scholarly journals Regression Equations for Estimating Landslide-Triggering Factors Using Soil Characteristics

2020 ◽  
Vol 10 (10) ◽  
pp. 3560
Author(s):  
Kyeong-Su Kim ◽  
Man-Il Kim ◽  
Moon-Se Lee ◽  
Eui-Soon Hwang
Keyword(s):  
Shear Strength ◽  
Void Ratio ◽  
Soil Characteristics ◽  
Degree Of Saturation ◽  
Geological Condition ◽  
Regression Equations ◽  
Uniformity Coefficient ◽  
Permeability Coefficients ◽  
Triggering Factors ◽  
Geological Conditions

Landslides, which often occur on natural slopes of mountainous areas and artificial slopes around urban areas during summer in South Korea, are mostly caused by localized heavy rainfalls and typhoons. A survey was conducted, and the characteristics of landslide occurrences in different geological conditions—in this case, granite soils in Sangju area and gneiss soils in Yangu area—were analyzed. Soil characteristics in the landslide and non-landslide areas and the surroundings of each geological condition were also evaluated. Triggering factors, namely permeability coefficients (k), shear strength with cohesion (c), and internal friction angle (φ) of soils that are closely linked to landslides around weathered soil layers were extracted based on the examined characteristics and a statistics method. The study used regression analysis to formulate equations to estimate the permeability coefficients and shear strength. Ultimately, the permeability coefficients showed significant results in terms of void ratio (e), the effective size of grains (D10), and uniformity coefficient (cu), while shear strength correlated with the proportion of fine-grained soil (Fines), uniformity coefficient (cu), degree of saturation (S), dry weight density (rd), and void ratio (e).

scholarly journals Development of Statistics-Based Estimation Model (SEM) for Landslide-Triggering Factors Using the Soil Physical Properties of the Landslide in Gneiss and Granite Areas of South Korea

2019 ◽  
Author(s):  
Kyeong-Su Kim ◽  
Man-Il Kim ◽  
Moon-Se Lee ◽  
Eui-Soon Hwang
Keyword(s):  
Physical Properties ◽  
Void Ratio ◽  
Mountainous Areas ◽  
Estimation Model ◽  
Uniformity Coefficient ◽  
Permeability Coefficients ◽  
Triggering Factors ◽  
Shearing Strength ◽  
Landslide Triggering ◽  
Natural Slopes

In South Korea, landslides are caused by localized heavy rainfall and typhoons, which often occur in the summer season at natural slopes in mountainous areas and artificial slopes in urban surroundings. Flow-type landslides frequently occur in mountainous areas. To evaluate flow-type landslides, it is essential to identify the physical characteristics of soil, giving focus to the soil on the top layers of various types of slope. This study conducts a survey and an analysis of the characteristics of landslides that occurred in the study area with different geological conditions of granite and gneiss. The characteristics of soil in the area and its surroundings that have or have not undergone landslides for every geological condition is also evaluated. Based on these characteristics and a statistics method, it extracts the triggering factors, permeability coefficients (k), and shearing strength with cohesion (c) and internal friction angel (φ) of soils that are highly related to landslides around weathered soil layers. As a result, the permeability coefficients show significant relevance with void ratio (e), the effective size of grains (D10), and uniformity coefficient (cu), while the shearing strength with the proportion of fine-grained soil (Fines), uniformity coefficient (cu), degree of saturation (S), dry weight density (rd), and void ratio (e). By obtaining this result, the study uses the regression analysis to suggest models to estimate the permeability coefficients and shearing strength. For the gneiss area, the statistics-based estimation model (SEM) is proposed as kgn = (1.488 × 10-02 × e) + (1.076 × D10) + (-1.629 × 10-04 × cu) - (1.893 × 10-02) for permeability coefficients; cgn = (-0.712 × Fines) + (-0.131 × cu) + 15.335 for cohesion; and φgn = (27.01 × rd) + (-12.594 × e) + 6.018 for internal frictional angle of soils. For the granite area, the statistics-based estimation model (SEM) is proposed as kgr = (8.281 × 10-03 × e) + (0.639 × D10) + (-2.766 × 10-05 × cu) - (9.907 × 10-03) for permeability coefficients; cgr = (-0.689 × Fines) + (-0.0744 × S) + 18.59 for cohesion; and φgr = (33.640 × rd) + (-0.875 × e) - 9.685 for internal frictional angle of soils. The use of statistics-based estimation models (SEMs) for landslide-triggering factors that trigger landslides will support the simple calculation of permeability coefficient and shearing strength (cohesion and internal frictional angle), only requiring information about the physical properties of soil at the natural slopes that have different geological features such as gneiss and granite areas.

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.

Capillary-based effective stress formulation for predicting shear strength of unsaturated soils

2015 ◽  
Vol 52 (12) ◽  
pp. 2067-2076 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Marc Lebeau
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Adsorbed Water ◽  
Soil Strength ◽  
Liquid Films ◽  
Degree Of Saturation ◽  
Stress Parameter ◽  
Effective Stress Parameter

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop’s parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types.

Using time domain reflectometry in triaxial testing

2000 ◽  
Vol 37 (6) ◽  
pp. 1325-1331
Author(s):  
J LH Grozic ◽  
M E Lefebvre ◽  
P K Robertson ◽  
N R Morgenstern
Keyword(s):  
Cyclic Loading ◽  
Water Content ◽  
Time Domain ◽  
Void Ratio ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Degree Of Saturation ◽  
Triaxial Testing ◽  
Empirical Correlations ◽  
Static And Cyclic Loading

Time domain reflectometry (TDR) can be used to determine the volumetric water content of soils. This note describes the utilization of a TDR miniprobe in triaxial testing. The TDR performance was examined with a series of tests that not only proved its reliability but also resulted in two empirical correlations. Using these correlations, the degree of saturation and volumetric water content during triaxial testing could be determined. The TDR was then put to use in a laboratory program designed to investigate the response of loose gassy sand under static and cyclic loading. Because of the TDR measurements it was possible to determine the degree of saturation and void ratio of the gassy specimens. The TDR miniprobe proved to be accurate, simple to use, and inexpensive to build.Key words: time domain reflectometry, TDR, triaxial testing, gassy, unsaturated.

scholarly journals Study on the Geological Condition Analysis and Grade Division of High Altitude and Cold Stope Slope

2021 ◽  
Vol 13 (22) ◽  
pp. 12464
Author(s):  
Ruichong Zhang ◽  
Shiwei Wu ◽  
Chenyu Xie ◽  
Qingfa Chen
Keyword(s):  
Low Temperature ◽  
High Altitude ◽  
Stable State ◽  
Geological Condition ◽  
Rock Layer ◽  
Eastern Slope ◽  
Geological Conditions ◽  
Grade Ii ◽  
Grade Division ◽  
Grade Iii

Analysis of the geological conditions of high-altitude and low-temperature stope slopes and the study of grade division are the basis for the evaluation of slope stability. Based on the engineering background of the eastern slope of the Preparatory iron mine in Hejing County, Xinjiang, we comprehensively analyse and summarize the factors that affect the geological conditions of high-altitude and cold slopes and finally determine nine geological conditions that affect the index parameters. Based on a back-propagation (BP) neural network algorithm, we establish an applicable network model to analyse the geological conditions of slopes in cold areas. The model is applied to the eastern slope to analyse and classify the geological conditions of the high-altitude and low-temperature slopes. The research results show that the skarn rock layer in the eastern slope is in a stable state and not prone to landslides, and its corresponding geological condition is Grade I; meanwhile, the monzonite porphyry rock layer is in a relatively stable state, with a potential for landslides and a corresponding geological condition Grade II. The marble rock layer is in a generally stable state, there is the possibility of landslide accidents, and the corresponding geological condition level is Grade III. The limestone rock layer is in an unstable state and prone to landslide accidents, it has a corresponding geology condition Grade IV. Therefore, the eastern slope can be divided into different geological condition regions: Zone I, Zone II, Zone III, and Zone IV, and the corresponding geological condition levels for these are Grade I, Grade II, Grade III, and Grade IV. These results may provide a basis for the stability evaluation of high altitudes and cold slopes.

Parametric study of electronics components joining using reactive films for high temperature applications

2019 ◽  
Vol 2019 (HiTen) ◽  
pp. 000016-000021
Author(s):  
Rabih Khazaka ◽  
Donatien Martineau ◽  
Toni Youssef ◽  
Thanh Long Le ◽  
Stéphane Azzopardi
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Film Thickness ◽  
Void Ratio ◽  
Phase Distribution ◽  
Applied Pressure ◽  
Acoustic Microscopy ◽  
External Power Source ◽  
Solder Reflow ◽  
Joint Quality

Abstract In this paper, in order to assemble electronic components onto substrates, a local rapid soldering process using an exothermic reactive foil sandwiched between solder preforms was evaluated. Among others, the main interest of this technique is that it can allow the use of high temperature melting solders, without the need to heat the whole assembly above this melting temperature. The reactive foil is commercially available and is formed from alternatively stacked nanolayers of Ni and Al until it reaches the total film thickness. Once the film is activated by using an external power source, a reaction takes place and releases such an amount of energy that is transferred to the solder preforms. If this amount of energy is high enough, solder preforms melt and insure the adhesion between the materials of the assembly. The process was evaluated using a standard SAC305 and a high temperature Au80Sn20 preforms. The influences of the applied pressure, the reactive film thickness as well as the solder and the attached materials nature and thicknesses were investigated. The initial joint quality was evaluated using scanning acoustic microscopy, scanning electron microscopy, and shear strength measurements. It was shown that the applied pressure during the process has a strong effect on the joint initial quality. The voids ratio between metallized diode dice and an Active Metal Braze (AMB) substrate decreases from 64% to 26% for pressure values between 0.5kPa and 100kPa respectively. Otherwise, under a constant low pressure of 13kPa, reducing the substrate metal thickness on a low thermal conductivity insulator allows the improvement of the initial joint quality and a voids ratio of about 15% was reached when using 35μm of copper on FR4 substrate. The use of aluminum instead of copper as a metal for the ceramic metallized substrate (with the same gold finishing layer) led to a reduction in the void ratio in the joint. The microstructure of the AuSn joint achieved using the reactive films shows very fine phase distribution compared to the one obtained using conventional solder reflow process in the oven. The mechanical properties of the joint were evaluated using shear tests performed on 350μm thick silicon diodes assembled on AMB substrates under a pressure of 100kPa. The reactive films were 60μm thick and were sandwiched between two 25μm thick SAC preforms. The void ratio was about 37% for the tested samples and shear strength values above 9.5MPa were achieved which remains largely higher than MIL-STD-883H requirements. Finally, the process impact on the electrical properties of the assembled diodes was compared with a commonly used solder reflow assembly and results show a negligible variation.

Study on the Compressibility of the Silt in Hangzhou, China

2013 ◽  
Vol 419 ◽  
pp. 853-857
Author(s):  
Zhen Ying Zhang ◽  
Da Zhi Wu ◽  
Cha Wang
Keyword(s):  
Laboratory Tests ◽  
Void Ratio ◽  
Soil Mechanics ◽  
Soil Samples ◽  
Compression Index ◽  
Uniformity Coefficient ◽  
Initial Void Ratio ◽  
Natural Density ◽  
Engineering Parameters ◽  
The Relationship

To investigate the compressibility of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the compression coefficient varies from 0.06 to 0.40MPa-1, and the compression index varies from 0.015 to 0.108. Finally, the properties of the compression are studied, and find that the compressibility of the silt soil is very large, and the relationship between the initial void ratio and the logarithm pressure is linear.

ANALYSIS OF EMPIRICAL COMPRESSION INDEX EQUATIONS USING THE VOID RATIO

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Amir Al-Khafaji ◽  
Krishnanand Maillacheruvu ◽  
Robert Jacobs
Keyword(s):  
Void Ratio ◽  
New Technique ◽  
Soil Types ◽  
Regression Equations ◽  
Compression Index ◽  
Data Set ◽  
Data Points ◽  
Compression Data ◽  
A New Technique ◽  
Selection Of

A new technique to assess the reliability of published compression index equations in terms of soil void ratio is presented. Several published equations pertaining to different soil types are examined in terms of accuracy and applicability. The new technique employs regression analysis to examine a substantial number of published compression data objectively. The traditional bias inherent in the selection of the number of data points and the range of void ratios for a given regression equation is eliminated. This was made possible by creating ranges for the compression index irrespective of the data set involved. This technique revealed that a strong correlation exists between the slopes and intercepts of all published equations. The slopes and intercepts of the newly developed regression equations were used to compare several well know published equations to assess accuracy and applicability. The proposed technique permits the examination of the authenticity of any published empirical equations relating to the compression index of clay to void ratio.

Leaf anatomy of Carex humilis does not correlate with orographic, geological and bioclimatic habitat conditions in C&SE Europe

Biologia ◽  
2014 ◽  
Vol 69 (3) ◽  
Author(s):  
Ksenija Jakovljević ◽  
Jasmina Šinžar-Sekulić ◽  
Snežana Vukojičić ◽  
Nevena Kuzmanović ◽  
Dmitar Lakušić
Keyword(s):  
Principal Component ◽  
Canonical Discriminant Analysis ◽  
Habitat Characteristics ◽  
Morphometric Study ◽  
Geological Condition ◽  
Habitat Conditions ◽  
Adaptive Responses ◽  
Geological Conditions ◽  
Anatomical Characters ◽  
Climatic Characteristics

AbstractThis paper presents the results of a multivariate morphometric study of leaf anatomical characters in different, geographically very distant populations of taxon Carex humilis from Hungary, Romania, Serbia, Bosnia & Herzegovina, Montenegro and Albania with the aim to reveal the trends of population differentiation. Analyses were performed on the cross-section of 173 leaves collected from 12 populations. In order to establish the overall morphological variation and relationships between individuals from all populations, principal component analyses (PCA) and canonical discriminant analysis (CDA) have been done. The UPGMA clustering analyses based on leaf anatomical characters and habitat climatic characteristics were carried out to explore whether the observed anatomical differences are a result of adaptive responses. Regression analysis (linear regression) was performed to identify the level of correlation between leaf anatomical characters and basic orographic, geological, and bioclimatic habitat characteristics. Quite unexpectedly, most of observed groups are formed of geographically very distant populations which are living in extremely different climatic and geological conditions, indicating that general anatomical differentiation in Carex humilis in C&SE Europe cannot be explained by the environmental impacts, and basically do not represent an adaptive response to different climatic or geological condition.

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