**3.2 Motions used in the analyses**

Building codes generally split possibility of earthquake levels into some groups, and the two of them have extensive use in geotechnical and earthquake engineering which are: (1) 2% chance of being exceeded in 50 years and (2) 10% chance of being exceeded in 50 years. They offer different response spectrum envelopes for each with the help of regional earthquake maps for the seismic design. To be used in the analysis, the possible local peak ground acceleration (PGA) was determined as 0.720 g for the studied area from the seismic maps which was just published in March 2018 by the Disaster and Emergency Management Authority (AFAD) under the Ministry of Interior in Turkey. Three different earthquakes happened in last

*Estimation of Excess Pore Pressure Generation and Nonlinear Site Response of Liquefied Areas DOI: http://dx.doi.org/10.5772/intechopen.88682*

20 years (Duzce, Kocaeli, and Van earthquakes) were chosen to produce possible regional earthquake scenarios. The details of the earthquakes used in the process are shown in **Table 5**.

All of the earthquakes can be considered as the big magnitude earthquakes as seen in the table. Two of the events were taken from the Pacific Earthquake Engineering Research Center (PEER) [28] and one from the Strong Motion Data Base of Turkey (SMDB-TR) [29], and all of them were scaled to the local PGA accordingly. **Figure 9** shows the scaled versions of the earthquakes, in other words possible earthquake schemes for the studied area for the probability of 10% chance of being exceeded in 50 years.

The duration of the earthquakes differs from 25 to 85 seconds, and PGAs were set to be 0.72 g for all of them. More high-frequency content is seen from top to


**Table 5.**

offered by the building codes, and the soil type of two borings is classified as ZE, and three of them are ZD. The fine content for the layers were obtained as well, and the variation is listed in the table. Layers have water content of 11–25%, and the unit weight of the soils samples laid in a range of 17.6–18.9 kN/m<sup>3</sup> throughout the profiles. Some triaxial tests were run in the laboratory to evaluate the strength of the sandy soils, and 33–38 degrees of friction angle along with 0–5 kPa cohesion were

*Geotechnical Engineering - Advances in Soil Mechanics and Foundation Engineering*

The dynamic properties (modulus reduction and damping behavior of soils at varying strains) of clays and sands were calculated adopting proposed models by Darendeli [26]. During the analyses, pore pressure generation was let to build up during cyclic loading in nonlinear analyses; however it was not possible by the frequency-dependent equivalent linear simulations. With the available information of the soil index properties, the required parameters were derived to model the pore

Building codes generally split possibility of earthquake levels into some groups, and the two of them have extensive use in geotechnical and earthquake engineering which are: (1) 2% chance of being exceeded in 50 years and (2) 10% chance of being exceeded in 50 years. They offer different response spectrum envelopes for each with the help of regional earthquake maps for the seismic design. To be used in the analysis, the possible local peak ground acceleration (PGA) was determined as 0.720 g for the studied area from the seismic maps which was just published in March 2018 by the Disaster and Emergency Management Authority (AFAD) under the Ministry of Interior in Turkey. Three different earthquakes happened in last

pressure generation behavior suggested by Matasovic and Vucetic [27].

detected.

**132**

**Figure 8.**

**3.2 Motions used in the analyses**

*Studied area and the active fault lines [29].*

*Reference earthquakes used in the analysis.*

**Figure 9.** *Scaled versions of the earthquake data.*

### *Geotechnical Engineering - Advances in Soil Mechanics and Foundation Engineering*

bottom of the figure, and these records were used as the base motions in the analyses.

the ground and the peak spectral accelerations, and maximum shear strains

*Estimation of Excess Pore Pressure Generation and Nonlinear Site Response of Liquefied Areas*

Regarding the surface acceleration predicted by two different approaches, there is a big deviation in the peaks and the time they occur. NL model shows that soil totally de-amplified the energy exerted by the motion, and the peak ground acceleration was noted around 0.25 g, whereas the peak-based acceleration was 0.72 g, and the main peaks happened around the similar time interval (3–5 seconds). However, an entirely different case was observed for the EL model. The prediction of the peak surface acceleration happened to be around 10 seconds extending the peakbased motion to 5–6 seconds, and not much de-amplification was noticed. In order to evaluate this behavioral diversity, the spectral acceleration at the surface was

The peak-based spectral acceleration (around 2 g) stays in a wide range of period between 0.1 and 0.8 seconds as seen in the figure. The NL model has compressed the behavior in terms of the size of peak ground and peak spectral accelerations. The model lessens the spectral acceleration 2–2.5 times at any period, whereas the EL model lengthened the peak spectral range to 0.9–1.8 seconds with almost no change in the amplitude. Another point about the EL model is that the initial flat part lasts longer than the base and NL model prediction. The last figure of the example set is the variation of the peak spectral acceleration and maximum shear

The difference between the models to estimate two parameters is concrete as observed from the figure. The peak-based acceleration was amplified a bit between 10 and 20 m and then de-amplified some for the rest of the profile by the EL model, whereas it was weakened all over the soil profile by the NL model. The soil profile was separated into three divisions, and it is supported by the related maximum shear strains at the same depths. It is obvious that two definite soil failures happened at the 8 m and 14 m according to the NL model, whereas the soil failures

*Peak spectral accelerations and maximum shear strains throughout the soil columns for the NL and EL models.*

strains through the soil column, and it is presented in **Figure 12**.

throughout the soil profile, respectively.

*DOI: http://dx.doi.org/10.5772/intechopen.88682*

presented below.

**Figure 12.**

**135**
