Application of In-situ Sonic Wave Test Method in the effect evaluation of grouting treatment in Weak Rock

AbstractWater tunnels built for hydropower passing through weak and heterogeneous rock mass pose challenges associated to slaking and disintegration, as they are first exposed to dry condition during excavation and are then filled with water to produce hydropower energy. Over the period of operational life, these tunnels are drained periodically for inspections and repair leading to drainage and filling cycles. The weakening of rock mass caused by cycles of drying, saturation and drainage may lead to the propagation of instabilities in the tunnels. Therefore, it is important to study the slaking and disintegration behavior of the weak rock mass consisting of clay and clay-like minerals. This paper assesses the mineralogical composition of flysch and serpentinite from the headrace tunnel of Moglicë Hydropower Project in Albania. Further, to determine the slaking and disintegration behavior of these rocks, extensive testing using both the ISRM, Int J Rock Mech Min Sci Geomech Abstr 16(2):143-151, (1979) suggested test method and a modified variant of this test are performed. Finally, comprehensive assessments, discussions and comparisons are made. It is found that the modified slake durability test better suits for the tunnels built as water conveying systems such as hydropower tunnels.

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Estimation of Creep-Fatigue Damage Through Indentation Test Method

Volume 3: Design and Manufacturing ◽

10.1115/imece2011-63445 ◽

2011 ◽

Author(s):

Raghu V. Prakash

Keyword(s):

Tensile Properties ◽

Fatigue Damage ◽

Indentation Test ◽

Creep Damage ◽

Test Method ◽

Specimen Preparation ◽

Creep Fatigue ◽

Critical Components ◽

The Cost

Creep, creep-fatigue damage is often estimated through in-situ metallography, tensile testing of specimens. However, these methods require specimen preparation which includes specimen extraction from critical components. Automated ball indentation testing has been used as an effective tool to determine the mechanical properties of metallic materials. In this work, the tensile properties of materials subjected to controlled levels of damage in creep, creep-fatigue is studied. It is found that the tensile properties such as yield strength and UTS deteriorates with creep damage, whereas the same specimens show an improved UTS values (at the cost of ductility) when subjected to creep-fatigue interactions.

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Modeling the Resilient Modulus Variation of In Situ Soils due to Seasonal Moisture Content Variations

Advances in Civil Engineering ◽

10.1155/2019/1793601 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Kevin Gaspard ◽

Zhongjie Zhang ◽

Gavin Gautreau ◽

Khalil Hanifa ◽

Claudia E. Zapata ◽

...

Keyword(s):

Moisture Content ◽

Resilient Modulus ◽

Optimum Moisture Content ◽

Test Method ◽

Large Scatter ◽

Controlling Parameter ◽

Base Course ◽

The Relationship ◽

Level 2

LTRC is conducting a research project to determine the seasonal variation of subgrade resilient modulus (MR) in an effort to implement PavementME. One objective of that project, which is presented in this paper, was to locally calibrate the Enhanced Integrated Climate Model’s (EICM Fenv) curve for seasonal subgrade MR changes. Shelby tube sampling was conducted on six different roadways to a depth of approximately 7.92 m beneath the shoulder pavement’s base course. The AASHTO T-99 MR test method was used on all samples with an additional eight specimens being tested with NCHRP 1–28A MR test method. Four soils from Louisiana which were not from the six roadways were also tested and included in the analyses. Once the MR tests were completed and plotted, it was noticed that there was a rather large scatter (R2 = −0.266) around the EICM Fenv curve. The authors hypothesized that this occurred due to the density differences between in situ and remolded specimens. Further analyses confirmed this hypothesis. LTRC developed a new method based on the EICM Fenv method to determine the relationship between changes in subgrade MR as a function of changes in moisture content with the in situ moisture content and MR used as the control. This method differs from the EICM Fenv in that the EICM Fenv uses optimum moisture content as the controlling parameter. The LTRC method can be used for design purposes as well as level 2 inputs into the EICM.

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Study on Compaction Effect and Process of Reclaimed Soil of Nonmetallic Mines in Xinjiang, China

Advances in Materials Science and Engineering ◽

10.1155/2020/1973458 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Kaikai Wang ◽

Zizhao Zhang ◽

Guobin Tang ◽

Xiaodong Tan ◽

Qianli Lv ◽

...

Keyword(s):

Numerical Simulation ◽

Land Reclamation ◽

Simulation Method ◽

Test Method ◽

Soil Thickness ◽

In Situ Test ◽

Factors Affecting ◽

Reclaimed Soil ◽

Different Thickness

Reclaimed soil is the key substrate for land reclamation and ecological restoration in the mine areas. The change of the density of reclaimed soil of the nonmetallic mines in Xinjiang during the land reclamation process was studied in this paper. Firstly, the in situ test method of static load was used to simulate the compaction of reclaimed soil with different thickness of overlying soil by different compaction times of mines reclamation machinery, and field in situ test compaction data were obtained. Then, the numerical simulation method was used to simulate the variation process of displacement and porosity at different depths for different thickness of the reclaimed soil under different compaction conditions. The numerical simulation and the in situ test results verified each other to acquire the compaction process and results of reclaimed soil under different compaction. The results showed that the numerical simulation results were consistent with the in situ test. The reclaimed soil thickness and compaction times were crucial factors affecting the compaction effect of the soil. The difference between the three times compaction and the uncompacted soil was obvious, and the effect of single compaction was weakened with the increase of compaction times. Under the same compaction action, the thicker the soil was, the less obvious the compaction effect would be. In the process of reclamation, the compaction effect of the surface part (at the depth of 10 cm) was visible, and the amount of compression and springback was larger. The research results can provide a reference to the land reclamation of nonmetallic mines in Xinjiang, China.

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