scholarly journals Experimental Study on Physical Mechanical Properties and Microstructure of Diatomite Soil in Zhejiang Province, China

2021 ◽  
Vol 12 (1) ◽  
pp. 387
Author(s):  
Lei Gao ◽  
Yi Luo ◽  
Yingeng Kang ◽  
Mingjun Gao ◽  
Omar Abdulhafidh
Keyword(s):  
Mechanical Properties ◽  
Strain Curve ◽  
Physical And Mechanical Properties ◽  
Friction Angle ◽  
Confining Pressure ◽  
Zhejiang Province ◽  
Dry Density ◽  
High Porosity ◽  
Engineering Project ◽  
Geotechnical Tests

Diatomite soil is a kind of bio-siliceous soil with complex composition and special structure, the physical and mechanical properties of diatomite soil are very important for the engineering project. In this paper, the physical properties, mechanical properties, and microstructure of diatomite soil in Zhejiang Province are studied by geotechnical tests and microscopic tests from the macroscopic and microscopic perspective. The results show that: (1) The diatomite soil has special properties different from other soils, including small particle size, low specific gravity value, high liquid-plastic limit, and low compressibility, and the strength indexes c and φ of diatomite soil will decrease with an increase in soil water content; (2) in the triaxial test, when the dry density of diatomite soil increases from 1.30 g/cm3 to 1.50 g/cm3, the effective internal friction angle of diatomite soil increases from 5.6° to 14.5° and the effective cohesion increases from 30.9 kPa to 49.6 kPa. The stress–strain curve of diatomite soil changes from weak softening type to weak hardening type when the confining pressure is above 200 kPa; (3) the diatomite soil has high porosity due to its unique microstructure; it is rich in aluminum oxides and minerals, which will greatly reduce the engineering performance of diatomite soil.

scholarly journals MECHANICAL PROPERTIES OF BOTTOM ASH – DREDGED MATERIAL MIXTURES IN LABORATORY TESTS

2013 ◽  
Vol 35 (3) ◽  
pp. 3-11 ◽  
Author(s):  
Lech Bałachowski ◽  
Zbigniew Sikora
Keyword(s):  
Mechanical Properties ◽  
Void Ratio ◽  
Bottom Ash ◽  
Physical And Mechanical Properties ◽  
Friction Angle ◽  
Ash Content ◽  
Dry Density ◽  
Dredged Material ◽  
Maximum Dry Density ◽  
Proctor Test

Abstract Bottom ash from EC Gdańsk and dredged material taken from the mouth of The Vistula were mixed to form an engineering material used for dike construction. Mixtures with different bottom ash content were tested in laboratory to determine its basic physical and mechanical properties. The optimum bottom ash-dredged material mixture, built in the corps of the test dike, contains 70% of ash. The optimum bottom ash content in the mixture was chosen taking into account high internal friction angle, good compaction and reduced filtration coefficient. The maximum dry density of the mixtures was measured in Proctor test for the mixtures formed in laboratory and on samples taken from the test dike. Minimum and maximum void ratio were also determined.

scholarly journals Mechanical Properties of Soft Soil considering the Influence of Unloading Stress Paths

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Wei Huang ◽  
Junjie Li ◽  
Yuming Lu ◽  
Dongsheng Li ◽  
Yaqing Mou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Numerical Analysis ◽  
Soft Soil ◽  
Strain Curve ◽  
Friction Angle ◽  
Confining Pressure ◽  
Stress Path ◽  
Hyperbolic Function ◽  
Mechanical Parameters ◽  
Current Design

The mechanical properties of soft soil are crucial for the design and construction of underground space excavation; however, the current design and numerical analysis of underground spaces consider the loading mechanical parameters, ignoring the influence of the unloading stress path resulting in frequent construction accidents in practice. Here, soft soil in Shenzhen, China, is taken as the research subject, and a series of consolidated-undrained unloading tests are performed. First, K0 consolidation is conducted. Then, unloading tests are performed with different unloading ratios to simulate different unloading stress paths. The test results show that the soft soil deformation characteristics are closely related to the stress path and unloading ratio. Under different unloading ratios, soft soil will undergo compression deformation or rebound deformation. Under unloading conditions, the deviator stress-strain curve satisfies a hyperbolic function and can be normalized with the average consolidation confining pressure. With the increase in the unloading ratio, the initial tangent modulus first decreases and then increases, the cohesion decreases, and the internal friction angle does not change significantly. The loading mechanical parameters are not suitable for numerical calculation in unloading engineering. In this paper, more unloading paths are considered, such as UU1.0 and UU0.5. The results of the study provide a theoretical basis for the calculation of the numerical analysis of the soil body at different depths in rich soft soil pits.

scholarly journals Research on Static Triaxial Mechanical Properties of New CementSoil Reinforced with Polypropylene Fiber

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Qiang Wang ◽  
Rui Tang ◽  
Qun Cheng ◽  
Xiankun Wang ◽  
Fang-ling Liu
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Polypropylene Fiber ◽  
Strain Curve ◽  
Friction Angle ◽  
Confining Pressure ◽  
Gypsum Content ◽  
Amplitude Increase ◽  
Dry Soil ◽  
Soil Weight

Through the laboratory test, the mechanical properties of cementsoil with adding desulfurization gypsum, fly ash, and polypropylene fiber were studied. Three different percentages (0%, 0.5%, and 1.0%) of polypropylene fiber were mixed into new cementsoil for which the cement content is 15% of the dry soil weight, the desulfurization gypsum content is 2% of the dry soil weight, and the fly ash content is 1.0% of the dry soil weight. The new cementsoil strength reinforced with polypropylene fiber was studied by triaxial test under different polypropylene fiber mixing ratio, different age, and different confining pressure. The experimental results show that, compared with ordinary soil, the deviatoric stress and the peak shear strength reinforced with polypropylene fiber have different amplitude increase. At the same time, the internal friction angle of new cementsoil with polypropylene fiber increases slightly with the growth of the age. The stress-strain curve of the polypropylene fiber cementsoil has the typical work hardening characteristic and has the characteristics of bulge fracture.

scholarly journals Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

2021 ◽  
Vol 13 (13) ◽  
pp. 7498
Author(s):  
Tan Li ◽  
Jianzhuang Xiao
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Strain Curve ◽  
Confining Pressure ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Model ◽  
Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

Anatomical, Chemical and Mechanical Properties of Fast-Growing Populus × Euramericana cv. ‘74/76’

IAWA Journal ◽  
2014 ◽  
Vol 35 (2) ◽  
pp. 158-169 ◽  
Author(s):  
Zhao Rongjun ◽  
Yao Chunli ◽  
Cheng Xianbao ◽  
Lu Jianxiong ◽  
Fei Benhua ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sandy Loam ◽  
Physical And Mechanical Properties ◽  
Wood Properties ◽  
Planting Density ◽  
Dry Density ◽  
Growth Rings ◽  
Fast Growing ◽  
Breast Height ◽  
Large Growth

The anatomical characteristics, chemical composition, and physical and mechanical properties of fast-growing Populus × euramericana cv. ‘74/76’ juvenile wood were investigated. Four- to five-year-old clonal plantation trees were harvested from two different experimental sites in the suburbs of Beijing. The Shunyi site had black alkali soil with a planting density of 4 × 6 m and the Miyun site had sandy loam soil with a planting density of 3 × 5 m. The test results showed that the poplar trees from the two sites were both fast growing, with poplar at Shunyi growing faster than at Miyun. There were no significant differences in wood properties between trees grown at the two sites. Fiber length at breast height varied from 872 to 1300 μm between growth rings, average fiber width varied from 21.0 to 25.5 μm and double wall thickness varied from 5.0 to 6.6 μm. Average cellulose, lignin and hemicellulose contents in the samples were 48.9%, 25.4%, and 18.8%, respectively. MFA was higher in the first two growth rings (20–25°), and then decreased rapidly to 12° close to the bark. The average air-dry density at breast height was 401 kg/m3 while the average MOE at breast height was 9.3 GPa. The trees showed large growth rates in both height and stem diameter during the growing season. However, wood properties of the juvenile poplar appeared to be similar to those of poplars with a slower growth rate.

Strength and Deformation Characteristics of Stabilized Silty Soil

2012 ◽  
Vol 594-597 ◽  
pp. 512-515
Author(s):  
Zheng Rong Zhao ◽  
Hong Xia Yang
Keyword(s):  
Internal Friction ◽  
Brittle Failure ◽  
Yellow River ◽  
Strain Curve ◽  
Friction Angle ◽  
Confining Pressure ◽  
Alluvial Plain ◽  
The Yellow River ◽  
Stress Strain Curve ◽  
Silty Soil

Combined with the silty soil characteristics of the Yellow River alluvial plain and the subgrade filling of Ji-He expressway, the paper discusses silty soil, stabilized silty soil strength and stress-stain characteristics through the indoor triaxial shear test. The results show that the remodeling silty soil has obvious peak, brittle failure, low residual strength after being destroyed and the stress-strain curve shows a softening type in confining pressure 100kPa lower stress level. In the confining pressure 400kPa higher stress level, soil samples peak is not obvious,mainly plastic failure and the stress-strain curve is close to a hardening type. Compared to mixed with 8% lime, stabilized silty soil of mixed with 4% cement and 4% lime shows that the partial stress peak is more obvious when destroyed and the residual strength is drastically reduced and more incline to brittle failure. In different the age, compared to mixed with 8% lime, stabilized silty soil of mixed with 4% cement and 4% lime shows that internal friction angle becomes larger and cohesion improves gradually whose amplitude is much larger than internal friction angle. Therefore, a more effective way to stabilize the silty soil of the Yellow River alluvial plain is to select silty soil mixed with 4% cement and 4% lime.

scholarly journals Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2350 ◽  
Author(s):  
Jun Peng ◽  
Sheng-Qi Yang
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Damage ◽  
Strain Curve ◽  
Treatment Temperature ◽  
P Wave ◽  
High Temperature Treatment ◽  
High Porosity ◽  
Compression Tests

High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

scholarly journals Determination and quality classification of rock mass of the Diatomite mine, Algeria

2021 ◽  
Vol 1 ◽  
pp. 17-24
Author(s):  
Abdessattar LAMAMRA ◽  
◽  
Dmitriy Leonidovich NEGURITSA ◽  
Samir BEDR ◽  
Ariant A. REKA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Underground Mining ◽  
Physical And Mechanical Properties ◽  
Friction Angle ◽  
Classification Systems ◽  
Natural Phenomenon ◽  
Underground Structures ◽  
Dilatancy Angle ◽  
Mining Work

Reserch relaevance. Most ground movements are generally due to rock instability, this natural phenomenon poses a risk to humanity. The properties of the rock mass directly influence the type of movement especially in underground structures. Research aim. Our goal is to characterize and classify the rock mass of diatomite from the sig mine using geomechanical classification systems such as the RQD and RMR in order to determine the quality of the rocks in the sig mine Western Algeria from the determination of the physical and mechanical properties. Methodology. In this article, the characterization analysis of the diatomite rock mass of the sig mine was carried out. First, determinations of the physical properties and carried out the triaxial test to determine the mechanical properties (young’s modulus, the friction angle, the dilatancy angle, the cohesion, the poisson’s ratio). Secondly to classify the deposit and give a recommendation to avoid stability problems. Research results. The results from physical and mechanical analyzes, it can be said that the nature of the rock present in the diatomite (underground mine) does not have enough resistance. Conclusion. Our study definitively proves that the rock mass of sig diatomite is of very low quality and it will be very dangerous for the underground mining work of the mine especially in places where the mineralized layer is very deep. And we suggest to replace the mining technique room and pillar currently used in the diatomite mine and put another mining method which includes roof support system to ensure the safety both of the miners and the equipment.

scholarly journals Use of Basalt Fiber-Reinforced Tailings for Improving the Stability of Tailings Dam

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1306 ◽  
Author(s):  
Binbin Zheng ◽  
Dongming Zhang ◽  
Weisha Liu ◽  
Yonghao Yang ◽  
Han Yang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Fiber Length ◽  
Basalt Fiber ◽  
Confining Pressure ◽  
Dry Density ◽  
Tailings Dam ◽  
Fiber Reinforced ◽  
Tailings Dams ◽  
The Stability

As one of the largest artificial geotechnical structures on earth, the tailings dams are classified as one of the high-risk sources in China’s industry. How to improve the stability and safety of tailings dams remains a challenge for mine operators currently. In this paper, an innovative method is presented for improving the stability of tailings dams, in which the basalt fiber is used to reinforce tailings. The mechanical properties of tailings used for dam-construction have a great influence on the stability of tailings dam. In order to investigate the mechanical performance of basalt fiber-reinforced tailings (BFRT), a series of laboratory triaxial tests were conducted. The effects of five parameters (fiber length, fiber content, particle size, dry density and confining pressure) on the mechanical properties of BFRT were studied. The microstructure and the behavior of interfaces between basalt fibers and tailings particles were analyzed by using scanning electron microscopy (SEM). The triaxial experimental test results show that the mechanical properties of BFRT increase with the increases of fiber length and content, particle size, dry density and confining pressure. The SEM results indicate that the interfacial interaction between fibers and tailings particles is mainly affected by particle shape.

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