In this survey many surface and subsurface specimens have collected from different parts of playa for laboratory tests (such as: soluble material, Aterberg limit, Hydrometer, direct shear, porosity and etc.) to determining geological engineering characteristics of the area. Many profiles of collapse and settlement parts have made to show the agent of damages. As a general rule two layer is determine in this area. The upper layer is called ?Salt layer with high porosity? and the lower layer is called ?High saline soft black mud? The component and engineering characteristics of each layer is mentioned in the main text.
Results show that the porosity and amount of solution material especially in top layer is extremely high, in other hand the rate of solubility and leaching of this layer is very high. Thus a light rainfall can solve a large amount of this material, omitting a big volume of sub grade and cause to collapse construction material of the road(fig 1). The lower layer is very low in plastic characteristics, weak in strength and high in soluble material. This layer has classified to high soluble soils and intermediate in liquefiable soil.