scholarly journals Analysis of Necessity and Feasibility for Ground Improvement in Warm and Ice-Rich Permafrost Regions

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
Honglei Wang ◽  
Hu Zhang ◽  
Mingtang Chai ◽  
Jianming Zhang ◽  
Zhizhong Sun ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Ground Improvement ◽  
Frozen Soil ◽  
Chemical Stabilization ◽  
Alternative Measure ◽  
Frozen Ground ◽  
Foundation Soil ◽  
The Stability ◽  
Permafrost Regions

Characterized by low bearing capacity and high compressibility, warm and ice-rich frozen soil is a kind of problematic soil, which makes the original frozen ground formed by of that unreliable to meet the stability requirements of engineering infrastructures and foundations in permafrost regions. With the design and construction of major projects along the Qinghai-Tibet Engineering Corridor (QTEC), such as expressway and airport runway, it is a great challenge to favor the stability of overlying structures by formulating the proper engineering design principles and developing the valid engineering supporting techniques. The investigations carried out in recent years indicated that warm and ice-rich permafrost foundations were widespread, climate warming was significant, and the stability of existing engineering structures was poor, along the QTEC. When the warm and ice-rich frozen ground is used as the foundation soil, the implementation of ground improvement is an alternative measure to enhance the bearing capacity of foundation soil and eliminate the settlement of structures during operation, in order to guarantee the long-term stability of the structures. Based on the key factors determining the physicomechanical properties of frozen soil, an innovative idea of stabilizing the warm and ice-rich frozen soil based on chemical stabilization is proposed in this study, and then, an in situ ground improvement technique is introduced. This study intends to explore the feasibility of ground improvement in warm and ice-rich permafrost regions along the QTEC based on in situ chemical stabilization and provide the technical support and scientific reference to prevent and mitigate the hazards in the construction of major projects in the future.

scholarly journals Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation

2021 ◽  
Vol 118 (25) ◽  
pp. e2025321118
Author(s):  
Ming-Hui Wu ◽  
Sheng-Yun Chen ◽  
Jian-Wei Chen ◽  
Kai Xue ◽  
Shi-Long Chen ◽  
...  
Keyword(s):  
Active Layer ◽  
Tibet Plateau ◽  
Permafrost Degradation ◽  
Soil C ◽  
C Cycling ◽  
Microbial Stability ◽  
The Stability ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Permafrost degradation may induce soil carbon (C) loss, critical for global C cycling, and be mediated by microbes. Despite larger C stored within the active layer of permafrost regions, which are more affected by warming, and the critical roles of Qinghai-Tibet Plateau in C cycling, most previous studies focused on the permafrost layer and in high-latitude areas. We demonstrate in situ that permafrost degradation alters the diversity and potentially decreases the stability of active layer microbial communities. These changes are associated with soil C loss and potentially a positive C feedback. This study provides insights into microbial-mediated mechanisms responsible for C loss within the active layer in degraded permafrost, aiding in the modeling of C emission under future scenarios.

scholarly journals THE RELIABILITY ANALYSIS OF EXISTING REINFORCED CONCRETE PILES IN PERMAFROST REGIONS

2017 ◽  
Vol 13 (2) ◽  
pp. 64-72 ◽  
Author(s):  
Vladimir S. Utkin ◽  
Leonid A. Sushev
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Reliability Analysis ◽  
Contact Zone ◽  
Limit State ◽  
Frozen Soil ◽  
Negative Consequences ◽  
Concrete Piles ◽  
Reinforced Concrete Piles ◽  
Permafrost Regions

The article describes the general problem of safe operation of buildings and structures with the dynamics of permafrost in Russia and other countries. The global warming on Earth will lead to global disasters such as failures of buildings and structures. The main reason of these failures will be a reduction of bearing capacity and the reliability of foundations. It is necessary to organize the observations (monitoring) for the process of reducing the bearing capacity of foundations to prevent such accidents and reduce negative consequences, to development of preventive measures and operational methods for the piles reliability analysis. The main load-bearing elements of the foundation are reinforced concrete piles and frozen ground. Reinforced concrete piles have a tendency to decrease the bearing capacity and reliability of the upper (aerial) part and the part in the soil. The article discusses the problem of reliability analysis of existing reinforced concrete piles in upper part in permafrost regions by the reason of pile degradation in the contact zone of seasonal thawing and freezing soil. The evaluation of the probability of failure is important in itself, but also it important for the reliability of foundation: consisting of piles and frozen soil. Authors offers the methods for reliability analysis of upper part of reinforced concrete piles in the contact zone with seasonally thawed soil under different number of random variables (fuzzy variables) in the design mathematical model of a limit state by the strength criterion.

Discussion on the Bearing Capacity Determination Methods of Shallow Foundation in Shanghai Region

2013 ◽  
Vol 339 ◽  
pp. 623-627
Author(s):  
De Fang Chen
Keyword(s):  
Bearing Capacity ◽  
Mechanical Tests ◽  
Shallow Foundation ◽  
Test Results ◽  
Foundation Soil ◽  
Capacity Calculation ◽  
Determination Methods ◽  
Preliminary Study ◽  
Inversion Analysis

Representative engineering geological data of Shanghai were collected in this article for analyzes differences between shallow land basic bearing capacity of soil between test values and situ test values. Microstructure of soil geographical is analysis by conventional physical and mechanical tests laboratory. Collect on-site load plate test results of Shanghai shallow foundation soil, and take inversion analysis of the carrying capacity and regression analysis to calculate the bearing capacity of foundation soil test values and in situ values rationality, do a preliminary study on the current bearing capacity calculation and selection.

Experimental Study on Bearing Characteristics of the Pad and Chimney Foundation in Salt Lake Area

2012 ◽  
Vol 256-259 ◽  
pp. 97-100 ◽  
Author(s):  
Yin Man ◽  
Xian Long Lu ◽  
Wei Feng Zheng
Keyword(s):  
Bearing Capacity ◽  
Saline Soil ◽  
Salt Lake ◽  
High Water ◽  
Foundation Engineering ◽  
Lake Area ◽  
In Situ Tests ◽  
Foundation Soil ◽  
Geological Conditions

Transmission line foundation engineering inevitably encounters the special geological conditions in salt lake area, such as strong corrosion of saline soil, weakness of foundation soil and high water table of groundwater. In-situ tests on bearing characteristics of the selected pad and chimney foundation were conducted. Ultimate uplift bearing capacity and ultimate compressive bearing capacity of the pad and chimney foundation in salt lake are obtained, which can verify the rationality and reliability for its engineering popularization.

Stability Analysis of the Scour Protection Structure for a Debarking Pipeline

2013 ◽  
Vol 325-326 ◽  
pp. 1333-1336
Author(s):  
Wen Bin Liu ◽  
Run Liu ◽  
Shu Wang Yan ◽  
Zhi Liang Huo
Keyword(s):  
Stability Analysis ◽  
Bearing Capacity ◽  
Gas Pipeline ◽  
Type Structure ◽  
Base Pressure ◽  
Silty Clay ◽  
Foundation Soil ◽  
The Stability ◽  
Scour Protection

The debarking location of a gas pipeline is at the area where typhoons take place frequently and the geotechnical condition of the slope is very complex. A sloping breakwater type structure is selected in this paper for the purpose of pipeline scour protection. Since part of the sloping foundation soil consists of silty clay whose strength is very low, the bearing capacity is checked with the base pressure induced by the breakwater. The stability of the foundation of the breakwater is analyzed with the method developed by Meyerhof. The scour protection structure is proved effective and stable.

Calculation Method for Bearing Capacity of Foundation Soil Based on Potential Slip Line Theory

2012 ◽  
Vol 256-259 ◽  
pp. 302-305
Author(s):  
Li Min Li ◽  
Guo Xiang Zhang
Keyword(s):  
Bearing Capacity ◽  
Influence Factors ◽  
Stability Factor ◽  
Sliding Surface ◽  
Element Analysis ◽  
Foundation Soil ◽  
Soil Failure ◽  
Line Theory ◽  
The Stability ◽  
Analytical Program

To solve the bearing capacity of foundation soil problem, through theoretical analysis and proof, a new method used to calculate bearing capacity of foundation soil is proposed, and the solving potential sliding curve and corresponding analytical program is devised. A continuous stress field of foundation soil is gained, by using the analysis of elastic-plastic finite element analysis of foundation soil for differ load; the numerical integration is used to make sure of the potential sliding curve, the most dangerous potential sliding surface, and the stability factor. The method has a rigor basis. Through many examples and engineering tests, the proposed method has good comparability with other method, and it can take into account many influence factors, such as the width and embedded depth of foundation, soil gravity, layered soil and etc, and it can also trace the trend of soil failure development and make clear the failure mechanism of foundation soil.

Influence of ion-milling on the T2 phase in Al-2.5%Li-2.5%Cu alloy

1989 ◽  
Vol 47 ◽  
pp. 288-289
Author(s):  
J. R. Reed ◽  
D. J. Michel ◽  
P. R. Howell
Keyword(s):  
Thin Foil ◽  
Icosahedral Symmetry ◽  
Ion Milling ◽  
Cu Alloy ◽  
Thin Foils ◽  
Heat Treated ◽  
Aluminum Solid Solution ◽  
In Situ Heating ◽  
The Stability

The Al6Li3Cu (T2) phase, which exhibits five-fold or icosahedral symmetry, forms through solid state precipitation in dilute Al-Li-Cu alloys. Recent studies have reported that the T2 phase transforms either during TEM examination of thin foils or following ion-milling of thin foil specimens. Related studies have shown that T2 phase transforms to a microcrystalline array of the TB phase and a dilute aluminum solid solution during in-situ heating in the TEM. The purpose of this paper is to report results from an investigation of the influence of ion-milling on the stability of the T2 phase in dilute Al-Li-Cu alloy.The 3-mm diameter TEM disc specimens were prepared from a specially melted Al-2.5%Li-2.5%Cu alloy produced by conventional procedures. The TEM specimens were solution heat treated 1 h at 550°C and aged 1000 h at 190°C in air to develop the microstructure. The disc specimens were electropolished to achieve electron transparency using a 20:80 (vol. percent) nitric acid: methanol solution at -60°C.

scholarly journals Underground Microseismic Event Monitoring and Localization within Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2830
Author(s):  
Sili Wang ◽  
Mark P. Panning ◽  
Steven D. Vance ◽  
Wenzhan Song
Keyword(s):  
Sensor Networks ◽  
Real Time ◽  
Information Needs ◽  
Localization Algorithm ◽  
Distributed Sensors ◽  
Distributed Sensor ◽  
Microseismic Events ◽  
The Stability ◽  
Stability And Accuracy

Locating underground microseismic events is important for monitoring subsurface activity and understanding the planetary subsurface evolution. Due to bandwidth limitations, especially in applications involving planetarily-distributed sensor networks, networks should be designed to perform the localization algorithm in-situ, so that only the source location information needs to be sent out, not the raw data. In this paper, we propose a decentralized Gaussian beam time-reverse imaging (GB-TRI) algorithm that can be incorporated to the distributed sensors to detect and locate underground microseismic events with reduced usage of computational resources and communication bandwidth of the network. After the in-situ distributed computation, the final real-time location result is generated and delivered. We used a real-time simulation platform to test the performance of the system. We also evaluated the stability and accuracy of our proposed GB-TRI localization algorithm using extensive experiments and tests.

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

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