# The Effect of the Water Table on the Bearing Capacity of a Shallow Foundation
## 3 Influence of Immersion on the Bearing Capacity of Shallow Buried Foundation  
The prediction of the immersion range of the reservoir is to calculate the stagnant groundwater height through the corresponding formula or seepage software and predict the  
Figure 3: Variation curve of LTC2\(-\)4 sample: (**a**) compression index with saturation; (**b**) consolidation quick shear index with saturation.  
Figure 2: Variation curve of LTC1\(-\)1 sample: (**a**) compression index with saturation; (**b**) consolidation quick shear index with saturation.  
groundwater return level elevation. The backwater elevation in a certain area is compared with the burial depth of the critical groundwater level; when the burial depth is higher than the critical groundwater level, it can be considered that the immersion phenomenon occurs. Therefore, determining a reasonable and effective immersion critical groundwater level is one of the key scientific issues in reservoir immersion impact assessment.  
According to the _Code for Hydropower Engineering Geological Investigation (GB50287-2006)_[41], the capillary rise height plus the depth of the building foundation is used as the critical burial depth of the building immersed in groundwater. The _Code for Engineering Geological Investigation of Water Resources and Hydropower (GB 50487-2008)_[42] has two standards, the living environment standard and the building safety standard. When the living environment is used as the standard, the critical burial depth of immersed groundwater is equal to the capillary rise of the topsoil. When the safety of the building is taken as the standard, the value of the critical burial depth of immersion groundwater is equal to the depth of the building foundation plus the capillary rise.  
From the experimental research results of the effect of different saturation on soil mechanical properties in Section 2.2, it can be seen that with the rise of the groundwater level, the water content of the soil gradually increases, and the soil changes from an unsaturated state to a saturated state. The compressive index increases, the compressive modulus, cohesion, and internal friction angle also decrease gradually, the soil gradually softens, and the shear strength decreases, which leads to the decrease in the bearing capacity of the foundation and the increase of the foundation deformation. However, the impact assessment of building immersion in the code does not consider the impact of immersion on the bearing capacity of the foundation. That is, the depth of the safe impact of groundwater level rise on the stability of the building foundation is not considered. For low liquid limit clay foundations, after the groundwater rises into the foundation bearing layer, it will impact the bearing capacity and deformation stability of the building foundation, and its degree will gradually become serious with the rise of the groundwater level.  
In this section, according to the load type, foundation type, and foundation buried depth of the building, the self-weight stress, additional stress, and foundation bearing capacity of the foundation at different buried depths of groundwater are analyzed and calculated according to the different depths of the groundwater level below the base. Based on the safety sensitivity analysis of the building foundation, an appropriate method to determine the critical buried depth of groundwater is sought. The typical building foundation of Luohuang Town in the immersion area of Xiaonanhai reservoir was analyzed as an example, which provides a strong basis for the delimitation of the treatment scope of immersion buildings in the reservoir area.