GGU-AXPILE: General information on piles according to EA piles
The Recommendations of the Working Group on Piles (EAP) were published in April 2007. These recommendations allow the design of a large number of cored and driven piles via design tables. In these terms, the EAP represents current best practice. Annexes to the DIN 1054 will be replaced in the future by references to the EAP.
The central input values are the cone pressure qc of the CPT in cohesion less soils or the shear strength cu,k in cohesive soils. This empirical data is represented in the EAP by way of pile type-related tables. For example, for bored piles these are Tables 5.12 (cone resistance in cohesion less soils), 5.13 (skin friction in cohesion less soils), 5.14 (cone resistance in cohesive soils) and 5.15 (skin friction in cohesive soils). There are two values in each table cell, representing a lower and an upper value. The EAP recommends use of the lower values.
The EAP table data are stored in the GGU-AXPILE program and can be summarised in a legend for the selected pile type (see menu item "Output preferences/Empirical data table"). The following table shows an example of the table containing empirical data for a bored pile, as it is shown in the program.
In the previous calculation of bored piles, the values sig02, sig03, sig10 and tau (qb,k02, qb,k03, qb,k10, qs,k) had to be defined for each soil (see “Theoretical principles: Bored piles according to DIN 4014 and DIN 1054”). According to EA piles, these values are now determined automatically via qc and cu,k from the corresponding tables.
By specifying qc and cu,k, the program can also distinguish between load-bearing soil and non-load-bearing soil. This means that queries can now also be made with regard to integration into load-bearing layers. This is implemented in GGU-AXPILE, as are a large number of other safety queries.
In terms of the magnitude of the pile tip resistance and the pile skin friction, reductions are required for the analysis of pre-cast driven piles. They are defined in the EAP (Table 5.5) by means of adjustment factors. These adjustment factors are incorporated in GGU-AXPILE.
If soils with different tip pressures from the cone penetration test qc (cohesionless soils) or undrained shear strengths cuk (cohesive soils) are present in the zone of influence of the pile base, these values are averaged over an area above and below the pile base.Using the averaged value, the base resistance of the pile can be read from the tables in the Recommendations on Piling (see examples in Recommendations on Piling). If both cohesionless and cohesive soils are present, this method cannot be adopted. In this case, it is possible to determine the base resistance of the pile using qc and cuk for each stratum from the Recommendations on Piling tables and then to form the average.