Assignment $1-$ Dry deep mixing, part $1$

Your consulting company has been awarded a relatively large project to design and estimate the cost of road construction in Arlanda, $40$ km north of Stockholm. Your team has been tasked with designing and estimating the cost of ground improvement

using Dry Deep Mixing columns where the road crosses a field with a deep layer of soft clay $($see Figure $1).$ The road is a country road with a width of $10$ m and a variable height, $H.$ After an initial assessment of the site's geotechnical conditions, the client has requested the installation of Dry Deep Mixing columns $($lime$-$cement design is based on the soil profile provided in Figure $1,$ with an assumed average

The design focuses on serviceability limit state $($SLS$)$ analysis, where the maximum maximum allowable limit state $($ULS$)$ analysis is not considered in this report. The information you need to provide to the client in the report includes:

The area ratio $($a$)$ and the center$-$to$-$center distance $($cc$)$ between the columns.

The number of columns.

A plan and section $($sketches are acceptable$)$ showing the design

Use the information provided in Table $1$ for your group. The results from the geotechnical investigation conducted at the site are shown in Figure $2$a$.$ The left compression modulus $M_h$ derived from these tests.

Without tested columns at this specific site, you must establish strength and stiffness based on guidelines and previous experience. In this particular case, you set the cohesion $c_{\text{c}\text{o}\text{l}}^{\text{'}}=50$kPa, and the friction angle ${}_{ct}=32.$ The stiffness, represented by the Young's modulus $E_{cot},$ will vary in relation to the soil stiffness; therefore, you

can use the values shown in Figure $2$b$.$

For the cost calculation, you can use the following rates:

$100,000$ SEK for establishment costs, including a graveled working area for

machines, tankers$,$ and access roads.

$800$ SEK per column.

$800$ SEK per column

$150$ SEK$/$m cost rate

$150$ SEK$/$m cost rate per meter of column with a diameter $D=600mm$

Table $1.$ Embankment hight $H,$ and Column diameter $D$ for the different groups.

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