The yellow arrow shows the direction of increasing the reactor height (H z ). It can be observed that the pile load increases by increasing the reactor height (H z ). Therefore, increasing (H z ) requires either a larger number of piles (m,n) or a longer embedment length (L P ). Piling configurations are denoted by radial lines (A), (B) and (C). These curves repre- sent various combinations of (m) and (n). Note that the slope of each curve increases by increasing the number of piles, as shown by the arrow rotating counterclockwise. Star symbols represent the points of intersection of line (L 1 ) with piling configurations (A), (B), (C). The x-coordinate denotes a fixed value (L P1 ), and the y-coordinate is variable, depending on the reactor height (H Z ) of configurations (A)- (C). Similarly, solid triangles identify the points of intersections with (L 2 ) and (H z ) of configurations (A)-(C). The difference in reactor heights between two configurations is denoted by (LP) [ δ H Z ] B-C . The subscript denotes the configuration tag being compared and the LHS superscript reference (L P ). The engineer can use two options to select the reactor sup- port configuration. In option (I), the pile embedment length (L p ) is fixed while modifying the pile-cap configuration to achieve the desired reactor capacity. This option is suitable to use on Greenfield projects or when the soil profile varies significantly, which may limit the depth of embedment length (L p ) to a specific length. In option (II), the engineer may fix the pile-cap size (or the number of piles) and modifies the pile embedment length (L p ). This scenario is suitable when the construction area of the pile cap is limited to a specific size. The engineer, in this case, may modify the pile length to achieve the target reactor capacity. Space limitations are frequently encountered in expansion or Brownfield projects. Analysis model Finite element models were developed to populate the design space using various reactor layouts. Computationally efficient models can be used in practice to analyse this class of reactor. Shell elements are used to model the support
β
α
Y
n
Reactor location
m
X
β α
L
F
S Y
S X
B F
Figure 2 Reactor support system of Section B-B
denoted by ( Φ P ), embedded length (L P ), and interior spacing (S X ) and (S Y ). Note that the pile longitudinal reinforcements must be projected inside the pile cap. Figure 3 illustrates the design space concept. The reactor height (H Z ) is plotted versus the maximum pile load (P P , Q P ). Vertical lines (L 1 ) and (L 2 ) denote pile capacities that are a function of the corresponding pile embedment lengths (L P1 , L P2 ). The bottom blue arrow shows the direction of increasing (L P ). It can be observed that by increasing (L P ), the maximum load on each pile is decreased. The rectangular area enclosed by green lines represents the feasible design domain of (L 1 ). Line segments enclosed by the feasible domain are shown in an identical colour and legend as (L 1 ). Lines outside the feasible domain are shown in a different colour and legend.
Pilling con guration ( C )
(L ) feasible design domain 1
Increasing (H ) Z
Pilling con guration ( B )
(L , H ) C P1 Z
(H ) Z
(L , H ) B P2 Z
L =f(L ) 1 m
[δH ] LP1
Pilling con guration ( A )
Z B-C
L =f(L ) 2 P2
(L , H ) B P1 Z
Increasing pile numbers ( m, n )
(L , H ) A P2 Z
[δH ] LP1
Z A-B
(L , H ) A P1 Z
(P , Q ) P P
Max
Increasing (L ) P
Figure 3 Schematic of design space concept
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PTQ Q3 2022
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