Soil Settlement SBR+ convinces with functional extensions

Just last November, FRILO expanded its product portfolio in foundation engineering to include the SBR+ Soil Settlement solution. In the course of the most recent Release 2021-2, the program, which precisely determines the time-delayed settlement of a building in any subsoil, has now been equipped with new, appealing functionalities. For example, a polygonal soil model can be automatically interpolated by defining drilling profiles.

 

Thanks to an unlimited superposition of linearly variable line and area loads, structural engineers can use the new FRILO Program "Soil Settlement SBR+" to calculate both constant and arbitrarily curved base stress profiles. As a result, not only settlement courses in the section, but also settlement depressions in the area can be mapped. In this way, the mutual influence of several foundations and load areas in the plane can be observed. This can be particularly important for the settlement calculation when building in existing structures. On the basis of DIN 4019/ÖNORM B 1997-1-2, SBR+ can also be used to provide evidence of the size and the time course of settlement and foundation tilting caused by changes in the volume or shape of the subsoil. In this calculation, the external loads can be modeled in the form of infinite area loads, arbitrarily positioned limited block loads or asymmetrical trapezoidal loads. The number of terrain loads, their type of action as well as the limit state to be considered and the design situation can be selected as required. The load cases are automatically superimposed. In addition, an excavation area can be freely defined in the program. Uplifts as a result of excavation relief can be calculated accordingly. The shares from immediate and consolidation setting are always calculated by default. Creeping can be added as an option.

Soil settlement from stresses

The analytical calculation method in the soil settlement solution SBR+ is based on the assumption of slack loads (structures). The indirect soil settlement calculation method is used. In this method, the subsoil stresses that are generated by a load are determined in the elastically isotropic half-space depending on the depth and the foundation geometry.

By assuming an elastically isotropic half-space, the theory of elasticity and thus the principle of superposition are fully valid. The proportional settlements in the observation point as a result of each individual load case can therefore be superimposed by adding them. The compressions in the soil in sub-layers are calculated on the basis of the calculated settlement-generating stress curve in the half-space. Real layer boundaries are taken into account. In the last step, the settlement is calculated by integrating the strains over the sub-layers mentioned up to a defined limit depth.

Interpolation of the soil layers from drilling profiles

The latest software update enables FRILO users to create a polygonal soil model by defining any number of drilling profiles, which is automatically interpolated from the information from the outcrops. The elevation of the top of the terrain and the individual layer boundaries are defined for each drilling profile. In addition, the geotechnical parameters of the respective layers can be determined. Basically, users can interpolate both the layer geometries and the soil properties of a single layer and thus model different stiffness ratios for one and the same layer. A linear interpolation is used for the automatic calculation of the soil model. The influence of a drilling profile on an observed section through the terrain decreases inversely proportionally with its distance.

Load transfer from the GEO and the FD+

The latest program version has another significant advantage for FRILO users. With the help of a load export, any number of foundation loads from the Building Model GEO and Foundation FD+ programs can be imported and superimposed at a freely definable point for a soil settlement calculation. In order to forward all the information required for the soil settlement calculation to SBR+, the global position of the foundations must be defined in the system input of the higher-level programs. In principle, any number of foundation positions can be exported from GEO and FD + to SBR+. To illustrate the linked positions, position couplings are created between the positions from GEO or FD+ and the SBR+ model. From the Building Model, only foundation loads from single and strip foundations can currently be transferred to SBR+. An extension to foundation slabs will be available in a subsequent version. In addition, an expansion of the function is planned, by means of which an application time can be assigned to each load, so that the time-settlement components of individual loads applied at different times can be superimposed. In this way, a more differentiated consideration of the time-settlement history could be made in order to obtain a realistic assessment of the abatement of the consolidation and the creep.

The evaluation of the results

The settlement can be output for any number of freely selectable design points. All stress influence values i, stress-settlement and time-settlement diagrams are graphically displayed for each load case and design point. Furthermore, a settlement depression can be displayed over the entire model area.

Find all the information you need to apply SBR+ in the programmes manual.

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