The automatic monitoring system of Manwan hydropower station has been in operation for 11 years. This paper introduced the main problems in operation. Accordingly, some innovation measures were implemented and good effect was achieved.

As the second largest hydropower station in China, Baihetan hydropower station has a total installed capacity of 16 000 MW. It has the characteristics of high water head, large installed capacity and large HD value. To ensure its safe operation, 38 900 tons of steel were used to make penstocks, including 10 100 tons of 800 MPa high-strength steel. This is the first case where thickness of 800 MPa penstock reaches 68 mm in domestic hydropower industry. By studies on 800 MPa high-strength steel and a large number of tests, it is proved that the use of 800 MPa high-strength steel meets the function requirements of large power stations.

After years' operation, seepage may occur at earth dams. This paper analysed the types and cause reasons for seepage, and, accordingly, advanced some preferred treatment schemes and issues calling for attention in construction, for reference.

Safety detecting refers non-destructive detecting using repetitive and temporary fixed instrument to detect dikes in order to find out perils or danger existing in dikes,so,it is very important for dike safety.At present,field safety detecting has become the weak part in dike has made an investigation and study on specifications and regulations concerned, analysis on technology status at home and abroad.1Moreover,the instruments,methods,and detecting results are introduced,some suggestions on improvement and detecting results are introduced,some suggestions on improvement and reinforcement are brought forward.

Elastic modulus of concrete is akind of imponant performance of concrete, which can reflect the relationship between stress and deformation, and is one of parameters in structure calculating. In order to improve crack resistance of concrete. we often increase tensile strength and ultimate elongation, and decrease elastic modulus and shrinkage of concrete. Decreasing elastic modulus will be beneftt to crack resistance of concrete. In this paper, we present the influencing factors of elastic modulus, and analysis the influence of aggregate and its content on elastic modulus by U.J.Counto model, and show the measures of decreasing elastic modulus of concrete, which will be helpful to averting of concrete crack.

The rock- bolted crane beam in underground powerhouse of Baihetan hydropower station is designed by use of rigid body limit equilibrium method and checked by finite element method, which verifies the rationality of design parameters of structural section and bolt. Due to the influence of complex geology and high in-situ stress, the excavation of rock-bolted crane beam in local area is difficult, so the technical measures of rock platform excavation and reinforcement are put forward. Analysis of the prototype observation results shows that the bolt stress of rock-bolted crane beam and the opening between crane beam and surrounding rock have met the requirements. During the load test, the increase of monitoring data is small, which verifies the rationality of the design method and construction measures of rock-bolted crane beam.

It is the first vast application of low-heat cement in the concrete used for construction of a 300 m super-high double curvature arch dam. Through the research and application of low-heat cement and low-heat cement concrete, the performance characteristics of concrete in the construction process have been comprehensively mastered. By giving full play to the characteristics of low-heat cement such as low hydration heat, high strength and good durability, the overall quality of concrete construction of Baihetan hydropower station has been effectively guaranteed.

Discussion was made on fitted line parameter of a sensor by different ways, so as to understand the meanings of the linearity in hydraulic monitoring sensor and the effect of different linearity in measurement using sensor or calibration sensor.

The height of Sanbanxi face-slab rock-fill dam is 185.5 m．With low storage water level, the seepage was less than 30 L/s．As water level rising rapidly in the flood season of 2007, the seepage increased, whose maximum was 303.10 L/ s.By underwater inspection, damage was found at the horizontal joints of the face－slab.Later, rehabilitation was carried out and good effect was gotten.This paper, combined with seepage monitoring data, analysed the seepage of the dam before and after the rehabilitation.

Crest settlement reservation of concrete face slab rockfill dams would effect flood prevention safety and visual image.Some dam crest elevation was found lower than design in operation as there was no settlement reservation in design, while some recorded settlement in operation exceeded the designed value as the settlement reservation in design was too small. By statistics of dams, the recorded settlement value was more than 0.1% of damheight. For enough settlement reservation in operation and good visual image of arch at middle part, settlement reservation no less than 0.5% of damheight was recommended.

This paper analysed the formation and characteristics of100-year return flood occurred in Weigan River basin on23rd July,2002, summarizing the general situation of this flood real-time forecasting and dispatching.?

A Chinese expression says, “An experience learned increases one' s knowledge.”Learning frompast dam failures allows us to gain wisdom to ensure dam safety by detecting possible deficiencies /defects for a dam under performance evaluation.As lessons learned, some typical potential failure modes (PFMs) and associated root causes (i.e., risk factors and possible reasons) were introduced for three common types of dams.A flow chart was provided to address the procedures of the recently developed PFMA methodology. A collaborative teamwork was emphasized. The views expressed here do not necessarily represent the views of any federal agency of the U.S.A.

A water conservancy project in Xinjiang is located in a cold and arid area. The water retaining structure is a RCC gravity dam with a maximum height of 75.5 m, and the total storage capacity is 294 million m3. The unfavorable climate, namely cold, hot, windy and dry in typical severe cold region and the intermittent construction method have increased the difficulty of temperature control and crack prevention of dam concrete. By taking a series of temperature control measures from design to construction, including pouring temperature control, pipe cooling optimization, permanent thermal insulation of dam surface, temporary thermal insulation in spring and autumn and overwintering thermal insulation of the lift surface and other exposed surfaces, and pouring plan optimization, the cracking risk of dam concrete has been substantially reduced, and the temperature cracks of dam concrete have been effectively controlled.