Factors Affecting the Swelling Pressure Measured by the Oedemeter Method

Abstract

Expansive soils are common in arid and semi-arid climate regions of the world and cause severe problems on civil engineering structures. The Swelling potential of the expansive soil mainly depends upon the properties of soil and environmental factors, and stress conditions. Swelling pressure is a key parameter used in designing structures in and on expansive soil. The swelling pressure of soil is measured in the laboratory using a representative soil samples. The size and the surface friction of the sample ring used in the swelling pressure test have effects on the measured swelling pressure and they have not properly been investigated. In this study, a series of constant volume swelling tests were conducted using an automated consolidation-swell apparatus to evaluate the effect of sample ring size, ring friction, initial dry density, and initial moisture content (IMC). Test results indicate an exponential growing trend of swelling pressure when the dry density is increased. Similarly, high swell pressures are achieved when the IMC is increased for the same dry density. A higher swelling pressure was measured when the friction of the specimen ring was reduced. The measured swelling pressure increases with increasing the height of the sampling ring and it decreases when the ring diameter is increased. Therefore, it is recommended to use a standard sample ring reducing inside wall friction using lubricants when measuring the swelling pressure in the laboratory. Further, the sample ring size, initial density and initial moisture content of soil should be given when reporting swelling pressure of soil.

Factors Affecting the Swelling‐Compression Characteristics of Clays in Yichang, China

“…Specifically, for moisture content of 10.10%, the swelling pressures were 29.92 kPa and 85.03 kPa while the dry densities were 0.14 kN/m 3 and 0.15 kN/m 3 , respectively. However, swelling pressure was 199.95 kPa for a dry density Jayalath et al [20], Çimen et al [24], and Dafalla [25] considered expansive stress decreased monotonically with a rise in the moisture content. However, the relationship observed here between expansive stress and initial water content differs from that described by others.…”

“…Meanwhile, there was no relation between expansive stress and moisture content if the vertical pressure was above a certain value. Jayalath et al [20] observed that the swelling pressure and dry density are positive correlation.…”

Factors Controlling Rainfall-Induced Slope Instability of Natural Slopes in North Maleny, Queensland

“…This area has been documented since the mid -1950's as a highly susceptible region for rainfallinduced slope failures [18][19][20][21]. Further, the region consists of expansive soil [22][23][24] which undergoes a significant volume change when drying and wetting. This soil needs to be stabilized before when lightweight structures such as roads, and residential houses are placed [25][26][27][28].…”

A double-porosity formulation for the THM behaviour of bentonite-based materials

“…34 Figure 2-19: (a) Variation of swelling pressure with dry density of several bentonites (Wang et al, 2012); (b) exponential correlation between swelling pressure and dry density of FEBEX bentonite materials (Hoffmann et al, 2007) …………………………………………………………………………………………………………………………. 35 Figure 2-20: Swelling pressure development in samples compacted at several dry densities and with distinct initial water contents (Jayalath et al, 2016) ………………………………………………………………………………. 35 Figure 2-21: Schematic representation of clay particle arrangements (after Lambe and Whitman, 1979) for undisturbed samples from (a) salt water and (b) fresh water deposits and for (c) remolded samples………………………………………………………………………………………………………………………………………………… 36…”

“…Figure 2-22: (Swelling pressure development at different (a) cell diameters (for a sample height of 18.5 mm); (b) sample heights (for a cell diameter of 76.0 mm). Grease was applied on the inner surface of the cells (Jayalath et al, 2016)…………………………………………………………………………………………………………………….. 37 Figure 2-23: Swelling pressure development with (WG) and without (WOG) the application of grease on the inner surface of the oedometer cell (with a diameter of 76.0 mm and a height of 25.5 mm) (Jayalath et al, 2016)…………………………………………………………………………………………………………………………………………… 38 Figure 2-24: The effect of the remolding procedure on the swelling measured at distinct initial water contents for a clayey soil in Jordan (Attom et al, 2006)………………………………………………………………………… 39 Figure 2-25: (a) Microfabric of a clay predominantly constituted of clay aggregates with larger pores among them (Gens and Alonso, 1992); (b) microfabric of a soil composed mainly by elementary clay particles (Gens and Alonso, 1992); (c) micrograph of FEBEX bentonite compacted at dry density of 1.40 Mg/m 3 (Lloret and Villar, 2007); (d) micrograph of MX-80 compacted at dry density of 1.80 Mg/m 3 after wetting/drying cycles (Seiphoori et al, 2014)……………………………………………………………………………………….. 40 Figure 2-26: Pore size distribution of compacted samples made of a granular mixture of FEBEX bentonite pellets at several dry densities (Hoffmann et al, 2007)…………………………………………………………………………. 41 Figure 2-27(a) Effect of the compaction effort on the pore size distribution of compacted samples of FEBEX bentonite (Lloret et al, 2003); (b) development of the pore size distribution of compacted MX-80 bentonite/sand mixtures under wetting path (Wang et al, 2013) ………………………………………………………….…”