The long-term compression behavior of clay is significantly affected by temperature paths. However, most studies on temperature paths focus on short-term changes in volume and pore pressure, with limited research on how temperature paths affect soil secondary consolidation characteristics. To experimentally investigate the time-dependent compression behavior of lateritic clay under different temperature paths, a series of temperaturecontrolled isotropic consolidation tests from 5 to 50 degrees C were conducted with consideration of heating/cooling rate and thermal cycle paths. The results indicate that the accumulation of thermal-induced pore water pressure increases with the rate of temperature variations, but a faster rate leads to smaller volumetric changes. Moreover, thermal cycling does not cause irreversible thermoplastic volumetric strain with a suitable heating/cooling rate, and the cycle paths do not influence this outcome. Furthermore, the creep rate of heated samples increases significantly, and the heating/cooling rate also affects the creep rate: a slower heating rate results in a faster creep rate. Additionally, the creep behavior ceased after the thermal cycle, and it appears that the thermal cycle paths have no effect on the creep rate. Finally, this study summarizes the mechanism of the influence of temperature on the creep behavior of clay, and reasonable explanations are proposed for the thermo-mechanical behavior caused by different temperature paths.

Lateritic clay is widely distributed in southern China, and its strength is greatly affected by water content. The elevated moisture content in lateritic clay during monsoon periods frequently results in insufficient shear strength for standard engineering applications. Large quantities of solid waste, including steel slag, fly ash, and granulated blast furnace slag, are produced as industrial by-products. This paper is based on the backfilling resource utilization of steel slag, fly ash, and ground-granulated blast-furnace slag as lateritic clay improvement admixtures, along with the stress-strain behavior, strength characteristics, and microstructure of steel-slag-modified lateritic clay, fly-ash-modified lateritic clay, and ground-granulated blast-furnace slag-modified lateritic clay, by combining uniaxial compression tests, straight shear tests, and scanning electron microscopy observation. The experimental results were analyzed to determine the appropriate dosages of three kinds of solid waste and their mechanisms in lateritic clay modification. The results indicate that the unconfined compressive strength of SS-modified lateritic clay exhibited an increase with an increase in SS dosage in the range of 1-7%, the unconfined compressive strength of FA-modified lateritic clay showed an increase with an increase in FA dosage in the range of 1-5%, and the unconfined compressive strength of GGBFS-modified lateritic clay increased with an increase in the use of GGBFS in the range of 1-5%. Under the condition of a 7-day curing age, the unconfined compressive strength of lateritic clay modified with 7% SS increased by approximately 397%, while that modified with 5% FA and 5% GGBFS exhibited increases of about 187% and 185%, respectively. The stress-strain relationship of fly-ash and blast-furnace slag-modified lateritic clays showed elastic-plastic deformation. But the stress-strain behavior of steel-slag-modified lateritic clay at a steel slag dose greater than 5% and a maintenance age greater than 7 days showed elastic deformation. Analyzing the SEM images shows that the more hydration products are generated, the relatively higher the unconfined compressive strength of modified lateritic clay is, and the form of deformation of modified lateritic clay is closer to elastic deformation. Through comparative analysis of modified lateritic clay samples, this study elucidates the property-altering mechanisms of waste powder additives, guiding their engineering utilization.

It is crucial to comprehend soil thermomechanical behavior while designing underground energy structures to ensure safety. Studies on the soil response to thermal cycles in terms of the generation of thermal-induced volume change and pore water pressure are rare, and relevant research on how these responses might affect soil consolidation parameters and shear strength is very limited. To experimentally investigate the effect of thermal cycling under drained and undrained conditions on the isotropic consolidation parameters and triaxial shear strength of lateritic clay, this paper employs a temperature-controlled triaxial apparatus to conduct a series of isotropic mechanical consolidation and thermal consolidation tests, as well as undrained triaxial shear tests. The thermal response in volume change and pore water pressure are discussed, and the changes in the consolidation parameters, the preconsolidation pressure, and the shear strength are identified. It is concluded that increments of irreversible contraction of lateritic clay are observed during thermal cycling under drained conditions and further lead to a slight increase in the preconsolidation pressure. Nevertheless, thermal cycling hardly affects the swelling and compression index. The shear strength increases after being subjected to thermal cycling under drained conditions, which can be attributed to the increase in cohesion. When drainage is not allowed during thermal cycling, the generation of pore water pressure occurs during temperature variations and completely dissipates after the thermal cycling phase, and its reversibility is unaffected by the stress level and number of cycles. Furthermore, thermal cycling has little effect on the consolidation parameters, preconsolidation pressure, and shear strength. This study provides new insights into the mechanisms controlling the response of clay to thermal cycling.

Lateritic clay is often used as a construction material for roads in tropical and subtropical areas. However, these materials exhibit high compressibility, high rate of creep, and susceptibility to severe cracking due to swelling and shrinkage behavior. These traits are closely linked to its hydro-mechanical and deformation properties. In this study, firstly, a boundary line between the swelling and compression deformation zone was determined based on the results of wetting tests. This boundary line is crucial for identifying the specific deformation mechanisms observed in unsaturated lateritic clays under varying water conditions. Secondly, an analysis of the relationship between pore size distribution and the soil water retention curve (SWRC) were conducted. A simple bimodal SWRC model, using the normal distribution function, was proposed. Additionally, the strength characteristics of lateritic clay were investigated over a wide suction range. It was observed that the existing strength model significantly underestimated the tested values in the medium to high suction range. To address this, a segmented strength equation was introduced based on unsaturated effective stress analysis. This approach allows enables enhanced predictions of the strength properties of lateritic clay. Altogether, these findings have greatly contributed to a better understanding of the engineering properties of lateritic clay.