Chapter 32 - Deep Foundations - Index of - Free

where p is the lateral force per unit pile length and y is the lateral deflection.is the initial slope and is expressed asK irKir = kirEir(32.45)is a dimensionless constant and is determined byk irk ir100⎧⎛⎪=⎝⎨⎪500⎩400x+ ------------- r ⎞3b ⎠forfor0 ≤ x r ≤3b> 3bx r(32.46)x r= depth below bedrock surface, b is the width of the rock socketE ir= initial modulus of rock.y ais the lateral deflection separating Segment 1 and 2, andya1.3332 025 rm irpur= ⎛ ⎞⎝ ⎜ .y K⎟⎠(32.47)wherey rm= k b(32.48)rmk rmpurP ura r q ur b 1 1.4is a constant, ranging from 0.0005 to 0.00005.is the ultimate resistance and can be determined by=⎧⎪⎛ +⎨⎝⎪5.2a r q ur b⎩x r--- ⎞b⎠forfor0 ≤ x r ≤3b> 3bx r(32.49)where= compressive strength of rock and is a strength reduction factor determined byq urα rRQDα r= 1−150RQD = rock quality designation for rock.32.6 Grouped Foundations0 ≤RQD≤100(32.50)32.6.1 GeneralAlthough a pile group is composed of a number of individual piles, the behavior of a pile group isnot equivalent to the sum of all the piles as if they were separate individual piles. The behavior ofa pile group is more complex than an individual pile because of the effect of the combination ofpiles, interactions between the piles in the group, and the effect of the pile cap. For example, stressesin soil from the loading of an individual pile will be insignificant at a certain depth below the pile© 2000 by CRC Press LLC