Seasonal pattern of matric suctions in highway subgrades

2010 ◽  
Vol 47 (3) ◽  
pp. 267-280 ◽  
Author(s):  
Quan Nguyen ◽  
Delwyn G. Fredlund ◽  
Lal Samarasekera ◽  
Brent L. Marjerison
Keyword(s):  
Thermal Conductivity ◽  
Seasonal Pattern ◽  
Membrane Surface ◽  
Matric Suction ◽  
Thin Membrane ◽  
Temperature Changes ◽  
Constant Equilibrium ◽  
Subgrade Soil

The performance of “thin membrane surface” (TMS) highways is largely controlled by the strength of the subgrade soil, which in turn is a function of matric suction. Thermal conductivity matric suction sensors were used to indirectly measure in situ matric suctions. In September 2000, 32 thermal conductivity sensors were installed under TMS highways at two locations; namely, Bethune and Torquay, Saskatchewan, Canada, to monitor matric suction and temperature changes with time. This paper presents and interprets the variations in matric suctions measured between the years 2000 and 2005 at the Torquay site. The readings in the field showed a clearly seasonal pattern of matric suction changes that bore a relationship to rainfall near the test sites. Relatively constant equilibrium matric suctions that ranged from 20 to 60 kPa throughout the years were measured under the driving lanes. Conversely, matric suctions under the side slopes were found to vary widely with time and depth, ranging from 100 to 1500 kPa over the years. The greatest variation in matric suction from one location to another location occurred during the month of April. The matric suctions showed low variability during June, whereas larger variations were observed from July to October.

Installation procedure for thermal conductivity matric suction sensors and analysis of their long-term readings

2007 ◽  
Vol 44 (2) ◽  
pp. 113-125 ◽  
Author(s):  
Elsa Tan ◽  
Delwyn G Fredlund ◽  
Brent Marjerison
Keyword(s):  
Thermal Conductivity ◽  
Ambient Temperature ◽  
Membrane System ◽  
Matric Suction ◽  
Soil Suction ◽  
Correction Factors ◽  
Temperature Changes ◽  
Subgrade Soil ◽  
Long Term Measurement

Thermal conductivity matric suction sensors have enabled continuous and long-term measurement of matric suction and temperature, even in remote locations. Long-term temperature and matric suction readings were obtained from below two thin-membrane-system sites in Torquay and Bethune, Saskatchewan. The method used to install the sensors and the data acquisition system is presented. An understanding of the subgrade soil suction and temperature changes throughout the year was obtained from the data. The change in matric suction and temperature with depth and distance was also determined. Observation of the amplitude and frequency of the fluctuations in the temperature readings provided a better understanding of the changing trends. Environmental effects, such as hysteresis associated with drying and wetting of the sensors and the effect of the ambient temperature on the sensors, were found to influence the matric suction readings. Several correction factors have been proposed to eliminate the influence of the ambient temperature, and the correction methods are compared.Key words: thermal conductivity, matric suction, sensors.

scholarly journals Method for determining the thermal conductivity of in situ formation rock using drilling cuttings

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065015
Author(s):  
Fu Yi ◽  
Xupeng Qi ◽  
Xuexin Zheng ◽  
Huize Yu ◽  
Wenming Bai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
In Situ Formation

Synergistic effect of phase structures and in situ sintering of silver fillers on thermal conductivity of epoxy/polyethersulphone/silver filler composites

Polymer ◽  
2021 ◽  
pp. 123726
Author(s):  
Hajime Kishi ◽  
Takashi Saruwatari ◽  
Takemasa Mototsuka ◽  
Sanae Tanaka ◽  
Takeshi Kakibe ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Synergistic Effect ◽  
Phase Structures

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

In-situ synthesized nanocrystalline UO2/SiC composite with superior thermal conductivity

2021 ◽  
Author(s):  
Dezhi Zhang ◽  
Yingru Li ◽  
Zhenliang Yang ◽  
Bingqing Li ◽  
Zhiyi Wang ◽  
...  
Keyword(s):  
Thermal Conductivity

Determination of Thermal Conductivity of Amorphous Silicon Thin Films via Non-Contacting Optical Probing

2006 ◽  
Vol 326-328 ◽  
pp. 689-692
Author(s):  
Seung Jae Moon
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Amorphous Silicon ◽  
Optical Transmission ◽  
Film Deposition ◽  
Transmission Measurement ◽  
Conductive Heat ◽  
Optical Transmission Measurement

The thermal conductivity of amorphous silicon (a-Si) thin films is determined by using the non-intrusive, in-situ optical transmission measurement. The thermal conductivity of a-Si is a key parameter in understanding the mechanism of the recrystallization of polysilicon (p-Si) during the laser annealing process to fabricate the thin film transistors with uniform characteristics which are used as switches in the active matrix liquid crystal displays. Since it is well known that the physical properties are dependent on the process parameters of the thin film deposition process, the thermal conductivity should be measured. The temperature dependence of the film complex refractive index is determined by spectroscopic ellipsometry. A nanosecond KrF excimer laser at the wavelength of 248 nm is used to raise the temperature of the thin films without melting of the thin film. In-situ transmission signal is obtained during the heating process. The acquired transmission signal is fitted with predictions obtained by coupling conductive heat transfer with multi-layer thin film optics in the optical transmission measurement.

scholarly journals In situ synthesis of MWCNT-graft-polyimides: thermal stability, mechanical property and thermal conductivity

RSC Advances ◽  
2020 ◽  
Vol 10 (23) ◽  
pp. 13517-13524
Author(s):  
Chunbo Wang ◽  
Bing Cong ◽  
Junyu Zhao ◽  
Xiaogang Zhao ◽  
Daming Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Property ◽  
Thermal Stability ◽  
In Situ Synthesis ◽  
Enhanced Thermal Conductivity

In situ synthesis of MWCNT-graft-polyimides enhanced thermal conductivity at a relatively low loading.

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