Define thixotropy of soil

Thixotropy is the property of certain soils that, when disturbed or remolded, will temporarily lose strength and become more fluid. However, if left undisturbed, the soil will regain its strength over time. This is due to the reorientation of the soil particles and the re-establishment of the soil structure.

Thixotropy is most commonly observed in clay soils, which are composed of small, plate-like particles that can easily slide past each other. When clay soil is disturbed, the particles become randomly oriented and the soil structure is disrupted. This causes the soil to lose strength and become more fluid. However, over time, the particles will slowly reorient themselves and the soil structure will be restored. This process of reorientation and restoration of strength is known as thixotropy.

Thixotropy can have important implications for the engineering of structures that are built on or in clay soils. For example, if a foundation is built on a thixotropic clay soil, it is important to allow the soil to rest for a period of time before loading the foundation. This will allow the soil to regain its strength and reduce the risk of settlement or failure.

Here are some of the key features of thixotropy in soil

It is a reversible process. When the shear stress is removed, the thixotropic material will regain its original viscosity.

It is time-dependent. The rate at which the viscosity decreases and then increases again depends on the time that the material is subjected to shear stress.

It is not affected by temperature. The thixotropic behavior of a material is the same at different temperatures.

Thixotropy is a complex phenomenon that is not fully understood. However, it is an important property of some soils that must be considered in engineering design.