The 178 m long, three-span Pic River Bridge near Marathon, Ontario is founded on relatively short friction piles driven into an 18 m deep soft to firm clay layer underlain by over 70 m of stratified silt and silty fine sand deposits under a maximum 6 m of artesian head. Due to the artesian pressure at depth, the capacity of long friction piles driven into the silt and sand deposits was determined by load testing to be significantly less than that of short friction piles installed within the clay deposit. The original foundation design in 1959 was therefore based on 16.5 m long friction piles installed within the clay deposit. The clay properties were improved by applying electro-osmotic treatment at the two piers and east abutment. The electro-osmotic treatment doubled the ultimate pile capacity from 300 to 600 kN per pile. Subsequent load tests on selected piles conducted from 1961 to 1992 indicated that the increased pile capacities were being sustained.

Rehabilitation of the bridge involving a superstructure replacement was carried out in 2015 and 2016 along with settlement monitoring of the existing foundations. Static pile load tests were conducted on selected piles in 2013 to confirm that the pile capacities have not diminished with time. The results indicate that the pile capacity improvements achieved by the electro-osmotic treatment of the clay have been sustained over a 54-year period. Static cone penetration tests and shear vane tests were also undertaken near the test piles to assess the improvement of clay properties due to the electro-osmotic treatment. Pre-rehabilitation settlement analyses predicted negligible immediate settlement and 10 to 20 mm of long-term settlement in 25 years. The monitoring data collected between 2015 and 2017 indicated generally less than 5 mm of settlement at abutments and piers.

The effects soil debonding and destructuration cannot be easily understood using conventional design methods. However, the impact of soil destructuring can be catastrophic for projects in certain soils.

The PLAXIS Creep-SCLAY1S constitutive model was developed to simulate the anisotropic, rate-dependent behavior of soft structured soils including creep. Champlain Sea clay is well known for its cemented structure and rapid transformations from a relatively brittle material to a liquid mass when disturbed. The structured behavior of the Champlain Sea clay makes it extremely sensitive to strains that may destroy the bonds between the soil particles. The Creep-SCLAY1S model is considered as an appropriate constitutive model for the analysis of Champlain Sea clay due to its ability to simulate the bonding and destructuration process of natural clays.

A calibration of the Creep-SCLAY1S model with site measured data from a site in Quebec was undertaken. Design parameters required for the Creep-SCLAY1S models were calibrated using the PLAXIS “Soil Test” module against laboratory tests and field testing measurements. The available laboratory tests were comprised of isotropically consolidated, undrained triaxial compression (CIUC), and 1-D incrementally loaded oedometer tests. Field testing included cone penetration testing (CPT) and peak and residual field vane measurements.

The PLAXIS “Soil Test” module outputs (Deviator vs. Axial Strain, PWP vs. Axial Strain) were plotted against available testing data and found to be comparable. Indicating that the PLAXIS Creep-SCLAY1S model was well calibrated to mimic the behavior of Champlain Sea clay at the site. This paper summarizes the range of calibrated PLAXIS input parameters for the Creep-SCLAY1S for Champlain Sea for a site in Quebec.

Several constitutive models for sands for cyclic applications have recently been developed, and far less for clays. The behavior of clays is known to be strongly rate-dependent, and although, various viscoplastic models for monotonic loading for clays have been published, the use of rate-dependent models to model the behavior of clay under cyclic loading has remained sparse. In this study, a new bounding surface viscoplastic clay model for cyclic loading is introduced.

The model is anchoring the framework of the bounding surface plasticity and Perzyna’s theory of viscoplasticity allowing it to consider underlying clay features such as anisotropy and consolidation state. In addition, the model captures more advanced clay features such as cyclic softening and rate effects. The performance of the model is validated against different monotonic and cyclic soil response. The model is shown to predict fairly well the behavior of clays under both rate-dependent and rate-independent monotonic and cyclic loading. The model recovers its rate-independent behavior under slow loading conditions. In addition, under higher loading rates, the model yields a higher soil stiffness response consistent with laboratory observations from previous researchers.

This paper documents the settlement behavior of an 18 m high embankment fill that was constructed over two gravel quarry wash ponds in support of a new 2.6 km roadway alignment located in Cochrane, Alberta.

Due to the time and cost constraints of the project, removal of the wash pond sediments (silt and sand accumulated from gravel washing) was not a viable option. Backfilling over the pond sediment was considered as an alternate approach to meet the project objectives.

The proposed road embankment crossed over two wash ponds which were separated by a gravel berm access road. The wash ponds were approximately 6 m to 8 m below the surrounding ground surface and the pond base consisted of wet, fully saturated, soft, sandy silt material varying between 2 m and 5 m thick overlying native clay till soils.

The development plan consisted of installing a drainage blanket to dissipate and drain the porewater within the pond sediment off site and allow the consolidation of the pond sediment. The drainage blanket was installed over both ponds and comprised of a 1.0 m thick gravel layer wrapped with geotextile reinforcement/fabric. Embankment fill was subsequently placed over the drainage blanket.

Given the size of the project and amount of fill required, various types of backfill were utilized including reclaimed cobbles and boulders, drainage gravel, remolded clay till, and mixed sandy silt soils.

A series of vibrating wire piezometers, vibrating wire settlement gauges, and settlement monuments were installed to track porewater pressure and settlement throughout the embankment (pond sediment, various fill types, and various elevations). Monitoring of the settlement behavior was conducted during and after construciton.

The results of the settlement monitoring and recorded field observations were compacted to the expected settlement of the embankment (included each backfill material type and pond sediment).

Assessment of consolidation settlement in clayey soils under a new highway requires scrutiny in terms of embankment heights and fluctuating clayey strata. Complications further arise when a project consists of adding new roads to an existing highway where embankments cover significant parts of the studied area and overconsolidation margins vary considerably under different sections of the new highway.

Traditional methods for evaluating settlement often evoke the examination of the critical section, which is selected by considering several factors, such as the heights of new embankments, the depths and elevations of subsoil layers, the hydrostatic conditions and the characteristics of compressible soils. This method is effective in evaluating settlements in the most vulnerable areas for which the geotechnical engineer provides the appropriate design solutions accordingly.

However, in vast areas covered with embankments and fluctuating clayey strata, the critical section may not yield the most efficient solutions. When such circumstances arise, geotechnical solutions established solely on the critical section(s) could lead to overt conservative design methods, which usually translates to higher costs and extended time periods during the execution of the project that could otherwise be avoided. Other solutions such as 3D modeling that study the entire area in its integrity could thus prove to be more efficient.

This seminar will examine settlement in clayey soils under a new highway using 3D FEM Modified Cam Clay theory. The construction of a new highway alongside autoroute 50 in Gatineau Quebec will be used as a case study and developed through GTS NX 3D settlement. The results obtained will be discussed in a thorough manner and compared with critical sections that were evaluated for the same area using 2D and 1D consolidation settlement theories. A technical comparative discussion regarding the design procedures and cost-effective solutions using the different techniques will then follow.

Several investigations were undertaken both by practitioners and academicians during the past five decades to understand and interpret the glaciomarine clay deposits of eastern Canada, The focus of these investigations and research studies was mainly directed to study the behavior of Champlain Sea Clay, which is widely deposited in eastern Ontario and Western Quebec. The body of knowledge on the Champlain Sea Clay is derived mainly from laboratory tests or in-situ field tests. Performing such tests routinely for the design of conventional projects such as the municipal or residential structures is cost-prohibitive. There is a vast amount of data that is collected on these clay deposits and summarized in several reports about various properties of clay, which include, Atterberg limits, particle size analysis, water content and unconfined compression tests. There is also a substantial amount of data available on more intricate tests that is useful to interpret the hydraulic and mechanical behavior of these soils; these include hydraulic conductivity, consolidation tests and the shear strength properties. The wealth of this data is compiled and synthesized into a searchable database. This article provides a summary of the methodology of compiling the available information into an accessible database. In addition, it also provides information of how the user can extract required information from queries along with statistical information. The focused research is an attempt to propose simple tools that can be used in engineering practice by the geotechnical engineers who routinely work with the Champlain Sea Clay deposits.