Dynamic compaction
To prepare the subgrade for a section of Interstate 65 in Alabama, dynamic deep compaction was selected to improve cone penetration values, $q_{c}$ from values as low as 25 kg/m² to greater than 100 kg/m² . A conventional crawler crane was used to drop a 20 ton circular weight (diameter = 3 m) from a height of 18.3 m. Estimate the depth of influence, assuming the subsurface is granular and free-draining.

Question

Dynamic compaction
To prepare the subgrade for a section of Interstate 65 in Alabama, dynamic deep compaction was selected to improve cone penetration values, [latex]q_{c}[/latex] from values as low as 25 kg/m² to greater than 100 kg/m² . A conventional crawler crane was used to drop a 20 ton circular weight (diameter = 3 m) from a height of 18.3 m. Estimate the depth of influence, assuming the subsurface is granular and free-draining.

Accepted Answer

Using Equation (7.21) (see Table 7.4), we have:

[latex]D_{e} = 0.5 [W_{x} h_{x}]^{0.5 }[/latex] (7.21)

[latex]D_{e} =0.5\sqrt{W_{x} h_{x} } =0.5\sqrt{\left(20 ton\right)\left(18.3 m\right) } =9.6 [/latex]

Table 7.4 Summary of effective depth equations
a	Menard and Broise Method (1975)
	[latex]D_{e} = [W_{x} h_{x}]^{0.5}[/latex]	(7.20)
b	Leonards–Cutter–Holtz Method (1980)
	[latex]D_{e} = 0.5 [W_{x} h_{x}]^{0.5 }[/latex]	(7.21)
c	Lukas Method (1980)
	[latex]D_{e} = (0.65–0.80) [W_{x} h_{x}]^{0.5 }[/latex]	(7.22)
d	Charles–Burford–Watts Method (1981)
	[latex]D_{e} = 0.4d [(E/A) (1/d) (1/s)]^{0.5} [/latex]	(7.23)
e	Fang and Ellis Method (1995)
	[latex]D_{e} = \Psi [W_{x} h_{x}]^{0.5}[/latex]	(7.24)

Question 7.5: Dynamic compaction To prepare the subgrade for a section of ...

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