(2) The final crack length computed using the

traditional method of analysis was 19.62 ft. The

In an effort to determine the effects of the large

fracture mechanics based prediction of 16.65 ft is

culvert located near the base of the monolith, a

only 15.1% less than the value of 19.62 ft computed

series of analyses was performed for a solid mono-

using the traditional analysis method. When the

lith in which the culvert was not considered. Anal-

culvert was considered, the discrepancy between the

ysis procedures were identical to those described in

final crack lengths was 43.7% (see Appendix A),

Appendix A. The open area of the culvert was

which is slightly more than three times the 15.1%

eliminated by simply adding elements and nodes to

of this case. The fact that the estimated crack

the mesh shown in Figure A-4 of Appendix A.

lengths are in much better agreement when the

Material properties and applied loads for this inves-

culvert is not considered indicates that the rigid

tigation were identical to those used for the analyses

behavior assumed by the traditional method of

in which the culvert was considered.

analysis more closely approximates the actual

behavior as the monolith becomes stiffer. This

should be expected since a solid monolith would

behave more like a rigid block than one with a

large culvert. Based on this observation, the

assumption of a rigid monolith in the traditional

method of analysis does not appear to be valid

(1) A series of nine analyses, each with a dif-

when a large culvert is present.

ferent specified crack length, was performed to

compute an initial estimate of the final crack length.

The prescribed crack lengths for these analyses

ranged from 6.0 ft to 18.0 ft in 1.5-ft increments.

(1) The normal stress profile along the base of

No analyses were performed for crack lengths

the monolith for a crack length of 16.65 ft is shown

greater than 18.0 ft because the value of *K*I for *a *=

in Figure B-2. In order to contrast the difference

18 ft was negative and *K*I was positive for all prior

between the traditional and proposed methods of

analyses. The final crack length of 16.65 ft was

analysis, the normal stress profile from the tradi-

found by re-meshing and comparing *K*I to *K*Ic as

tional method of analysis is also included in

described in paragraph 3*d*(1) of Appendix A. The

Figure B-2. The distance along the base of the

results of each analysis are summarized in

monolith is measured from the toe of the monolith

Table B-1. The variations of *K*I and *K*II over the

to the heel of the monolith and a negative stress

range of crack lengths are shown in Figure B-1.

indicates compression. Comparison of the normal

KI

KII

∆Hcrest

a

CMOD

ksi .

√in

ksi√ .

in

ft

in.

in.

6.00

0.566

0.628

0.00715

-0.0667

7.50

0.500

0.648

0.00791

-0.0690

9.00

0.435

0.665

0.00859

-0.0712

10.50

0.366

0.682

0.00919

-0.0732

12.00

0.291

0.700

0.00969

-0.0750

13.50

0.209

0.719

0.01006

-0.0764

15.00

0.117

0.740

0.01028

-0.0775

16.50

0.012

0.764

0.01028

-0.0780

16.65

0.000

0.766

0.01027

-0.0770

18.00

-0.108

0.792

0.00962

-0.0748

B-1