settlement_of_shallow_foundations_on_granular_soils (Lutenegger ang DeGroot)

s = settlement
h, =the thickness of each "i" soil layer or sublayer being considered, ll.h, = H
i =the ith layer in a total of n layers (total thickness of H)
M; =the applicable vertical !-dimension modulus of compressibility in the "i" the soil layer
(=vertical stress increase/vertical strain)
( = vertical stress increase/volume strain)
ll.crv' = effective stress increase at the mid-height of each "i" layer that produces the settlement
The first term in brackets in Equation 5.112 computes the vertical strain, which is then multipled
by the layer thickness to obtain the consolidation settlement for that layer, and all such layers are
then summarized to give the total settlement.
The step-by-step procedure presented by Schmertmann is presented below.
Method A - Ordinary Method
I. Perform a DMT sounding at each settlement analysis location
and determine profiles of M through the soil layers of interest.
2. Divide the compressible soils into layers and/or sublayers of similar
soil type and stiffness.
3. Determine the average M value from the DMT results for each layer
and sub layer in 2.
4. Calculate the vertical stress increase ll.crv at the mid-height of each
layer and sublayer in 2 using any suitable method to calculate the
vertical stress increase.
5. Calculate the 1-D settlement of each later or sub layer using
the following equation:
Settlement= (stress increase x thickness)/(modulus)
= ll.crvRfM
6. Obtain the total 1-D settlement by adding all the contributions from
the layers and sublayers in step 5.
7. Make corrections to the settlement calculated in step 6, as
appropriate and using DMT experience with similar soils and loadings.
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