In loess, expansive soil, soft soil and frozen soil, the engineering properties and particularity of engineering geological problems are related to the function of water. If the loess collapses when it meets water, the loess caves formed by the self-weight collapse of loess and groundwater erosion will often cause the destruction of engineering buildings and the sudden collapse of overlying soil or engineering buildings. .

Expansion and contraction of expansive soil due to water loss. If it expands and contracts for many times, the strength of the building will rapidly decline, which will lead to problems such as cracking, sinking and instability of engineering buildings built on expansive soil. Therefore, as long as the moisture in expansive soil changes, it will cause expansion and contraction deformation. Soft clay itself is in a soft-plastic-flowing state because of its high natural water content, poor water permeability and high compressibility, and its bearing capacity and shear strength are very low. Buildings built on soft soil foundation are damaged due to large deformation, poor water permeability and low bearing capacity. The formation of frozen soil must be related to water. The diseases in frozen soil areas are mainly frost heave and thaw settlement, which makes the engineering properties of frozen soil change greatly and the properties are poor. For example, when cutting is excavated in frozen soil area, the upper limit of frozen soil will be lowered, which will cause problems such as basement subsidence and slope collapse.

The engineering geological problems of the above-mentioned special soils are all related to water factors. Therefore, drainage is one of the effective measures to solve these special geotechnical engineering geological problems. Drainage can effectively alleviate or inhibit the collapsibility of loess and the occurrence of loess potholes; Drainage or water retention can effectively reduce or inhibit the expansion and contraction characteristics of expansive soil; Drainage can improve the consolidation strength, bearing capacity and bad properties of soft soil. Drainage can inhibit the occurrence of frost and improve the engineering quality of rock and soil in frozen soil area.

In a word, the engineering properties and engineering geological problems of special soil are closely and directly related to water factors. It is very important to solve these engineering geological problems, improve the engineering properties of special soil and eliminate water factors. .