Application Of Slip Line Theory To A Retaining Wall-Unsaturated Soil Interaction Study

Computational Framework/ Numerical Method

There is a need for Project Managers to properly understand different theories and analysis that are used to evaluate soils and foundation designs. The extensive Computational geomechanics is a wide study that helps mechanics in their day to day study of soil and rocks, learning their features and soil composition. In this report, we are looking at a study of in geometric whereby slip line theory has been applied to a retaining wall–unsaturated soil so that it can be applied to solve soil interaction problem. An extensive study of soil and its behaviors, on unsaturated soil, whereby it is presented and applied to a rigid wall that is rotating into unsaturated soils. A properly managed study of the phenomenon of slip line theory that has been applied to solve the problem of to a retaining wall–unsaturated soil in soil suction, must have effective results. There are many methods used to deal with earth pressure. However both methods are good and give estimated results. The finite and domain. Computationally, Differential Equations governs slip line theory. In this case the soil is in the unsaturated form. The method of Suction is then introduced to the soil strength and stress state using the idea that is effective of stress. (Reddy, 2010)

According to (Hao, 2008)Computational framework is the basis of observing chemical processes reactions in the soil. In the research method of slip line theory that has been applied to a retaining wall,–unsaturated soil analysis of two phase saturated suction method, computational framework/numerical model is suction. Suction in this case is influenced with different factors such as soil type and soil structure. This method is usually used in engineering and mathematical physics to come up with solutions of numeric. This approach have its own limitations. Since the soil is more rigid, the process of increment and absolute strain ratios are usually the same. Also the level of assuming the non-coaxially, in case additional kinematic constraint needs to be specified and therefore the displacement analysis might lead to a higher complication. (Athanasios and Thomas, 2010)

One of the features of the suction is experimental campaign. This is where drafts are made and lab tests of suction bucket foundation in sand. Many test experiments are carried out, then an estimate is chosen.

Another feature of the computational framework is using numerical model in suction. This is where simulations sequences and Lagrangian and combined Lagrangian models are used. Specific results are always obtained. No estimates. (Celebi, Goktepe and Karahan, 2012)

Main features of Computational Framework

The third feature in the suction method is numerical simulation method.   

In computational geomechanics, the force that keeps collection of particles is known as Effective stress. Mostly it applies to most kind of soils namely sand, soil, or gravel. We see that the importance of effective stress was discovered by Karl Terzaghi. (Lutz, 2007). This stress in the soil is passed through small particles through the mass of the soil at the point of its contact. In other words, this is also known as the inter-granular stress and denoted by σ’. Compression of the soil mass may be incurred when there is greater resistance than the grain resistance, after soil has been loaded. This compression is usually caused by the elasticity of the grains where there is physical or chemical connectivity or contact. Therefore, effective stress best describes this load per unit area of the soil mass. The major advantages of effective stress is the roles it plays in soil, namely shear strength of the soil and soil settlement.

Mohr-Coulomb study is usually used in this model, here both unsaturated and saturated soil wall interface are used. At soil model and interface model, there is assumption during calculations the friction of the angle is mobilized at every point in the where there is unsaturated soil. Mostly the greatness of the friction of the angle can be significally be greater.

 Governing equations is whereby, mass is conserved and energy too is conserved in fluid. In wave propagation analysis, the porous media can be compressed with viscid fluids.  

Infinite Element Formulation

This is where shape decays with distance and zero is reaches infinity. The shape functionality does not matter a lot here. This methods consists of two main steps whereby, there is need of analytical identification solution of the problem and derivation of the shape from it. This method in cooperates several solutions.

I.D analytical approach is one of the solutions of the infinite element foundation whereby element functions shapes are derived from it. Shape functions is another type of infinite element solution whereby the shape functions are the key elements. Property functions is another approach whereby all directions are shown. (Joonsang, 2012)

Retaining wall problem commonly have four parts, which are intense inspection, demonstration of the results, testing and analyzing the findings. In inspection, the common methods used are usually the five senses which are tasting, touching, seeing, smelling or olfactory. (Jien and Andrew, 2012)This is used to identify the accuracy and efficiency of the in Suction during slip line theory that is usually applied to a retaining wall–unsaturated soil analysis. Two experiment are carried out and then they are compared to verify the similarities. Example, a problem with 1D problem that consists the form of saturated porous media that has been subjected to a uniformly harmonic loading with frequent circular frequency. A diagrammatically presentation of the task and the suction the near the immediate field is discretized using the formula of eight-node isoperimetric. A good example of RWP is a typical wall is that is used for experiment. We are going to imagine that the wall is 5 m high, we have unsaturated soil and water is 10m below.

Effective stress

Theoretically suction method has more advantages compared to other methods on calculating unsaturated soils. The most known advantage is stability. (Karl and Ralph, 2013). Moreover suction method is more stable compared to the other methods and easy to establish. It is good to know prior so that one will not use it unknowingly.

Convergence is another advantage of Suction because variation forms usually are consistent with governing equations. The approximation of Suction usually follows from best approximate results.

The Suction is easily adaptable thus making adaptivity the third advantage of Suction over the others. This is where you have to rely on indication and not estimation.  The other method show where error might be and not the exact place.

Computationally, Suction also has some advantages as listed below,

Hybridization this is where the mixed formulation method is used, where you use second order term as systems of two first order terms.

Inhomogeneity this is when one used higher order quadrature rule in Sanction naturally.

Complex geometrics, this is where in Suction is used to solve problems theoretically given that one has a good mesh generator, without changing a code.

Boundary conditions, this is whereby finite element method is used to resort conditions that are considered weak.

With the above comparisons, of suction model of unsaturated soil, over the other methods, the advantages make the method seem to be the most efficient method to use in the testing’s. (Delwyn and Murray, 2012)

Conclusion

In conclusion, slip line theory that has been applied to a retaining wall–unsaturated problems of the soil have been fully analyzed and it is seen that that have saturated the soils in great way. This includes domains that are unbounded. Computational geomechanics should be incorporated more and many approaches used to come up with an accurate answer or method. Application of the element is discussed into length to show efficiency of the proposed element. The Suction may seem to be the best, but keeping in mind the other methods too are all well perceived. The main aim is to come up with a better method that will give accurate results irrespective of the shape of the soils or surfaces. To conclude, when the two methods are in cooperated or used together, they tend to bring out accurate results, until when  elements are introduced and then the numerical results seems to disappear. For project managers to come up with the best method, they need to test and proof test the method and finally use the one that does not strain, or limit them in any way possible.

References

Athanasios, P., & Thomas, B. (2010) Soil Engineering. Berlin: Heidelberg.

Braja, M. (2016) Principles of Foundation Engineering. Australia: Cengage Learning.

Celebi, E., Goktepe, F., & Karahan, N. (2012) Non-linear finite element analysis for prediction of seismic response of buildings considering soil-structure interaction. Copemicus GmbH.

Delwyn, G., & Murray, D. (2012) Unsaturated soils mechanics in engineering. Hoboken, N.J: Wiley.

Hao, L. (2008). Diffraction of SH-waves by surface or sub-surface topographies with application to soil-structure interaction on shallow foundations. Los Angeles: California.

Jien, H., & Andrew, J. (2011) Advances in geotechnical Engineering. Reston: VA

Joonsang, P. (2012) Wave motion in finite and infinite media using the thin layer method.

Karl, T., & Ralph, B. (2013) Soil Mechanics in Engineering practice. England: Read Books Ltd.

Lutz, L. (2007) Wave propagation in infinite Domains: with applications to structure interaction. Dordrecht: Springer.

Reddy, R. (2010) Soil Engineering. New Delhi: GeneTech Books.

Rodney, L. (2013) Soil and Water conservation engineering. St. Joseph: Mich.

Sunjay, K. (2017) Fundamentals of Fibre-Reinforced Soil Engineering. Singapore: Springer Singapore.