## 3 Results and Discussion
### The Effect of Consolidation on the Soil Response to Cyclic Loading
The \(M_{\Delta u}\) value had a similar characteristic, although the maximum value was achieved around cycle 40. In the case of samples 1.2 and 1.3, the resilient modulus also reached a maximum value around cycle 50 and then decreased. The maximum \(M_{r}\) was equal to 45.0 MPa, 64.5 MPa, and 70.3 MPa respectively. Figure 12: Cont. The excess pore water modulus followed the same pattern. After reaching the maximal value, \(M_{\Delta u}\) decreased, this characteristic was linear in the semi-logarithmic after cycle 100 in all three cases. On Figure 13 results of \(M_{r}\) and \(M_{\Delta u}\) calculations for \(K_{0}\) consolidated samples are presented. The modulus characteristics were different from the characteristics that were observed in the case of the samples consolidated in an isotropic manner. Both modulus values first rose to around the 10 th cycle and then started to decrease. When the local minimum was reached in cycle 800 for sample 2.1 and in the 500 th cycle for sample 2.2 the soil resilient modulus started to increase. The \(M_{\Delta u}\) followed the same pattern but it preceded the \(M_{r}\) value change. This is helpful information when performing the stiffness change forecasting. The hardening process, which is indicated by the resilient modulus growth, was in both cases going to end. The question was if in example test 2.2 the resilient modulus would decrease again. Similar phenomena could be observed in the case of sample 2.5 where after numerous cycles, the soil resilient modulus was reaching its lowest value (around cycle 3000) and then rose again. During the test 2.3 the plastic strain rate was the lowest. Therefore, the modulus characteristic was less obvious than in the previously mentioned test. Nevertheless, two local minima of modulus value could be observed. Test 2.4 in which the CSR value was the highest shows that the resilient modulus, as well as the excess pore water pressure modulus, decreased. The local characteristic change might be spotted around cycle 5000 but there was no stiffness increase after this event. Samples with high CSR value had a similar pattern of responding to cyclic loading. We can see that the \(M_{\Delta u}\) value started to decrease, which meant that for the same amount of strain the pore pressure growth was smaller than in previous cycles and which meant that the effective stresses would increase. This might result in another phase of softening or might indicate that the soil achieved some state of equilibrium. Nevertheless, it is worth to note that the previous phase of softening and hardening took around 1000 cycles and now the repeating of the process would take many more cycles to occur. Figure 12: Resilient modulus and excess pore water pressure modulus change during the cyclic loading for isotropic consolidated samples: (**a**) \(\sigma^{\prime}_{3,0}=45\) kPa, (**b**) \(\sigma^{\prime}_{3,0}=90\) kPa, and (**c**) \(\sigma^{\prime}_{3,0}=135\) kPa. Figure 13: _Cont._  
The pore pressure build-up based on stress-controlled cyclic stress can be analyzed based on the empirical models. This model is able to analyze excess pore water pressure with the number of cycles to a certain event, which in non-cohesive soils is liquefaction. In the case of cohesive soils, the pore  
Figure 13: Resilient modulus and excess pore water pressure modulus change during the cyclic loading for \(K_{0}\) consolidated samples: (**a**) \(\sigma^{\prime}{}_{3,0}\) = 65.0 kPa, (**b**) \(\sigma^{\prime}{}_{3,0}\) = 125.0 kPa (**c**) \(\sigma^{\prime}{}_{3,0}\) = 139.7 kPa, (**d**) \(\sigma^{\prime}{}_{3,0}\) = 94.2 kPa, and (**e**) \(\sigma^{\prime}{}_{3,0}\) = 44.9 kPa. pressure analysis can be conducted to maximal pore pressure occurrence. The parameter that governs this analysis is pore pressure ratio, which can be presented as:  
Figure 9:0  
where the \(\Delta u_{max}\) is the maximum pore pressure in one cycle. The pore pressure empirical models were developed over the years. One of the best known is the pore pressure model developed by [PERSON] et al.