防水型单层衬砌的叠合面力学性能试验研究

Study on composite surface of waterproof single-layer lining by tests

防水型单层衬砌由具有双面黏结性能的喷涂防水层和多层喷射混凝土叠合而成。叠合层之间有无错动,将引起结构承载机理的变化,故叠合界面抗错动性能的测定,是定量分析防水型单层衬砌力学性能的前提。由于防水型单层衬砌在喷射混凝土之间还夹有一层材料力学性能迥异的喷涂防水层,其叠合面力学行为复杂,是研究防水型单层衬砌面临的主要问题。为解决该问题,将防水型单层衬砌的喷涂防水层和接触面处的喷射混凝土共同定义为界面层,通过对界面层的剪压试验和单轴拉伸试验得到界面层的极限强度包络线,并将其作为防水型单层衬砌各叠合层间有无错动的判据,再通过弯曲梁试验,测定界面层两侧喷射混凝土的抗裂强度,进而得到整个叠合衬砌结构的极限强度。通过对青岛地铁试验段防水型单层衬砌进行数值仿真,发现其界面层的正应力和剪应力组合均位于极限强度包络线以内,衬砌可按无错动的整体承载结构进行分析,且衬砌最大拉应力小于喷射混凝土抗裂强度,因此衬砌结构安全。试验段的现场取样测试亦表明,施做的防水型单层衬砌界面层位置过度平滑,无开裂错动,其性能达到了试验所模拟的力学性能,研究的技术路线满足该衬砌在地铁隧道的应用。

The waterproof single-layer lining was composed of spraying waterproof material with double-sided bonding property and multi-layer shotcrete. Whether there was dislocation between the composite structures will cause changes in the load-bearing principle of the structure. Therefore, obtaining the anti dislocation performance of the interface of the composite structure was the premise of quantitative analysis of the mechanical properties of waterproof single-layer lining. There was a layer of sprayed waterproof layer with different mechanical properties between the sprayed concrete of waterproof single-layer lining. So the mechanical behavior of its composition surface was complex, which was the main problem in the study of waterproof single-layer lining. In order to solve this problem, the sprayed waterproof layer and the shotcrete at the contact surface were defined as the interfacial layer. The ultimate strength envelope of the interfacia layer was obtained by shear compression test and tensile tests, which can be used as the criterion of the staggered action between the laminated layers of waterproof single layer lining. Through the bending beam tests, the crack strength of shotcrete on both sides of the interfacia layer was measured, and then the ultimate strength of the whole composite lining structure was obtained. Through the numerical simulation of the waterproof single-layer lining of Qingdao metro tunnel, it is found that the normal stress and shear stress of the interfacial layer are within the ultimate strength envelope, and the lining can be analyzed as an integral bearing structure. Moreover, the maximum tensile stress of the lining is less than the crack strength of shotcrete, so the lining structure is safe. The field test of the applied tunnel also shows that the interface layer of the waterproof single-layer lining is smooth and has no crack dislocation.So the waterproof single-layer lining can achieve the mechanical properties simulated in the test, and the technical route obtained from the research can meet the needs of the application of this type of lining in metro tunnel.