Research progress on disturbance mechanisms, evaluation methods and control measures for sampling of soft clay

The soft clay, characterized by high moisture content, strong compressibility and high sensitivity, is prone to disturbance during the sampling process, resulting in significant changes in the strength and deformation characteristics of soils. Understanding the mechanical mechanism behind sampling disturbance, reducing its impact and accurately evaluating the sample quality are crucial for determining the representative soil parameters in engineering design. To address these issues, the current researches on sampling disturbance in soft clay are summarized, including the mechanical mechanisms of sampling disturbance, the macroscopic and microscopic effects, the methods for the sample quality evaluation and the strategies to reduce disturbance. The researches show that there are abundant results on the macroscopic mechanical mechanisms of sampling disturbance. However, there is a lack of corresponding microscopic experimental evidence and analysis to support these macroscopic results. Furthermore, the most existing quality evaluation indices are designed for the clay and may not applicable to the low-plasticity intermediate soils such as silty clay and silt. Currently, there is still no unified quality evaluation system for the soil samples with varying properties. The reconsolidation methods can effectively reduce the stress release during the soil sampling process, but they cannot restore the soil structure damaged by sampling disturbance. Based on this, four suggestions and prospects for future researches are proposed.