Subgrades may be subjected to intermittent cyclic loads such as traffic loads. Under these loading conditions, excess pore water pressure can accumulate in clayey soils during cyclic loading period and dissipate during resting time. The deformation behaviour of clayey soil after reconsolidation process may be different from that under consecutive cyclic loading. A series of undrained cyclic triaxial tests, including reconsolidation process between cyclic loading stages, were performed on kaolin clay. The axial strain accumulation, excess pore water pressure accumulation, deviatoric stress-strain loop and resilience modulus under different cyclic stress ratios, initial confining pressures and degrees of reconsolidation were discussed and presented. Test results show that the reconsolidation process has significant effects on the deformation characteristics of clayey soil. The coupling effects of change of void ratio and effective mean stress result in a non-monotonic relationship between normalised total axial strain and degree of reconsolidation. In addition, an increase in the degree of reconsolidation leads to an increase in the normalised excess pore water pressure increment during 2nd cyclic loading stage, regardless of cyclic stress ratio and initial confining pressure. Furthermore, the steady resilience modulus at the end of each cyclic loading stage depends on the effective cyclic stress ratio and initial confining pressure, irrespective of reconsolidation process.

This study investigated the impact of adding different proportions of ground granulated blast furnace slag (GGBS) on the engineering properties of expansive soils. GGBS proportions ranging from 0 to 40% by weight of soil were tested. A comprehensive series of experiments was conducted to determine the consistency limits, modified compaction characteristics, unconfined compression test of soil, and California bearing ratio (CBR) values under varied curing conditions of the stabilized soil mixtures. The results indicated that a GGBS content of 30% provided the optimum improvement, enhancing the strength and stability of the material. Additionally, a laboratory dynamic cone penetration test was performed inside a CBR mould to further examine the improved performance of the expansive soil samples with incorporated GGBS. The findings demonstrate that GGBS can significantly enhance the engineering behavior of expansive soils when added at 30% by weight. The research underscores the significant positive impact of GGBS on the engineering properties of expansive soils, offering an effective and environmentally friendly means of disposing of steel industry waste.

In practical engineering, the magnitude of soil unloading rebound is closely related to the physical and mechanical properties of the soil. Therefore, there are significant differences in geological conditions among the different regions. As such, targeted research on the rebound law and calculation methods of foundation pits is needed. This article reports indoor experiments and numerical simulation methods which are used to study the trends and calculation methods of foundation pit rebound based on typical geological conditions in South China. Our findings are as follows. 1) At maximum consolidation stress ranging from 100 kPa to 400kPa, the maximum rebound rate of plain fill soil in typical soil layers is 0.0539-0.0704, the rebound rate of silty clay is 0.0373-0.0528, the rebound rate of coarse sand is 0.0296-0.0343, the rebound rate of gravelly cohesive soil is 0.0159-0.0305, the rebound rate of fully weathered granite is 0.0175-0.0344, and the rebound rate of strongly weathered granite is 0.0170-0.0379. 2) The rebound indices do not change with changes in the unloading ratio or initial consolidation stress. The rebound indices of the soil layer from top to bottom are 0.0143, 0.0119, 0.0077, 0.0096, 0.0083, and 0.0076, respectively, and a formula for calculating the rebound modulus of typical soil layers in South China was proposed. 3) The pore ratio of the soil after the end of the recompression process is lower than that which occurs after the first compression. The difference between the compression porosity ratio of the soil layer from top to bottom and the compression porosity ratio is 0.1, 0.08, 0.02, 0.06, 0.02, and 0.03, respectively. 4) The calculation of the depth of influence by the self-weight stress offset method is based on the theory of eliminating self-weight stress and unloading stress. The calculation depth is not affected by geological conditions, the formula for calculating the rebound modulus is consistent with the formula obtained from experimental research, and the calculation results are in good agreement with the numerical values.