Particle shape: The more irregular the particle shape and the more obvious the edges and corners, the less tightly arranged and the greater the porosity.

Arrangement: Cubes are the loosest, tetrahedrons are the most dense, and are mostly between 0.25 and 0.47 in nature.

Particle sorting degree: The better the sorting, the greater the porosity; the worse the sorting, the smaller the porosity (when the sorting is poor, small particles will fill in the pores of large particles)

Particle shape and cementitious filler: mainly clay soil, structure and secondary pores are often important factors affecting porosity

Particle size: The larger the particles, the larger the pores

Arrangement: Reference porosity

Structural and secondary pores: cohesive soils

The ratio of the weight of water contained in the pores of loose rock (Gw) to the weight of dry rock (Gs) is called gravimetric water content.

The ratio of the volume of water (Vw) to the volume of rock including pores (V) is called volumetric water content.

The influence of lithology on water supply: mainly manifested in the size and number of gaps.

Influence of initial groundwater level burial depth: When the initial groundwater level burial depth is less than the maximum capillary rise height, after the groundwater level drops, part of the gravity water will be converted into supporting capillary water and remain above the groundwater level, thus causing the water supply to deviate. Small.

When the groundwater level decline rate is large, the water supply degree is small. For homogeneous loose rocks with relatively fine particles, only when the initial water level burial depth is large enough and the water level decline rate is very slow can the water release be relatively sufficient and the water supply degree reach its theoretical maximum value.

The relationship between water supply, water retention and porosity is: water supply, water retention = porosity.

Influencing factors

Definition: Water molecules outside the solid surface-bound water layer are affected by gravity greater than the attraction of the solid surface and operate under the influence of gravity, which is gravity water.

Capillary action: When a glass capillary tube is inserted into the water, the water surface in the capillary tube will rise to a certain height. This is the capillary phenomenon that occurs at the interface of solid, liquid, and gas.

Supported capillary water: Due to the action of capillary force, water rises from the groundwater surface along the small pores to a certain height, forming a capillary water zone. The lower part of the capillary water in this zone is supported by the groundwater surface, so it is called supported capillary water.

Suspended capillary water: When fine-grained layers and coarse-grained layers alternate to form layers, under certain conditions (such as a drop in water level), due to the capillary force of the upper and lower menisci, water that is not connected to the groundwater surface will remain in the fine soil layer. Capillary water, this kind of capillary water is called hanging capillary water.