The evaluation of stability of slopes and embankments requires knowledge and experience of earthwork, computer programs, soil mechanics, groundwater, erosion and risk management – and SME experts can help you.

Slopes and embankments often experience settlement, stability and erosion problems requiring specialized geotechnical capabilities including expertise with earthwork, groundwater flow, erosion, computer slope stability programs, and risk management. SME has invested in computer software, instrumentation, laboratory equipment and professional development devoted to this challenging area of our practice. In the last 10 years, we have completed more than 500 projects involving slope and/or embankment design, stabilization,

Slopes

SME has extensive experience with slope stability analysis, design for safe slopes and excavations, and the design of slope-retaining structures. We are frequently called upon to design earth slopes and to assess the cause of failure for existing slopes. Our Geotechnical experts first execute a subsurface exploration programs to obtain soil and rock samples, then perform a variety of laboratory tests. The resulting site characteristics are interpreted and analyzed using state-of-the-practice slope stability software.

Based on the results of our testing and analyses, we determine causes of failure and develop remedial designs. Existing slope failures may be caused by factors such as unaccounted for loads, weak soil or rock layers, or high levels of ground water. Remedial schemes might involve removal of undesirable material, flattening the slope angle, constructing a stabilizing buttress, lowering/controlling ground water levels, employing tie-back anchors, using soil nails, constructing a reinforced soil slope.

SME provides slope design, stabilization and failure analysis services for the following types of projects:

  • Natural and excavated soil and/or rock slopes
  • Reinforced soil slopes
  • Mechanically stabilized earth slopes and walls
  • Cast-in-place retaining walls
  • Coastal, marine and riverbank shorelines
  • Short-term and service life stability evaluations
  • Landslide risk assessments

Steep Reinforced Slopes

Steep reinforced slopes are designed and constructed using reinforcing to strengthen the mass of earth such that a steep slope can be formed. SME has designed steep reinforced slopes as steep as 1:1 (horizontal:vertical). Steep reinforced slopes, when designed properly for the site, can save significant construction cost as compared to retention structures. Our experts can provide complete design services for steep reinforced slopes plus monitoring services during construction.

Embankments

SME’s geotechnical experts have extensive experience with the design and construction of soil and rock embankments, including roads and bridge approach embankments and property developments. The key geotechnical issues for design and construction of embankments include stability and settlement of the embankment soil and underlying soils, the impact of the stability and settlement on the construction staging and time requirements, and the impact to adjacent and nearby structures such as buildings, bridge foundations, dams and utilities. Embankment design and construction requires careful evaluation of both the embankment foundation soil and the fill soils.

Over Soft Soil

Embankments constructed on soft soils have a tendency to spread laterally because of horizontal earth pressures acting within the embankment. These earth pressures cause horizontal shear stresses at the base of the embankment that must be resisted by the foundation soil. If the foundation soil does not have adequate shear strength, failure can result. Properly designed horizontal layers of high strength geotextiles or geogrids can provide reinforcement to increase stability and prevent such failures. The reinforcement may also reduce horizontal and vertical displacements of the underlying soil and thus reduce differential settlement.

Lightweight Fills

One alternative for reducing the embankment load on the subgrade is to use lightweight fill material. The type of lightweight fill (such as geofoam, slag, wood chips) depends on the site conditions, height of fill and cost of obtaining and placing the lightweight materials.

Surcharge/Preload

Another alternative to address excessive settlement is to surcharge/preload the embankment to reduce future settlement. The surcharge/preload is applied and allowed to settle over time. After the wait period is complete and the significant settlement has taken place, the embankment can then perform as needed. The time rate of settlement can be enhanced by installing sand or wick drains. Settlement can be monitored using settlement plates. In some cases, additional instrument devices (piezometers, inclinometers, etc.) are used to help monitor the embankment.

Related Services

Service Experts

Matthew C. Desjardins, PE

Senior Project Engineer
Geotechnical-Design Services

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Jeffery M. Krusinga, PE, GE

Regional Office Manager
Geotechnical Services

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