Microzonation of Liquefaction Hazard using Liquefaction Index in Babol City

Liquefactio

Liquefaction assessment by microtremor measurements in Babol city

The recent researchers have discovered microtremor applications for evaluation of the liquefaction potential. Microtremor measurement is a fast, applicable and cost-effective method with extensive applications. In the present research the liquefaction potential has been reviewed by utilization of microtremor measurement results in Babol city. By using the fundamental frequency and amplification factor, the value of vulnerability index (Kg) was calculated and the liquefaction potential has been evaluated. For controlling the accuracy of this method, its output has compared with the results of Seed and Idriss method in 30 excavated boreholes within the study area. These two methods show an acceptable conformity with each other. Also, the artificial neural network (ANN) with different inputs was trained. Regarding the results of the three methods, we can conclude the threshold value of liquefaction potential is Kg=5. By reviewing and comparing these three methods, it will be observed that microtremors have the capability of assessing the liquefaction potential with desirable accuracy

1- Geoinvironmental Disasters.pdf

Background: During an earthquake, significant damage can result due to instability of the soil in the area affected<br>by internal seismic waves. Liquefaction is known as one of the major causes of ground failure due to the<br>earthquake. Various procedures have been classified for assessing liquefaction phenomenon into two main groups,<br>including the deterministic and probabilistic approaches.<br>Results: Four deterministic methods and one probabilistic approach, which is a reliability procedure are considered for<br>assessing the liquefaction potential in Babol City. The main purpose of this comprehensive research is to evaluate the<br>liquefaction potential and to determine the validation and accuracy of the reliability approach. For this purpose, 60<br>boreholes including almost 600 field records in different parts of Babol City are analyzed and liquefaction and nonliquefaction areas are identified. Microzonation maps are provided by result analysis of the deterministic and<br>probabilistic procedures. Finally, a 2D borderline, including (CSR) and (Nspt) is obtained by analyzing all data.<br>Conclusions: The present study illustrates that the evaluation of liquefaction potential by using reliability approach is accurate and this procedure can be recognized as one of the best methods for assessing liquefaction. The map obtained utilizing a reliability approach and the borderline provided in this study, can be utilized for recognizing liquefaction and non-liquefaction areas based on different safety factor and probabilistic procedures

A study of the Effect of Soil Improvement Based on the Numerical Site Response Analysis of Nat-ural Ground in Babol City

A series of numerical calculations have been performed to investigate the effect of soil improvement on seismic site response. Seismic site response analyses were also performed using data collected from a study area in Babol city. The improved site is a composite ground and has more or less different mechan-ical properties than the natural ground. In this research, the influence of the elastic modulus of the pile, the pile distance ratio, ground motion input, distance to fault rupture, and PGA of the earthquakes on seismic response characteristics are especially investigated. The results reveal that the values of the PGA and amplification factor on the surface of the natural and improved grounds depend strongly on the fun-damental period of the site, the predominant period, and the intensity of the ground motion input. The acceleration response spectra also are affected by the characteristics of ground motion input and soil layers. Changing the pile distance ratio doesn't have a significant effect on the seismic response of the site

Reliability analysis of soil liquefaction based on standard penetration: a case study in Babol city

There are more probabilistic and deterministic<br>liquefaction evaluation procedures in order to judge<br>whether liquefaction will occur or not. A review of this<br>approach reveals that there is a need for a comprehensive<br>procedure that accounts for different sources of uncertainty<br>in liquefaction evaluation. In fact, for the same set of input<br>parameters, different methods provide different factors of<br>safety and/or probabilities of liquefaction. To account for<br>the different uncertainties, including both the model and<br>measurement uncertainties, reliability analysis is necessary.<br>This paper has obtained information from Standard<br>Penetration Test (SPT) and some empirical approaches such<br>as: Seed et al, Highway bridge of Japan approach to soil<br>liquefaction, The Overseas Coastal Area Development<br>Institute of Japan (OCDI) and reliability method to<br>studying potential of liquefaction in soil of Babol city in the<br>north of Iran are compared. Evaluation potential of<br>liquefaction in soil of Babol city is an important issue since<br>the soil of some area contains sand, seismic area, increasing level of underground waters and consequently saturation of soil; therefore, one of the most important goals of this paper is to gain suitable recognition of liquefaction potential and find the most appropriate procedure of evaluation liquefaction potential to decrease related damages