Soil matrix suction: some examples of its measurement and application in geotechnical engineering

Géotechnique ◽  
2003 ◽  
Vol 53 (2) ◽  
pp. 241-253 ◽  
Author(s):  
A. M. Ridley ◽  
K. Dineen ◽  
J. B. Burland ◽  
P. R. Vaughan
Keyword(s):  
Geotechnical Engineering ◽  
Soil Matrix ◽  
Matrix Suction

The Stability Studies of Soil Slope under the Action of Short-Time Heavy Rainfall

2012 ◽  
Vol 170-173 ◽  
pp. 1192-1195
Author(s):  
Zhong Ming He ◽  
Xin Tong Zhao ◽  
Ling Zeng ◽  
Yan Qi Qin
Keyword(s):  
Shear Strength ◽  
Heavy Rainfall ◽  
Soil Slope ◽  
Soil Matrix ◽  
Water Load ◽  
Safety Coefficient ◽  
Rainwater Infiltration ◽  
Matrix Suction ◽  
Short Time ◽  
Slope Safety

Based on the saturated-unsaturated seepage theory and the unsaturated shear strength, the numerical simulations of soil slope seepage field in short-time heavy rainfall was carried out, and on this basis calculated the slope safety coefficient at different rainfall time. The research shows that: the rainfall infiltration will cause the slope soil matrix suction decreased or even disappeared which leads to the slope shear strength reduce; Rainwater infiltration increases the transient water load of infiltration area; and under the dual role of matrix suction reduction and transient water load increasing, the slope safety coefficient has the downward trend obviously.

Factors controlling debris avalanche initiation

1990 ◽  
Vol 27 (5) ◽  
pp. 659-675 ◽  
Author(s):  
P. Buchanan ◽  
K. W. Savigny
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Debris Avalanche ◽  
Soil Matrix ◽  
Debris Avalanches ◽  
Root Cohesion ◽  
Group I ◽  
Whatcom County ◽  
Matrix Suction ◽  
Forest C

Heavy rainfall during a January 1983 storm triggered numerous debris avalanches and associated debris torrents in the Smith Creek basin, western Whatcom County, Washington, United States. Four classes of debris avalanches are recognized: wedges, drainage depressions, logging roads, and discontinuity surfaces. Nine different debris avalanche headscarps that are representative of these four classes are studied in detail. The geometric configuration of each headscarp, the properties of soils comprising the headscarps, and water tables based on numerical models of hillslope hydrology are used in limit equilibrium slope stability analyses to back-calculate root cohesion (Cr) values at failure. The calculated values are consistent with those reported by others. Four groups of Cr values are proposed and correlated with forest vegetation: group I, understory, Cr range from 1.6 to 2.1 kPa; group II, scrub forest, Cr range from 2.1 to 2.5 kPa; group III, mixed forest, Cr range from 2.5 to 3.0 kPa; and group IV, old growth forest, Cr greater than 3.0 kPa. Circular and noncircular failure surfaces are tested to determine the most likely failure configuration. Most computer-generated failure surfaces are consistent with those observed in situ. One debris avalanche is attributed to hydraulic erosion rather than Coulomb shear. Soil matrix suction contributes significantly to slope stability under drained, initial conditions. Loss of soil matrix suction during rainstorms and loss of root cohesion at failure cause a sharp reduction of soil shear strength. The stability of each headscarp is modeled during a moderately severe comparison storm in December 1979. Failure was probable at only two of the nine sites, and field evidence of prior failure is found at one of these. Sites with group I vegetation were also susceptible to failure during this storm. Pore-pressure increases triggered the debris avalanches; however, soil depth, soil density, the presence of smooth bedrock discontinuities, and root cohesion are shown to be important factors controlling initiation locations. The conclusions of this study are based on modeling results, which are only verified by post-failure observations at the avalanche headscarps. Direct field measurement of the hydrologic and shear strength parameters is required before the modeling results and conclusions drawn can be confirmed. Key words: slope stability, debris avalanche, hydrology, root cohesion, forested hillslope, factor of safety, Whatcom County, Washington.

scholarly journals Interfacial Shearing Behavior along Xanthan Gum Biopolymer-Treated Sand and Solid Interfaces and Its Meaning in Geotechnical Engineering Aspects

2020 ◽  
Vol 11 (1) ◽  
pp. 139
Author(s):  
Minhyeong Lee ◽  
Jooyoung Im ◽  
Gye-Chun Cho ◽  
Hee Hwan Ryu ◽  
Ilhan Chang
Keyword(s):  
Moisture Content ◽  
Xanthan Gum ◽  
Soil Stabilization ◽  
Ground Improvement ◽  
Geotechnical Engineering ◽  
Interfacial Shear ◽  
Interface Condition ◽  
Interface Shear ◽  
Soil Matrix ◽  
Treated Soil

Recently, environment-friendly microbial biopolymer has been widely applied as a new construction material in geotechnical engineering practices including soil stabilization, slope protection, and ground injection. Biopolymer is known to exhibit substantial improvements in geotechnical properties, such as shear strength enhancement and hydraulic conductivity reduction, through the formation of direct ionic bonds with soil particles, especially clay particles. Moreover, the rheological characteristics (e.g., pseudoplasticity, shear-rate dependent thixotropy) of biopolymers render distinctive behaviors such as shear thinning and lubrication effect under a high strain condition, while recovering their viscosities and shear stiffnesses when they are at rest. To ensure the practical applicability of biopolymer-based soil treatment, it is important to understand the interfacial interaction (i.e., friction) between biopolymer-treated soil and adjoining structural members which can be constructed in a biopolymer-treated ground. Thus, in this paper, interfacial shearing behavior of biopolymer-treated soil along solid surfaces as well as internal shearing on biopolymer-soil matrix were explored via direct and interface shear test. Experimental results show a predominant effect of the soil moisture content on the interfacial shear behavior of biopolymer-treated soil which attributes to the rheology transition of biopolymer hydrogels. At low moisture content, condensed biopolymer biofilm mobilizes strong intergranular bonding, where the interfacial shear mainly depends on the physical condition along the surface including the asperity angle. In contrast, the biopolymer induced intergranular bonding weakens as moisture content increases, where most interfacial failures occur in biopolymer-treated soil itself, regardless of the interface condition. In short, this study provides an overall trend of the interfacial friction angle and adhesion variations of xanthan gum biopolymer-treated sand which could be referred when considering a subsequent structural member construction after a biopolymer-based ground improvement practice in field.

scholarly journals Cementation of sand soil by microbially induced calcite precipitation at various degrees of saturation

2013 ◽  
Vol 50 (1) ◽  
pp. 81-90 ◽  
Author(s):  
Liang Cheng ◽  
Ralf Cord-Ruwisch ◽  
Mohamed A. Shahin
Keyword(s):  
Soil Stabilization ◽  
Geotechnical Engineering ◽  
Contact Point ◽  
Soil Strength ◽  
Degree Of Saturation ◽  
Sieve Analysis ◽  
Calcite Precipitation ◽  
Engineering Applications ◽  
Soil Matrix ◽  
Microbially Induced Calcite Precipitation

A newly emerging microbiological soil stabilization method, known as microbially induced calcite precipitation (MICP), has been tested for geotechnical engineering applications. MICP is a promising technique that utilizes the metabolic pathways of bacteria to form calcite precipitation throughout the soil matrix, leading to an increase in soil strength and stiffness. This paper investigates the geotechnical properties of sand bio-cemented under different degrees of saturation. A series of laboratory experiments was conducted, including sieve analysis, permeability, unconfined compressive strength, consolidated undrained triaxial, and durability tests. The results indicate that higher soil strength can be obtained at similar CaCO3 content when the treatment is performed under a low degree of saturation. The experimental results are further explained with a mathematical model, which shows that the crystallization efficiency, i.e., actual volume of crystals forming at the contact point where they contribute the most to strength, can be calculated from the degree of saturation and grain size. Fine sand samples exhibited higher cohesion, but lower friction angle than coarse sand samples with similar CaCO3 content. The results also confirm the potential of MICP as a viable alternative technique for soil improvement in many geotechnical engineering applications, including liquefiable sand deposits, slope stabilization, and subgrade reinforcement. The freeze–thaw and acid rain resistance of MICP-treated sand has also been tested.

scholarly journals New Progress in the Study of Intergranular Suction and Shear Strength of Unsaturated Soil

2016 ◽  
Vol 20 (1) ◽  
pp. 1-13
Author(s):  
Liansheng Tang ◽  
Haitao Sang ◽  
Liqun Jiang ◽  
Yinlei Sun ◽  
Muhammad Ashraf
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Influence Factors ◽  
Confining Pressure ◽  
Soil Matrix ◽  
Soil Particles ◽  
Quantitative Calculation ◽  
Matrix Suction

<p>The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction, which has been widely used since the discipline of unsaturated soil mechanics was established. In fact, the concept of matrix suction is from soil science and reflects the water- absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which are not in conformity with the principle of the effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: the effective, cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of unsaturated soil.</p>

Overview of Measurements of Unsaturated Soil Matrix Suction

2014 ◽  
Vol 955-959 ◽  
pp. 3615-3619
Author(s):  
Yan Hui Liu ◽  
Hong Zhang ◽  
Chao Guo
Keyword(s):  
Field Test ◽  
Unsaturated Soil ◽  
Measurement Range ◽  
Test Method ◽  
Soil Matrix ◽  
Matrix Suction ◽  
Physical Principles ◽  
Field Test Method

Matrix suction is very important in researching the properties of unsaturated soil. At present, there have been a lot of measurements of matrix suction. Basing on the physical principles of each kind of measurements, this paper divides them into indoor test method and field test method and evaluates them by equipment needed, operation steps, measurement range and matters needing attention.

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