Characterisation of the Undrained Shear Strength of Expansive Clays at High Initial Water Content Using Intrinsic Concept

Abstract

Twenty-four direct shear tests were conducted on remolded/reconstituted specimens to study the effect of initial water content on the undrained shear strength of expansive clays. The laboratory tests illustrate that the shear behavior of the studied clayey soil is dependent on both the confining pressure and the initial water content at which the specimen was prepared. In fact, the undrained shear strength decreases with increasing initial water content. Similarly to the compression behavior, the intrinsic concept can also be used to predict the undrained shear strength of the studied soil. Additionally, the relationship between the void index, which is a normalized invariant of void ratio, and the undrained shear strength can be defined uniquely by a straight line. The experimental results also show that the normalized undrained shear strength, which is defined as the ratio of the peak undrained shear strength to the normal stress, varies with the initial water content from 0.25 to 0.50. Moreover, a decreasing trend is found for the range of pre-consolidation stress between 50 and 400 kPa.

Compression Behaviour of Highly Expansive Clays Stabilised With a Green Stabiliser of Magnesium Chloride

“…The in-situ water content of the samples were measured immediately after collection and was 40% [24]. The laboratory tests also state that the shear strength of the black clay is highly dependent on the initial water content [25]. The particle size distribution (PSD) curves of the studied soil are illustrated in Fig.…”

Analytical Study of the Strength Characteristics of Compacted Soil

“…Here, regarding the material parameters, λ is the expansion index; κ is the compression index; M is the limit state parameter; ν is the Poisson's ratio; 𝒌𝒌 𝒂𝒂 is permeability [m/day]; 𝒌𝒌 𝒘𝒘 is saturated hydraulic conductivity [m/day]; s G is the soil particle density; m is the unsaturated permeability coefficient of Mualem [9]; a is a magnification parameter of consolidation yield stress by unsaturation; n is the 𝑬𝑬 𝒄𝒄 model parameter; 𝒆𝒆 𝟎𝟎 is the initial void ratio; 𝜸𝜸 𝒕𝒕 is wet unit volume weight; 𝑺𝑺 𝒓𝒓𝟎𝟎 is the critical saturation; 𝒏𝒏 𝑬𝑬 is the enlargement ratio of yield surface; m is the subloading surface parameter; and 𝒑𝒑 𝒔𝒔𝒂𝒂𝒕𝒕 ′ is consolidation yield stress due to unsaturation.…”

The Comparison of the Soft Clay Settlement Under an Embankment Load Using Field Instrumentation and Empirical Formulation

“…This study has examined more than 130 undisturbed specimens obtained from different depths which are results of two years geotechnical studies located at south-west of Iran. Habibbeygi and Nikraz [15] obtained a new CC formula for remolded clay, namely Cc = 0,666eL -0,830e p ; Daoud, Kasama, Saleh, Negm [16] declared the best correlation for Cc is 0,2608e and Cc = 0,0093Wc, and Sari and Firmansyah [17] also obtained a new Cc formula, namely Cc = 0.6787eo-0.1933 obtained from 466 soil samples from 77 points of data bore holes at 25 locations spread in Surabaya area. Those empirical formulations were not used in this study because the data used is only valid for the local area.…”