"Symbols and definitions used in geotechnical engineering" is quoted from "Lexicon in 8 languages" (the fifth edition) published in 1981 by International Society for Soil Mechanics and Geotechnical Engineering.
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4. Mechanical properties of soil
a) Sampling
Symbol  Dimension  Unit  Measured quantity  Description 
\(C_a\)    %  Area ratio (of a sampler)  \(C_a=\frac {\left(D_2^2D_1^2 \right)} {D_1^2}\) with \(D_1=\) inner diameter of cutting nose; \(D_2=\) outer diameter of cutting nose 
\(C_i\)    %  Inside clearance ratio (of a sampler)  \(C_i=\frac {\left(D_3D_1 \right)} {D_1}\) with \(D_1=\) inner diameter of cutting nose; \(D_3=\) inner diameter of container 
\(C_o\)    %  Outside clearance ratio (of a sampler)  \(C_o=\frac {\left(D_2D_4 \right)} {D_4}\) with \(D_2=\) outer diameter of cutting nose; \(D_4=\) outer diameter of barrel shaft 
(Note: concepts of \(C_a, C_i, C_o\) are defined by Hvorslev in 1949) 
b) Consolidation (one dimensional)
Symbol  Dimension  Unit  Measured quantity  Description 
m_{v}  M^{1}LT^{2}  (kPa)^{1}  Coefficient of volume change  Ratio between change of volume per unit volume and corresponding change of effective normal stress:\[m_v=\frac {\left(e_oe\right)} {\left(1+e_o\right)\cdot\Delta{\sigma }^{_{´}}}\] 
E_{oed}  ML^{1}T^{2}  kPa  Oedometric modulus  \[E_{oed}=\frac {1} {m_v}\] 
C_{c}    1  Compression index  Slope of virgin compression curve in a semilogarithmic plot "effective pressure ~ void ratio": \[C_c=\frac {\Delta e} {\quad \Delta\lg {\sigma}^{_{´}}}\] 
C_{s}    1  Swelling index  Average slope of an unloadreload cycle in a semilogarithmic plot of effective pressure ~ void ratio: \[C_s=\frac {\Delta e} {~~ \Delta\lg {\sigma}^{_{´}}}\] 
C_{\(\alpha\)}    1  Rate of secondary consolidation  Slope of the final portion of the change of volume per unit volume ~ time curve in a semilogarithmic plot: \[C_\alpha=\frac {\Delta e} {\; \left(1+e_o\right)\cdot\Delta\lg t}\] 
c_{v}  L^{2}T^{1}  m²/s  Coefficient of consolidation  \[c_v=\frac{k}{m_v\cdot \gamma_w}\] 
d, H  L  m  Drainage path  Thickness of layer drained on one side only, or halfthickness of layer drained on both sides 
T_{v}    1  Time factor  \[T_v=\frac{t\cdot c_v}{d^2}\] t being the time elapsed since application of a change in total normal stress 
U    1, %  Degree of consolidation  Ratio of mean effective stress increase at a given time to mean final effective stress increase 
\(\sigma_{vo}^{´}\)  ML^{1}T^{2}  kPa  Effective overburden pressure  Insitu effective vertical pressure existing prior to sampling or excavation 
\(\sigma_{p}^{´}\)  ML^{1}T^{2}  kPa  Preconsolidation pressure  Maximum vertical effective past pressure 
c) Shear Strength
Symbol  Dimension  Unit  Measured quantity  Description 
\(\tau_f\)  ML^{1}T^{2}  kPa  Shear strength  Shear stress at failure in rupture plane through a given point 
\(c\;^{_{´}}\)  ML^{1}T^{2}  kPa  Effective cohesion intercept  
\(\phi\;^{_{´}}\), \(\varphi\;^{_{´}}\)    °  Effective angle of internal friction  Shear strength parameters with respect to effective stresses. Defined by the equation: \(\tau_f=c\;^{_{´}}+\sigma^{_{´}}\tan \phi^{_{´}}\) 
\(c_u\)  ML^{1}T^{2}  kPa  Apparent cohesion intercept  
\(\phi_u\), \(\varphi_u\)    °  Apparent angle of internal friction  Shear strength parameters with respect to total stresses. Defined by the equation: \(\tau_f=c_u+\sigma\tan \phi_u\) In undrained situation, with saturated cohesive soils, \(c_u\) is also called undrained shear strength 
\(c_r\)  ML^{1}T^{2}  kPa  Remoulded undrained shear strength  Shear strength of remoulded soil in undrained situation 
\(S_t\)    1  Sensitivity  Ratio between undrained shear strength of undisturbed and of remoulded soil:\[S_t=\frac{c_u}{c_r}\] 
\(\tau_R\)  ML^{1}T^{2}  kPa  Residual shear strength  Ultimate shear strength in rupture plane which a soil maintains at large displacement 
\(c\;^{_{´}}_R\)  ML^{1}T^{2}  kPa  Residual cohesion intercept  
\(\phi\;^{_{´}}_R\), \(\varphi\;^{_{´}}_R\)    °  Residual angle of internal friction  Residual shear strength parameters with respect to effective stresses, defined by the equation: \[\tau_R=c\;^{_{´}}+\sigma\;^{_{´}}\tan\phi\;^{_{´}}_R\] 
d) Insitu Tests
Symbol  Dimension  Unit  Measured quantity  Description  
\(q_c\)  ML^{1}T^{2}  kPa  Static point resistance (or cone resistance)  Average pressure acting on the conical point in the standard static penetration test  
\(f_s\)  ML^{1}T^{2}  kPa  Local side friction  Average unit side friction acting on the friction sleeve in the standard static cone penetration test  
\(q_d\)  ML^{1}T^{2}  kPa  Dynamic point resistance  Average pressure acting on the conical point in the standard dynamic penetration test (\(q_{dA}\) and (\(q_{dB}\) for tests of type A and B, respectively)  
\(r_d\)  ML^{1}T^{2}  kPa  Dynamic resistance  Standardized result of the dynamic penetration test (\(r_{dA}\) and \(r_{dB}\) for tests of type A and B, respectively)  
\(N_d\)    1  Number of blows per 0.2 m  Standardized result of the dynamic penetration test (\(N_{dA}\) and \(N_{dB}\) for tests of type A and B, respectively)  
\(N\)    1  SPT blow count  Standardized result of the Standard Penetration Test  
\(N_{ht}\)    1  Number of halfturns for 0.2 m  Standardized result of the Weight Sounding Test  
\(P_1\)  ML^{1}T^{2}  kPa  Pressuremeter limit pressure  Limit pressure defined in the standard Ménard pressuremeter test  
\(E_M\)  ML^{1}T^{2}  kPa  Pressuremeter modulus  Conventional modulus defined in the standard Ménard pressuremeter test  
