A failure of a massive concrete dam could cause catastrophic consequences. The purpose of monitoring is to detect anomalies and damage at an early stage to prevent failure. Data-based models for anomaly detection are based on the hypothesis that the behaviour of an undamaged dam will follow an expected pattern, and deviation from this pattern is an indication of damage. In this study, simulations were used to create time series for an undamaged dam and three different damage scenarios at three different locations in the dam body. Three common data-based models were used to predict a dams crest displacements, both on the generated artificial data and the corresponding measurements from the dam. Prediction bands for future measurements were created, and the ten time-series were used to test the ability to detect damage. All models could detect instantaneous damage but struggle to detect progressive damage; the Neural network outperforms the two regression models. The choice of the mathematically optimal threshold limit leads to a large number of false alerts. Requiring three consecutive values outside the threshold before an alert is issued, increases the possibility to receive an early alert compared to the standard approach where observations are classified individually.

Dams located in cold areas are subjected to large seasonal temperature variations and many concrete dams have cracked as a result. In the 14th International Commission on Large Dams (ICOLD) Benchmark Workshop, a case study was presented where contributors should predict the cracking and displacements due to seasonal variations. In this paper, the conclusions from this case study are presented. Overall, the results from the contributors are well in line with the observations that can be made on the dam and the measurements performed. This shows that using non-linear numerical models is a suitable tool to accurately predict cracking and estimate the displacements of cracked dams. This case study also highlighted important aspects that need special consideration in order to obtain realistic results that can be used to predict the crack pattern, these being: (1) the importance of performing transient thermal analyses based on robin boundary conditions; (2) the influence of contact formulation between the concrete dam and the foundation; and (3) the use of realistic non-linear material properties. The results and conclusions presented in this paper constitute one important step in achieving best practices to estimate dam safety and better understand the potential failure modes and ageing of concrete dams.

Passive rock bolts are commonly used to anchor concrete dams, and they may have a significant impact on stability-evaluations. However, these bolts are often omitted from dam safety analysis due to uncertainties regarding their condition and the size of displacements required in the dam-rock interface to mobilize significant bearing forces in the passive rock bolts. This paper address the latter question by studying the failure process of a small concrete dam anchored with rock bolts. Failure simulations were performed with the increased density method in a finite element model consisting of a dam, the corresponding part of the rock and rock bolts. Two types of approaches are used to simulate the anchorage of the rock bolts; a method where the anchorage to the rock is simulated using a fixed boundary condition; and a method where the anchoring of the bolts are modelled using springs. Depending on the method of analysis, the rock bolts contribute with 40–75% of the load-carrying capacity of the dam. The rock bolts increase the load-bearing capacity of the dam, partly through anchorage forces, but also by keeping the contact surface between rock and concrete together and thereby increase the shear capacity of the interface.

In the assessment of concrete dams in cold climate, it is common that the theoretical stability becomes insufficient for load cases that include ice loads. However, the magnitude and return period of these ice loads have a high degree of uncertainty. This study estimates the magnitude of ice loads on eight concrete dam monoliths using measurements of their displacement from 29 winters. In the displacement signals, events are identified and assumed to be caused solely by ice loads. The observed displacement during an event is interpreted as an ice load using a load–displacement relationship derived from FE simulations of each dam. These simulations show that ice loads of the magnitudes given in design guidelines and recorded in previous measurements would significantly affect the structural response of the studied dams. However, only small traces of ice loads can be found in the observed responses of the studied dams. The estimated ice loads are significantly lower than the ice loads recorded in traditional ice load measurements. These results indicate that the average magnitude of ice load on an entire monolith is significantly lower than the measured local pressures. This would imply that ice loads may be a smaller concern regarding dam safety than previously believed.