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

Labile trace metal contribution of the runoff collector to a semi-urban river

International audienc

Urban water quality

Anthropogenic activities which are common to urban areas generate a range of physical, chemical and biological pollutants which are subsequently incorporated in stormwater runoff, leading to the deterioration of receiving water environments. This poses risks to both human and ecosystem health including carcinogenic and neurological effects and the loss of aquatic biodiversity. Water environments are an essential asset for enhancing urban liveability. Significant research has been undertaken in relation to stormwater pollutant characterisation and pollutant processes, which forms the baseline knowledge for developing effective stormwater pollution mitigation strategies. The current practice of formulating strategies to improve stormwater quality relies on the fundamental understanding that pollutants accumulate on urban surfaces during dry weather periods and are subsequently washed-off during rainfall. However, there are significant gaps in the current knowledge base in relation to how pollutant load and composition could vary temporally and spatially, which is critical for understanding the dynamic nature of stormwater quality in urban catchments. This acts as a major constraint to informed decision-making in the context of designing effective stormwater pollution mitigation strategies. Moreover, climate change is a significant influential factor in relation to urban stormwater pollution. The predicted changes to dry and wet weather conditions would lead to changes to pollutant accumulation on urban surfaces, change pollutant characteristics and increase the likelihood of discharging shock loads of pollutants to receiving waters. Research is needed to understand the complex mechanisms underpinning pollutant processes and their influential factors and the role of climate change in order to enhance the well-being of urban communities