水电能源科学

为揭示高地温引水隧洞单向加热环境对混凝土支护体系界面力学性能的影响，设置5种单向加热养护工况，开展2种岩性下岩石-混凝土界面直剪试验，系统分析了剪切强度、变形等力学性能变化规律。结合数字图像相关技术(DIC)与声发射(AE)监测手段，进一步探明了加载过程中岩石-混凝土界面损伤的时空演化特征及破坏机制。结果表明，随着养护温度增加，花岗岩-混凝土(HC)、砂岩-混凝土(SC)界面的抗剪强度均呈先增后减趋势，均在60℃时强度达到峰值。与常温相比，HC、SC抗剪强度分别升高28.6%、49.8%。砂岩因表面粗糙多孔，其界面抗剪强度显著高于花岗岩。随温度升高，HC、SC峰值剪应变呈先减后增趋势。HC剪切带平直集中，SC剪切带呈波状并向两侧扩展。温度变化显著影响岩石-混凝土声发射活动。60℃下试样AE活动更加集中，破坏转折点后移，继续升温则AE能量释放增强、破坏过程更为剧烈。裂纹扩展以张拉型为主，其占比随温度先增后降，60℃时HC占比为77%。高温养护导致声发射b值下降提前，各温度养护下HC试样b值波动较大，b值骤降可作为界面失稳的临界预兆。研究为高地温引水隧洞混凝土支护结构安全服役提供了重要理论依据。

In order to reveal the impact of unidirectional heating environment of high geothermal diversion tunnel on the interface mechanical properties of concrete support system, five kinds of unidirectional heating curing conditions were set up to carry out the direct shear test of rock-concrete interface under two kinds of lithologies. The mechanical properties of shear strength and deformation were systematically analyzed. Combined with digital image correlation(DIC) and acoustic emission(AE) monitoring methods, the spatial and temporal evolution characteristics and failure mechanism of rock-concrete interface damage during loading were further explored. The results show that with the increase of curing temperature, the shear strength of granite-concrete(HC) and sandstone-concrete(SC) interfaces increases first and then decreases, and the strength reaches the peak at 60 ℃. Compared with normal temperature, the shear strength of HC and SC increased by 28.6% and 49.8%, respectively. The interface shear strength of sandstone is significantly higher than that of granite due to its rough and porous surface. With the increase of temperature, the peak shear strain of HC and SC decreased first and then increased. The HC shear band is straight and concentrated, and the SC is wavy and extends to both sides. The temperature change significantly affects the acoustic emission activity of rock-concrete. At 60 ℃, the AE activity of the sample is more concentrated, and the failure turning point moves backward. When the temperature continues to rise, the AE energy release is enhanced and the failure process is more intense. The crack propagation is dominated by tensile type, and its proportion increases first and then decreases with temperature. At 60 ℃, the proportion of HC is 77%. High temperature curing leads to the decrease of b value in advance, and the sharp decrease of b value can be used as a critical omen of interface instability. The b value of HC sample fluctuates greatly under different temperature curing. This study provides an important theoretical basis for the safe service of concrete supporting structure of high ground temperature diversion tunnel.