scholarly journals A proposed method to determine in-situ shear modulus and shear strain decay curves in different structured soil

2019 ◽  
Vol 92 ◽  
pp. 18004
Author(s):  
Ran An ◽  
Lingwei Kong ◽  
Aiguo Guo ◽  
Xianwei Zhang
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Soft Soil ◽  
Soft Rock ◽  
High Standard ◽  
Small Strain ◽  
Residual Soil ◽  
Resonant Column Test ◽  
Granite Residual Soil

This paper illustrates the application of the self-boring pressuremeter test and the seismic dilatometer test to acquire the in-situ decay curves of stiffness with shear strain level (G-γ decay curves) of three types of structural soil, which are granite residual soil, structural soft soil and expansive soft rock. The proposed approach in combines the functions of SBPT and SDMT to provide the high standard of accuracy for the small-strain stiffness (from SDMT) and the major attenuation stage of stiffness (from SBPT). Using the proposed mathematical model can properly describe the tendency in typical in-situ G-γ decay curves based on the data of tests. To analyse the suitability of the proposed approach, the G-γ curve obtain from the resonant column test of granite residual soil is also employed to compare with the in-situ curves. The shear modulus G obtained from laboratory tests is found to be smaller and the stiffness attenuation rate is found to be faster than the curve of the in-situ test, which reflects the process of sampling, transporting and preparation of soil samples could cause unrecoverable damages in soil.

scholarly journals Effect of cementation on the small-strain stiffness of granite residual soil

2021 ◽  
Vol 61 (2) ◽  
pp. 520-532
Author(s):  
Xinyu Liu ◽  
Xianwei Zhang ◽  
Lingwei Kong ◽  
Xinming Li ◽  
Gang Wang
Keyword(s):  
Small Strain ◽  
Residual Soil ◽  
Small Strain Stiffness ◽  
Granite Residual Soil

Small strain stiffness for granite residual soil: effect of stress ratio

2021 ◽  
Author(s):  
Xianwei Zhang ◽  
Xinyu Liu ◽  
Lingwei Kong ◽  
Gang Wang ◽  
Cheng Chen
Keyword(s):  
Stress Ratio ◽  
Small Strain ◽  
Residual Soil ◽  
Resonant Column ◽  
Residual Soils ◽  
Column Tests ◽  
Small Strain Stiffness ◽  
Deviator Stress ◽  
Granite Residual Soil ◽  
Stress Ratios

Most previous studies have focused on the small strain stiffness of sedimentary soil while little attention has been given to residual soils with different properties. Most studies also neglected the effects of the deviator stress, which is extensively involved in civil engineering. This note considers the effects of the deviator stress on the small-strain stiffness of natural granite residual soil (GRS) as established from resonant column tests performed under various stress ratios. Although increasing the stress ratio results in a greater maximum shear modulus for both natural and remolded residual soils, remolded soil is more sensitive to changes in the stress ratio, which highlights the effects of soil cementation. The data herein offers new insights to understand the stiffness of residual soil and other weathered geomaterials.

scholarly journals Nonlinear dynamic properties of silty clay from Warsaw area

2016 ◽  
Vol 48 (3) ◽  
pp. 201-220
Author(s):  
Wojciech Sas ◽  
Katarzyna Gabryś ◽  
Emil Soból ◽  
Alojzy Szymański
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Nonlinear Dynamic ◽  
Dynamic Properties ◽  
Small Strain ◽  
Silty Clay ◽  
Resonant Column ◽  
Material Damping ◽  
Nonlinear Dynamic Properties ◽  
Low Amplitude

Abstract In this work, the small-strain and nonlinear dynamic properties of silty clay samples were studied by means of the low- and high-amplitude resonant column (RC) tests at various mean effective stresses (p’). The tested specimens were collected from the centre of Warsaw, district Śródmieście. Initially, the low-amplitude tests (below 0.001%) were conducted. Subsequently, the nonlinear testing was performed, at shearing strains greater than 0.001%. These tests were carried out in order to receive the dynamic properties of silty clay specimens in the nonlinear shear strain range. The small-strain material damping ratios (Dmin) of silty clay samples were also measured during the low-amplitude resonant column testing. The results show that increasing shear strain (γ) above the elastic threshold (γte) causes a decrease of the shear modulus (G) and normalized shear modulus (G/Gmax) of analyzed soil samples. Simultaneously, it is observed a increase of its damping ratio (D) and normalized damping (D/Dmin) with increasing shear strain (γ). Predictive equations for estimating normalized shear modulus and material damping of silty clay soils were presented here as well. The equations are based on a modified hyperbolic model and a statistical analysis of the RC tests results. The influence of unloading process on dynamic properties of the tested material was also discussed in the paper.

scholarly journals Characterization on the correlation between SPT-N and small strain shear modulus Gmax of Jiangsu silts of China

2021 ◽  
Vol 25 (2) ◽  
pp. 225-235
Author(s):  
Ya Chu ◽  
Songyu Liu ◽  
Guojun Cai
Keyword(s):  
Shear Modulus ◽  
Soil Layer ◽  
Small Strain ◽  
Penetration Test ◽  
Undisturbed Soil ◽  
Improvement Project ◽  
Small Strain Shear Modulus ◽  
Piezocone Penetration Test ◽  
Regression Relations

Small strain shear modulus plays a fundamental role in the evaluation of site response parameters. Only few authors used measured density and shear wave velocity (Vs) to estimate small strain shear modulus. In this study, an attempt has been made to develop the regression relationship between standard penetration test (SPT) N values and the small strain shear modulus (Gmax). For this purpose, field investigations SPT and seismic piezocone penetration test (SCPTU) data from locations in Su-Xin Expressway of China, have been used, which were also used for ground improvement project. The in situ density of soil layer was estimated using undisturbed soil samples from the boreholes. The Vs profiles with depth were obtained for the locations close to the boreholes. The values for small strain shear modulus have been calculated by measured Vs and in situ soil density. About 50 pairs of SPT-N and Gmax values were used for regression analysis. The differences between measured and corrected values which were used in fitted regression relations were analyzed. Most of the existing correlations were developed based on the studies carried out in Japan and in India, where N values are measured with hammer energy of 78%, which may not be directly applicable for other regions because of the variation in SPT hammer energy which in China is about 55%. A new correlation has been generated using the measured values in silts of China. From this study, it is found that uncorrected values of N and modulus gives the best fit regression relations when compared to corrected N and corrected modulus values. With most equation was used for sand and clay, the regression relations between corrected values of N and modulus gives the equation of silts in China.

Threshold Shear Strain for Dynamic Ramberg-Osgood Model in Soils Based on Thermomechanics

2014 ◽  
Vol 1065-1069 ◽  
pp. 255-259
Author(s):  
Xiao Xia Guo ◽  
Xiang Sun
Keyword(s):  
Friction Coefficient ◽  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Characteristics ◽  
Fundamental Property ◽  
Small Strain ◽  
Dissipation Function ◽  
Dynamic Shear Modulus ◽  
Soil Behavior ◽  
Skeleton Curve

The threshold shear strain is a fundamental property of the soil behavior subjected to cyclic loading. Starting from the unloading and reloading hysteretic curves of dynamic Ramberg-Osgood model, construct small-strain dynamic dissipation function and explain small-strain dynamic characteristics by use of the skeleton curve back stress assumption. The plotting results of yield curves in true stress space indicate that there exist two threshold shear strains which are defined as the first threshold shear strain and the second threshold shear strain respectively which represent boundaries between fundamentally different dynamic characteristics of cyclic soil behavior. The yields of soil are controlled by the constant friction coefficient, the variable friction coefficient and dilatancy-related microstructural changes respectively. Both the first threshold shear strain and the second threshold shear strain do depend significantly on the maximum dynamic shear modulus coefficient and exponent. Comparison between the two threshold shear strain values and shear modulus reduction curves obtained on exactly the same soils confirms that the soil behavior is considerably at nonlinear at , the secant shear modulus,Gs, of the four soils studied is between 0.6 and 0.8 of its maximum value.

scholarly journals Characteristics of Gravelly Granite Residual Soil in Bored Pile Design: An In Situ Test in Shenzhen

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Shuai Luan ◽  
Fenglai Wang ◽  
Tiehong Wang ◽  
Zhao Lu ◽  
Weihou Shui
Keyword(s):  
Back Analysis ◽  
Design Methods ◽  
Design Parameters ◽  
Residual Soil ◽  
In Situ Tests ◽  
Rotary Drilling ◽  
Construction Methods ◽  
Pile Design ◽  
Granite Residual Soil

Granite residual soil is widely distributed in south China and is treated as a special soil. Its design parameters in rotary drilling bored piles are a matter of debate due to lack of in-situ pile load tests. Back-analysis of test piles is a reliable means of studying the geotechnical capacity of granite residual soil for pile design. In this study, a series of in situ tests was conducted comprising six full-scale instrumented test piles in gravelly granite residual soil in Shenzhen to consider the effects of different construction methods. The six piles were constructed with three different rotary drilling methods. Two commonly used design methods were investigated in the back-analysis: the SPT and effective stress methods. The results of the loading tests and strain gauges were used to obtain the back-analyzed parameters of the ultimate shaft resistance and ultimate base resistance for gravelly granite residual soil with these two design methods.

scholarly journals Optimizing modified triaxial testing for small strain zone using local displacement transducers and bender element for cement-treated soft soil

2021 ◽  
Vol 331 ◽  
pp. 03003
Author(s):  
Muhammad Akmal Putera ◽  
Noriyuki Yasufuku ◽  
Adel Alowaisy ◽  
Ahmad Rifai
Keyword(s):  
Shear Modulus ◽  
Soft Soil ◽  
Strain Range ◽  
Small Strain ◽  
Secant Modulus ◽  
Bender Element ◽  
Treated Soil ◽  
Local Displacement ◽  
Settlement Behavior ◽  
Bender Element Test

The settlement behavior is a common problem on the railway structure that can be optimized by applying cement-treated soil as ground restoration. However, the application of a high cement mixing content needs a proper estimation that can be achieved by adjusting the element testing. The strain measurement devices can estimate the deformation characteristics, such as secant modulus, Poisson ratio, and shear modulus that can describe the settlement behavior and stiffness of cement-treated soil. This research is focused on a static analysis of triaxial consolidated undrained (CU¯) testing that is improved by the axial and radial local displacement transducer (LDT) and bender element to increase the accuracy of measurement results. Furthermore, the secant modulus and shear modulus is more accurate when the combination of radial and axial LDT is used due to a small strain range. Lastly, the shear modulus measurement is improved by using a filler in the cement-treated soil for the bender element test. To conclude, this system of testing for the static condition can be utilized for the dynamic condition, because the measurement shows a reliable result for a small strain range which is the parameter of the dynamics condition.

Laboratory and field determinations of small-strain shear modulus for a structured Champlain clay

1994 ◽  
Vol 31 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Guy Lefebvre ◽  
Denis Leboeuf ◽  
Muhsin E. Rahhal ◽  
Alain Lacroix ◽  
Joseph Warde ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Surface Waves ◽  
Small Strain ◽  
Test Surface ◽  
Resonant Column ◽  
Shear Moduli ◽  
Small Strain Shear Modulus ◽  
Laboratory Values ◽  
Clay Deposits

Values of small-strain shear modulus Gmax, for a Champlain Sea clay deposit were obtained both under an embankment built 18 years ago, and outside of the area influenced by this embankment. The small-strain shear moduli Gmax were measured in the laboratory by using resonant column tests and in the field by spectral analysis of surface waves. In addition to verifying the two methods, comparison of the in situ and laboratory values allowed evaluation of the influence of the sampling and the need to correct the laboratory values to account for the age of the deposit. The test program also made it possible to verify the influence of the deposit's consolidation and the existing models predicting small-strain shear moduli in clay deposits. Key words : shear modulus, shear-wave velocity, resonant column, in situ test, surface waves, soft clay.

scholarly journals Laboratory model test study of the hydrological effect on granite residual soil slopes considering different vegetation types

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Chen ◽  
Xue-wen Lei ◽  
Han-lin Zhang ◽  
Zhi Lin ◽  
Hui Wang ◽  
...  
Keyword(s):  
Root System ◽  
Heavy Rainfall ◽  
Storage Capacity ◽  
Water Storage ◽  
Laboratory Model ◽  
Residual Soil ◽  
Vegetation Types ◽  
Water Storage Capacity ◽  
Granite Residual Soil ◽  
Stem Leaf

AbstractThe problems caused by the interaction between slopes and hydrologic environment in traffic civil engineering are very serious in the granite residual soil area of China, especially in Guangdong Province. Against the background of two heavy rainfall events occurring during a short period due to a typhoon making landfall twice or even two typhoons consecutively making landfall, laboratory model tests were carried out on the hydrological effects of the granite residual soil slope considering three vegetation types under artificial rainfall. The variation in slope surface runoff, soil moisture content and rain seepage over time was recorded during the tests. The results indicate that surface vegetation first effectively reduces the splash erosion impact of rainwater on slopes and then influences the slope hydrological effect through rainwater forms adjustment. (1) The exposed slope has weak resistance to two consecutive heavy rains, the degree of slope scouring and soil erosion damage will increase greatly during the second rainfall. (2) The multiple hindrances of the stem leaf of Zoysia japonica plays a leading role in regulating the hydrological effect of slope, the root system has little effect on the permeability and water storage capacity of slope soil, but improves the erosion resistance of it. (3) Both the stem leaf and root system of Nephrolepis cordifolia have important roles on the hydrological effect. The stem leaf can stabilize the infiltration of rainwater, and successfully inhibit the surface runoff under continuous secondary heavy rainfall. The root system significantly enhances the water storage capacity of the slope, and greatly increases the permeability of the slope soil in the second rainfall, which is totally different from that of the exposed and Zoysia japonica slopes. (4) Zoysia is a suitable vegetation species in terms of slope protection because of its comprehensive slope protection effect. Nephrolepis cordifolia should be cautiously planted as slope protection vegetation. Only on slopes with no stability issues should Nephrolepis cordifolia be considered to preserve soil and water.

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