，可结合北京地区的相关背景和特点： Wet sink loess foundation Wet sink loess is a type of soil that is common in North China, and the Beijing area or even the North China Plain in particular has encountered and encountered a great deal of it. This type of soil is characterized by weak lateral and vertical shear strength, excessive water absorption and low compression strength, so it should be considered when constructing buildings in these areas and solutions adopted to ensure structural stability.
The origin of wet sink loess can be traced back to the Quaternary period. The origin of the soil was mainly a combination of wind-transported silt and clay particles that came from the adjoining mountain systems. During the Quaternary period, large igneous rocks were exposed to frost and wet erosion, which gradually reduced the rock size to loose soils, wet sink loess being one of the results.
As a result of their origin, the structure of loess soils consists of fine particles, including silt and clay, with no considerable bedding or layers. Their particle size is mainly concentrated in the silt and fine sand range 0.02-2mm, with a large amount of particles smaller than 0.004mm. The grains are angular, and the void ratio is equal to 1 or larger. The weak shear strength and low compression strength let the soil be highly susceptible to moisture under wet conditions and undergo physical changes, resulting in subsidence, collapse and the possible failure of structures built on the site.
The physical and mechanical properties of the wet sink loess are further affected by its thickness, depth, water content and consistently high water table. As the thickness of the weak soil increases, the shear strength of the soil decreases. The soil can also become very soft and plastic when it is unusually wet, making it difficult to construct structures on top as the poor mechanical properties make it prone to subsidence. It is also worth noting that when the moisture content of loess is between 0.3 and 0.5, the strength of the soil weakens significantly, and this type of soil is very susceptible to over-consolidation and liquefaction when there is an earthquake.
Given the characteristics of this type of soil in the Beijing area, excavation and deep foundations are often necessary. Before the construction, it is important to perform weak soil detection tests to identify the depth, depth and quality of the soil, and then select the appropriate foundation method based on the data collected. In addition to the traditional mud foundation and pile foundation construction methods, sensitive soil measures can also be adopted, such as pre-loose compaction and grouting, to enhance the load bearing capacity of the soil and protect the foundation from the potential problems subjected by weak soil.
To conclude, wet sink loess is a type of soil common to North China, particularly the Beijing area. This type of soil is characterized by weak lateral and vertical shear strength, excessive water absorption and low compression strength, so it is important to take these preliminary considerations into account when constructing buildings in these areas, whether for residential or commercial use. By performing weak soil detection tests prior to construction and taking appropriate sensitive soil measures, the load bearing capacity of the soil can be enhanced, thus minimising the risk of subsidence and possible failure of the structures.
