岩石点荷载试验在隧道动态围岩分级中的应用——以郑万高铁向家湾隧道为例

Application of Rock Point Load Tests in Dynamic Surrounding Rock Classification of Tunnels:Take Xiangjiawan Tunnel along Zhengzhou—Wanzhou High-speed Railway as Example

点荷载试验可以在施工现场简便快捷地获取岩石强度,但现有的点荷载强度和单轴抗压强度经验换算公式在不同地区、不同岩性的岩石中难以具有普适性。因此,应针对特定的工程地质条件进行专门研究,得到适用于该地质环境的换算公式,服务于小区域的工程建设。以向家湾隧道三叠系灰岩为研究对象,开展了大量点荷载与单轴抗压对比试验;并采用数值模拟研究了不同形状岩块在点荷载作用下的应力分布,从理论上印证了点荷载试验在不同形状的岩块中的适用性;在此基础上建立了适用于兴山地区三叠系灰岩的点荷载强度和单轴抗压强度经验换算公式,并以此为依据对向家湾隧道试验段灰岩围岩进行了亚分级,为今后具有相似工程地质条件的地区的工程建设提供借鉴。

Rock strength can be tested by point load test quickly and conveniently at construction site,but the existing empirical conversion formula of point load strength and uniaxial compressive strength is not universally suitable for rocks of different areas and different lithology.Therefore,specific research for rocks in specific engineering geological condition is necessary,the conversion formula obtained can be applicable for the construction in similar geological condition.The Triassic limestone of Xiangjiawan tunnel was taken as the research object,a large number of tests were carried out.The stress distributions of rock blocks of different shapes under point load were studied by numerical simulation.The result proves the applicability of point load test for rock blocks of different shapes in theory.On this basis,the empirical conversion formula of point load strength and uniaxial compressive strength of Triassic limestone in Xingshan area was established,and the surrounding rock of test section of Xiangjiawan tunnel was sub-level classified.The empirical formula can provide reference for construction projects in areas with similar geological conditions.