The mining and reclamation of opencast coal mines affect the soil volumetric water content (SVWC1). An accurate measurement of the SVWC is critical for land reclamation. However, traditional methods often damage the soil structure and are time-consuming. Thus, a rapid and non-destructive method is required to measure the SVWC in reclaimed mining areas. This study aimed to evaluate the feasibility and effectiveness of using ground penetrating radar (GPR) for estimating SVWC in reclaimed mining areas. We obtained GPR data and collected soil profile samples from the South Dump of the Antaibao opencast coal mine in Pinglu District, Shuozhou City, Shanxi Province. Random Hough transformation and inverse distance weighted interpolation were used to analyze the two-dimensional soil water layer thickness (SWLT) and SVWC in different soil layers and profiles. The radar estimated and the sampling measured value of SVWC were consistent with the soil depth. The Pearson correlation coefficient (r) between the radar estimated and the sampling measured values of SVWC was 0.850 in different soil layers, the lowest root mean squared error (RMSE) was 0.43%, and the lowest relative root mean square error (RRMSE) was 3.80%. The r was up to 0.959, the lowest RMSE was 0.58% to 0.90%, and the lowest RRMSE was 1.46% in different profiles. These results demonstrate the method's feasibility and effectiveness, enabling the precise non-destructive estimation of SVWC. The results provide valuable technical support for the efficient reclamation and restoration of mining areas.

The vacuum preloading technique is extensively employed for ground improvement, particularly for slurry ground characterized by high-water content and low strength. Such ground frequently exhibits a delay in pore water pressure dissipation when treated with prefabricated vertical drains. To clarify the drainage and consolidation behaviour of high-water content slurry ground under vacuum preloading, this study proposed a two-stage combined model that integrates both filtration and consolidation processes. Initially, an axisymmetric filtration model was used to describe the formation of the soil column through the radial migration and compaction of the particles. The end-of-filtration radial distributions of void ratio, permeability coefficient, and effective pressure served as initial conditions for the consolidation stage analysis. This stage was depicted using a large strain consolidation model based on the free strain condition. The results showed the necessity of incorporating the filtration stage to capture the overall drainage mechanism and characteristics of slurry ground with vacuum preloading treatment.

The demand for raw materials is increasing rapidly, leading to higher production targets for mining industries. Currently, largescale opencast mining operations are causing extensive damage to forest areas, agricultural land, and various habitats for humans and animals. Despite these negative impacts, mining plays a crucial role in our national economy, serving as the second backbone of the country after agriculture. Given the inevitability of mining operations, it is essential to carry them out in a sustainable manner, minimizing or even eliminating environmental harm. This study focuses on the challenges associated with iron ore mining and emphasizes the significance of ecological restoration and land reclamation in mitigating environmental consequences. The focus of this research work is the implementation of a comprehensive procedural approach to achieve sustainable mine reclamation in an easy way. The primary objective is to restore the biodiversity of the Saranda Forest ecosystem. To accomplish this, a three-tier plantation model was adopted, involving the strategic planting of 2,664 trees and 3,136 herbs/shrubs in 1.5 hector degraded backfilled area. This initiative aims to rehabilitate the degraded land that has been adversely affected by mining activities.

The subsidiary of Yunnan Phosphate Group Co., Ltd., Kunyang Phosphate Mine's mining area is the subject of study. The mining of open-pit phosphate mines has caused significant damage to the ecological environment. Therefore, carrying out ecological restoration and green reclamation of the ecosystem in the mining area has become the top priority for current development. This article establishes an evaluation system for ecological restoration indicators, selecting four indicators including vegetation coverage, soil and water conservation, restoration of native plants, and Plant Species Diversity Index to assess the effects of ecological restoration and green reclamation of phosphate mines. The techniques of reconstructing soil ecological structure using phosphate tailings substrate and improving acidic soil with soil conditioner and calcium-magnesium phosphate compound fertilizer were applied. A series of other measures were taken, including: drafting scientific ecological restoration plans; employing physical, chemical, and biological methods for ecological restoration and green reclamation; selecting suitable plant species for planting; enhancing planting techniques; and strengthening post-restoration ecological monitoring and regulation. After ecological restoration and green reclamation, the Ecological Remediation Effect Index (EREI) for the years 2020, 2021, and 2022 were 48.40, 87.38, and 93.23 respectively, indicating significant improvement in the ecological environment. Furthermore, the difficulties encountered during the ecological system restoration process of the mine and the future development directions were summarized, providing practical and guiding significance for ecological restoration and green reclamation of abandoned mining areas both domestically and internationally.

In densely populated countries, underground construction and land reclamation could be possible options to solve the demand for land space, thus securing sustainable long-term development of the nation. For example, in Singapore, land reclamation has been widely conducted using excavated materials from underground development. The excavated materials are commonly marine clays that contain sandy soils. To improve the mechanical properties of these soft soils, cement-treated soil stabilization is popularly adopted. In fact, many researchers have investigated the properties of pure cemented clay or pure cemented sand using conventional design parameters such as water content (water/solids) and cement content (cement/dry soil). However, can these terminologies be still used to accurately examine the role of sand in cemented sandy clay mixtures? Through unconfined compression testing, it is herein shown that the use of existing mix design approaches in the literature cannot properly explain the variation of strength with sand content for cemented sandy clay mixtures. A new mix design approach is thus proposed in this study, which ensures that the role of sand in a cemented clay matrix can be quantified.