# Abrasion-Resistant and Temperature Control of
## 4 Analysis of Temperature Monitoring Data  
The casting of sidewall C\({}_{90}\)50 silica fume concrete lining was carried out by using a novel self-developed tunnel steel trolley. The trolley consists of a frame system, template system, vertical reciprocating lift system, automatic concrete spreading system, hydraulic running system, suspension system, shifting and jacking system, etc. When casting sidewall concrete, the vertical lift system of the trolley first lifts the stock bin with normal concrete to the predetermined height. After that, the electric hoist is enabled to drag the stock bin until it is right above the concrete spreader. Finally, both the concrete spreader and the stock bin are enabled so that the concrete spreader transports concrete to the inner side of the template and thus realizes the automatic casting of sidewall normal lining concrete. The field construction is shown in Figure 11.  
Based on the performance test and numerical simulation results, in the construction of sidewall C\({}_{90}\)50 silica fume concrete lining, the cooling measure of \"early-throughput, high-flow and short-duration\" was used for temperature control and crack prevention. In the view of the concentrated hydration heat and high heat production of C\({}_{90}\)50 silica fume concrete in the early stage, it is suggested that the cooling measure of condition seven in the numerical simulation be adopted during construction to avoid excessively fast temperature rise of lining concrete. During the casting process and over 1-2 day after casting, 12 \({}^{\circ}\)C \"high-flow and low-temperature\" cooling water was guided in at a flow of approximately 3.5 m\({}^{3}\)/h. Within 3-7 day after casting, because of the template removal, with increasing radiating surface and reducing template constraints the temperature dropped abruptly. In contrast, the temperature inside the concrete still maintained a rising trend, resulting in a relatively large internal/external temperature difference. Under the action of expansion caused by heat and contraction caused by cold, tensile stress increased rapidly, making it susceptible to temperature cracking. To avoid excessively high peak temperature and excessively large internal/external temperature difference for lining concrete, during construction, 17 \({}^{\circ}\)C river water at a flow of 1.8 m\({}^{3}\)/h was guided in, and the 8# iron wire hooks with length of 20 cm were pre-buried at the top of the sidewall at intervals of 1 m; after sidewall demolding, the PVC (polyvinyl chloride) perforated pipes were hung on the pre-buried iron wire hooks and the water from a cooling water pipe was used to supply normal flowing water on the concrete surface for curing purposes. After 7 day, the temperature inside the concrete basically began to decrease over time. To avoid excessively fast cooling of concrete, cooling water should be suspended and surface flowing water alone could be sufficient for the cooling purpose. Silica fume concrete is susceptible to early-stage plastic cracking; when the concrete surface is observed to turn white or the surface water evaporation rate was \(>\)0.5 kg/(m\({}^{3}\)h), a wind shield should be used for screening and spraying should be used to maintain a necessary humidity level on the concrete surface. In low-temperature seasons or in the case of a sudden drop in air temperature,  
Figure 11: Construction of spillway tunnel sidewall lining concrete. the demolding time should be properly postponed; in particular, demolding should be avoided in cold evenings, otherwise concrete may crack due to a large internal/external temperature difference. After demolding of fresh concrete, the transverse joint plane should be immediately covered with thermal insulation materials. In the process of concrete casting, resistance thermometers were buried inside the concrete for real-time monitoring of concrete temperature.