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The strength change characteristics of weathering soil due to repeat freezing-
thawing and drying-wetting
Les caractéristiques de changement de résistance du sol aux intempéries suite aux repetitions
de la congélation-décongélation et du séchage-amortissement
Kim Y.S., Seong J.H.
Korea Infrastructure Safety and Technology Corporation, Republic of Korea
Kim S.S.
The Land and Housing Institute, Republic of Korea
ABSTRACT: Most researches are concentrated on sedimentary soil, and focused on the mechanical behavior of weathered soil from
the viewpoint of sedimentary soil. Weathered soil shows great difference in engineering properties as the progression of weathering
including the properties of parent rock. In this study, repeated freezing and thawing, drying and wetting test is conducted to recreate
the effect of moisture and temperature, which might be considered as important for occurrence and efficacy on weathering among
various factors in nature. In addition, to evaluate the strength changed by weathering degree, uniaxial test is conducted on sample with
repeated freezing/thawing and drying/wetting. The specific gravity of the sample with the drying and wetting repeated decreased
bigger than that with the freezing and thawing performed. In general, as the repetition number of freezing-thawing and drying-wetting
increase, the compression stress of each sample decreased by a similar ratio. Especially, the strength change in the beginning by the
repetition was significant. The uniaxial compression strength by the change of weathering degree decreases similarly for all the
samples, but the axial deformation rate increases as the repetition numbers of the freezing and thawing and the drying and wetting
increase.
RÉSUMÉ : La plupart des recherches se concentrent sur les sols sédimentaires et mettent l’accent sur le comportement mécanique des
sols altérés du point de vue du sol sédimentaire. Le sol soumis aux intempéries montre une grande différence dans les propriétés
mécaniques comme la progression de l’altération dont les propriétés de la roche mère. Dans cette étude, des tests de répétitions de
congélation et de décongélation, de séchage et de mouillage sont effectués pour recréer l’effet de l’humidité et de la température, ce
qui peut être considéré comme important pour l’apparition et l’efficacité sur l’altération des différents facteurs dans la nature. En
outre, pour évaluer la résistance aux intempéries changée par degrés, l’essai uniaxial est effectué sur un échantillon répétés de
congélation/ décongélation et séchage/humidification. Le poids spécifique de l'échantillon avec l'humidification et de séchage répétés
diminution plus importante que celle de la congélation et la décongélation effectuée. En général, comme le nombre de répétitions de
gel-dégel et séchage-mouillage augmente, la contrainte de compression de chaque échantillon a diminué dans une proportion
similaire. Surtout, le changement de la force au début de la répétition est important. La résistance à la compression uniaxiale par le
changement de degré intempéries diminue de même pour tous les échantillons, mais le taux de déformation axiale augmente à mesure
que le nombre de répétition de la congélation et la décongélation et le séchage et de mouillage augmentation.
KEYWORDS: strength change characteristics, weathering soil, freezing/thawing, drying/wetting
1 INTRODUCTION
For weathering soil different from general deposit soil, its
engineering properties sharply differ depending on the progress
of weathering along with the characteristics of parent rock,
which makes the study on this field difficult prior to an
engineering research. In order to grasp the engineering
properties of weathering soil, it is not enough to make a study
from the dynamic view but a comprehensive investigation
should be made from geological mineralogy, physics,
chemistry, and dynamics. Through this, it is necessary to
present how the properties of the soil from these views are
expressed as a dynamic property and used in an engineering
aspect.
Therefore, this study is to clarify the change of characteristics
of granitic weathering soil due to the changes of temperature
and water set by examining the existing studies on the effect of
weathering factors on granitic weathering soil and considering
the frequency and effect among the factors existing in the
natural world. And for this, we are to promote the weathering
artificially to express the weathering feature and weathering
degree caused by weathering progress exponentially and
consider correlations with the changes of soil's engineering
characteristics so that a useful result may be drawn to accurately
clarify the characteristics of granitic weathering soil in the
future.
2 WEATHERING CHANGE TEST
For the weathering occurring in the real natural environment,
various factors work together composite and the time scale of
weathering is big that the effect of specific weathering factors
on weathering and weathering acceleration are required in the
study on weathering of soil. Thus, a test that controls the
weathering speed and factors artificially by creating an extreme
environment is suggested and it is necessary to identify the
changes of soil's characteristics due to weathering in a
quantitative aspect.
The most important thing in the weathering change test is to
draw out the relation between testing environment and real
environment as well as the relation between the weathering
generated in the testing process and that in the real environment.
In this study, repetition tests of freezing and thawing as well
as drying and wetting are conducted in order to reproduce the
effect of temperature changes and water which are considered
important in the aspect of occurrence frequency and effect
among the various weathering factors existing in the natural
world.
2.1. Repeat Freezing and Thawing
In the past, strength decrease due to freezing and thawing is
thought to be caused by frozen gravitational water or absorption
