This study examines the potential of the soft computing technique—namely, Gaussian process regression (GPR), to predict the ultimate bearing capacity (UBC) of cohesionless soils beneath shallow foundations. The inputs of the model are width of footing (B), depth of footing (D), footing geometry (L/B), unit weight of sand (γ), and internal friction angle (ϕ). The results of the present model were compared with those obtained by two theoretical approaches reported in the literature. The statistical evaluation of results shows that the presently applied paradigm is better than the theoretical approaches and is competing well for the prediction of UBC (qu). This study shows that the developed GPR is a robust model for the qu prediction of shallow foundations on cohesionless soil. Sensitivity analysis was also carried out to determine the effect of each input parameter.

The effectiveness of the use of waste fly ash (FA) and cement (OPC) in the stabilization of subgrade soils and the reasons likely to influence the degree of stabilization were investigated. Incorporating waste fly ash (FA) and cement (OPC) as additives leads to significant environmental and economic contributions to soil stabilization. This study involves laboratory tests to obtain the Atterberg limit, free swell index (FSI), the unconfined compressive strength (UCS), the California bearing ratio (CBR), and the scanning electron microscope (SEM). The test results for the subgrade soil illustrate that the Atterberg limit, plasticity index, and free swell index are decreasing with the addition of different proportions of fly ash and cement, i.e., 0%, 5%, 10%, 15%, and 20% and 0%, 2%, 4%, 6%, and 8%, respectively. The CBR value of untreated soil is 2.91%, while the best CBR value of fly ash and cement mixture treated soil is 10.12% (20% FA+8% OPC), which increases 71.34% from the initial value. The UCS of untreated soil is 86.88 kPa and treated soil with fly ash and cement attains a maximum value of 167.75 kPa (20% FA+8% OPC), i.e., increases by 48.20% from the initial value. The tests result show that the stability of a subgrade soil can be improved by adding fly ash and cement. While effectiveness and usability of waste FA and cement are cost-effective and environmentally friendly alternatives to expansive soil for pavement and any other foundation work in the future.

In this study, the effects of waste marble powder and magnesium phosphate cement on the properties of soil were investigated. The incorporation of waste marble powder (MP) and (MPC) magnesium phosphate cement as a novel additive, lead the significant environmental and economic contributions in soil stabilization. The key properties of natural soil were extracted and several tests, such as specific gravity, Atterberg limits, sieve analysis, unconfined compression strength test, Direct shear box test, modified Proctor test, California bearing ratio, and Scanning electron microscopy test were performed on soil samples prepared with different percentages of MPC and MP, i.e. 0%, 2.5%, 5%, 7.5% and 0%, 5%, 10%, 15%, respectively. An unconfined strength test was used to obtain desired comprehensive strengths following 7, 14, 28 days of curing time. The overall experimental results revealed that MP and MPC can be added to enhance the stability of the soil. While usability and effectiveness of MPC and MP are cost-effective and eco-friendly as the substitution of natural soil for deep foundations.

A large number of toxic gases such as carbon monoxide (CO) and nitrogen oxides (NOx) are produced from the blast models during the drill and blast tunneling excavation. However, the emission characteristics of blast design models have never been mentioned in previously published studies.To acquire the cleanest blast model and reduce environmental pollution, this paper for the first time compares the emission characteristics of CO and NOx from three traditional blast design models, i.e., NTNU, Swedish, and China models, which is the most used in tunneling. Firstly, the detailed blasting parameters of three models are put forward based on one certain 42.3m 2 cross-section tunnel. After that, the emission characteristics of each model is evaluated based on the indexes of total emission, emissions per area, and emission increment. Meanwhile, the tunnel face of the models is divided into four functional sections, i.e. cut zone, stoping zone, lifter zone, and contour zone to explore the influence of functional blastholes on gas emissions. Finally, these results indicate that the CO and NOx emissions of the China model are the least, followed by Swedish and NTNU models. And the total emissions are dominated by the stoping blastholes. Therefore, it is effective to reduce environmental pollution by adjusting the parameters of the stoping zone. This research can provide a reference for the tunnel engineers to design blast models to reduce environmental pollution.

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