EVALUATING PASSIVE EARTH PRESSURE TRENDS OF LARGE-SCALE PLATE LOAD TESTING OF GEOGRIDSTABILISED AGGREGATE LAYERS OVER CLAY
Date
2023-07-13
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0009-0004-9538-4955
Type
Thesis
Degree Level
Masters
Abstract
The manuscripts presented in this thesis focus on two main topics. The first manuscript describes
the procedures and material characterisation of the large-scale plate load testing, while the
second manuscript focuses on relating the large-scale plate load tests to Meyerhof’s punching
shear bearing capacity theory. The abstracts for the two manuscripts are presented below.
Part 1: Large-Scale Plate Load Testing of Geogrid-Stabilised Aggregate Layers over Clay
Geogrid stabilised aggregate layers are used to increase the bearing capacity of weak subgrade
material. Applications of these geogrid-aggregate composite layers include, but are not limited
to, temporary working platforms, road construction, and railway ballast. The inclusion of the
geogrid in aggregate creates an interlocked structure that improves the bearing capacity of the
composite layer. In this study, what we believe to be the largest full-scale controlled plate load
testing was carried out near Clavet, Saskatchewan, to test various geogrid-aggregate composite
layers. A 1m2
plate pushed stabilised and non-stabilised aggregate pads within a pre constructed
trench above a silty clay past their ultimate bearing capacity using a hydraulic cylinder with a
capacity of 100 tonnes. Load and displacement were measured directly. The cylinder was
attached below a moveable steel platform equipped with counterweights to account for the large
loads required to fail the testing pads. Analyses, including cone penetration testing,
photogrammetry, and intensive material characterisation, were done before and after plate load
testing.
Part 2: Evaluation of Meyerhof’s Semi-Empirical Bearing Capacity Solution Using Large
Scale Plate Load Testing of Geogrid Stabilised Working Platforms
Increasing the bearing capacity of aggregate layers placed over soft subgrades by stabilising the
aggregate with geogrids is a relatively novel practice with limited standardized design
procedures. This is caused by the growing number of stabilising geogrid products that are
becoming available as well as how each of these products will have a unique interaction with the
geogrid used in design. The research presented relates large-scale plate load testing results to
Meyerhof’s widely used punching shear bearing capacity theory of a strong layer overlying a
weak layer. Mobilisation trends for two different thicknesses of unstabilised aggregate layers are
compared to Meyerhof’s originally proposed trend of δ = 0.667φ. Mobilisation trends of the
aggregate stabilised with three different types of geogrid are then determined.
Description
Keywords
Bearing Capacity, Stabilisation, Geogrid, Plate Load Testing
Citation
Degree
Master of Science (M.Sc.)
Department
Civil and Geological Engineering
Program
Civil Engineering