2. Reference solution

2.1. Calculation method

The reference solution comes from example 4 in the Griffiths article [1].

The safety factor was calculated using both method SRM (« strength reduction method ») based on the finite element method and the traditional method assuming the sliding circles [2].

The results of both methods are consistent.

2.2. Benchmark result

By varying the parameter \(\lambda\) between 0.25 and 4, the variation in the safety factor is plotted as a function of the foundation-slope ratio, as illustrated in fig2-FS-varie.

During the hardening of the foundation, two mechanisms were identified of breakdowns shown by fig3a-mecanisme and fig3b-mecanisme.

In the case of a weak foundation, the sliding circle deepens in the foundation so that the slope slides in conjunction with the foundation. The safety factor increases proportionally. The transition state corresponds to \(\lambda =1.5\), at which point the safety factor no longer depends on the ownership of the foundation.