Investigation on the seismic response of geogrid reinforced soil walls backfilled with cement-fiber-treated soil through 1-g shaking table tests

2021 ◽  
pp. 1-54
Author(s):  
A.M. Safaee ◽  
A. Mahboubi ◽  
A. Noorzad

Improving the characteristics of local low-strength soils at the construction site is one of the appropriate approaches to employ the soils as a backfill of geogrid reinforced soil (GRS) walls. In this study, the fiber-cement-treated sand-silt mixture was used as the backfill of walls. The post-earthquake performance of the walls was evaluated by applying the sinusoidal waves on 1-m high reduced-scale physical models and conducting a series of 1-g shaking table tests. A comparison of the wall models constructed with treated and untreated backfill indicated the advantages of geogrid-reinforced fiber-cement-treated soil walls subjected to strong ground motion. The results revealed the better behavior of the wall models backfilled with treated soil mixtures under dynamic loading. Such improved performance was more evident in (1) deformation responses, including the lateral displacement of wall facing, deformation mode, failure surfaces, and settlement of backfill surface and (2) acceleration response in different locations, including facing, reinforced, and retained zone of walls.

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Sihan Li ◽  
Xiaoguang Cai ◽  
Liping Jing ◽  
Honglu Xu ◽  
Xin Huang ◽  
...  

This paper presents experimental results from shaking table tests on two reduced-scale geogrid reinforced soil-retaining walls (RSRWs) constructed using standard soil, modular facing blocks, and uniaxial geogrid reinforcement to investigate the distribution of the geogrid strain and the mode of potential failure surface for dynamic loading conditions. Similitude relationships for shaking table tests in a 1 g gravitational field were used to scale the specimen geometry, applied characteristics of the earthquake motions. The lateral displacement of the top model is sufficiently large for the top-model block to fall down, and the RSRW is thus destroyed. The tensile strain at the lower part is greater than that at the upper part of the RSRW. The tensile strain in different layers for two-tiered RSRW is consistent with single-step RSRW. On comparing the measured maximum tensile strain lines of the geogrid with the result of the existing calculation method of the potential failure surface, it can be observed that the existing partial calculation method is conservative. Based on the calculation methods of various potential failure surfaces and the measured data, the use of a two-tiered fold-line failure surface is proposed for the two-tiered RSRW while taking into consideration the width of the platform. And it is advised that the failure surface calculation method of BS8006 be used as the calculation method for the potential failure surface of the single-step RSRW under dynamic motion.


Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.


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