Granular lateritic soil is commonly used for road construction in humid tropical and subtropical regions. However, the high plastic clay content and poor particle distribution of some laterite materials make them unsuitable for bases and subbases. Lime treatment is a widely used method for improving problematic lateritic soil, and liquid ionic stabilizers are considered an environmentally friendly solution for reinforcing such soils. However, using only lime or only stabilizers may not be optimal. This study investigated the effect of treating granular lateritic soil with hydrated lime and a new liquid stabilizer, Zhonglu-2A (ZL-2A). A series of indoor tests, including compaction, California bearing ratio, and unconfined compressive strength tests, were conducted to evaluate the effects of hydrated lime content and stabilizer content on the mechanical properties, mineralogical composition, and microstructure of the soil. The results show that an increase in hydrated lime dosage increases the optimal moisture content and decreases the maximum dry density. The CBR of lime-stabilizer-treated laterite was at least 2–3 times higher than that of the only-lime-treated soil. The highest CBR was observed in samples treated with 0.2‰ ZL-2A stabilizer. The sample with 6% lime and 0.2‰ ZL-2A stabilizer exhibited the highest unconfined compressive strength, and a nearly linear increase was observed between the unconfined compressive strength and CBR. Further investigation of the stabilization mechanism using X-ray diffraction mineralogy analysis and scanning electron microscopy revealed that the inorganic substances of the ZL-2A stabilizer and the hydrated lime provided the basic conditions for the reaction and generated cementitious hydrates on the clay particles. The mixture of granular lateritic soil and hydrated lime was wrapped by the ZL-2A stabilizer, forming a complex spatial structure and improving the strength of the soil. To improve the bearing capacity of subgrades in actual subgrade engineering, a combination of a liquid ionic stabilizer and lime should be used to treat laterite.

At present, the cumulative storage of coal gangue in China exceeds 7 billion tons, covering an area of approximately 70 km². The engineering application of unburned coal gangue is mainly utilized as concrete aggregate or cement production after the overfire process. However, it is prone to environmental pollution and has limited consumption. Using unburned coal gangue as roadbed filling not only alleviates the difficulty of land acquisition and soil collection for road constructions in mining areas, but also consumes a large amount of accumulated unburned coal gangue. This study conducts research on the road performance of unburned coal gangue. A series of laboratory tests have been performed to determine the physical and chemical properties of the unburned coal gangue and its performance as a filling material in cold regions. The influence of compaction effort, clay content, and number of freezing–thawing cycles on the mechanical performance of the unburned coal gangue was investigated. The typical unburned coal gangue in the Heilongjiang region is mainly composed of SiO₂, Al₂O₃, and Fe₂O₃, which accounts for approximately 91% of the total mass. The unburned coal gangue meets the minimum CBR requirement of 8% after 7 freezing–thawing cycles. This study helps fully and reasonably utilize typical unburned coal gangue in the local area, providing technical support for achieving the overall goal of “green development, conservation and intensification, and low-carbon environmental protection”.

To analyze the excavation stability and reasonable reinforcement measures of cutting slope with a goaf collapsed roadway and collapsed mining face, the finite element software Midas GTS NX was used to model and analyze the change in the slope stability coefficient under different excavation slope ratios. Combined with the scope of the project land, it is proposed that the slope ratio of grades 1–3 (close to the top of the cut) is 1:1.5, while the slope ratio of grades 4–6 (close to the bottom of the cut) is 1:1, to excavate the slope. During the excavation process, the change in the plastic zone after each level of slope excavation was further analyzed, and the control variable method was used to analyze the influence of the collapsed roadway and the collapsed mining face on the slope stability. We found that the collapsed mining face was one of the main factors affecting the stability of the slope. During the reinforcement of the slope, the reinforcement effects of different schemes were analyzed, and we found that the slope can be stabilized by reinforcement of the third- and fourth-level slopes adjacent to the collapsed mining face. In this study, the old goaf and cutting slope excavation are combined, and the stability of slope excavation with a goaf collapsed roadway and collapsed mining face is analyzed by coupling. This research provides a scientific basis for the stability analysis of cutting slope excavation in old goafs in the future and has great practical engineering significance.