5.2. RUBBLE-MOUND STRUCTURES
203
studies where armor unit movement was monitored in a physical model with
the inference that fracture would most likely occur in units that moved or
rocked. An example of this type of modeling was reported by Boer (1985)
who used single-frame camera exposures to detect rocking of dolosse in
a 1:45 scale model of a prototype structure armored with units having a
mass of 15,000-kg (15-metric-ton). Boer concluded that the number of
displaced model armor units plus the number of observed rocking model
units corresponded well with the number of dolosse broken in the prototype.
This conclusion was limited by Boer to that portion of slope above the still
water level and to the tested wave conditions and prototype armor unit
size.
Although Boer (1985) found reasonable correspondence, inferring breakage from rocking is a subjective measure of damage because the capability
of a slender armor unit to tolerate movement varies greatly with the size of
the unit (Timco and Mansard 1983; Mansard 1990; Burcharth, et al. 1991).
In other words, if Boer’s (1985) physical model was scaled up to represent
smaller 5,000-kg (5-metric-ton) dolosse, the same conclusion relating breakage to movement would probably not be valid because significant movement
without fracture could occur with the smaller units.
Similitude requirements for modeling concrete armor unit stresses in
physical models and the associated modeling techniques are presented in
the following sections.
Similitude Requirements for Armor Unit Stresses
Force loading that can produce stresses in artificial (concrete) armor units
were listed by Burcharth (1983) and Burcharth, et al. (1991) as follows:
• Static Loads due to armor unit weight and wedging during settlement
• Dynamic Pulsating Loads induced by gradually varying
wave forces (including slamming)
• Dynamic Impact Loads due to unit rocking or rolling,
impact by a broken armor unit “missile”, and placement
during construction
• Thermal Loads induced by environmental temperature
variation and concrete hardening
Burcharth, et al. (1991) also listed abrasion by suspended material and
corrosion of reinforcement material as additional factors leading to the deterioration of concrete armor units.
203
studies where armor unit movement was monitored in a physical model with
the inference that fracture would most likely occur in units that moved or
rocked. An example of this type of modeling was reported by Boer (1985)
who used single-frame camera exposures to detect rocking of dolosse in
a 1:45 scale model of a prototype structure armored with units having a
mass of 15,000-kg (15-metric-ton). Boer concluded that the number of
displaced model armor units plus the number of observed rocking model
units corresponded well with the number of dolosse broken in the prototype.
This conclusion was limited by Boer to that portion of slope above the still
water level and to the tested wave conditions and prototype armor unit
size.
Although Boer (1985) found reasonable correspondence, inferring breakage from rocking is a subjective measure of damage because the capability
of a slender armor unit to tolerate movement varies greatly with the size of
the unit (Timco and Mansard 1983; Mansard 1990; Burcharth, et al. 1991).
In other words, if Boer’s (1985) physical model was scaled up to represent
smaller 5,000-kg (5-metric-ton) dolosse, the same conclusion relating breakage to movement would probably not be valid because significant movement
without fracture could occur with the smaller units.
Similitude requirements for modeling concrete armor unit stresses in
physical models and the associated modeling techniques are presented in
the following sections.
Similitude Requirements for Armor Unit Stresses
Force loading that can produce stresses in artificial (concrete) armor units
were listed by Burcharth (1983) and Burcharth, et al. (1991) as follows:
• Static Loads due to armor unit weight and wedging during settlement
• Dynamic Pulsating Loads induced by gradually varying
wave forces (including slamming)
• Dynamic Impact Loads due to unit rocking or rolling,
impact by a broken armor unit “missile”, and placement
during construction
• Thermal Loads induced by environmental temperature
variation and concrete hardening
Burcharth, et al. (1991) also listed abrasion by suspended material and
corrosion of reinforcement material as additional factors leading to the deterioration of concrete armor units.