Soil Properties

In the Soil Properties tab, you can enter the basic parameters for soil modeling. These settings apply regardless of whether the subsoil is defined as single-layered or multi-layered.

Subsoil

In this section, you can manually define specific soil properties. The input options include:

Soil conditions

In the list, you can select between drained and undrained soil conditions.

Concrete Foundations and Subsoil Conditions

Definition Type

The definition type determines how the soil structure is modeled for the geotechnical analysis. It is selected directly in the soil properties. The following variants are available:

1. Single-Layered Soil: The subsoil consists of a single homogeneous layer. Parameters such as thickness and material are defined manually.
2. Borehole: The soil layers are automatically taken from a stored borehole.
3. Soil Massif: The soil layers are automatically taken from a stored soil massif so that the correct soil layer is automatically assigned to each foundation

Soil Definition Types for Geotechnical Analysis

Soil Properties

The following parameters describe the geotechnical properties of the soil and form the basis for the design of concrete foundations.

Friction Angle

• Angle of soil friction δ_s,k

Here, you can define the friction angle between the foundation base and the soil. The following options are available for selection:

1. φ_k for in-situ concrete foundations
2. 2/3 φ_k for smooth precast foundations

• Angle of wall friction δ_w,k

The wall friction angle defines the friction angle for the side walls of the foundation. Options include:

1. -φ_k: Raw foundation wall
2. -2/3φ_k: Rough foundation wall
3. 0: Smooth foundation wall

Concrete Foundation and Friction Angle in Geotechnical Engineering

Ground Water

Depending on the definition type, the effect of ground water can be taken into account in two different ways:

1. Single-layered soil: Activate the Ground Water button to consider the effect of ground water. It is necessary to enter the depth of the groundwater level in the d_GWL text box.
2. Multi-layered soil – Borehole/soil – Soil massif: The groundwater level is automatically taken from the borehole if the borehole contains the groundwater level.

Self-Weight for Concrete Foundations

Earth Covering

Earth covering refers to a layer of soil or material above the top edge of the foundation.

1. Single-layered soil: The thickness c is entered manually if earth covering is to be taken into account.
3. Multi-layered soil – Borehole/Multi-layered soil – Soil massif: If the defined soil structure contains an earth covering, RFEM automatically calculates the efficiently covering thickness from the layer model. Manual input is not required here.

Important

To ensure that the self-weight of the earth covering is taken into account in the design calculation, it is necessary to activate the Self-weights for concrete foundations option in the load case. Then, you can select the Active earth covering check box in the Concrete Foundations tab.

Self-Weight for Concrete Foundations