H-2 Stiffness Factors

H-2.1 The lateral soil resistance for granular soils and normally consolidated clays which have varying soil modulus is modeled according to the equation:

where

p = lateral soil reaction per unit length of pile at depth z below ground level;

$y =$ lateral pile deflection; and

$\eta_{\mathrm{h}} =$ modulus of subgrade reaction for which the recommended values are given in Table 10.

H-2.2 The lateral soil resistance for over-consolidated clays with constant soil modulus is modeled according to the equation:

where

where $k_{1}$ is Terzaghi's modulus of subgrade reaction as determined from load deflection measurements on a 30 cm square plate and B is the width of the pile (diameter in case of circular piles). The recommended values of $k_{1}$ are given in Table 11.

NOTE — The $\eta_{h}$ values may be interpolated for intermediate standard penetration values, N.

NOTE — For $q_{\mathrm{u}}$ less than 25, $k_{1}$ may be taken as zero, which implies that there is no lateral resistance.

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H-2.3 Stiffness Factors

H-2.3.1 For Piles in Sand and Normally Consolidated Clays

Stiffness factor $T$, in $\mathrm{m} = \sqrt[5]{\frac{EI}{\eta_{\mathrm{h}}}}$ where

H-2.3.2 For Piles in Over-Consolidated Clays

H-3 Criteria for Short Rigid Piles and Long Elastic Piles

Having calculated the stiffness factor $T$ or $R$, the criteria for behaviour as a short rigid pile or as a long elastic pile are related to the embedded length $L_{\mathrm{e}}$ as given in Table 12.