"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) | \(C_a=\frac {\left(D_2^2-D_1^2 \right)} {D_1^2}\) with \(D_1=\) inner diameter of cutting nose; \(D_2=\) outer diameter of cutting nose |
| \(C_i\) | - | % | Inside clearance ratio (of a sampler) | \(C_i=\frac {\left(D_3-D_1 \right)} {D_1}\) with \(D_1=\) inner diameter of cutting nose; \(D_3=\) inner diameter of container |
| \(C_o\) | - | % | Outside clearance ratio (of a sampler) | \(C_o=\frac {\left(D_2-D_4 \right)} {D_4}\) 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)
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b) Consolidation (one dimensional)
| Symbol | Dimension | Unit | Measured quantity | Description |
| mv | M-1LT-2 | (kPa)-1 | Coefficient of volume change | Ratio between change of volume per unit volume and corresponding change of effective normal stress:\[m_v=\frac {\left(e_o-e\right)} {\left(1+e_o\right)\cdot\Delta{\sigma }^{_{´}}}\] |
| Eoed | ML-1T-2 | kPa | Oedometric modulus | \[E_{oed}=\frac {1} {m_v}\] |
| Cc | - | 1 | Compression index | Slope of virgin compression curve in a semi-logarithmic plot "effective pressure ~ void ratio": \[C_c=-\frac {\Delta e} {\quad \Delta\lg {\sigma}^{_{´}}}\] |
| Cs | - | 1 | Swelling index | Average slope of an unload-reload cycle in a semi-logarithmic 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 semi-logarithmic plot: \[C_\alpha=-\frac {\Delta e} {\; \left(1+e_o\right)\cdot\Delta\lg t}\] |
| cv | L2T-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 half-thickness of layer drained on both sides |
| Tv | - | 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-1T-2 | kPa | Effective overburden pressure | In-situ effective vertical pressure existing prior to sampling or excavation |
| \(\sigma_{p}^{´}\) | ML-1T-2 | kPa | Preconsolidation pressure | Maximum vertical effective past pressure |
c) Shear Strength
| Symbol | Dimension | Unit | Measured quantity | Description |
| \(\tau_f\) | ML-1T-2 | kPa | Shear strength | Shear stress at failure in rupture plane through a given point |
| \(c\;^{_{´}}\) | ML-1T-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-1T-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-1T-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-1T-2 | kPa | Residual shear strength | Ultimate shear strength in rupture plane which a soil maintains at large displacement |
| \(c\;^{_{´}}_R\) | ML-1T-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) In-situ Tests
| Symbol | Dimension | Unit | Measured quantity | Description | ||||
| \(q_c\) | ML-1T-2 | kPa | Static point resistance (or cone resistance) | Average pressure acting on the conical point in the standard static penetration test | ||||
| \(f_s\) | ML-1T-2 | kPa | Local side friction | Average unit side friction acting on the friction sleeve in the standard static cone penetration test | ||||
| \(q_d\) | ML-1T-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-1T-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 half-turns for 0.2 m | Standardized result of the Weight Sounding Test | ||||
| \(P_1\) | ML-1T-2 | kPa | Pressuremeter limit pressure | Limit pressure defined in the standard Ménard pressuremeter test | ||||
| \(E_M\) | ML-1T-2 | kPa | Pressuremeter modulus | Conventional modulus defined in the standard Ménard pressuremeter test | ||||
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