The study investigates the interaction between geogrids and two distinct granular backfill materials, Yamuna sand and coal mine overburden through a combination of laboratory experiments and numerical simulations. It evaluates the physical and mechanical properties of coalmine overburden and Yamuna sand, and the pullout performance of geogrid embedded in both materials. A large-scale pullout box was utilised to conduct the experiments, and the results showed that coalmine overburden offers higher pullout resistance than Yamuna sand. The effect of physical parameters such as elasticity of geogrid, geogrid geometry and angle of inclination were analysed using the discrete element method. The pullout resistance of geogrids mainly depends on the elastic properties of the material. The study also shows the existence of an optimum spacing between longitudinal and transverse ribs.

Mine overburden material (OBM) is the discarded soil-rock mixture, which is abundantly dumped around coal mines. These dumps create a lot of instability and environmental issues. The present study attempts to sustainably utilize the mine OBM in the construction of mine haul roads. Mine OBM is generally a soil-rock mixture with differently graded materials lacking the specific requirements for use in pavement subgrade. To utilize the OBM, stabilizers like lime and cement alone may not work due to the heterogeneity of the OBM. Hence, Road Building International (RBI) grade 81, a novel calcium-based stabilizer was used in this study to increase the mechanical properties of the soils, as it can stabilize various ranges of soils. The collected soils were silty sand (SM), intermediate compressible clay (CI), and clayey sand (SC), which possessed different plasticity characteristics. To assess the strength properties of modified mixtures, the California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were conducted along with rutting resistance at different curing periods. The study shows that increasing RBI content enhances the soaked CBR values, with a peak of 135% for stabilized mixtures (SM) soil stabilized with 4% RBI. While the UCS values rose 16 to 18 times, reaching 1,355 kPa for intermediate compressive clay (CI) soil with 4% RBI. Wheel tracking tests demonstrated a 5 to 30-fold reduction in rut depth, dropping below 1.5 mm at 520 kPa stress, even at lower RBI levels for all composite mixtures. The use of RBI has proven to be effective in increasing the subgrade performance for all types of soils in OBM, while for CI soils it is more effective.

With continuous increasing of mining activities, some problems, such as environmental issues, occupy a lot of space, and the risks caused by the instability of mine waste depots are far occurred than ever. One possible way to reduce mentioned problems is to stabilize and reuse mine wastes as road construction materials. On the other hand, the most significant parameter for pavement design, either using empirical or mechanistic-empirical methods, is the resilient modulus (Mr) of road materials, which shows the influence of repetitive loading on the stress-strain behavior of materials. To obtain iron ores, it is required to remove the soil resting on the iron ore storage in deeper layers. This soil is typically in the form of alluvium and is known as mine overburdens (MOs). In this study, after identification of the geotechnical characteristics of two types of MO of the Golgohar mine in Sirjan, Iran, these materials were stabilized by using three different percentages of Portland cement (5, 7, and 9%) and were cured for 7 and 28 days, respectively and the resilient modulus were measured using repetitive triaxial loading equipment at different stress levels. Results show that cement stabilization does not enhance the Mr significantly when bulk stress or confining pressure is low. As the bulk stress or confining pressure increase, the Mr of cement-stabilized MOs increases significantly compared to raw MOs. Another justification is that the Mr of cement-stabilized MOs is a function of bulk stress, and deviatoric stress has a negligible effect on the Mr. The comparison between different nonlinear models revealed that the 'Universal' model has the best fit with the measured Mr values of raw and stabilized MOs.

Sudden and unforeseen seismic failures of coal mine overburden (OB) dump slopes interrupt mining operations, cause loss of lives and delay the production of coal. Consideration of the spatial heterogeneity of OB dump materials is imperative for an adequate evaluation of the seismic stability of OB dump slopes. In this study, pseudo-static seismic stability analyses are carried out for an OB dump slope by considering the material parameters obtained from an in-situ field investigation. Spatial heterogeneity is simulated through use of the random finite element method (RFEM) and the random limit equilibrium method (RLEM) and a comparative study is presented. Combinations of horizontal and vertical spatial correlation lengths were considered for simulating isotropic and anisotropic random fields within the OB dump slope. Seismic performances of the slope have been reported through the probability of failure and reliability index. It was observed that the RLEM approach overestimates failure probability (Pf) by considering seismic stability with spatial heterogeneity. The Pf was observed to increase with an increase in the coefficient of variation of friction angle of the dump materials. Further, it was inferred that the RLEM approach may not be adequately applicable for assessing the seismic stability of an OB dump slope for a horizontal seismic coefficient that is more than or equal to 0.1.

Grouting is a fundamental ground improvement technique that plays a pivotal role in stabilizing and enhancing the properties of soil and rock formations for construction purposes. It involves injecting a slurry into the soil or rock to enhance engineering properties. Cement grout is a common choice; however, the use of cement is not environmentally sustainable. In this study, an attempt has been made to prepare a sustainable grout mix by utilizing dolomite mine overburden as a partial replacement for cement. To assess the viability of this modified grout mix, the current research investigates the fresh-state properties of the grout mix, such as flowability and bleeding characteristics, as well as its hardened state properties, including compressive strength and drying shrinkage. Variations in the water-cement ratio from 0.35 to 0.45 and the use of a PCE-based superplasticizer in the range of 0.8-1.6% are considered. The findings indicate that replacing cement with dolomite mine overburden significantly improves workability while reducing bleeding properties. Additionally, incorporating dolomite mine overburden enhances compressive strength and reasonably reduces shrinkage. The results demonstrate that replacing 10-15% of cement with dolomite mine overburden is a viable option for sustainable grout mixes. This study suggests that using dolomite mine overburden as a partial cement replacement in grout mixes can be a way toward eco-friendly ground improvement practices.