The approach using substitute foundation, the approach using punching shear failure and the approach using shear surface are introduced. Three approaches were applied to design foundation on inhomogeneous subsoil for two cases: stronger soil underlain by weaker soil and vice versa. Meyerhof and Hanna prescribe to determine adhesive force and passive force per unit length of the vertical planes crossing foundation sidewall. By Meyerhof and Hanna, adhesive force depends on cohesion of stronger layer and also on ratio between bearing capacity of stronger soil and weaker soil.
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Non-dimensional coefficients of inclination of a load induced by the H horizontal force equal:. Full Pressiometric Calculations are based on a user-defined curve as a result of on-site pressiometric research. Soil type is a significant parameter on the reference level of the foundation.
The soil type determines coefficients used in the calculations of load capacity and are adopted based on appendix E. Calculations of the load capacity value qu are performed based on section 3. The foundation depth is assumed as the minimum foundation depth Dmin less the depth d the disregarded part of the foundation depth. Fascicule 62 Titre 62 The general load capacity condition can be expressed as follows:. All values in the above formula are adopted according to the formula, based on section B.
Stress Pressiometric The soil load capacity for this method is adopted based on a user-defined value. The user-defined allowable characteristic qu value, ULS or SLS, is always converted to the characteristic value qu, and next, based on that value the limit stress value qlim is calculated according to the formulas: DTU If rectification is selected, rectification of a user-specified value due to geometry and loads is performed. Real dimensions of the foundation, such as the influence of horizontal loads and moments eccentricities are taken into account.
This is reflected in calculations of the coefficients kp, idb. The soil type determines coefficients used in the calculations of load capacity and is adopted based on appendix E. Load capacity value calculation proceeds as follows. For conditions with drainage, formula B.
Dimensionless factors of the shape are equal to:. Dimensionless factors of the load inclination resulting from the horizontal force H parallel to the longer and to the shorter sides, respectively, are equal to:. Coefficients of the foundation depth equal: where: For conditions without drainage, formula B. Dimensionless factor of the load inclination resulting from the horizontal force H is equal to: Note that the soil parameter: Cohesion without drainage - c u is applied here.
EN EC 7 Analysis of the load capacity of the soil is based on points 6. The coefficient can be modified in Job preferences. The load capacity value calculation is carried out in the following way: Load capacity value calculation proceeds as follows. Dimensionless factors of the load inclination resulting from the horizontal force H parallel to the longer and to the shorter sides, respectively, are equal to: Coefficients of the foundation depth equal: where: For conditions without drainage, formula B.
Partial coefficients for EN EC 7 For the EN code, there is a possibility to modify the partial coefficients for the R pressure and resistance and M soil parameters sets 2. Default values of the parameters can be found in the Job preferences. The general load capacity condition: can be made more rigorous by introduction of a safety factor greater than 1. Calculation of the load capacity value proceeds as follows Z :. Dimensionless factors of the load capacity are equal to:.
Dimensionless factors i are determined on the basis of the code nomograms fig. SNiP 2. As a result of design the reliability factor of a structure is obtained, which equals:.
Calculation of the load capacity value proceeds as follows 16 :. Dimensionless factors of load capacity N are calculated according to table 7 of the code. Linear interpolation between values is performed. The dimensionless factors of shape x are calculated as follows 17 :.
Comparison of Spread Foundation Design in Case of Inhomogeneous Subsoil