SYMB

DESCRIPTION

BASIC REDUCTION FORMULAE

p₀

Corrected First Reading

p₀ = 1.05 (A – Zm + DA) – 0.05 (B - Zm - DB)

Zm = Gage reading when vented to atm.
However, if DA & DB are measured with
the same gage used for current readings
A & B, set Zm = 0  (Zm is compensated)

p₁

Corrected Second Reading

p₁ = B - Zm - DB

I_D

Material Index

I_D = (p₁ - p₀)  /  (p₀ - u ₀)

u ₀ = pre-insertion pore pressure

K_D

Horizontal Stress Index

K_D = (p₀ - u ₀) / s’ _V0

s’ _V0 = pre-insertion overburden stress

E_D

Dilatometer Modulus

E_D = 34.7 (p₁ - p₀)

E_D is NOT a Young’s modulus E.
E_D should be used only AFTER combining
it with K_D (Stress History). First obtain
M _DMT = R _M E_D, then e.g.  E »  0.8 M _DMT

K₀

Coeff. Earth Pressure in Situ

K_{0, DMT} = (K_D  / 1.5) ^0.47 -  0.6

for I_D < 1.2

OCR

Overconsolidation Ratio

OCR _DMT  =  (0.5 K_D ) ^1.56

for I_D < 1.2

c_u

Undrained Shear Strength

C_u,DMT = 0.22  s’ _V0 (0.5 K_D ) ^1.25

for I_D < 1.2

j

Friction Angle

j _safe,DMT = 28 + 14.6 log Kd – 2.1 log ² Kd

for I_D > 1.8

c_h

Coefficient of Consolidation

C_h,DMTA » 7cm² / T_flex

T_flex from A-log t   DMTA-decay curve

k_h

Coefficient of Permeability

k_h = C_h g_w / M_h      (M _h » K₀ M _DMT)

^g

Unit Weight and Description

(see chart)

M

Vertical Drained Constrained Modulus

M _DMT = R _M E_D

If (I_D £ 0.6)         R _M = 0.14  + 2.36 log Kd

If (I_D ³ 3)            R _M = 0.5 + 2 log Kd

If (0.6 < I_D< 3)    R _M= R _M,0+ (2.5 - R _M,0) log Kd

                                   where R_M,0=0.14 + 0.15(I_D-0.6)

If Kd > 10            R _M = 0.32 + 2.18 log Kd

If R _M < 0.85        set R _M= 0.85

U₀

Equilibrium Pore Pressure

U ₀ = p₂ » C – Zm + DA

In freely draining soils