Mechanical Characteristic of Buffer/Backfilling Materials After Different Temperatures

2011 ◽  
Vol 347-353 ◽  
pp. 852-857
Author(s):  
Ming Qing Yan ◽  
Fa Cheng Yi ◽  
Bao Long Zhu
Keyword(s):  
Modulus Of Elasticity ◽  
Temperature Increase ◽  
Strain Curve ◽  
Peak Stress ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Different Temperatures ◽  
Backfill Materials ◽  
Increasing Temperature

Based on uniaxial compression test, the mechanical properties of buffer/backfilling materials after different temperatures are studied. The study analyzed buffer/backfilling materials of stress-strain curve，peak stress，modulus of elasticity，peak strain, with the variation of temperature. The buffer/backfilling materials of strengthening and degradation in different temperature are discussed briefly. The test result show that below 200°C, buffer/backfilling materials of stress-strain curve of slope，peak stress，modulus of elasticity，peak strain ,are increase with increasing temperature increase. The main reason is that with increasing temperature, adsorbed water in the sample will evaporate, and brittleness of sample will improve; mineral particles of expansion lead to the original cracks closing, the porosity will reduce, and improve friction properties between particles. 300 °C,buffer / backfill materials of stress - strain curve of slope, peak stress, elastic modulus, decreased to varying degrees compared to 200 °C. the main reason is that thermal stress damage to the internal structure of the samples, resulting in new small cracks. The peak strain of buffer / backfill materials in the 25 °C～100 °C is increase with increasing temperature increase.100°C～200°C, peak strain is decrease with the increase of temperature. In the 200 °C～300 °C, the peak strain change little.

scholarly journals Dynamic Characteristics of Sandstone under Coupled Static-Dynamic Loads after Freeze-Thaw Cycles

2020 ◽  
Vol 10 (10) ◽  
pp. 3351
Author(s):  
Bo Ke ◽  
Jian Zhang ◽  
Hongwei Deng ◽  
Xiangru Yang
Keyword(s):  
Energy Absorption ◽  
Dynamic Characteristics ◽  
Shear Failure ◽  
Strain Curve ◽  
Peak Stress ◽  
Peak Strain ◽  
Compression Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Freeze Thaw

The effect of temperature fluctuation on rocks needs to be considered in many civil engineering applications. Up to date the dynamic characteristics of rock under freeze-thaw cycles are still not quite clearly understood. In this study, the dynamic mechanical properties of sandstone under pre-compression stress and freeze-thaw cycles were investigated. At the same number of freeze-thaw cycles, with increasing axial pre-compression stress, the dynamic Young’s modulus and peak stress first increase and then decrease, whereas the dynamic peak strain first decreases and then increases. At the same pre-compression stress, with increasing number of freeze-thaw cycles, the peak stress decreases while the peak strain increases, and the peak strain and peak stress show an inverse correlation before or after the pre-compression stress reaches the densification load of the static stress–strain curve. The peak stress and strain both increase under the static load near the yielding stage threshold of the static stress–strain curve. The failure mode is mainly shear failure, and with increasing axial pre-compression stress, the degree of shear failure increases, the energy absorption rate of the specimen increases first and then decreases. With increasing number of freeze-thaw cycles, the number of fragments increases and the size diminishes, and the energy absorption rates of the sandstone increase.

Stress-Strain Model for Confined Concrete in Cross-Shaped Columns

2012 ◽  
Vol 450-451 ◽  
pp. 822-826
Author(s):  
Lin Zhu Sun ◽  
Tie Cheng Wang ◽  
Fang Yang
Keyword(s):  
Strain Curve ◽  
Peak Stress ◽  
Confined Concrete ◽  
Peak Strain ◽  
Test Results ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
The Cross ◽  
Strain Model ◽  
Variation Rule

To establish complete stress-strain curve equations for confined concrete in cross-shaped columns, we designed 7 test specimens corresponding to the usable eigenvalue range of stirrup of the cross-shaped columns. We obtained the test results of the reinforced concrete cross-shaped columns through axial compression test, got the system parameters of a stress-strain model through statistical analysis of the test data, and then established stress-strain curves for confined concrete in the cross-shaped columns. This model reflects the variation rule of the stress-strain curve of confined concrete in cross-shaped columns. Compared with the stress-strain model for confined concrete in square columns, the confined concrete in cross-shaped columns has smaller peak stress, larger peak strain, and relatively steeper descending part of curve. The research results provide theorotical basis for nonlinear analysis of cross-shaped columns.

Effects of temperature gradient on the granite’s mechanical properties

2021 ◽  
pp. 1-10
Author(s):  
Jinyong Pei ◽  
Huagang He ◽  
Dongtao Hu ◽  
Shanke Lv ◽  
Jing Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Strain Curve ◽  
Peak Stress ◽  
Tangent Modulus ◽  
Peak Strain ◽  
Compression Tests ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Increasing Temperature

Temperature gradient significantly affects the production of surrounding rock stress in mining engineering. The mechanics and deformation characteristics of the rock will change under the temperature gradient, thereby increasing the probability of accidents in the roadway. This paper conducts uniaxial compression tests on granite at different temperatures from room temperature to 250∘C, and analyzes in detail the changes in the stress-strain curve, peak stress, peak strain and tangent modulus of granite under high temperature and different temperature gradient conditions. The results of this study are as follows: (1) Under high temperature conditions, the granite’s peak stress and tangent elastic modulus increased with temperature from 17 to 100∘C, then decreased from 100∘C to 250∘C, whereas the granite’s peak strain increased steadily with increasing temperature; (2) under temperature gradient, the granite’s peak stress and tangent modulus first decreased and then increased with increasing temperature gradient, while the granite’s peak strain first decreased and then increased at 100∘C, but first increased and then decreased from 150∘C to 250∘C.

scholarly journals Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1257
Author(s):  
Shuling Gao ◽  
Guanhua Hu
Keyword(s):  
Strain Rate ◽  
Lateral Pressure ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Pressure Level ◽  
Strain Rates ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

A unified expression to estimate the stress-strain curve of polyamides at different temperatures

2018 ◽  
Vol 6 (1) ◽  
pp. 015304
Author(s):  
H S da Costa Mattos ◽  
J F S Brandão ◽  
F C Amorim ◽  
P V S Araújo ◽  
J M L Reis
Keyword(s):  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Different Temperatures

Numerical Simulation of the Effect of Temperature on the Failure Strength of Rock

2013 ◽  
Vol 690-693 ◽  
pp. 1737-1740
Author(s):  
Lin Bu ◽  
Tao Xu ◽  
Yun Jie Zhang
Keyword(s):  
Mechanical Properties ◽  
Rock Fracture ◽  
Strain Curve ◽  
Peak Stress ◽  
Effect Of Temperature ◽  
Peak Strain ◽  
Failure Strength ◽  
Stress Strain Curve ◽  
Physical Tests ◽  
Compression Condition

The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.

scholarly journals A Stress-Strain Model for Brick Prism under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Yongjei Lee ◽  
Yong-Ha Hwang
Keyword(s):  
Strain Curve ◽  
Peak Stress ◽  
Test Results ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Proposed Model ◽  
Relationship Model ◽  
Strain Relationship ◽  
Strain Model

This study proposes a simple and rational stress-strain relationship model applicable to brick masonry under compression. The brick prism compression tests were conducted with different mortar strengths and with constant brick strength. From the observation of the test results, shape of the stress-strain curve is assumed to be parabola. In developing the stress-strain model, the modulus of elasticity, the strain at peak stress, and the strain at 50% of the peak stress on the descending branch were formulated from regression analysis using test data. Numerical and statistical analyses were then performed to derive equations for the key parameter to determine the slopes at the ascending and descending branches of the stress-strain curve shape. The reliability of the proposed model was examined by comparisons with actual stress-strain curves obtained from the tests and the existing model. The proposed model in this study turned out to be more accurate and easier to handle than previous models so that it is expected to contribute towards the mathematical simplicity of analytical modeling.

Experimental Study on Stress-Strain Curve of Recycled Coarse Aggregate Concrete under Uniaxial Compression

2013 ◽  
Vol 357-360 ◽  
pp. 1415-1419 ◽  
Author(s):  
Zhi Heng Deng ◽  
Li Chen ◽  
Jian Qian ◽  
Chao Lou Meng
Keyword(s):  
Coarse Aggregate ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Recycled Coarse Aggregate ◽  
Rational Expression ◽  
The Difference ◽  
Two Stages

In order to study the mechanical properties of recycled concrete with the same strength, three kinds of recycled concrete have been made which their intensities reached C25, C30, C35 at the recycled coarse aggregate replacement ratios (0%, 50%, 100%), and severally completed the stress-strain curve test on the same strength of recycled concrete, separately analyzed the variance about failure pattern and peak strain, elastic modulus that all belonged to recycled concrete under the condition of the same strength. Studies have shown that the overall shape of recycled concretes stress-strain curves is similar to normal concretes under the same strength, and the difference is small, modulus of elasticity decreases with the increase of recycled coarse aggregate replacement ratio, while the peak strain basicly remains unchanged. Their curves can be used two stages respectively and also be represented by three fitting polynomial and rational expression, their descent stages steepened gradually with the increase of recycled coarse aggregate replacement rate.

scholarly journals Stress–Strain Curve and Carbonation Resistance of Recycled Aggregate Concrete after Using Different RCA Treatment Techniques

2021 ◽  
Vol 11 (9) ◽  
pp. 4283
Author(s):  
Long Li ◽  
Dongxing Xuan ◽  
Chisun Poon
Keyword(s):  
Elastic Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Treatment Techniques ◽  
Carbonation Resistance

Five recycled coarse aggregate (RCA) treatment techniques including flow-through carbonation, pressurized carbonation, wet carbonation, nano silica (NS) pre-spraying and combined pressurized carbonation with NS pre-spraying, were utilized to improve the performance of recycled aggregate concrete (RAC). The characteristics of the stress–strain curves of RACs including peak stress, peak strain, elastic modulus, ultimate strain and toughness were evaluated after using the above RCA treatment techniques. A theoretical model for natural aggregate concrete was used to analyse the stress–strain curve of RAC. Additionally, the carbonation resistance of RAC after using different RCA treatment techniques were investigated. The results showed that the calculated stress–strain curve of RAC based on the theoretical model matched well with the experimental results. Among the three types of carbonation techniques, pressurized carbonation caused the highest improvement in peak stress and elastic modulus of RAC, followed by flow-through carbonation, the last was wet carbonation. The NS pre-spraying method contributed to even higher improvement in peak stress and elastic modulus of RAC than the pressurized carbonation method. The combined pressurized carbonation with NS pre-spraying exhibited the highest enhancement of RAC because both the RCA and the new interface transition zone (ITZ) were improved. The carbonation resistance of RAC was improved after using all the studied RCA treatment techniques.

scholarly journals Performance of Circular Concrete-Filled FRP-Grooved Steel Composite Tube Columns under Axial Compression

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3638
Author(s):  
Kunting Miao ◽  
Yang Wei ◽  
Xi Zhang ◽  
Kaiqi Zheng ◽  
Fenghui Dong
Keyword(s):  
Failure Modes ◽  
Linear Part ◽  
Strain Curve ◽  
Peak Stress ◽  
Steel Tube ◽  
Peak Strain ◽  
Test Results ◽  
Stress Strain ◽  
Composite Tube ◽  
Steel Composite

A new structure termed “concrete-filled FRP-grooved steel composite tube (CFGCT) column” is proposed, which is composed of a stress-released steel tube (i.e., grooved steel tube), fiber-reinforced polymer (FRP) and concrete. Axial load tests were carried out on twenty-four specimens to investigate the constraint effect of this structure. Three main experimental variables were considered: the steel tube thickness, the FRP type, and the FRP layer. The failure modes, stress-strain relationships and the effect of the main experimental variables were discussed. The stress-strain curves of this new structure are composed of an initial linear part, a nonlinear transition part, a strengthening part and a residual part. The test results demonstrate that the bearing capacity of the structure was improved, and that the mechanical mechanism of the structure was simplified due to the stress-released grooves. Based on the test results and previous studies, formulas for calculating the ultimate stress (fcu), ultimate strain (εcu), peak stress (fcc) and peak strain (εcc) were proposed. In addition, models for predicting the stress-strain curves of CFGCT columns were put forward, and the models could precisely simulate the stress-strain curve of this new composite structure. Hence, this study indicates that a structure composed of FRP and stress-released steel tube can effectively constrain concrete.

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