新近系红层岩体力学参数与隧道围岩分级探讨  

Discussion on mechanical parameters and engineering classification of tunnel surrounding rock for Neogene red beds

作　　者：刘颖[1] 赵天宇 王发旺 李锦 

机构地区：[1]甘肃省水利水电勘测设计研究院,兰州730000 [2]甘肃省交通规划勘察设计院有限责任公司,兰州730030

出　　处：《工程勘察》2016年第8期11-18,共8页Geotechnical Investigation & Surveying

基　　金：甘肃省交通厅科技项目"新近系红层公路隧道围岩变形机制与修筑技术研究"(2016-02)

摘　　要：红层软岩的强度与变形特性在很大程度上控制着隧道围岩的稳定性及其支护强度,对公路隧道工程造价和安全运营有很大影响。借助于开挖的试验平硐,本文采用原位剪切试验和刚性承压板法等,测试分析了红层岩体抗剪(断)强度、变形参数及岩体声波特性,并探讨了研究区新近系红层软岩的围岩分级方法。结果表明,研究区红层岩体剪切破坏基本属于塑性破坏,剪切曲线表现为应变软化型,变形曲线具有明显的塑性变形和回滞环。依据岩体力学参数及声波特性,结合红层岩体开挖后的围岩特征,笔者指出红层软岩的隧道围岩定量分级结果与实际情况存在差异,认为施工期和使用期不遭受饱水浸泡的粘土质软岩应采用天然抗压强度作为其岩石强度的代表值,并提出了软质岩的BQ值计算修正方法,其计算结果与围岩实际开挖情况基本吻合。The stability and supporting intensity of tunnel surrounding rock are controlled largely by the deformation and strength of red-bed soft rock,which influences significantly on the construction cost and tunnel safety. Based on the in-situ shear test and plate bearing test,the characteristics of shear strength,deformation and acoustic waves of Neogene red beds are studied,and the engineering classification methods of tunnel surrounding rock is also discussed. The test results show that the shear tests of red-bed rock in the study area are generally belong to plastic failure type,and the shear curves could be classified into strain softening type. The deformation curve presents plastic deformation characteristic and hysteresis loop. According to the mechanical parameters,sonic wave velocity and the characteristics of tunnel surrounding rock,it is found that the engineering classification based on quantitative analysis is different from the actual situation. It is proposed that natural compressive strength should be used as the representative value of the rock strength for the clay soft rock without full water-soaked in the period of construction and operation. A revised calculation method of BQ value for red-bed soft rock is put forward and it is proved consistent with the practice.

关 键 词：红层 软岩 强度 围岩分级 

分 类 号：TU452[建筑科学—岩土工程]