditions that can be destructive. These include wind, wave action, stream flow, and rainfall which can result in land loss through erosion or slope movements, which often pose a risk to infrastructure such as buildings, buried utilities, roads and bridges. Slope and erosion assessments involve developing a thorough understanding of soil stratigraphy, erosion protection, shear strengths as well as water / groundwater levels. Proper risk management to such natural hazards involves the use of the most appropriate and/or sophisticated investigation techniques and analysis methods to interpret how slopes will behave under imposed loads. Our approach to these problems has proven success on numerous remedial bank stabilization and erosion protection works of varying scale for public and private clients.

Our services related to riverbanks and erosion include:

• Geotechnical site characterization
• Instrumentation and monitoring of slope movements and groundwater conditions
• Finite-element seepage and stress analysis
• Limit-equilibrium slope stability analysis
• Probabilistic slope stability analysis for specialized applications
• Construction drawing and specification development, tendering and contract administration
• Quality assurance inspection of earthworks, slope stabilization, erosion protection and ground improvement works

Excavations and Shoring

Temporary excavations and shoring are often required in construction. The stability of temporary excavations and shoring is dependent on soil and groundwater conditions, the size, shape and depth of the excavation, and the duration that the excavation will remain open. Additionally, an understanding of potential impacts to adjacent structures and complicated soil-structure interactions related to retaining walls all need to be considered. We work closely with our clients to provide a solution that best manages risks in a cost effective fashion.

Our services related to excavation and shoring include:

• Geotechnical site characterization
• Slope stability analysis and design of stabilization works
• Provision of lateral earth pressures for cantilevered and braced shoring
• Reinforced earth structures
• Excavation and shoring construction observation
• Ground displacement and vibration monitoring

Water Retention and Dams

Water retention structures and dams are required in mining, flood protection, irrigation, and hydro- electric projects. These structures are often expensive and have very high consequences in the event of failure. The long term performance of any water retaining structure requires that designs protect against internal erosion, settlement/overtopping, slope movements and surface erosion. Dam safety guidelines are tending towards probabilistic assessments of geotechnical reliability, therefore requiring advanced statistical knowledge and unique probabilistic analyses to either qualitatively or quantitatively address the probability and consequences of dam failures.

• Geotechnical site characterization
• Advanced finite element modelling (seepage and deformation)
• Limit equilibrium slope stability assessments
• Laboratory testing (hydraulic and mechanical properties)
• Instrumentation installation and monitoring
• Construction inspection and field testing
• Dam safety reviews
• Probabilistic slope stability analysis
• Observational approach for design and construction

Waste Containment Facilities

Waste containment facilities are used to prevent the migration of potentially hazardous materials into the surrounding environment. Examples of such facilities are tailings dams, Municipal Solid Waste (MSW), hazardous waste or non-hazardous waste landfills and waste water lagoons. The embankments and liners that make up these facilities are typically designed to strict standards given the risks associated with their failure. In this regard, geotechnical input is required during embankment design and construction to determine safe side slopes, embankment compaction requirements and remedial measures when excessive settlements are possible. Similarly, liners for these facilities must meet project and regulatory requirements, whether natural (in-situ) or engineered (e.g. HDPE, GCL, etc.) and geotechnical quality control is integral in meeting these requirements.

Our services related to waste containment facilities include:

• Geotechnical site characterization
• Aerial photography interpretation, borrow source investigation and quantity estimates
• Laboratory testing (compaction, permeability)
• Geotechnical instrumentation (piezometers, settlement sensors)
• Stress-deformation and slope stability analysis
• Geotechnical input to closure plans and cover design
• Mobile quality control soils laboratory and field compaction testing
• Construction Quality Assurance inspection of HDPE Geomembranes, GCL and BGM liners

Bridges and Embankments

Bridges are unique structures that involve numerous facets of geotechnical engineering. Issues related to structural design such as span lengths and girder depths must be balanced with river hydraulic considerations including ice loading, flood frequency and conveyance requirements, as well as geotechnical factors including embankment settlement, slope stability and foundation constructability and capacity. Soil-structure interaction is a key consideration for deep foundations within settling embankments, where advanced finite-element modelling of embankment consolidation settlement, mitigation works and associated effects such as pile down-drag must be employed. High-strain dynamic testing of piles using the Pile Driving Analyser (PDA) is a rapidly expanding area of geotechnical engineering whereby driving stresses, pile integrity and load capacity are confirmed during pile installation, for which higher factored resistances can be assumed in recognition of greater quality control during foundation installation.

Our services related to bridges and embankments include:

• Geotechnical site characterization
• Laboratory testing (advanced strength, consolidation)
• Geotechnical instrumentation (settlement sensors, piezometers)
• Embankment consolidation analysis (1-dimensional and finite-element)
• Design of settlement mitigation works (wick drains and ground improvement)
• Slope stability analysis and design of stabilization works
• Limit States Design (LSD) and Allowable Stress Design (ASD) of foundations
• Excavations and shoring
• Reinforced earth structures
• Observation of construction (foundations, slope stabilization, ground improvement)
• Materials testing (soil compaction, concrete, asphalt)

Cold Regions Engineering

TREK is committed to providing our services in a manner to protect Canada’s north and the people who live there. Although less than one percent of Canadians live in permafrost affected regions, these northern regions comprise almost 40 percent of Canada’s land mass. About half of Canada is underlain by permafrost ranging from a few centimeters thick at the southern extreme to over 300 m in the far North. The occurrence and distribution of permafrost is dependent on physiographical differences in latitude, climate, and terrain. The need for knowledgeable and experienced engineering in areas of permafrost (either continuous or discontinuous) cannot be over-stated; differential frost heave and thaw-settlement are but two of many challenges associated with northern development, in particular in warm permafrost regions where the frozen ground is in a state of delicate balance between remaining permanently frozen and thawing. The effects of climate change (warming) can also be significant and must be understood. Effects of permafrost degradation (thawing) include soil erosion, landslides, disappearance of lakes, and significant ground subsidence. The overarching key consideration for engineering in the north is how development may affect the ground thermal regime. In this regard, essential requirements for the success of engineered works are a thorough site investigation to characterize ground conditions, thermal modelling, and the design of measures to either prevent or compensate for the adverse effects of permafrost thawing. Offsetting the effects of global warming often may require the consideration of additional fill material thickness, insulation, thermosyphons or other techniques.

TREK’s engineers have direct experience in the design and construction of numerous permafrost related projects throughout Nunavut, Northwest Territories, Yukon, northern Manitoba and northwest Ontario. 

Our services specific to Cold Regions Engineering include:

• Site assessments in remote areas and communities with a focus on Inuit and First Nation involvement
• Specialized sub-surface investigation techniques to define key permafrost conditions such as ground temperature and ground ice
• Thermistor installation, remote monitoring and data collection
• Terrain analysis to assess the presence/absence of permafrost, evaluate permafrost degradation, identify linear infrastructure alignments and borrow sources
• Thermal modelling
• Climate change assessment
• Foundation design for northern regions – thermosyphons and adfreeze piles
• Site supervision and quality control materials testing in remote locations