Innovative, Expert Geotechnical Engineering
From investigation to stabilization, SESI Consulting Engineers works hand-in-hand with our clients to design and ensure safe, effective retention systems, foundations, and more. With a pragmatic approach that combines expertise with experience, the SESI team of engineers provides expert geotechnical engineering services within New Jersey, New York, and Pennsylvania.
What is Geotechnical Engineering?
Geotechnical engineering is concerned with the engineering behavior of earth materials. It uses the principles and methods of soil and rock mechanics in order to investigate subsurface geologic conditions and engineer the solutions to a clients’ project. Geotechnical engineers use reporting and scientific methods to understand the relationship between the subsurface composition/qualities and the project needs in order to design safe/successful earth retention systems, foundations, and other civil engineering works.
Subsurface Investigation and Analysis
This evaluation identifies the surface and subsurface soil and groundwater conditions through a desktop study followed by a field investigation consisting of drilling borings, excavating test pits, advancing Cone Penetrometer Tests, etc. The information gathered from the investigation is used to determine appropriate site-preparation procedures and building foundation support options based on the proposed development. Factors assessed include liquefaction, compressibility, shear strength, bearing capacity, settlement and soil composition and soil parameters.
Excavations greater than 15 feet are considered deep excavations and typically require additional steps including braced-retaining walls to prevent negative impact to adjacent sites. SESI has designed all types of excavation support systems including soils nails, slurry walls, secant walls, soldier beam and lagging walls, sheet pile walls, etc.
These systems often use pumps during the construction process to allow for subsurface excavation for foundations or shoring by removing or draining surface and groundwater from a riverbed or construction sites. This may include localized dewatering or a more comprehensive well point system.
Pavement Failure Evaluations
Pavement is typically a small aspect of a project but may be an early indicator of a deeper problem. SESI can evaluate premature pavement failures and provide recommendations for repair that can extend the life of the pavement and avoid premature deterioration.
Foundation Design Recommendations
SESI evaluates the surface and subsurface soils to identify different foundation options for support of the proposed buildings. SESI provides multiple options to the Owner, providing an analysis for each option with associated risks, costs, and timing. SESI works with the Owner to educate them on the potential risks, and associated cost and time implications for each of the options so that the most appropriate option to suit their needs is selected.
Laboratory Soil Testing
Laboratory tests are conducted to determine various soil index properties used in the design phase and during construction.
Slope and Rock Stabilization
Safe construction on or around inclined soil or rock involves a stabilization plan, determined based on soil mechanics, geology, and geotechnical engineering approaches. SESI can evaluate the type of rock and determine appropriate stabilization measures which may include scaling, netting, shotcreteing, bolting, etc.
SESI can design pavement sections for the project, often using alternative materials. Factors considered in the process include subsurface soil conditions, drainage, traffic demands, as well as the expectations of pavement performance/reliability, lifecycle of the pavement, and availability and cost of materials
Conventional Deep Foundations
Project constraints such as large loads, or poor soil conditions may rule out shallow foundations. Examples of conventional deep foundations include driven piles, drilled piles, micropiles, and helical piles, among others.
Retaining Wall Analysis and Design
A retaining wall allows for soil materials to be held back at a near vertical angle and withstand the pressure of the material from lateral shifting. The type of retaining wall is determined by the project needs, site geometry, and the subsurface soil profile. SESI evaluates the site geometry and slopes to determine the most appropriate type of wall system. SESI has designed and inspected a wide range of wall types including small and large block retaining walls, gabion walls, concrete walls, soldier beam and lagging walls, etc. As part of the wall design and analysis, global stability calculations are also performed to evaluate the wall and slopes as a whole.
The collection and evaluation of site samples, historical data, and other available information to reconstruct a site to understand why there was a failure of the development or part thereof.
If ground improvement is required to prepare the property, surcharging may be the solution to apply vertical pressure using loads of soil, construction equipment, embankments, or other materials. The type and length of surcharge depends on the subsurface soil profile, construction schedule, and type of proposed construction. This approach is typically used on sites where compressible organic soils, and silts and clays are present.
Soil Stabilization/ Modification
These processes change the physical properties of the targeted soil, to enhance the shear strength and increase its load bearing capacity. This is valuable for many reasons including greater support of foundations, higher resistance, and lower permeability. This process can also be used to treat soils that are over-optimum moisture content to reduce the moisture content, increase the optimum moisture content, and reduce the plasticity of the soils, making them more workable and able to be compacted as a structural fill. The soils can be treated with a wide range of materials including cement, lime, fly ash, or kiln dust.
Deep Dynamic Compaction
This type of ground improvement densifies loose or uncontrolled fill soils by using a concentrated mass, from a high height, with multiple impacts, over a specified area. The dynamic compaction process turns an uncontrolled fill into a controlled fill by imparting sufficient energy at the ground surface resulting in a uniform soil mat that will allow the building to be constructed on spread footings with a slab on grade.
Ground Improvement Techniques
While a deep foundation will provide the required building support, it is also the most-costly foundation support option. SESI evaluates alternative ground improvement techniques for every project that may be appropriate for the development. These ground improvement techniques are usually more economical, and can often save time to implement. Alternative options include Rigid Inclusions, Aggregate Piers, Compaction Grouting, Dynamic Compaction, Surcharging, heavy proofrolling, treatment of soils with cement, lime, and fly ash and others.
Expert Witness Testimony
When a project faces litigation, an SESI expert can review materials available to provide an opinion on the subject of litigation related to design or construction claims. SESI offers expert witness testimony, including preparation of expert reports and during depositions and/or trials.
Construction Observation Services
SESI provides construction oversight during the site preparation and foundation construction to verify that the work is being done in conformance with the plans and specifications. Our representative functions as the eyes and ears of the owner, and can proactively help to identify and address issues before they become problematic in order to avoid increased project costs and project delays. Our representative works with the Owner and contractor to solve problems in a timely and cost-effective solution. SESI is not just a testing lab – our personnel provide additional value-added solutions during construction.