Weathering of soil in tropical region results in weakly bonded iron coated silica grains. Prediction of in-situ behaviour requires modelling of chemical dissolution, hydraulic fracturing and mechanical volume change. The three-phase modeling would provide better understanding of stability of collapsible, dispersion and dolomitic-sinkhole formation.
Residual soil is created by rock decomposition, which is one of the tropic’s most prevalent geological formations. It is extremely organized in nature and depending on the degree of weathering can also be cemented. Residual soil’s undrained shear strength and stress-strain behaviour are known to be significantly influenced not only by the original history of porosity and stress history, but also by particle bonds. Though residual soil is frequently found in the tropical region during construction, studies are far from adequate on its engineering characteristics (Meng & Chu, 2011).
Based on multiple geological origins and related procedures such as weathering, erosion, transport and sedimentation, soils are created. Parent rocks’ in-situ weathering is as a result of chemical and/or physical processes that ultimately produce residual soils. Since residual soils have been created from in-situ weathering, the features of their engineering are greatly affected by stress history, grain strength, bonding, discontinuity of relics, anisotropy and void ratio (Blight 1997). As portion of the soil structure, the presence of bonding or cementation was acknowledged. This bonding is frequently discovered in a broad variety of earth materials deemed to be geotechnical soils (Leroueil & Vaughan 1990).
In latest years, geotechnical engineers have gained growing attention to the characteristics of residual soils. In specific, a number of researchers in this area have discussed the extent to which conventional soil mechanics ideas apply to residual soils. A commonly held opinion appears that direct applications of such ideas to residual soils are likely to lead to false findings about the characteristics of at least some of these soils (Rao & Prasad, 2016).
Chemical processes, however, affect the mechanical characteristics of geomaterials, leading in either strengthening or weakening impacts, the latter being especially critical in civil and energy engineering for long-term safety evaluation. Starting with a micro-structural chemo-mechanical model, the coupling of chemical and mechanical processes in cemented soils and rocks is explored. The model comprises of an assembly of grains and bonds that undergo dissolution or mineral mass precipitation, affecting the assembly’s geometric features. The main features of this kind are the evolution of specific surface area and cross-sectional bond region at the micro-scale, and macro-scale porosity, which become important factors connecting the processes of micro-scale and macro-scale. This structure has the benefit of preventing unphysical circumstances like the occurrence of mineral precipitation with no accessible pore space or the event of dissolution without left cementing material. The evolution of significant micromechanical amounts is monitored, such as the amount of active bonds and their cross section. A reactive chemical-plasticity model is coupled with a connected geomaterial model at the macro-scale. The resulting micro-to macro-scale transformation, schematically applied to both reactive grain components and bonds and materials with only reacting bonds, is validated against the available experimental proof regarding calcarenite with both reactive bonds and grains produced from the same mineral. It is thus demonstrated that the model provides a flexible structure for coherent interpretation of experimental loading routes and can be easily expanded to more complicated circumstances (Gajo, Cecinato, & Hueckel, 2015).