scholarly journals The New Empirical Equation Describing Damping Phenomenon in Dynamically Loaded Subgrade Cohesive Soils

2019 ◽  
Vol 9 (21) ◽  
pp. 4518 ◽  
Author(s):  
Soból ◽  
Głuchowski ◽  
Szymański ◽  
Sas
Keyword(s):  
Shear Strain ◽  
Effective Stress ◽  
Damping Ratio ◽  
Strain Range ◽  
Cohesive Soil ◽  
Plasticity Index ◽  
Dynamical Analysis ◽  
Soil Parameters ◽  
Cohesive Soils ◽  
Resonant Column Device

The damping ratio (D) is one of the key soil parameters in geotechnical issues where the soil is subjected to dynamic loads, like machines foundation, city tram and subway traffic, and driving of sheet pile or precast pile. Each of the abovementioned geotechnical problems is connected with significant damping, so its effect should be included in the dynamical analysis. Therefore, this article focuses on the damping phenomenon in cohesive soils from the capital of Poland, which is described by damping ratio (D). In this research, a set of the damping tests by free vibration method in resonant column device were conducted, and the influence of four selected factors, i.e., shear strain (γ), effective stress (p’), plasticity index (PI), and void ratio (e) on damping ratio in wide strain range was investigated and discussed. Based on the laboratory tests, the shear strain has the most impacts on the damping ratio characteristics; the plasticity index and the effective stress also have a significant influence. Based on the performed analysis, the authors propose the empirical equations with two sets of variables, the first for low and medium cohesive soil (PI < 20%) and the second for very cohesive soils (PI > 20%).

Effective stress vane shear strength correction factor correlations

1994 ◽  
Vol 31 (3) ◽  
pp. 335-342 ◽  
Author(s):  
Peter H. Morris ◽  
David J. Williams
Keyword(s):  
Shear Strength ◽  
Correction Factor ◽  
Effective Stress ◽  
Liquid Limit ◽  
Plasticity Index ◽  
Soil Parameters ◽  
In Situ Stresses ◽  
Rate Effects ◽  
Made In

A recent effective stress model of vane shear strength testing in soils can relate measured torques to vane shear strengths using theoretical analysis in terms of effective stress parameters. The strength estimates are based on known in situ stresses and soil parameters derived from laboratory testing. The model may be applied, for example, in obtaining theoretical estimates of conventional undrained vane shear strengths for comparison with field data and for use in stability analyses. However, the model incorporates a correction factor μv, analogous to Bjerrum's field vane shear strength correction factor μ, intended to compensate for pore-pressure and shearing-rate effects. This correction factor must be evaluated before reliable torque or shear strength estimates can be made in any given case. To facilitate this, the paper presents correlations of μv with both liquid limit and plasticity index, based on world-wide data from clays and silts. The correlations are compared with independent data from Norwegian clays. Key words : clay, correction factor, effective stress, liquid limit, plasticity index, silt, vane shear strength.

scholarly journals Dynamic Properties of Sand-Sawdust Mixture for Modeling Deposit Soil

2019 ◽  
Vol 9 (18) ◽  
pp. 3863
Author(s):  
Pan ◽  
Li ◽  
Lu ◽  
Chen
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Shaking Table Test ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Strain Range ◽  
Confining Pressure ◽  
Shaking Table ◽  
Triaxial Tests ◽  
Hysteresis Curve

Soil mixtures with various materials such as scraps of rubber tire, iron powder, and synthetic fibers have been widely used in civil engineering for experimental research or infrastructure construction and maintenance. However, these materials are not only expensive, but may also result in environmental concerns. In recent years, sawdust, because of its light-weight, inexpensive, and environmental friendly characteristics, has frequently been used in the shaking table test to adjust the dynamic properties of experimental soil. However, the dynamic properties of a sand-sawdust mixture for the shaking table test are still unclear. In this paper, the dynamic properties and the hysteresis curve characteristics of the sand-sawdust mixture as well as the influence of the sawdust content and confining pressure on the dynamic properties were studied using a series of consolidated drained dynamic triaxial tests. The test results show that, with the increase of the shear strain, the shape of the hysteresis loops changes from symmetrical willow-leaf to asymmetry sharp-leaf. For a given confining pressure, both the shear modulus and damping ratio decreases as the sawdust percentage increases. It was observed that, with an increase in confining pressure, the shear modulus increased while the damping ratio decreased slightly in the shear strain range of 10−3 to 7×10−3. It was also observed that the maximum shear modulus increased as the confining pressure increased, while the maximum damping ratio remained nearly constant. In addition, both the maximum shear modulus and the maximum damping ratio decreased as the sawdust content increased. Finally, the normalized shear modulus and damping ratio were established, which can be used in simulations using the shaking table test.

Model for the Erosion Rate Curve of Cohesive Soils

2017 ◽  
Vol 2657 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Reza Rahimnejad ◽  
Phillip S. K. Ooi
Keyword(s):  
Shear Stress ◽  
Water Content ◽  
Erosion Rate ◽  
Critical Shear Stress ◽  
Cohesive Soil ◽  
Ordinary Least Squares ◽  
Plasticity Index ◽  
Rate Curve ◽  
Parameter Estimates ◽  
Cohesive Soils

The scour rate found by the cohesive soil-erosion function apparatus (SRICOS-EFA) method provides more accurate and realistic scour predictions than the Richardson and Davis equation, which tends to overpredict scour, especially in cohesive soils. Scour of cohesive soil occurs more slowly than scour of cohesionless soils. The time-dependent nature of scour of cohesive soils can be understood by considering both the variation of flood intensity over time and the scour characteristics of the soil, with an erosion rate curve obtained with an erosion function apparatus (EFA). One drawback of the SRICOS-EFA method is that the EFA requires a significant cost outlay. A model for the erosion rate curve is proposed on the basis of EFA tests conducted on 31 undisturbed fine-grained soils from five water channels on the island of Oahu, Hawaii. A hyperbolic regression model was developed with four explanatory variables: water content, liquid limit, plasticity index, and activity, which are easily measured in the laboratory. Parameter estimates for the model were then obtained using nonlinear ordinary least squares. A key element of the model is that the parameter estimates logically affect the sign and magnitude of critical shear stress, in accord with observed soil behavior—that is, it was found that the model captured the effects of water content and plasticity index on the critical shear stress quite effectively. Also, the model provided reasonable estimates of the 31 erosion rate curves. Use of this model in the SRICOS-EFA method to estimate scour depth can result in less scour and can result in significant bridge cost savings.

Dynamic Experimental Study on Highly Weathered Granite

2014 ◽  
Vol 518 ◽  
pp. 132-137
Author(s):  
Lei Niu ◽  
Quan Jie Song ◽  
Shuang Xu ◽  
Xiao Ming Guo
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Response Analysis ◽  
Weathered Granite

The shear modulus and damping ratio are two important index in equivalent nonlinear model which is widely used in seismic response analysis. GDS resonant-column is used to study the shear modulus and damping ratio of highly weathered granite by controlling the consolidation confining pressure and pore water pressure. Variation of resonant frequency, shear modulus and damping ratio can be observed when different effective stress which is changed with confining pressure and pore water pressure applied on the sample. Hadin-Drnevich fitting curves are given on the basis of experimental data, and damping mechanism of highly weathered granite is discussed by making use of frictional theory. We can conclude from the results that there is a positive correlation between resonance frequency and shear strain, while there is a negative correlation between samples damping ratio and shear strain. The effective stress impact both samples shear modulus and damping ratio. However, pore water pressure can only act on damping ratio.

The Principle of Effective Stress Theory Research Based on Channel Rate

2013 ◽  
Vol 275-277 ◽  
pp. 336-342
Author(s):  
Xiao Feng Wu ◽  
Guang Fan Li ◽  
Wan Cheng He
Keyword(s):  
Effective Stress ◽  
Permeability Coefficient ◽  
Cohesive Soil ◽  
Stress Equation ◽  
Jump Problem ◽  
Stress Theory ◽  
Conventional Calculation ◽  
Earth Pressures ◽  
Stress Surface ◽  
Theory Research

Based on the debate of effective stress principle applicability on cohesive soil in recent years and the predecessor's research achievements, this paper puts forward the idea that the effective stress surface including hydrated film surrounding soil particles. And we obtained the extended soil effective stress equation by establishment of the model of channel rate.Combined with the physical significance of permeability coefficient and substantial experimental data, it can establish the fitting equation between permeability coefficient and new proposed physical parameter channel rate. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results.

Shear Modulus and Damping Ratio of Gravel Material

2011 ◽  
Vol 105-107 ◽  
pp. 1426-1432 ◽  
Author(s):  
De Gao Zou ◽  
Tao Gong ◽  
Jing Mao Liu ◽  
Xian Jing Kong
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Strain Amplitude ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Dynamic Shear ◽  
Data Points ◽  
Shear Strain Amplitude

Two of the most important parameters in dynamic analysis involving soils are the dynamic shear modulus and the damping ratio. In this study, a series of tests were performed on gravels. For comparison, some other tests carried out by other researchers were also collected. The test results show that normalized shear modulus and damping ratio vary with the shear strain amplitude, (1) normalized shear modulus decreases with the increase of dynamic shear strain amplitude, and as the confining pressure increases, the test data points move from the low end toward the high end; (2) damping ratio increases with the increase of shear strain amplitude, damping ratio is dependent on confining pressure where an increase in confining pressure decreased damping ratio. According to the test results, a reference formula is proposed to evaluate the maximum dynamic shear modulus, the best-fit curve and standard deviation bounds for the range of data points are also proposed.

Laboratory Model Tests on Dredger Fills by Vacuum Preloading with No Sand Cushion

2012 ◽  
Vol 170-173 ◽  
pp. 655-660
Author(s):  
Ya Jun Wu ◽  
Jian Bo Yang
Keyword(s):  
Fine Particles ◽  
Soil Strength ◽  
Plasticity Index ◽  
Laboratory Model ◽  
Soil Parameters ◽  
Grain Composition ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Water Contents ◽  
Sand Cushion

It is difficult to operate on the hydraulic-filled mucky soil foundation which the water content is high, so the vacuum preloading method with no sand cushion is used to deal with the foundation in some areas in China. Although there are still many problems in it’s application, such as, the effective range of the prefabricated vertical drains(PVDs) is small, the surrounding soil is easy to be accumulated and the soil strength increases little. For these problems, a laboratory model test on dredger fills made from the 4th layer of the Shanghai mucky soil by vacuum preloading with no sand cushion is performed. The changes and distributions in the settlement, water contents, permeability, plasticity index and grain composition of the dredger fill are studied in the process of the vacuum preloading. It is found that the water contents and permeability of the soft clay near the PVD (the diameter is about 40 to 50cm) are much lower than the outside, while the content of fine particles, plasticity index and soil strength near the PVD is much higher than the others. The measured data shows that the fine particles gather to a soil column at the center of the PVD under the action of vacuum negative pressure, then the permeability and the grain composition of the soil around the PVD is changed. As a result, soil parameters are not evenly distributed. Finally, some suggestions about how to reduce the non-uniformity are proposed.

Experimental Study on Critical Shear Stress of Cohesive Soils and Soil Mixtures

2021 ◽  
Vol 64 (2) ◽  
pp. 587-600
Author(s):  
Xiaojing Gao ◽  
Qiusheng Wang ◽  
Chongbang Xu ◽  
Ruilin Su
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
Cohesive Soil ◽  
Future Research ◽  
Cohesive Soils ◽  
List Type ◽  
Soil Mixture ◽  
Linear Relationships ◽  
Soil Mixtures

HighlightsErosion tests were performed to study the critical shear stress of cohesive soils and soil mixtures.Linear relationships were observed between critical shear stress and cohesion of cohesive soils.Mixture critical shear stress relates to noncohesive particle size and cohesive soil erodibility.A formula for calculating the critical shear stress of soil mixtures is proposed and verified.Abstract. The incipient motion of soil is an important engineering property that impacts reservoir sedimentation, stable channel design, river bed degradation, and dam breach. Due to numerous factors influencing the erodibility parameters, the study of critical shear stress (tc) of cohesive soils and soil mixtures is still far from mature. In this study, erosion experiments were conducted to investigate the influence of soil properties on the tc of remolded cohesive soils and cohesive and noncohesive soil mixtures with mud contents varying from 0% to 100% using an erosion function apparatus (EFA). For cohesive soils, direct linear relationships were observed between tc and cohesion (c). The critical shear stress for soil mixture (tcm) erosion increased monotonically with an increase in mud content (pm). The median diameter of noncohesive soil (Ds), the void ratio (e), and the organic content of cohesive soil also influenced tcm. A formula for calculating tcm considering the effect of pm and the tc of noncohesive soil and pure mud was developed. The proposed formula was validated using experimental data from the present and previous research, and it can reproduce the variation of tcm for reconstituted soil mixtures. To use the proposed formula to predict the tcm for artificial engineering problems, experimental erosion tests should be performed. Future research should further test the proposed formula based on additional experimental data. Keywords: Cohesive and noncohesive soil mixture, Critical shear stress, Erodibility, Mud content, Soil property.

Experimental Study on Dynamic Characteristics of Ionic Soil Stabilizer Reinforcing Red Clay

2011 ◽  
Vol 374-377 ◽  
pp. 1391-1395
Author(s):  
Xue Song Lu ◽  
Wei Xiang
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Condition ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Natural Soil ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Red Clay ◽  
Soil Stabilizer

Based on the red clay of Wuhan reinforced by Ionic Soil Stabilizer, the red clay soil is treated by different matches of ISS at first, then is tested in the Atterberg limits test and dynamic triaxia test. The results show that the plastic index decreases, and the red clay were greatly improved under the dynamic condition, the maximum dynamic shear modulus ratio acquired an incensement of 27.72% on average after mixing the ISS into the red clay. In addition, It was concluded that the confining pressure influenced the dynamic shear modulus and damping ratio to a certain extent. Given the same strain conditions, with the incensement of confining pressure increases, the dynamic shear modulus increased and the damping ratio decreased. Moreover, when plotting the dynamic shear modulus versus the dynamic shear strain, the similar curve can be formed for both the natural soil and the modified one, the dynamic shear modulus monotonously decreased with the incensement of the dynamic shear strain. However, the value of dynamic shear modulus differed in the same shear strain between the natural soil and the soil modified by ISS.

Riveted single lap joints Part 2: Fatigue life prediction

1997 ◽  
Vol 211 (2) ◽  
pp. 123-128 ◽  
Author(s):  
C-P Fung ◽  
J Smart
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Effective Stress ◽  
Fatigue Testing ◽  
Strain Range ◽  
Lap Joints ◽  
Total Strain Range ◽  
Single Lap Joints ◽  
Data Points ◽  
Fretting Damage

Fatigue lives of snap and countersunk riveted single lap joints with either one-row or two- rows of rivets have been predicted with fatigue laws using either local total strain range or effective stress obtained from finite element analyses and data obtained from fatigue testing of plates with holes. The finite element models of the joints were subjected to an alternating cyclic load; plasticity and nonlinear geometry are considered. The failures have also been metallurgically examined and gave evidence of fretting damage. It was found that all the data points lie within a narrow band using the strain-life law although the band is wider when using the effective stress-life law, but it is impossible to predict the fatigue life from one kind of specimen to another using the conventional stress-life law.

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