BN3060: Residual Valuation of a Development Property Report Answer

Part 1: Slope Stability

i)

Figure 1: Scale diagram of the embankment

(Source: Generated in paint )

A extending line from the ground level to the top of the crest shows the slope. The bottom of the slope is marked with a "T," and the top is marked with a “C”. A possible slip circle centre is also found and marked as SC. The Fellenius-Jumikis method is then used to get a rough idea of where the most important slip circle centre is.

To calculate the X, Y directions of important places,

The Toe of the embankment (T): Situated at (0,0)

Peak of the embankment (C): Situated at (10,6)

Utilizing the Fellenius-Jumikis technique, the basic slip circle focus (SC) by drawing tangents from the peak and toe of the bank to meet at a point along the incline. This point addresses the area of the most basic slip circle focus.

The X coordinate of the basic slip circle focus (SC) is assessed to be the midpoint between the X directions of the toe (T) and peak (C). Since the X direction of the peak was 10 and the X direction of the toe is 0, the midpoint is (10 + 0)/2 = 5.

The Y direction of the basic slip circle focus (SC) is assessed to be the midpoint between the Y directions of the toe (T) and peak (C). Since the Y direction of the peak was 6 and the Y direction of the toe is 0, the midpoint is (6 + 0)/2 = 3.

ii)

Figure 2: Analysis for 3 types of soil

(Source: Acquired from Geosolve slope)

Geosloe provides a comparative analysis of three different types of soil, Soil A, Soil B and Soicl C. Each variety possesses a unique set of features that have an impact on drainage, the retention of nutrients, and the usefulness of the material for agricultural use, construction, and environmental preservation.

Figure 2: Bishop method of slicing

(Source: Acquired from Geosolve slope)

The above figure has been shown here for the half of the embankment and it appears to be a graph of the results of a Bishop method slice stability analysis. The Bishop method is a limit equilibrium method used to assess the stability of slopes. The approaches has been considered as the different method from the ordinary method of slices. On the other hand, the method has been found to be accurately providing minor variance from the actual FoS of slopes.

iii) The change in the drained cohesion of soil a directly impacts the overall calculated safety factor for the slope. An expansion in the drained cohesion can typically shows the result as a higher safety factor, showing more stability of the slope (Gu, 2023). On the other hand, a decline in drained cohesion can lead to a lower safety factor, recommending decreased stability. This has played huge role for geotechnical plan, as it features the sensitivity of slope stability to changes in soil properties. Furthermore, required in reinforcement techniques or slope geometry to mitigate potential stability issues arising from changes in soil cohesion. Changes in soil union might affect the plan and development costs. Higher cohesion soils can require less support, while lower union soils can require greater stabilization measures, in this manner influencing project spending plans.

iv)

Figure 3: Tailor’s Curve

(Source: Acquired from Geosolve slope)

The above image shows a graph that can illustrate the connection between Taylor's stability number (λ) on the x-axis and the factor of safety on the y-axis. The curve addresses Taylor's stability curve, which is utilized in geotechnical designing to evaluate slope stability. The x-axis values probably represent dimensionless ratios, while the y-axis values address the factor of safety against slope failure. The curve's shape shows what changes in λ affect the factor of safety, with higher values of λ compared to higher variables of safety. This image also assists engineers withanalyze slope stability under different loading conditions.

v)

Figure 4: Poor Pressure ratio for each slice of bishop model
(Source: Acquired from Geosolve slope)

The above image has been shown here for the poor water pressure ratio of bishop model. In order to calculate the average pore pressure ratio in the embankment, the formula is, U = γw.h / γ.H.

Here,

U is the pore pressure ratio.

γw is the unit weight of water.

h is the height of the water table above the base of the embankment.

γ is the effective unit weight of the soil.

H is the total height of the embankment.
Based on the research, the water table height is 6 m and on the other hand, the total height of the embankment is considered as 16 m (from the base of the embankment to the top of the canal).
Now, substitute the value into the formula,
U = /m³.6 m/ 20kN/m³.16 m

U = 58.86/320

U = 0.1839

Figure 5: Poor Pressure ratio for each slice of morgenstern price model
(Source: Acquired from Geosolve slope)

The above image has been considered as the x-axis demonstrates height, while the y-axis shows the strain proportion, beginning at 1 and expanding to around 1.1 with a rise. Data points plotted on the graph probably compare to determined or estimated pressure proportions at specific elevations. This perception examines how pore water pressure changes with height in the slant, giving experiences into potential dependability contemplations and illuminating geotechnical plan choices.

Figure 6: sliding mass of morgenstern price model
(Source: Acquired from Geosolve slope)

The above image provides a sliding mass calculation program assessing slope stability. With a factor of safety at 2.672, the slope is deemed stable. The figure analyzes factors such as total weight (3918.9 kN), resisting and activating moments (92,701 kNm and 34,696 kNm, respectively), and corresponding forces. This is by the process of implementing the Morgenstem-Price method, a limit equilibrium technique that assumes rigid plastic soil and a circular arc failure surface.

vi) The safety factors determined through different methods may differ due to various factors. Firstly, various strategies consider various aspects of slope stability. However, Bishop and Morgenstern’s diagrams integrate pore pressure impacts, while Taylor's bends center around general solidness disregarding pore pressure. Moreover, varieties in soil properties, for example, such as cohesion and internal friction angle, can lead to discrepancies in calculated safety factors (Nazir, 2023).The Fellenius-Jumikis strategy can be incorrect due to it improves on suppositions and constraints. It accepts round slip surfaces and homogeneous soil properties, which can not precisely address true circumstances. Moreover, it doesn't represent pore pressure impacts, which can altogether impact slope strength, especially in immersed soils. Besides, the technique depends on the manual determination of the basic slip circle, presenting subjectivity and expected risk (Shariati et al. 2024). Therefore, the Fellenius-Jumikis technique gives a primer gauge, more refined examinations consolidating pore pressure impacts and realistic soil behavior are necessary for accurate slope stability assessment.

Part 2: Flexible Retaining Wall

i)

Figure 7: Stability analysis of fully embedded wall

(Source: Acquired from Geosolve slope)

The table provides the result of an assessment of the stability of a wall that is submerged and directed utilizing the strength factor approach. This record gives a rundown of safety considerations for various soil qualities and toe heights. Strut elevations, moments, and equilibrium factors are also included in the information that is included in this document. These data give bits of data into the soundness of the wall under an assortment of soil conditions and mathematical setups, which helps in the plan and enhancement of the construction to guarantee that it is both protected and effective.

Figure 8: Bending moment and Displacement Curve

(Source: Acquired from Geosolve slope)

The above image shows two graphs that appear to be the results of a geotechnical engineering simulation. The top graph shows the bending moment, which is the force that makes a beam bend the displacement of the bar. Another chart shows the shear force, which is the force that can in general reason the pillar to slide sideways, versus the displacement of the beam. The diagrams show that the bending second is positive on the left side of the shaft and negative on the right side. The shear force is positive on the lower part of the beam and negative on the top. The text on the picture demonstrates that the reproduction has been performed by applying a load of 1000 kN/m at an elevation of 22.00 m.

Figure 9: Effect of stiffness at the Elevation

(Source: Acquired from Geosolve slope)

The image has been considered here a design's pressure information is displayed in the table, which incorporates a posting of the hub numbers, y organizes, viable burdens, water tensions, and soil pressures over an assortment of burden stages and heights. Thus, it offers bits of knowledge into the dissemination of stresses inside the construction under an assortment of stacking situations.

ii) Case (c) is the most crucial for designing the sheet piles since it involves the canal being emptied for maintenance and the water table in the embankment aligning with the base of the canal (Agung et al. 2023). In this scenario, the sheet piles experience the whole lateral soil pressure without any hydrostatic pressure from water, which might result in elevated soil pressures on the wall.

Excluding anchors might greatly affect the intended dimensions and durability of the sheet piles. Insufficient lateral support from anchors may necessitate the use of longer and more robust sheet piles to provide stability against overturning pressures (Yashmin & Chakraborty, 2023). Without anchors, there can be higher bending moments and deflections in the sheet piles, requiring bigger and stronger sections to handle the loads.

Part 3: Tower Crane

I) The maximum compression of each pile has been considered here by Qult = A*qult this formula.

Where,

Qult = The ultimate load capacity of the pile

A = Cross-sectional area of the pile

qult = Bearing capacity of the soil

In this case,

The tower base weight = 700 kN

There are 4 piles supporting the base

Spacing between piles = 3.0 m

Size of the tower base = 4.0 m square

The total ultimate load on each pile,

Qult = 700kN/4 = 175 kN

ii) Reinforced concrete piles are great for this situation because of their robustness and load-bearing capacity. By joining concrete's compressive strength with reinforcement bars' tensile strength, they can endure heavy loads and give reliable support for structures like crane tower bases (Zuluaga-Astudillo et al. 2024). Furthermore, their durability guarantees long-term stability, making them a better decision for projects needing significant structural support.

iii) The research has been considered here to calculate the dimensions for the pile and in this case the formula is, A = Qult /qult*F

The factor of safety F=3

Now, assuming the value for qult is 200 kPa

A = 175kN/200 kPa*3
= 175*1000/ 200*3

= 17500/600

= 291.67 mm²

For the circular pile, the formula for area of circle is,
A = π*r²

r² = 291.67/ π

r = √291.67/ π

r = 9.63 mm

Therefore, the diameter of the pile can be 2*9.63 = 19.26 mm.

Part 4: Settlement

I) In order to calculate the immediate settlement in Soil B beneath the embankment center using Steinbrenner’s coefficients,
Sb= Δ σav/ EB *CB

Where,

Δ σav = Average Increase Stress

EB = Modulus of elasticity of Soil B

CB = Steinbrenner's coefficient for Soil B

Sb= Δ σav/ EB *CB

= 20 kN/ M²/16mn/M² 5.50*10^-5 m²/kN

= 1.375 * 10^-6m

= 1.375 mm

ii) The immediate settlement in Soil C beneath the embankment center,

Sc= Δ σav/ Ec*CC

Ec = Modulus of elasticity of Soil C

Cc = Steinbrenner's coefficient for Soil C

For Soil C,

Sc= Δ σav/ Ec*CC

= 60kN/m²/ 32 MN/m²* 1.92*10^-5 m²/kN

=1.375× 10^-6mm

=1.375mm

iii) Calculate the total settlement at a point 40m from the embankment center,

STotal = SB+Sc

= 1.375 mm +3.6 mm

= 4.975 mm

iv) Total settlement,

 STotal (40m)= SB+Sc

The settlement at 40m can be the same as the total settlement beneath the embankment center, which is 4.975 mm.

References

Agung, P. A. M., Lutfiyani, H., Hasan, M. F. R., & A’isyah Salimah. (2023). Clayshale stabilization using liquid calcium carbonate to increase soil shear strength. IOP Conference Series.Earth and Environmental Science, 1218(1), 012033.Retrieved from: https://iopscience.iop.org/article/10.1088/1755-1315/1218/1/012033/pdf [Retrived on:07/02/2024].

Gu, M. (2023). Application of computer geological model in geotechnical engineering investigation. Journal of Physics: Conference Series, 2665(1), 012017. Retrieved from: https://iopscience.iop.org/article/10.1088/1742-6596/2665/1/012017/pdf [Retrived on:07/02/2024].

Nazir, R. (2023). Design to failure: What went wrong? IOP Conference Series.Earth and Environmental Science, 1249(1), 012002. Retrieved from: https://iopscience.iop.org/article/10.1088/1755-1315/1249/1/012002/pdf [Retrived on:28/01/2024].

Shariati, M., Afrazi, M., Kamyab, H., Rouhanifar, S., Toghroli, E., Safa, M., . . . Afrazi, H. (2024). A state-of-the-art review on geotechnical reinforcement with end-life tires. Global Journal of Environmental Science and Management, 10(1), 385-404. Retrieved from: https://www.gjesm.net/article_707739.html [Retrived on:07/02/2024].

Yashmin, S. S., & Chakraborty, A. (2023). Analysis and parametric assessment of reinforced soil wall. IOP Conference Series.Materials Science and Engineering, 1282(1), 012016. Retrieved from: https://iopscience.iop.org/article/10.1088/1757-899X/1282/1/012016/pdf [Retrived on:07/02/2024].

Zuluaga-Astudillo, D., Slebi-Acevedo, C., Ruge, J. C., Camacho-Tauta, J., & Caicedo-Hormaza, B. (2024). Diatomaceous soils and advances in geotechnical Engineering—Part II. Buildings, 14(1), 48.Retrieved from: https://www.mdpi.com/2076-3417/13/1/549/pdf [Retrived on:07/02/2024].

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