Abstract
In order to study the influence of saturated characteristics of soft clay on unconfined compressive strength, the soft clay of Guangdong-Hong Kong-Macao Bay Area is taken as the research object, comparing and contrasting on unconfined compression test of saturated clay and unsaturated clay in laboratory, studying the variation law of unconfined compressive strength and sensitivity of unsaturated and saturated soft clay. The test results show that: 1. During the failure of unsaturated soft clay samples, oblique fractures appear, showing brittle shear failure, while the saturated clay samples appear constant bulging in the middle, and finally a “cross” is broken in the central bulging part, showing plastic shear failure.2. The unconfined compressive strength of unsaturated clay is about 10kPa higher than that of saturated soft clay, and its corresponding sensitivity is also about 0.4 higher. It can be shown that the soil saturation has a certain influence on the soil strength. The difference between saturated soil and unsaturated soil is the existence of gas phase. To be more precise, the existence of gas phase in unsaturated soil, i.e. the existence of suction, makes the soil stronger and presents the brittle shear failure form, while the saturated soil basically presents the plastic shear failure form.
Highlights
IntroductionSaturated soil has only two phases, i.e. solid phase and liquid phase (i.e. soil particles and water); unsaturated soil is generally recognized as four phases, namely solid phase (soil particles), liquid phase (water), gas phase (air) and shrinkage membrane (water air interface)
Saturated soil has only two phases, i.e. solid phase and liquid phase; unsaturated soil is generally recognized as four phases, namely solid phase, liquid phase, gas phase and shrinkage membrane
Because the influence of gas and water air interface can be excluded in saturated soil, it can be regarded as a kind of ideal soil, so the research theory of saturated soil is better Comprehensive improvement
Summary
Saturated soil has only two phases, i.e. solid phase and liquid phase (i.e. soil particles and water); unsaturated soil is generally recognized as four phases, namely solid phase (soil particles), liquid phase (water), gas phase (air) and shrinkage membrane (water air interface). Due to the existence of gas phase in unsaturated soil, the properties of soil are more complex than that of saturated soil. The matric suction is mainly affected by the change of soil water content or saturation, and the osmotic suction is mainly affected by the change of salt content. It is an important factor affecting the strength characteristics of unsaturated soil. Domestic and foreign scholars have studied the influence of suction on the engineering properties of unsaturated soil [1~3]. Through unconfined compressive strength test, Jinfeng Li [7] proved that water and salt have influence on the permeability and suction of unsaturated soil. The results are expected to promote the further understanding of gas phase in soil, and promote the further development of saturated soil mechanics
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