Soil Mix Verification
Verification of soil mix wall is performed for bending and shear.
Calculated internal forces are determined in the same way as for lagging and can be multiplied by the reduction coefficient of bearing capacity before the verification. This coefficient reflects the degree of uncertainty of determining the theoretical values of the internal forces and brings the safety into the calculation.
Bending verification:
Bearing capacity for bending is calculated according to the formula:
where: | σEd | - | normal stress in cross-section |
UCS | - | compressive strength of soil mix |
Utilization of cross-section is calculated according to the formula:
Normal stress in cross-section is calculated according to the formula:
where: | NEd | - | normal force |
h | - | wall thickness |
Normal force is calculated according to the formula:
where: | MEd | - | bending moment |
hred | - | arc rise (calculated as 2/3 of steel cross-section height, or inputted manually) |
Angle α is calculated according to the formula:
where: | d | - | spacing of profiles |
Shear verification:
Shear bearing capacity is calculated according to the formula:
where: | τEd | - | shear stress in cross-section |
τ | - | shear resistance of soil mix |
Utilization of cross-section is calculated according to the formula:
Normal stress in cross-section is calculated according to the formula:
where: | VEd | - | shear force |
The compressive strength UCS is the basic material input for soil mix. Other parameters can be calculated according to the UCS, or they can be inputted manually:
Shear resistance τ is calculated as follows (intermediate values are interpolated):
for: | UCS = 0.0 MPa | τ = 0.5UCS | |
UCS = 1.0 MPa | τ = 0.4UCS | ||
UCS = 1.5 MPa | τ = 0.35UCS | ||
UCS = 3.5 MPa | τ = 0.3UCS | ||
UCS ≥ 4.0 MPa | τ = 0.2UCS |
Modulus of elasticity E is calculated as follows (intermediate values are interpolated):
for: | UCS = 0.0 MPa | E = 50UCS | |
UCS = 2.0 MPa | E = 300UCS | ||
UCS = 5.0 MPa | E = 1000UCS |
Shear modulus G is calculated according to the formula:
Literature:
Nicolas Denies, Noel Huybrechts: Deep mixing method for the construction of earth and water retaining walls, Rilem Technical Letters (2017) 2:1-9.
A.Porbaha: State of the art in deep mixing technology. Part IV: design considerations, Ground Improvement (2000) 3, 111-125.