喷射混凝土与围岩之间的粘结强度是喷射混凝土最重要的性能指标之一,也是地下洞室工程建设中一项重要的检测内容。以丰宁抽水蓄能电站地下厂房为依托工程,基于钻芯取样方法,开展了地下洞室喷射混凝土与围岩粘结特性现场试验研究。首先针对钻孔取芯过程中芯样频繁发生断裂的现象,介绍了提高取样效率而进行的现场改进尝试和实际效果;然后,提出将钻芯直接制取试样的单一步骤调整为现场取样、室内加工制样2步,并通过修复试样使其符合试验尺寸要求;最后,进行试件的性能测试。结果表明:采用室内修复加工方法获得的试件能够用于混凝土-基岩粘结力测试,试验结果可靠,反映了喷射混凝土-基岩的实际粘结性能。测试数据显示,主厂房与主变室内的喷射混凝土-围岩粘结强度平均值分别为0.74 MPa与0.83 MPa,即主变室喷射混凝土-围岩粘结强度略高于主厂房的喷射混凝土-围岩粘结强度。

The bond strength between shotcrete and surrounding rock is a most crucial performance indicator of shotcrete, and also an important content of inspection in the construction of underground caverns. With Fengning Pumped Storage Power Station's underground powerhouse as a background project, field experimental study on the bonding characteristics of shotcrete and surrounding rocks in underground caverns was carried out by using drilling core sampling and reprocessing. The causes of the frequent breakage of core samples during drilling were analyzed. The single step of directly preparing samples from the drill core was adjusted into two steps: on-site sampling and indoor processing; subsequently the samples were repaired to meet test requirements. Test results show that the bond strength between shotcrete and surrounding rock in the main transformer room of Fengning Pumped Storage Power Station is slightly higher than that of the main building. The results demonstrated that the drilled core specimens undergone indoor processing and restoration can be used for the test of bonding strength between shotcrete and surrounding rock. The test results are reliable and reflect the actual bonding strength between shotcrete and surrounding rock.