scholarly journals RESULTS OF COMPRESSION TESTING ON PSEUDO-COHESIVE SOIL

Vestnik MGSU ◽  
2015 ◽  
pp. 61-72
Author(s):  
Vadim Grigor’evich Ofrikhter ◽  
Yan Vadimovich Ofrikhter
Keyword(s):  
Void Ratio ◽  
Retaining Wall ◽  
Time Moment ◽  
Cohesive Soil ◽  
Cohesive Soils ◽  
Test Results ◽  
Creep Tests ◽  
Compression Process ◽  
Secondary Compression ◽  
Deformation Equation

Natural non-treated sand reinforced with randomly oriented short polypropylene fibers of 12 mm in length was tested to determine creep characteristics. This study is a part of the research aimed at encouraging fibrosand (FRS) application in subsoils, embankments and retaining wall constructions. Fiber content was accounted for 0.93 %. Twin specimens were put to creep tests (1-D compression) using the two curve method. The test results were analyzed and checked with the use of ageing, hardening and hereditary creep theories. On the basis of approximation of the test results the creep deformation equation at constant stress for tested fibrosand was obtained. The assessment of fibrosand secondary compression was carried out by the FORE method. As a result, the value of the void ratio by the end of the secondary compression had been eu=0.7041. For determination of the beginning of the secondary compression the rate equation was superimposed on the empirical curve. The point of the graph divergence is the beginning of the secondary compression process. The secondary compression had begun by the time moment being equal to 9360 min. The void ratio by the beginning of the secondary compression had amounted to 0.70574. Fibrosand is a specific type of improved soil relating to so-called pseudo-cohesive soil. This type of soil is characterized by cohesion like cohesive soils, but, at the same time, by the filtration coefficient of about 1 m per day like non-cohesive soils. Pseudo-cohesive soil testing helps to understand the distinctive features of the stress-strain state of this kind of materials. Municipal solid waste also relates to them.

scholarly journals On the Possibility of Testing Miocene Clay from Cracow Area using Weight Sounding Test (WST)

2014 ◽  
Vol 36 (1) ◽  
pp. 71-78
Author(s):  
Sebastian Olesiak
Keyword(s):  
Laboratory Tests ◽  
Site Investigation ◽  
Cohesive Soil ◽  
Field Investigation ◽  
Testing Equipment ◽  
Cohesive Soils ◽  
Test Results ◽  
Carpathian Foredeep ◽  
Characteristic Values ◽  
Complete Interpretation

Abstract Polish standards concerning field investigation with the use of a Weight Sounding Test (WST) probe give interpretation of results for non-cohesive soils only. The lack of such interpretation for cohesive soils excludes this testing equipment from use. This paper presents the results of geotechnical site investigation and laboratory tests performed for Miocene clays in Carpathian Foredeep in the Cracow area. Based on the analysis of the results a correlation was determined between the characteristic values for the WST probe (number of half-turns NWST) and the selected properties of Miocene clays. The article is an attempt to create a complete interpretation of test results obtained for cohesive soil with WST equipment.

On the use of the Kozeny–Carman equation to predict the hydraulic conductivity of soils

2003 ◽  
Vol 40 (3) ◽  
pp. 616-628 ◽  
Author(s):  
Robert P Chapuis ◽  
Michel Aubertin
Keyword(s):  
Hydraulic Conductivity ◽  
Specific Surface ◽  
Void Ratio ◽  
General Rule ◽  
Saturated Hydraulic Conductivity ◽  
Practical Reasons ◽  
Cohesive Soils ◽  
Test Results ◽  
Hydraulic Radius ◽  
Empirical Relationships

The saturated hydraulic conductivity of a soil can be predicted using empirical relationships, capillary models, statistical models, and hydraulic radius theories. A well-known relationship between permeability and the properties of pores was proposed by Kozeny and later modified by Carman. The resulting equation is largely known as the Kozeny–Carman (KC) equation, although the two authors never published together. In the geotechnical literature, there is a large consensus that the KC equation applies to sands but not to clays. This view, however, is supported only by partial demonstration. This paper evaluates the background and the validity of the KC equation using laboratory permeability tests. Test results were taken from publications that provided all of the information needed to make a prediction: void ratio, and, either the measured specific surface for cohesive soils, or the gradation curve for noncohesive soils. The paper shows how to estimate the specific surface of a noncohesive soil from its gradation curve. The results presented here show that, as a general rule, the KC equation predicts fairly well the saturated hydraulic conductivity of most soils. Many of the observed discrepancies can be related to either practical reasons (e.g., inaccurate specific surface value; steady flow not reached; unsaturated specimens, etc.) or theoretical reasons (some water is motionless; hydraulic conductivity of soils is anisotropic). These issues are discussed in relation to the predictive capabilities of the KC equation.Key words: permeability, prediction, gradation curve, specific surface.

scholarly journals Performance Study of Grass-Derived Nano-Cellulose and Polycaprolactone Composites for 3D Printing

2021 ◽  
Vol 11 (3) ◽  
pp. 1273
Author(s):  
Chen Feng ◽  
Jiping Zhou ◽  
Xiaodong Xu ◽  
Yani Jiang ◽  
Hongcan Shi ◽  
...  
Keyword(s):  
3D Printing ◽  
Mechanical Test ◽  
Chemical Properties ◽  
Test Results ◽  
Performance Study ◽  
Compression Process ◽  
Ansys Fluent ◽  
Nano Cellulose ◽  
Physical And Chemical ◽  
And Chemical Properties

In recent years, 3D printing has received increasing attention from researchers. This technology overcomes the limitations of traditional technologies by printing precise and personalized scaffold with arbitrary shapes, pore structures, and porosities for the applications in various tissues. The cellulose nanocrystal (CNC) is extracted from Humulus Japonicus (HJS) and mixed with poly(ε-caprolactone) (PCL) to prepare a series of CNC/PCL composites for printing. Based on the analysis of the physical and chemical properties of the series of the CNC/PCL composites, an optimal mass ratio of CNC to PCL was obtained. The Solidworks was used to simulate the stretching and compression process of the scaffolds with three different patterns under an external force. The flow of nutrient solution in the scaffolds with different patterns was simulated by ANSYS FLUENT, and then a new optimization scaffold pattern with a concave hexagon shape was advised based on the simulation results. Collectively, the mechanical test results of the material and scaffold confirmed that the optimal filling amount of the CNC was 5%, and the scaffold pattern with concave hexagon shape exhibited better mechanical properties and suitable for the transport of cells and nutrients, which is expected to be more widely used in 3D printing.

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.

scholarly journals Experimental Study on Improvement of Marine Soft Soil with Alkali Residue

2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Soft Soil ◽  
Compressive Modulus ◽  
Engineering Properties ◽  
Test Results ◽  
Use Of Resources ◽  
One Year

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.

A Study on Estimation of Internal Pressure Creep Life Using Small Punch Creep (SPC) Tests for Boiler Pipes

2009 ◽  
Author(s):  
Toshimi Kobayashi ◽  
Toru Izaki ◽  
Junichi Kusumoto ◽  
Akihiro Kanaya
Keyword(s):  
Internal Pressure ◽  
Residual Life ◽  
Test Results ◽  
Creep Life ◽  
Creep Tests ◽  
Good Correspondence ◽  
Small Punch ◽  
Uniaxial Creep ◽  
Wide Range ◽  
The Relationship

The small punch creep (SPC) test is possible to predict residual creep life at a high accuracy. But, the results of SPC tests cannot be compared with uniaxial creep or internal pressure creep results directly. In this report, the relationship between SPC test results and uniaxial creep test results in ASME A335 P11 (1.25Cr-0.5Mo Steel) was studied. The obtained relationship between SPC load and equivalent uniaxial creep stress formed a simple linear equation under the wide range of test temperature and test period. Then, the SPC results can be compared with uniaxial results by converting SPC loads to the equivalent uniaxial creep stresses. The relationship between SPC test results and internal pressure creep tests results was also studied. The internal creep life of as-received P11 pipe was almost same as SPC result when the hoop stress was converted to the SPC load. The creep lives of internal pressure creep influenced materials also showed good correspondence with SPC results. Therefore SPC can estimate the residual life of internal pressure creep influenced materials.

Experimental Study on Critical Shear Stress of Cohesive Soils and Soil Mixtures

2021 ◽  
Vol 64 (2) ◽  
pp. 587-600
Author(s):  
Xiaojing Gao ◽  
Qiusheng Wang ◽  
Chongbang Xu ◽  
Ruilin Su
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
Cohesive Soil ◽  
Future Research ◽  
Cohesive Soils ◽  
List Type ◽  
Soil Mixture ◽  
Linear Relationships ◽  
Soil Mixtures

HighlightsErosion tests were performed to study the critical shear stress of cohesive soils and soil mixtures.Linear relationships were observed between critical shear stress and cohesion of cohesive soils.Mixture critical shear stress relates to noncohesive particle size and cohesive soil erodibility.A formula for calculating the critical shear stress of soil mixtures is proposed and verified.Abstract. The incipient motion of soil is an important engineering property that impacts reservoir sedimentation, stable channel design, river bed degradation, and dam breach. Due to numerous factors influencing the erodibility parameters, the study of critical shear stress (tc) of cohesive soils and soil mixtures is still far from mature. In this study, erosion experiments were conducted to investigate the influence of soil properties on the tc of remolded cohesive soils and cohesive and noncohesive soil mixtures with mud contents varying from 0% to 100% using an erosion function apparatus (EFA). For cohesive soils, direct linear relationships were observed between tc and cohesion (c). The critical shear stress for soil mixture (tcm) erosion increased monotonically with an increase in mud content (pm). The median diameter of noncohesive soil (Ds), the void ratio (e), and the organic content of cohesive soil also influenced tcm. A formula for calculating tcm considering the effect of pm and the tc of noncohesive soil and pure mud was developed. The proposed formula was validated using experimental data from the present and previous research, and it can reproduce the variation of tcm for reconstituted soil mixtures. To use the proposed formula to predict the tcm for artificial engineering problems, experimental erosion tests should be performed. Future research should further test the proposed formula based on additional experimental data. Keywords: Cohesive and noncohesive soil mixture, Critical shear stress, Erodibility, Mud content, Soil property.

Creep Tests of Rotating Disks at Elevated Temperature and Comparison With Theory

1954 ◽  
Vol 21 (3) ◽  
pp. 225-235
Author(s):  
A. M. Wahl ◽  
G. O. Sankey ◽  
M. J. Manjoine ◽  
E. Shoemaker
Keyword(s):  
Elevated Temperatures ◽  
Experimental Program ◽  
Test Results ◽  
Rotating Disks ◽  
Creep Tests ◽  
Shear Theory ◽  
Heat Treated ◽  
Long Time ◽  
Average Tension ◽  
Creep Deformations

Abstract A theoretical and experimental program involving methods of calculating creep in rotating disks at elevated temperatures is described. This program consisted primarily of the following: (a) Obtaining forged disks from the same ingot of 12 per cent chrome steel, all disks being forged and heat-treated in the same manner; (b) making spin tests at 1000 F on three of these disks for periods up to about 1000 hr; ( ) making long-time tension-creep tests at 1000 F on many specimens cut out circumferentially from several of the other disks at stresses approximating those of the spin tests; (d) investigating theoretical methods of calculation of creep deformation in such disks; and (e) comparison of spin-test results with those calculated theoretically using average tension-creep data. It was found that available methods of calculating rotating disks based on the Mises criterion gave creep deformations too low compared to the test values, i.e., on the unsafe side for design. Considerably better agreement between test and theoretical results is obtained if the latter is based on the maximum-shear theory. Some discussion is given of the reasons for the better agreement obtained using the latter theory; these are believed to be related in part to the anisotropy of the forged material tested. Further tests on other materials are necessary before general conclusions can be drawn; however, in the absence of test data it is suggested that a conservative course in design for such disks is to apply the maximum-shear theory.

Characteristics of groundwater seepage with cut-off wall in gravel aquifer. I: Field observations

2015 ◽  
Vol 52 (10) ◽  
pp. 1526-1538 ◽  
Author(s):  
Yong-Xia Wu ◽  
Shui-Long Shen ◽  
Ye-Shuang Xu ◽  
Zhen-Yu Yin
Keyword(s):  
Hydraulic Conductivity ◽  
Clayey Soil ◽  
Retaining Wall ◽  
Ground Surface ◽  
Test Site ◽  
Second Phase ◽  
Confined Aquifer ◽  
Test Results ◽  
Sandy Gravel ◽  
High Hydraulic Conductivity

This paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in Hangzhou, China. The groundwater system at the test site is composed of a phreatic aquifer underlain by an aquitard and a confined aquifer with coarse sand and gravel. The sandy gravel stratum has very high hydraulic conductivity. The maximum depth of the excavation is 24 m below the ground surface, which reaches the middle of the aquitard strata, where the thickness of the clayey soil is insufficient to maintain the safety of the base of the excavation. To understand the hydrological characteristics of gravel strata, single- and double-well pumping tests were conducted, where a cut-off wall was installed 43 m deep with its base penetrating 2 to 3 m into the aquifer. Test results show that this partial cut-off of the aquifer cannot effectively protect the base of the excavation from the upward seepage force of the groundwater during excavation. Therefore, a new cut-off wall (second phase) was constructed to a depth of 54 m to cut off the confined aquifer. A second pumping test was conducted after the construction of the second phase cut-off wall, and test results show that this full cut-off combined with dewatering can control groundwater effectively during excavation. This finding indicates that when a deep excavation is conducted in a confined aquifer with high hydraulic conductivity, determination of the depth of the retaining wall should be based on three factors: the stability of the base, the upward seepage stability, and settlement control.

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