The Influence of Cracks on the Structural Behaviour of a Buttress Dam

• Buttress dams located in cold areas are often subjected to severe environmental conditions. Recent assessments and investigations of buttress dams in northern Sweden reveal several types of cracks. Theoretical analysis and field measurements have showed that the most of the cracks are either developed or propagated as a result of the seasonal temperature variations.Cracks influence the behaviour of the dams in different ways, such as reducing the tightness of the dam and increasing the hydraulic pressure within the cracks. Furthermore, cracks may have impact on the stiffness and stability of the dam. The ordinary sliding and overturning stability analyses are not sufficient when the supporting structure is cracked. The cracks may comprise the integrity and the homogeneity of the structure. A cracked, and for that matter even repaired structure, can’t be regarded as a homogenous structure and should be treated accordingly. Consequently other types of models instead of the conventional design models should be utilized for the stability analyses of the cracked and repaired dams.There are at least two major aspects which must be considered when a cracked or repaired structure is being analysed. The first aspect is the principle of superposition and the second aspect is probability of the failure. It is well known that a cracked structure does not behave linearly, consequently the principle of superposition can’t be applied to determine the overall effects of the several simultaneously acting events.The mode of failure is one of the decisive elements considering determination of the probability of the failure. The condition for crack initiation and the trajectory of the crack propagation are the decisive factors which govern the failure mode. Ordinary design methods and advanced numerical models which are based on the elastic behaviour of the structure can’t be utilized, since these models are not able to describe the non-linear behaviour and to predict the failure mode of the structure.A finite-element model based on the non-linear fracture mechanics has been utilized to study crack development in a buttress dam. The aim of the project was to study crack trajectories and to determine the influences of cracks on the overall behaviour of the structure, for instance in the global stiffness of the structure and possible failure modes. The paper will present the structure, the numerical model and the results.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Infrastrukturteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Infrastructure Engineering (hsv//eng)

Keyword

Buttress dams

fracture mechanics

crack propagation

thermal cracks

Publication and Content Type

ref (subject category)

kon (subject category)