The Effects of Fines on Post Liquefaction Strength and Deformation Characteristics of Sand

2012 ◽  
Vol 594-597 ◽  
pp. 23-27 ◽  
Author(s):  
Yan Li Wang ◽  
Yong Wang
Keyword(s):  
Axial Strain ◽  
Strain Curve ◽  
Critical Value ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Recovery Stage ◽  
Fines Content ◽  
System A ◽  
Strength Recovery ◽  
Strength And Deformation

This study has been carried out to determine how the fines content affects the post liquefaction strength and deformation characteristics of sand. With the GDS dynamic triaxial system, a series of monotonic undrained compression tests of the sand after liquefaction with variation in fines content from 0 to 40% were conducted, and effects of fines content on the post liquefaction strength and deformation characteristics of sand were analyzed. Results show that with the addition of fines up to a fines content of 30%, the stress-strain curve moves downward and axial strain at low intensive stage is increased, beyond this critical value of fines content the trend is reversed. However, shear strength of post-liquefied sand first decreases with increasing fines content, and beyond the critical value of fines content it increases with increasing fines content at the strength recovery stage when are subjected to monotonic loading. At the same time, the strength recovery rate decreases firstly and then increases with the increasing fines content.

scholarly journals Effects of loading rate on strength and deformation characteristics of gypsum mixed sand

2019 ◽  
Vol 92 ◽  
pp. 05008
Author(s):  
Zain Maqsood ◽  
Junichi Koseki ◽  
Hiroyuki Kyokawa
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Constitutive Modelling ◽  
Strain Rates ◽  
Deformation Characteristics ◽  
Wide Range ◽  
Strength And Deformation ◽  
Loading Tests ◽  
Rational Evaluation ◽  
Strain Responses

It has been unanimously acknowledged that the strength and deformation characteristics of bounded geomaterials, viz. cemented soils and natural rocks, are predominantly governed by the rate of loading/deformation. Rational evaluation of these time-dependent characteristics due to viscosity and ageing are vital for the reliable constitutive modelling. In order to study the effects of ageing and loading/strain rate (viscosity) on the behaviour of bounded geomaterials, a number of unconfined monotonic loading tests were performed on Gypsum Mixed Sand (GMS) specimens at a wide range of axial strain rates; ranging from 1.9E-05 to 5.3E+00 %/min (27,000 folds), and at different curing periods. The results indicate shifts in the viscous behaviour of GMS at critical strain rates of 2.0E-03 and 5.0E-01 %/min. In the light of this finding, the results are categorized into three discrete zones of strain rates, and the behaviour of GMS in each of these zones is discussed. A significant dependency of peak strength and stress-strain responses on strain rate was witnessed for specimens subjected to strain rates lesser than 2.0E-03 %/min, and the effects of viscosity/strain rate was found to be insignificant at strain rate higher than 5.0E-01%/min.

scholarly journals Influence of initial fines content on fabric of soils subjected to internal erosion

2016 ◽  
Vol 53 (2) ◽  
pp. 299-313 ◽  
Author(s):  
Mao Ouyang ◽  
Akihiro Takahashi
Keyword(s):  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Internal Erosion ◽  
Experimental Investigations ◽  
Compression Tests ◽  
Fines Content ◽  
Instability Zone ◽  
Before And After ◽  
Undrained Behavior

Seepage-induced internal erosion often happens in earth structures. This paper presents experimental investigations on the influence of initial fines content on fabric of soils subjected to internal erosion. The tested materials were the binary mixtures of silica No. 3 and silica No. 8, which correspond to the coarse and fine fractions, respectively. One group of specimens was prepared with initial fines contents of 0, 15%, 25%, and 35% by weight. The undrained monotonic compression tests were performed on this group to examine the influence of fines content on the undrained behavior. The other group was prepared with initial fines contents of 15%, 25%, and 35% by weight, on which the seepage tests and subsequent undrained compression tests were carried out to demonstrate the mechanical influence of the internal erosion. The undrained behavior of the first group of specimens reveals that the presence of fines would decrease the peak and residual strengths. A comparison between the undrained behavior of soils with erosion and that of soils without erosion shows that the soils become less contractive after the internal erosion. When the axial strain is less than 0.4%, the undrained secant stiffness of soils with erosion is larger than that without erosion at the same axial strain. Meanwhile, the undrained peak strength and residual strength are larger for soils with erosion than that for soils without erosion. The less amount of excess pore-water pressure is generated during the undrained compression for the eroded soils comparing to those of the uneroded soils. Furthermore, the eroded soils show a wider instability zone than that of the uneroded soils, which suggests that the instability zone be enlarged by the internal erosion. Besides, one-dimensional upward seepage tests were performed to investigate the change of fabric of the mixed sand with 15%, 25%, and 35% fines contents due to internal erosion. The recorded microscopic images of soils before and after erosion reveal that the fabric is altered by the internal erosion.

scholarly journals Experimental Research on Deformation Characteristics of Waste-Rock Material in Underground Backfill Mining

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 102 ◽  
Author(s):  
Pengfei Zhang ◽  
Yubao Zhang ◽  
Tongbin Zhao ◽  
Yunliang Tan ◽  
Fenghai Yu
Keyword(s):  
Field Test ◽  
Axial Strain ◽  
Deformation Modulus ◽  
Rock Material ◽  
Waste Rock ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Slow Increase ◽  
Steel Cylinder ◽  
Backfill Mining

Waste-rock material used in underground backfill mining has a granular texture and acquires non-linear deformation characteristics when compressed. The deformation modulus of waste-rock measured by a laboratory compression test is significantly different from the true deformation modulus in the field, due to the complete confining effect of the loading steel cylinder. In this study, we performed a series of laboratory-based compression tests on waste-rock samples. The results showed that lab-acquired deformation modulus variations of waste rock could be divided into three stages: slow increase, accelerated increase, and rapid increase. We also measured the true deformation modulus of backfill waste rock by conducting a field test in gob areas of the Tangshan coal mine, China. The hardening process of backfill waste rock during the field test was analyzed, and could be divided into four stages: roof contact, rapid compression, slow compression, and long-term stable. With the increase of axial strain, the lab- and field-measured deformation moduli of waste rock both increased exponentially. A correction parameter was proposed to investigate the relationship between the field-generated true deformation modulus and the lab-tested deformation modulus. The correction parameter k positively correlated with the axial strain, in the form of an exponential function. The magnitude of k was between 0.5616 and 0.6531.

The Study on BFRP Binding Force of Secondary Compression Tests of Concrete Short Columns

2011 ◽  
Vol 418-420 ◽  
pp. 116-120
Author(s):  
Wei Ha Ma
Keyword(s):  
Initial Stress ◽  
Strain Curve ◽  
Peak Stress ◽  
Stress And Strain ◽  
Compression Tests ◽  
Secondary Stress ◽  
Stress Strain Curve ◽  
Binding Force ◽  
Short Columns ◽  
Strength And Deformation

This article has test researched on the BFRP constraint compression of the concrete short columns secondary stress axial compression , got C20, C25 reinforced concrete specimens of stress-strain curve test, studies show that strengthened specimens of strength and deformation of the increased significantly, and the degree of improve related with the size of initial stress. Through testing the processing and analysis of data, concludes that the calculation formula of peak stress and strain of the strengthening specimens under the secondary stress and can reflect the influence of different condition of initial stress .

Analysis on Bolt Supporting Mechanism for Roadways Driving along next Goaf Based on Triaxial Compression Test

2012 ◽  
Vol 594-597 ◽  
pp. 1159-1162
Author(s):  
Sheng Zhong ◽  
Yong Jie Yang ◽  
Min Wang
Keyword(s):  
Mechanical Test ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test System ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Conventional Triaxial Compression ◽  
Strength And Deformation ◽  
Rock Mechanical Test ◽  
Triaxial Compression Tests

Conventional triaxial compression tests of coal specimens are carried out by MTS815 servo-controlled rock mechanical test system, and the strength and deformation characteristics of coal under different confining pressure are analyzed. On that basis, bolt supporting mechanism of surrounding rocks of roadways driving along next goaf is studied.

Numerical Simulation of Damage and Deformation Characteristics of Rock Mass with Transfixion Joint

2013 ◽  
Vol 405-408 ◽  
pp. 369-372
Author(s):  
Lei Wang ◽  
Jiang Yu ◽  
Jian Xin Han
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Strain Curve ◽  
Simulation Method ◽  
Joint Surface ◽  
Deformation Characteristics ◽  
Stress Strain Curve ◽  
Deformation Parameters ◽  
Strength And Deformation ◽  
Set Up

Use FLAC3D, the interface command to define joint surface, set up rock mass models with 15 °, 30 °, 60 °, etc. different dip joint, and in accordance with the laboratory test data of rock and joint surface for a variety of strength and deformation parameters setting, carries on the numerical simulation of uniaxial compression. Got failure mode, plastic zone evolution and the stress strain curve of rock mass with different dip joint, and the result compared with the actual test has a higher similarity, to prove the feasibility of the numerical simulation method.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

Concrete Strength and Deformation Property under Sea Water Erosion Environment

2012 ◽  
Vol 446-449 ◽  
pp. 2554-2559 ◽  
Author(s):  
Jian Jun Cai ◽  
Feng Zhang ◽  
Wei Cui ◽  
Shou Shan Chen ◽  
Pu Lun Liu
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Deformation Property ◽  
Sea Water ◽  
Dynamic Stiffness ◽  
Concrete Strength ◽  
Strain Curve ◽  
Water Erosion ◽  
Strength And Deformation ◽  
Erosion Environment

In order to effectively assess the concrete strength and deformation property under sea water erosion environment, concrete stress and strain curve was researched with the number of wet and dry cycle of 0 times, 10 times , 20 times, 30 times, 40 times, 50 times and 60 times based on the large-scale static and dynamic stiffness servo test set. The stress - strain curves of concrete was tested for the lateral pressure 10.8MPa, 14.4MPa, and 18.8MPa at different dry-wet cycles, The failure modes and superficial cracking characteristics of specimens are reported at different dry-wet cycles. Concrete elastic modulus and compressive strength were researched. Based on concrete mechanical theory , the classic Kufer-Gerstle strength criteria of concrete was used, a large number of test samples of multivariate data were nonlinear regressed, a biaxial concrete strength criterion was established taking into account the stress ratio and the number of dry-wet cycles.

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