Thixotropy is the property of a soil that allows it to regain its shear strength after it has been remoulded or disturbed. When a soil is remoulded, its particles are rearranged and its structure is disrupted, resulting in a loss of shear strength. However, with time, the soil can regain its original shear strength due to the process of thixotropy.

Thixotropy is commonly observed in cohesive soils, such as clays, which consist of fine particles that can easily rearrange themselves. When the soil is subjected to a shearing force, the particles align and interlock, providing shear strength. However, when the soil is remoulded or disturbed, the particle alignment is disrupted, and the soil loses its shear strength.

The process of thixotropy involves the reformation of particle alignments and interlocking over time. As the soil particles settle and rearrange themselves, the soil gradually regains its shear strength. This phenomenon is attributed to the presence of water in the soil, which acts as a lubricant and allows the particles to move and reorient themselves. Over time, the water gradually dissipates and the soil particles become more compacted and interlocked, leading to the restoration of shear strength.

Thixotropy is an important property of soils, especially in engineering and construction applications. It allows the soil to recover its strength after it has been disturbed, ensuring the stability and performance of structures built on or with the soil. By understanding and accounting for thixotropy, engineers can design and construct foundations, retaining walls, and other structures that can withstand the effects of soil remoulding and regain their strength over time.

In conclusion, thixotropy is the property of a soil that enables it to regain its shear strength after remoulding. It is a result of the gradual reformation of particle alignments and interlocking over time. Thixotropy is an important consideration in engineering and construction to ensure the stability and performance of structures built on or with cohesive soils.