# Abrasion-Resistant and Temperature Control of
## 5 Conclusions  
Due to the characteristics of high water head, high velocity, large discharge and complex shape, as well as the erosion of sediment and frequent use, there are bound to be higher requirements for the material performance, pouring construction technology and temperature control of concrete for the large-scale spillway tunnel. In order to meet the requirements of erosion resistance and wear resistance of the spillway tunnel, C\({}_{90}\)50 silica fume concrete is used for the lining of the side wall and bottom plate of the tunnel. The hydration heat is concentrated and it is easy to produce temperature cracks. Therefore, strict comprehensive temperature control measures should be taken during construction to avoid concrete cracking due to a large temperature difference between inside and outside. The above-mentioned concrete anti-erosion and wear resistance and temperature control and crack prevention are two major problems faced by large-scale spillway tunnel projects and they are closely related and mutually affected. Therefore, the anti-scouring and abrasion resistance and temperature control of C\({}_{90}\)50 silica fume concrete were studied. (1) The doping of fly ash, silica fume, PVA fiber and other auxiliary cementing materials indicated that (a) fly ash with a dosage of 20% could reduce water consumption and micro-cracks via its \"morphological effect\"; (b) silica fume with a dosage of 5% could improve the early strength of cement concrete and make up for the strength loss caused by the fly ash; (c) PVA fiber with the dosage of  
Figure 13: Temperature variation curve of concrete at typical side wall stake number. 0.9 kg/m\({}^{3}\) could enhance the concrete durability. The doping of these three additives can increase both the strength and abrasion resistance of concrete. (2) The peak temperature of concrete occurred roughly 2 day after casting. Properly strengthening the early-stage throughput, increasing throughput flow and decreasing cooling water temperature could achieve a satisfactory cooling effect. This study proposed a new temperature control and crack prevention measure, i.e., the \"early-throughput, high-flow and short-duration\" cooling strategy, which proved to be effective in reducing the maximum temperature rise inside the concrete. In the casting process, within 1-2 day after casting, cooling water at roughly 12 \({}^{\circ}\)C was guided in at a flow of approximately 3.5 m\({}^{3}\)/h; within 3-7 day after casting, river water at roughly 17 \({}^{\circ}\)C was guided in at a flow of approximately 1.8 m\({}^{3}\)/h; 7 day later, using surface flowing water alone for curing could achieve the cooling effect. The field temperature monitoring data indicated that the temperature of the sidewall lining concrete had a qualification rate of \(>\)91%, suggesting that the temperature control and crack prevention measures can effectively reduce the maximum temperature rise inside the concrete and achieve a satisfactory temperature control effect. (3) Through comprehensively utilizing the optimal mix proportion design, complex-curved novel template, self-propelled steel trolley, throughput cooling and other quality control measures, this paper guaranteed the construction quality of anti-scouring and abrasion-resistant concrete for the spillway tunnel and the fine shape control, smooth and flat surface and satisfactory crack control of cast concrete. The Dagangshan Spillway Tunnel began to take part in the flood discharge of the Dagangshan Reservoir in flood seasons in July 2015; at the end of 2015, its cumulative flood discharge duration reached 1784 h; at the end of December 2016, the cumulative running hours of the spillway tunnel reached 2690 h. Its annual average service frequency exceeded 2000 h/a, the highest among the same-type hydropower stations in China. According to the results of the inspection over the spillway tunnel after two years of frequent use, the concrete surface was as smooth as a mirror, without any obvious scouring trace, pot hole or crack failure.