scholarly journals Development of Some Novel Suction-Based Correlations for Swell Behavior of Expansive Soils

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Bakht Zamin ◽  
Hassan Nasir ◽  
Khalid Mehmood ◽  
Qaiser Iqbal ◽  
M. Tariq Bashir ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Expansive Soils ◽  
Water Pressure ◽  
Expansive Soil ◽  
Field Testing ◽  
Published Data ◽  
The Novel ◽  
Field Instrumentation ◽  
Swell Potential ◽  
Unsaturated Expansive Soils

Swelling and shrinkage are the two distinctive characteristics of expansive soils, and due to this behavior, these soils are considered a natural hazard for infrastructure. Many structures in different regions have been impaired due to the swell/shrink behavior of the expansive soil. Most of the severe distress is impeded because of the inherent suction (negative pore water pressure) present in expansive soils. Both suction and swelling parameters are greatly affected by the surrounding moisture content. Due to this feature of expansive soil, geotechnical engineers are interested in utilizing the suction-based correlations for the assessment of unsaturated expansive soils. The current investigation was carried out to develop novel correlations incorporating lab testing and field instrumentation. To fulfill the objectives, eight sites of the local expansive soil in Pakistan were selected for samples collection and field testing. Conventional odometer testing was conducted to measure the swell pressure (Sp) and swell potential (S) of the fabricated/remolded specimens. Gypsum block (G-block) sensors were additionally utilized for estimating the matric suction in the field. To expand the database, the previously published data of the same nature was also incorporated. Based on the results, the power form of the novel correlations (suction-based) is highly significant for estimating (Sp), while for swell potential, the logarithmic correlation with R2 = 0.6551 is more significant than other forms of correlations. The proposed suction-based correlation can be equally utilized for the estimation of field suction as well as for swell behavior of expansive soil having a plasticity index (PI) ≥ 22%.

Model for the simulation of swelling-pressure measurements on expansive soils

1998 ◽  
Vol 35 (1) ◽  
pp. 96-114 ◽  
Author(s):  
Fangsheng Shuai ◽  
D G Fredlund
Keyword(s):  
Pore Water ◽  
Volume Change ◽  
Unsaturated Soil ◽  
Pore Water Pressure ◽  
Expansive Soils ◽  
Water Pressure ◽  
Expansive Soil ◽  
Swelling Pressure ◽  
Oedometer Test ◽  
Free Swell

Numerous laboratory swelling tests have been reported for the measurement of swelling pressure and the amount of swell of an expansive soil. These test methods generally involve the use of a conventional one-dimensional oedometer apparatus. Few attempts, however, have been made to formulate a theoretical framework to simulate the testing procedures or to visualize the different stress paths followed when using the various methods. The simulation of the oedometer tests on expansive soils is required to fully understand the prediction of heave. The correct measurement of swelling pressure is required for an accurate prediction of heave. It is further anticipated that some information on unsaturated soils property functions may be approximated from the back-analysis of the data. A theoretical model is proposed to describe the pore-water pressures with time and depth in a specimen as well as the volume changes during various oedometer swell tests. The model is formulated based on equilibrium considerations, constitutive equations for an unsaturated soil, and the continuity requirement for the pore fluid phases. The transient water flow process is coupled with the soil volume change process. The model can be used to describe the volume-change behaviour, pore-water pressure, and vertical total stress development in an unsaturated soil during an oedometer test performed by any one of several test procedures. The model has been put into a finite element formulation using the Galerkin technique. All the parameters required to run the model can be obtained by performing independent, common laboratory tests. The proposed model was used to simulate the results from free-swell, constant-volume, constant water content, and loaded-swell oedometer tests. Computed values of volume change, vertical total stress, and pore-water pressure are in good agreement with measured values.Key words: unsaturated soil, expansive soil, swelling pressure, theoretical simulation, constant-volume oedometer test, free-swell oedometer test, loaded-swell oedometer test.

Applied Research on Dynamic Replacement Method in Tailings Residue Subgrade Reinforcement

2013 ◽  
Vol 639-640 ◽  
pp. 943-946
Author(s):  
Jiao Long He ◽  
Yong Zhou ◽  
Zhong Ai Jiang
Keyword(s):  
Applied Research ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Testing ◽  
Standard Penetration Test ◽  
Load Test ◽  
Test Results ◽  
Replacement Method ◽  
Dynamic Replacement ◽  
Testing Experiment

Based on the reinforcing mechanism of dynamic replacement method ,this article put forward the construction parameters and measures of dynamic replacement method , combining with the result of actual engineering field testing experiment. The field load test, standard penetration test and pore water pressure test results show that the characteristic value of subgrade bearing capacity is more than 130 kpa when the tailings residue subgrade has been managed with dynamic replacement method, providing references for applied research on dynamic replacement method in tailings residue subgrade reinforcement.

scholarly journals Numerical Simulation Of The Treatment Of Soil Swelling Using Grid Geocell Columns

2015 ◽  
Vol 23 (2) ◽  
pp. 9-18 ◽  
Author(s):  
Mohammed Y. Fattah ◽  
Raid R. Al-Omari ◽  
Haifaa A. Ali
Keyword(s):  
Finite Element ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Expansive Soil ◽  
Matric Suction ◽  
Degree Of Saturation ◽  
Axial Forces ◽  
Column Material ◽  
Cap Model

Abstract In this paper, a method for the treatment of the swelling of expansive soil is numerically simulated. The method is simply based on the embedment of a geogrid (or a geomesh) in the soil. The geogrid is extended continuously inside the volume of the soil where the swell is needed to be controlled and orientated towards the direction of the swell. Soils with different swelling potentials are employed: bentonite base-Na and bentonite base-Ca samples in addition to kaolinite mixed with bentonite. A numerical analysis was carried out by the finite element method to study the swelling soil's behavior and investigate the distribution of the stresses and pore water pressures around the geocells beneath the shallow footings. The ABAQUS computer program was used as a finite element tool, and the soil is represented by the modified Drucker-Prager/cap model. The geogrid surrounding the geocell is assumed to be a linear elastic material throughout the analysis. The soil properties used in the modeling were experimentally obtained. It is concluded that the degree of saturation and the matric suction (the negative pore water pressure) decrease as the angle of friction of the geocell column material increases due to the activity of the sand fill in the dissipation of the pore water pressure and the acceleration of the drainage through its function as a drain. When the plasticity index and the active depth (the active zone is considered to be equal to the overall depth of the clay model) increase, the axial movement (swelling movement) and matric suction, as a result of the increase in the axial forces, vary between this maximum value at the top of the layer and the minimum value in the last third of the active depth and then return to a consolidation at the end of the depth layer.

scholarly journals Effect of Compaction Energy on Engineering Properties of Expansive Soil

2017 ◽  
Vol 3 (8) ◽  
pp. 610 ◽  
Author(s):  
Sadam Hussain
Keyword(s):  
Expansive Soils ◽  
Energy Levels ◽  
Expansive Soil ◽  
Substantial Improvement ◽  
Engineering Properties ◽  
Engineering Structures ◽  
Expansive Clays ◽  
Swell Potential ◽  
Compaction Energy ◽  
Strength And Deformation

Swelling of expansive clays is one of the great hazards, a foundation engineer encounters. Each year expansive soils cause severe damage to residences, buildings, highways, pipelines, and other civil engineering structures. Strength and deformation parameters of soils are normally related to soil type and moisture. However, surprisingly limited focus has been directed to the compaction energy applied to the soil. Study presented herein is proposed to examine the effect of varying compaction energy of the engineering properties i.e. compaction characteristics, unconfined compressive strength, California bearing ratio and swell percentage of soil. When compaction energy increased from 237 KJ/m3 to 1197 KJ/m3, MDD increased from 1.61 g/cm3 to 1.75 g/cm3, OMC reduced from 31.55 percent to 21.63 percent, UCS increased from 110.8 to 230.6 KPa, and CBR increased from mere 1 percent to 10.2 percent. Results indicate substantial improvement in these properties. So, compacting soil at higher compaction energy levels can provide an effective approach for stabilization of expansive soils up to a particular limit. But if the soil is compacted more than this limit, an increase in swell potential of soil is noticed due to the reduction in permeability of soil.

Application Study on Dynamic Compaction Technology in Mine Tailings Foundation Reinforcement

2012 ◽  
Vol 170-173 ◽  
pp. 3054-3058
Author(s):  
Jiao Long He ◽  
Zhong Ai Jiang
Keyword(s):  
Mine Tailings ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Testing ◽  
Standard Penetration Test ◽  
Dynamic Compaction ◽  
Application Research ◽  
Loading Test ◽  
Application Study ◽  
Compaction Method

The dynamic compaction parameters and measures for tailings foundation are proposed based on actual engineering field testing result.Results of field loading test,standard penetration test and pore water pressure test show that when tailings foundation is reinforced by dynamic compaction method,the bearing capacity value is greater than 130kpa.These provide a reference to application research of dynamic compaction in the tailings foundation.

Analysis of a New Expansive Soils Stabilization Method Made from Eco-Cement and Fiber Reinforcement

2013 ◽  
Vol 649 ◽  
pp. 217-222
Author(s):  
Mircea Aniculaesi ◽  
Anghel Stanciu ◽  
Irina Lungu
Keyword(s):  
Portland Cement ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Fiber Reinforcement ◽  
Synthetic Fiber ◽  
Expansive Clay ◽  
Swelling Potential ◽  
Stabilization Method ◽  
Swell Potential ◽  
Main Factor

The main factor that governs the shrink-swell behavior of expansive soils is the change in water content and the amount and type of clay size in the soil. In this paper, the research made are focused in reducing the swell potential of the studied clay by improvement in two ways: first by stabilization with a combination of eco-cement and Portland cement (1:1 ratio), and second by synthetic fiber reinforcement. A series of laboratory tests were performed on synthetic fiber reinforced expansive soil to determine the potential for using synthetic fiber reinforcement to reduce swell potential of soils. Specimens tested were prepared at two different synthetic fiber dosages 0.2% and 0.4%. The treatment of expansive clay with 5% eco-cement and 5% Portland cement revealed a better improvement of the swelling potential. The synthetic fiber reinforcement of the expansive soil doesn’t lead to a significant improvement of the soil.

scholarly journals The mechanical behavior of an expansive soil due to long-term seasonal rainfalls

2020 ◽  
Vol 195 ◽  
pp. 02019
Author(s):  
Kai LI ◽  
Liang Kong ◽  
Hossein Nowamooz ◽  
Cyrille Chazallon
Keyword(s):  
Mechanical Behavior ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Direct Determination ◽  
Model Parameters ◽  
Continuous Change ◽  
Step Method ◽  
Steady Solutions ◽  
Unsaturated Expansive Soils

Expansive soils, susceptible to be affected by the environmental conditions, expand when water is added and shrink when they dry out. This continuous change in soil volume is able to cause structures built on them to move unevenly and crack. To investigate the hydro-mechanical behavior of unsaturated expansive soils, many laboratory tests on these materials have been carried on and numerous models have also been proposed with a relatively large number of parameters. In this study, a simplified model based on Zarka method has been developed for unsaturated expansive soils. The direct determination of the steady solutions in Zarka analysis is able to replace classic step-by-step method and needs less model parameters. In this context, this paper presents a Zarka-based model to predict the volume change in unsaturated expansive soils under seasonal drought and rainfall cycles and the proposed model is implemented in the finite element code to simulate long-term behavior of a 2D structure consisting of expansive soils and subjected to successive drought and rainfall cycles. Finally, the numerical calculation defines the plastic strain field and the inelastic displacement field of the studied structure.

Challenges to modelling heave in expansive soils

2006 ◽  
Vol 43 (12) ◽  
pp. 1249-1272 ◽  
Author(s):  
Hung Q Vu ◽  
Delwyn G Fredlund
Keyword(s):  
Numerical Modelling ◽  
Volume Change ◽  
Void Ratio ◽  
Expansive Soils ◽  
Ground Surface ◽  
Expansive Soil ◽  
Coupled Analysis ◽  
Coupled Equations ◽  
Mathematical Equations ◽  
Unsaturated Expansive Soils

There are challenges associated with the numerical modelling of unsaturated expansive soils. The challenges are primarily related to the quantification of the void ratio constitutive surface, the characterization of the void ratio constitutive surface at low stresses and (or) suction, and the solution of coupled equations with several nonlinear unsaturated soil property functions. This study suggests that the void ratio constitutive surface of an expansive soil subject to a monotonic wetting path can be estimated from volume change indices obtained from conventional laboratory tests. The constitutive surfaces for both the soil structure and the water phase can be described using mathematical equations that allow net normal stress and suction to be reduced to zero. The solutions for two typical volume change problems are presented using both a coupled approach and an uncoupled approach. The first example problem simulates water leakage from a pipe under a flexible cover. The second example problem simulates the infiltration of water at ground surface. The results of the analyses are in accordance with anticipated behaviour. The results also show that the answers from an uncoupled analysis compared well with those from a coupled analysis. It is suggested that an uncoupled analysis may be adequate for most prediction of heave problems involving unsaturated expansive soils.Key words: heave prediction, numerical modelling, expansive soil, constitutive surface, uncoupled analysis, matric suction.

Stability Analysis of Unsaturated Expansive Soil Slope Covered by Geo-Membrane

2015 ◽  
Vol 744-746 ◽  
pp. 597-600
Author(s):  
Hong Yu Zhang ◽  
Jiang Hu Chen ◽  
Wen Qing Wu ◽  
Jun Hua Wu
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Expansive Soil ◽  
Construction Process ◽  
Soil Slope ◽  
Seepage Field ◽  
Lower Slope ◽  
Unsaturated Expansive Soil

In view of the holes appearing in different area of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil slope, the VADOSE/W is used to analyze the wetting-drying cycles caused by rainfall and evaporation on slopes covered by geo-membrane. The influence on the pore-water pressure and volume water content were discussed just caused by the holes. The results show that the hole is nearer to the toe of slope, its impact on the whole seepage field is greater. In addition, the hole appears on the top of slope that the wetting-drying cycle effect is remarkable. It is ensured that the integrity of the geo-membrane which in the lower slope and take some drainage measures in the construction process.

Numerical Study of Unsaturated Expansive Soil Canal Slope Covered by Geo-Membrane

2015 ◽  
Vol 744-746 ◽  
pp. 551-554
Author(s):  
Wen Qing Wu ◽  
Jiang Hu Chen ◽  
Hong Yu Zhang ◽  
Jun Hua Wu
Keyword(s):  
Water Content ◽  
Water Level ◽  
Soil Water ◽  
Soil Water Content ◽  
Pore Water Pressure ◽  
Numerical Study ◽  
Water Pressure ◽  
Expansive Soil ◽  
Seepage Field ◽  
Unsaturated Expansive Soil

In view of the holes appearing in different areas of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil canal slope, the VADOSE/W is used to analyze the pore-water pressure of the internal canal slope by changing the falling water level. The results show that the hole is nearer to the toe of slope, its effect on the whole seepage field is greater. The greater the rate is, the soil water content is greater.

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