Evaluation of Dynamic Properties and Ground-Response Analysis of Soil Reinforced with Cement and Biopolymer

Abstract

In Korea, earthquakes have continued to occur even after the occurrence of Gyeongju and Pohang earthquakes of 2016 and 2017, respectively, raising awareness of earthquakes. Because earthquakes cause damage to not only structures but also humans, it is essential to improve the seismic performance and design earthquake-resistant structures to minimize earthquake damages. If the seismic performance of a structure is improved through ground improvement and reinforcement, ground response analysis should be performed considering the dynamic properties of the site of the structure. In addition, cement has been widely used as a material for ground improvement, but recently, ground improvement methods in which biopolymers are utilized for ecofriendly construction have been investigated extensively. However, studies on the changes in the dynamic properties of ground improved using biopolymers, and the ground-response analysis has not been investigated in detail. In this study, resonant column tests were performed using samples mixed with cement and sodium alginate to evaluate the effects o f ground improvement using a biopolymer. In addition, the dynamic properties of the improved samples were adopted in performing the ground response analysis, which demonstrated confirmed the ground stability after ground improvement. From the results, the ground dynamic properties, shear modulus, and damping ratio were influenced when the biopolymer and cement were mixed with the soil. Furthermore, the ground response analysis confirmed that the maximum ground acceleration on the surface decreased.

Influence of Seismic Loads Considering Soil Properties and Wave Passage Effect on the Seismic Response of a Multi-Span PSC Girder Bridge

“…The shear wave velocity of the bedrock was 500 m/s, 571 m/s, In order to estimate the seismic load considering the soil properties of the bridge construction area, an equivalent linear seismic site response analysis was carried out. Equivalent linear ground response analysis is a linear analysis method that performs iterative calculations to consider the nonlinear dynamic properties of the soil, and was performed using the commercial program DEEPSOIL [35]. Considering the soil properties of the bridge's installation area, the seismic load with a peak acceleration of 0.301 g modified to meet the U.S. NRC (Seismic Load 2), as shown in Figure 9a, was amplified by ~35.0% and transformed into a seismic load with a peak acceleration of 0.406 g (Seismic Load 3).…”

“…The seismic loads from the bedrock to the ground surface can be amplified or diminished depending on the properties of the soil. Therefore, it is necessary to accurately estimate the seismic load transmitted to the ground surface by performing a ground response analysis that reflects the properties of the soil for the seismic load observed in the bedrock [35]. The location of the bridge considered in this study was randomly selected, When comparing the design response spectrum prepared by complying with the U.S. NRC standard and the response spectrum calculated by the Seismic Load 1, it was observed that the response spectrum was up to 45.0% larger than the design response spectrum in intervals below 1 Hz.…”

“…Therefore, it is necessary to accurately estimate the seismic load transmitted to the ground surface by performing a ground response analysis that reflects the properties of the soil for the seismic load observed in the bedrock [35]. The location of the bridge considered in this study was randomly selected, and the soil properties at the bridge site referred to the study of Ahn et al [35]. The ground consisted of granite weathered residual soil of ~5.0 m thickness, silt sand of ~7.0 m thickness, and a bedrock layer.…”

“…Sci. 2022,12, x FOR PEER REVIEW 7 of 16and the soil properties at the bridge site referred to the study of Ahn et al[35]. The ground consisted of granite weathered residual soil of ~5.0 m thickness, silt sand of ~7.0 m thickness, and a bedrock layer.…”