scholarly journals Model Testing on Deformation Characteristics of an Unsaturated Compacted Clay Slope Under Cyclic Wetting and Drying

2021 ◽  
Author(s):  
Yue Huang ◽  
Huiguo Wu ◽  
Jian Liu ◽  
Yuedong Wu
Keyword(s):  
Fine Sand ◽  
Soil Mass ◽  
Deformation Characteristics ◽  
Test Results ◽  
Compacted Clay ◽  
Slope Surface ◽  
Wetting And Drying ◽  
Image Velocimetry ◽  
Unsaturated Clay ◽  
Model Slope

The effect of wetting-drying cycles on deformation characteristics of an unsaturated clay model slope is investigated in this study. The model slope was compacted using kaolin clay mixed with thirty percent of fine sand. The deformations of slope were measured using particle image velocimetry (PIV) technique. The test results revealed that the model slope deforms mainly within a depth of 300 mm and the displacements of soil mass are nearly perpendicular to slope surface in the first two cycles. Such displacements, however, vanish gradually in the subsequent cycles. On the other hand, the magnitude of displacement along slope surface increases with the number of wetting-drying cycles. The depth affected by wetting-drying cycles increases gradually with the number of wetting-drying cycles and becomes stable finally.

scholarly journals Mechanical Properties and Micro Mechanism of Nano-Clay-Modified Soil Cement Reinforced by Recycled Sand

2021 ◽  
Vol 13 (14) ◽  
pp. 7758
Author(s):  
Biao Qian ◽  
Wenjie Yu ◽  
Beifeng Lv ◽  
Haibo Kang ◽  
Longxin Shu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Void Ratio ◽  
Soil Mass ◽  
Direct Shear ◽  
Test Results ◽  
The Sustainable Development ◽  
Direct Shear Tests ◽  
Soil Cement ◽  
Nano Clay ◽  
New Material

To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified in terms of soil mass percentage. The shear strength of CSR (recycled sand blended soil-cement) was investigated by direct shear test and four groups of specimens (CSR-1, CSR-2, CSR-3 and CSR-4) were obtained. In addition, 8% nano-clay was added to four CSR groups to obtain the four groups of CSRN-1, CSRN-2, CSRN-3 and CSRN-4 (soil-cement mixed with recycled sand and nano-clay), which were also subjected to direct shear tests. A detailed analysis of the modification mechanism of soil-cement by recycled sand and nano-clay was carried out in combination with scanning electron microscopy (SEM) and IPP (ImagePro-Plus) software. The test results showed that: (1) CSR-3 has the highest shear strength due to the “concrete-like” effect of the incorporation of recycled sand. With the addition of 8% nano-clay, the overall shear strength of the cement was improved, with CSRN-2 having the best shear strength, thanks to the filling effect of the nano-clay and its high volcanic ash content. (2) When recycled sand and nano-clay were added to soil-cement, the improvement in shear strength was manifested in a more reasonable macroscopic internal structure distribution of soil-cement. (3) SEM test results showed that the shear strength was negatively correlated with the void ratio of its microstructure. The smaller the void ratio, the greater the shear strength. This shows that the use of reclaimed sand can improve the sustainable development of the environment, and at the same time, the new material of nano-clay has potential application value.

Arching effect in fine sand due to base yielding

2010 ◽  
Vol 47 (3) ◽  
pp. 366-374 ◽  
Author(s):  
Jamshid Sadrekarimi ◽  
Alireza Abbasnejad
Keyword(s):  
Relative Density ◽  
Experimental Work ◽  
Fine Sand ◽  
Soil Mass ◽  
Flow Process ◽  
Flow Phenomenon ◽  
Dense Sand ◽  
Arching Effect ◽  
Different Diameters ◽  
Upper Boundary

This paper presents results of an experimental work on the arching effect in loose and dense sand. The apparatus comprises concentric circular trapdoors with different diameters that can yield downward while stresses and deformations are recorded simultaneously. As the trapdoor starts to yield, the whole mass of soil deforms elastically. However, after a specified displacement that depends on the trapdoor diameter and soil relative density, the soil mass behaves plastically. This behavior, which is due to flow phenomenon, continues until the stress applied onto the trapdoor decreases to a minimum value. Then the stress carried by the trapdoor shows an ascending trend. This indicates the gradual separation of the yielding mass from the whole soil body. Finally, the flow process creates a stable arch of sand. This process is called the arching mechanism. Depending on the trapdoor diameter, there is a critical relative density at and beyond which the test leads to the formation of a stable arch. The results are also compared with Terzaghi’s theory and the assumption of an upper boundary solution is discussed.

Influence of Acetic Acid on Gypseous Soil

2020 ◽  
Vol 1002 ◽  
pp. 511-519
Author(s):  
Lamyaa Najah Snodi ◽  
Israa Saleh Hussein
Keyword(s):  
Acetic Acid ◽  
Soil Mass ◽  
Test Results ◽  
Shear Strength Parameters ◽  
Steel Cylinder ◽  
Soaking Time ◽  
Gypsum Content ◽  
Thick Steel ◽  
Laboratory Models ◽  
Gypseous Soil

Gypseous soil disturbed in many regions in the world. Existence of this soil with high gypsum content caused many damages to the buildings and structures that built on it due to dissolve and leaching of the gypsum slates by the flow of water through the soil mass. Therefore, it is necessary to study the properties of such soil. The dissolve of gypsum depends on many factors such as (gypsum content, temperature and other factors). Another important factor which is the acidity of the dissolution liquid must be considered. This study observes the influence of Acetic acid (CH3COOH) on the gypseous soil. Laboratory models includes (270 mm diameter) and (500 mm height) thick steel cylinder container and 17.1 kN/m3 density gypseous soil compacted in three layers, with gypsum content about 58% . The relation between the soaking time and the shear strength parameters was investigated. Also, plastic square container dimensions (250 mm x 250 mm x 300mm) used with same conditions to observed the deformation of the soil. The aim of this study is to simulate the infiltration of Acid in Gypseous soil. Test results show that increase cohesion of soil for diluted acid while decrease cohesion values for concentrated acid. Angle of friction for soil was increase for diluted and concentrated acid.

EFFECT OF LASER HARDENING OF STEEL ON THE WEAR PROCESS IN AN ABRASIVE SOIL MASS

Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 63-69 ◽  
Author(s):  
Jerzy NAPIÓRKOWSKI ◽  
Łukasz KONAT ◽  
Marta PIETRUSZEWSKA
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
Resistance Index ◽  
Soil Mass ◽  
Abrasive Wear Resistance ◽  
Laser Hardening ◽  
Test Results ◽  
Wear Process ◽  
Hardening Treatment ◽  
Type Machine

This paper presents the results of tests for the effects of laser hardening on the course and intensity of wear of 38GSA (38MnSi4) and Hardox 600 steels in an abrasive soil mass. The tests were carried out under laboratory conditions, using a “rotating bowl” type machine. Two types of soil, i.e. light and medium, were used as the abrasive mass. Based on the obtained test results, it was found that hardness decreased (in relation to asdelivered condition). The performed laser surface hardening process significantly increased the abrasive wear resistance only for 38GSA (38MnSi4) steel. As regards to Hardox steel, the hardening treatment reduced the abrasive wear resistance index compared to the as-delivered condition of the steel.

Effect of Wetting on the Pullout Resistance of Grouted Soil Nails

2012 ◽  
Vol 226-228 ◽  
pp. 1304-1307
Author(s):  
Jason Y. Wu ◽  
Jr Min Chang
Keyword(s):  
Fine Sand ◽  
Shear Resistance ◽  
Test Results ◽  
Pullout Capacity ◽  
Interface Shear ◽  
Soil Nails ◽  
Soaking Time ◽  
Pullout Resistance ◽  
Soil Nail ◽  
Pullout Tests

In this research, laboratory pullout tests were conducted on grouted soil nails to study the effect of wetting on the interface shear resistance between nail and soil during pullout. Deformed bars with equal size to the true soil nails were used as model nails. The soil used was silty fine sand collected at the site and prepared to a very dense condition. Rainfall infiltration was simulated using duplicated soil nails inundated by water for different periods. Test results indicated that the peak pullout resistance strongly decreases upon wetting, with a reduction of about 60% after soaking for 28 days. However, the experiments showed that there is a threshold water content (or soaking time) beyond which the effect of infiltration on the pullout resistance is reduced. The laboratory protocols developed in this study offered an easy scheme for the prediction of the pullout capacity of a grouted soil nail upon wetting.

Benchmarking of VIV Suppression Systems

2008 ◽  
Author(s):  
Kenneth J. Schaudt ◽  
Christopher Wajnikonis ◽  
Don Spencer ◽  
Jie Xu ◽  
Steve Leverette ◽  
...  
Keyword(s):  
Reynolds Number ◽  
The Body ◽  
Test Results ◽  
In Situ Tests ◽  
Image Velocimetry ◽  
High Reynolds ◽  
Viv Suppression ◽  
Almost All ◽  
Flow Splitter

A new form of Vortex-Induced Vibration (VIV) suppression device, the AIMS Dual-fin Flow Splitter (ADFS), has been developed, tested and benchmarked against bare-pipe, 5d and 15d pitch strakes and conventional teardrop fairings. Testing included high-mode number in-situ tests as well as low Reynolds number (<300,000) and high Reynolds number (<1.9 million) forced and free tank tests. Finally, wind tunnel tests and in-water Particle Image Velocimetry (PIV) were used to test the hypothesis that the dual-fin flow splitter replaces the oscillating wake of a blunt body with a stable, attached circulation behind the body and between the fins. Such a replacement was hypothesized to result in reduced drag, and the elimination of almost all VIV. The paper will describe the testing program and results, and present the incorporation of the test results into riser models.

scholarly journals Local velocity scaling in an impeller discharge flow in T400 vessel agitated by tooth impeller in a fully turbulent region

2018 ◽  
Vol 180 ◽  
pp. 02102 ◽  
Author(s):  
Radek Šulc ◽  
Pavel Ditl ◽  
Ivan Fořt ◽  
Darina Jašíkova ◽  
Michal Kotek ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Reynolds Number ◽  
Test Results ◽  
Flat Bottom ◽  
Time Resolved ◽  
Discharge Flow ◽  
Image Velocimetry ◽  
Fully Developed Turbulent Flow ◽  
Inner Diameter ◽  
High Level

Hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. The velocity fields were measured in the impeller discharge flow for impeller rotation speeds from 300 rpm to 700 rpm and three liquids of different viscosities (i.e. (i) distilled water, ii) a 28% vol. aqueous solution of glycol, and iii) a 43% vol. aqueous solution of glycol), corresponding to the impeller Reynolds number in the range 68 000 < Re < 221 000. This Re range secures the fully-developed turbulent flow of agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The radial turbulence intensity was found to be in the majority in the range from 0.3 to 0.9, which corresponds to the high level of this quantity.

scholarly journals Deformation Caused by Dynamic Load and Support Requirements in a Deep Gob-Side Entry Rock Mass

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Yandong Zhang ◽  
Yongjie Yang ◽  
Changhua Zhuge
Keyword(s):  
Dynamic Loading ◽  
Dynamic Load ◽  
Rock Properties ◽  
Optimized Design ◽  
Deformation Characteristics ◽  
Test Results ◽  
Support Design ◽  
Deformation And Failure ◽  
Ground Support ◽  
Bolt Support

Gob-side entries in deep coal mines can be subjected to dynamic loading when driving along the goaf. The effects of this dynamic loading and improved ground support requirements are investigated in the Gaojiabao Coal Mine, China. Numerical modeling is first used to simulate the deformation characteristics of rock surrounding the gob-side entry under dynamic load with the original support design. Dynamic loading in this scenario causes continual deterioration in rock properties, and deformation accumulates as the number of dynamic loads increases. Therefore, the overall strength and rigidity of the bolt support design need improvement, especially in terms of using yielding bolts that assist in releasing unnecessary support loads. The deformation characteristics of the rock surrounding the gob-side entry are combined with the concept of coupled pressure support to provide an optimized bolt support design. The support effects of the optimized design are then also numerically simulated and compared with the original support design. Deformation in the optimized design is significantly reduced, and roadway control is improved. Finally, the optimized design is applied and measured in a gob-side entry excavation. The field test results show that the potential for loosening, deformation, and failure of the surrounding rock is effectively controlled.

scholarly journals Effects of Variable Humidity on the Creep Behavior of Concrete and the Long-Term Deflection of RC Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Pengfei Li ◽  
Shiqin He
Keyword(s):  
Experimental Data ◽  
Relative Humidity ◽  
Creep Strain ◽  
Analytical Models ◽  
Deformation Characteristics ◽  
Rc Beams ◽  
Test Results ◽  
Sustained Loads ◽  
Average Relative Humidity

The influences of variable humidity on the creep behaviors of concrete and the long-term deflections of RC beams are analyzed in this paper. A total of 6 prismatic specimens and 5 RC beams were subjected to sustained loads and 3 types of variable humidity conditions for 331 days. The creep strains of the prismatic specimens and the deflections of the RC beams were recorded to investigate the long-term deformation characteristics. The test results reveal that both the creep strain and the deflection of specimens under cyclic humidity conditions exhibit approximately linear tendencies that are obviously less than those of specimens exposed only to natural air. During certain wetting cycles, the deformation rate became slower and the creep strain even recovered with an increase in the humidity, especially for shorter wetting-drying cycles. Long-term deflections predicted using the CEB-FIP 90 and ACI 209R models were compared with the test results to evaluate the versatility of these current specifications. The findings included rather large errors between the predicted results and experimental data when the average relative humidity was adopted in the analytical models.

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