scholarly journals Assessment of Small Strain Dynamic Soil Properties of Railway site Agartala, India by Bender Element Tests

2021 ◽  
Author(s):  
Rajat Debnath ◽  
Rajib Saha ◽  
Sumanta Haldar
Keyword(s):  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Relationship ◽  
Small Strain ◽  
Response Analysis ◽  
Bender Element ◽  
Primary Input ◽  
Wide Range ◽  
Properties Of Soil ◽  
Dynamic Properties Of Soil

Abstract Small strain dynamic properties of soil is the primary input parameter in seismic ground response analysis studies. This study examines the small strain shear modulus (Gs or Gmax) and damping ratio (ξ) using bender element tests on subsoil samples along with evaluation of liquefaction potential (Sandy soil) collected from a railway construction site at Agartala, India. The objective of this study is to develop a database and empirical relationship on dynamic properties of soil Agartala which may help to carry out site specific seismic hazard studies of Agartala city. In present study, both undisturbed and disturbed soil samples were collected from twelve boreholes near the study area which is mainly of soft marshy ground with localized deposits of peat layer. Similar type of soil is often found in various parts of Agartala basin and other regions of India. Experimental results indicate that Vs, Gmax and ξ vary within a wide range depending upon the type of soil and a closed form empirical equation are proposed to calculate Gmax for different types of soil which would be applicable for evaluating dynamic properties for similar nature soil available across various sites of India.

scholarly journals Very-small to large strain dynamic behaviour of unsaturated sand in a wide range of suction

2020 ◽  
Vol 195 ◽  
pp. 03002
Author(s):  
Ali Akbar Karimezadeh ◽  
Fardin Jafarzadeh ◽  
Anthony Kwan Leung ◽  
Adel Ahmadinezhad
Keyword(s):  
Transition Zone ◽  
Unsaturated Soil ◽  
Simple Shear ◽  
Dynamic Properties ◽  
Large Strain ◽  
Damping Ratio ◽  
Small Strain ◽  
Soil Parameters ◽  
Static And Dynamic Analysis ◽  
Wide Range

Shear modulus (Gmax at very small strain and G at large strain) and constraint modulus at very small strain (M) are important soil parameters for static and dynamic analysis in geotechnical applications. However, these dynamic properties of unsaturated soil are rarely reported. In this study, a cyclic simple shear apparatus was newly-modified for allowing both the shear and constrained moduli at both very small and large strains to be measured. Benders or ultrasonic sensors were embedded in an unsaturated soil sample for transmitting/receiving shear- and pressure-wave, respectively. Two very-small-strain tests were conducted to determine the Gmax, M and soil damping ratio of a sand for a wide range of suction covering from the boundary-effect, transition and residual zone of the water retention curve of the sand. In addition, six large-strain cyclic simple shear tests were carried out to investigate G. The test results showed that Gmax and M were approximately constant before reaching the air-entry value, but there was a significant increase in Gmax as the sand dried further. Yet, M dropped within the transition zone, and interestingly when the suction was beyond the residual value, M increased. M along the wetting path was higher than that along the drying path. The damping ratio, on the other hand, first reduced before reaching the air-entry value, but it increased at the transition zone and then decreased within the residual zone. At large strain, G/Gmax also increased as suction increased until reaching the residual zone, beyond which the normalised value show substantial decreased.

scholarly journals Multi-Scale Study of The Small-Strain Damping Ratio of Fiber-Sand Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2476
Author(s):  
Haiwen Li ◽  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Dynamic Properties ◽  
Wide Spectrum ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Small Strain ◽  
Treatment Method ◽  
Fiber Content ◽  
Polypropylene Fibers ◽  
Test Results ◽  
Fiber Reinforced

The use of polypropylene fibers as a geosynthetic in infrastructures is a promising ground treatment method with applications in the enhancement of the bearing capacity of foundations, slope rehabilitation, strengthening of backfills, as well as the improvement of the seismic behavior of geo-systems. Despite the large number of studies published in the literature investigating the properties of fiber-reinforced soils, less attention has been given in the evaluation of the dynamic properties of these composites, especially in examining damping characteristics and the influence of fiber inclusion and content. In the present study, the effect of polypropylene fiber inclusion on the small-strain damping ratio of sands with different gradations and various particle shapes was investigated through resonant column (macroscopic) experiments. The macroscopic test results suggested that the damping ratio of the mixtures tended to increase with increasing fiber content. Accordingly, a new expression was proposed which considers the influence of fiber content in the estimation of the small-strain damping of polypropylene fiber-sand mixtures and it can be complementary of damping modeling from small-to-medium strains based on previously developed expressions in the regime of medium strains. Additional insights were attempted to be obtained on the energy dissipation and contribution of fibers of these composite materials by performing grain-scale tests which further supported the macroscopic experimental test results. It was also attempted to interpret, based on the grain-scale tests results, the influence of fiber inclusion in a wide spectrum of properties for fiber-reinforced sands providing some general inferences on the contribution of polypropylene fibers on the constitutive behavior of granular materials.

Shear modulus reduction and damping ratio curves for earth core materials of dams

2019 ◽  
Vol 56 (1) ◽  
pp. 14-22 ◽  
Author(s):  
DongSoon Park ◽  
Tadahiro Kishida
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Relationship ◽  
Embankment Dams ◽  
In Situ Data ◽  
Earth Core ◽  
Dynamic Analyses ◽  
Modulus Reduction ◽  
Core Materials

It is essential to obtain shear modulus reduction and damping ratio curves to perform dynamic analyses of earth-cored embankment dams. Many studies have been performed for dynamic properties of clayey soils, but they have been limited for earth core materials of dams. This study conducted resonant column tests to obtain shear modulus reduction (G/Gmax) and damping ratio (D) curves for 31 specimens (17 undisturbed and 14 remolded specimens) from 13 earth-cored embankment dams. Empirical G/Gmax and D curves are proposed for dynamic properties of clayey earth core materials. Fitting curves are provided by using the functional forms of the Ramberg–Osgood and Darendeli models. The observation shows that the undisturbed earth cores yield relatively higher G/Gmax and lower D curves than the remolded cores. G/Gmax curves of compacted earth cores are relatively higher than those of Vucetic and Dobry curves for a similar level of plasticity index. Uncertainty and bias are calculated by performing residual analysis, which shows that there is no clear bias in predicting G/Gmax and the uncertainties between undisturbed earth core materials and natural deposits are at a similar level. A proposed empirical relationship of G/Gmax and D curves for earth core materials can be utilized for dynamic analyses of embankment dams for cases where there is insufficient in situ data.

Dynamic properties of soil organic carbon in Hunan's Forests

2015 ◽  
Vol 35 (13) ◽  
Author(s):  
李斌 LI Bin ◽  
方晰 FANG Xi ◽  
李岩 LI Yan ◽  
项文化 XIANG Wenhua ◽  
田大伦 TIAN Dalun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Dynamic Properties ◽  
Properties Of Soil ◽  
Dynamic Properties Of Soil

scholarly journals A semi-empirical relationship for the small-strain shear modulus of soft clays

2019 ◽  
Vol 92 ◽  
pp. 04005
Author(s):  
Vashish Taukoor ◽  
Cassandra J. Rutherford ◽  
Scott M. Olson
Keyword(s):  
Shear Modulus ◽  
Effective Stress ◽  
Void Ratio ◽  
Empirical Relationship ◽  
Small Strain ◽  
High Plasticity ◽  
Bender Element ◽  
Stress History ◽  
Small Strain Shear Modulus ◽  
Semi Empirical

The small-strain shear modulus (Gmax) is a soil property that has many practical applications. The authors compiled a database of Gmax measurements for 40 normally consolidated to slightly overconsolidated low to high plasticity clays. Using these data, the authors propose a semi-empirical relationship between Gmax, effective stress (σ'v or σ'c), preconsolidation stress (σ'p) and in-situ void ratio (e0) for four ranges of plasticity index (Ip): Ip < 30%, 30% ≤ Ip < 50%, 50% ≤ Ip < 80% and 80% ≤ Ip < 120%. With results from bender element tests on a Gulf of Mexico clay subjected to multiple load-unload consolidation loops, the authors were able to validate the proposed relationships for 30% ≤ Ip < 50% and 50% ≤ Ip < 80%. The proposed relationship for 30% ≤ Ip < 50% and 50% ≤ Ip < 80% captures changes in laboratory Gmax resulting from variations in effective stress (σ'c), maximum past stress (σ'v,max), and void ratio. The proposed relationships are a simple and efficient tool that can provide independent insight on Gmax if the stress history of a clay is known, or on stress history if Gmax is known.

Test Study on the Dynamic Parameters of Compound Composite Foundation

2012 ◽  
Vol 450-451 ◽  
pp. 1548-1552
Author(s):  
Na Wang ◽  
Zhen Feng ◽  
Yong Da ◽  
Wei Lin
Keyword(s):  
Regression Analysis ◽  
Seismic Design ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Composite Foundation ◽  
Dynamic Parameters ◽  
Simple Method ◽  
Test Study ◽  
Wide Range

Influence of factors such as displacement ratio and confining pressure on the dynamic properties of composite specimen with GC pile and CFG pile was studied under a wide range of strains by regression analysis，a simple method for calculating the dynamic elastic modulus and damping ratio is Proposed and an empirical formula considering the mentioned factors above is also presented to provide a elementary reference for anti-seismic design of composite foundations with GC piles and CFG piles.

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