评价岩石脆性指标对滚刀破岩效率的影响

 脆性是岩石重要的力学性质之一。岩石脆性与滚刀破岩效率密切相关，但目前还没有统一的用于评价滚刀破岩效率的岩石脆性指标。总结现有的35种脆性指标，将其分为基于强度、应变、应变能、硬度、莫尔包络线、特殊试验和其他等7种类型。为研究岩石脆性与滚刀破岩效率之间的关系，通过滚刀贯入试验，引入归一化比能概念，提出表征岩石脆性的新指标，重点研究基于强度和贯入试验的脆性指标与归一化比能之间的关系。试验结果表明：(1) 滚刀更难贯入高强度岩石；(2) 脆性指标B2和B4与归一化比能之间呈强烈的指数函数关系，随着脆性的增高，归一化比能降低，滚刀破岩效率增高，应优先选用脆性指标B2来评价滚刀破岩效率，其次是脆性指标B4；(3) 将单轴抗压强度约20 MPa定义为单轴抗压强度过渡值，滚刀不适宜切削单轴抗压强度小于20 MPa的软岩。试验结果对评价滚刀破岩效率时岩石脆性指标的选取具有一定的指导意义。

Evaluation of rock brittleness indexes on rock fragmentation efficiency by disc cutter

Brittleness is one of the most important mechanical properties of rock. The fragmentation efficiency of rock is closely related to the rock brittleness. No unified brittleness index of rock is confirmed in evaluating rock fragmentation efficiency by disc cutter. The existing 35 different brittleness indices were summarized and classified into seven categories with respect to strength，strain，strain energy，hardness，Mohr envelope，special tests，etc. In order to study the relations between the rock brittleness and the rock fragmentation efficiency by disc cutter，the normalized specific energy concept was introduced after carrying out the indentation tests with disc cutter，and a new index of rock brittleness was proposed. In addition，the relations between the normalized specific energy and brittleness indexes based on strength and indentation test were mainly studied. The results show that it is more difficult to penetrate into the rock of high strength for disc cutter. The relationships between the normalized specific energy and brittleness indexes B2 and B4 were found to be exponential. With the increasing of brittleness indexes B2 and B4，the normalized specific energy decreased but the rock fragmentation efficiency increased. Therefore，the brittleness index B2 can be firstly used for evaluating the rock fragmentation efficiency，followed with the brittleness index B4. The uniaxial compressive strength of about 20 MPa can be defined as the transitional uniaxial compressive strength，and disc cutter may be not suitable for cutting the soft rock with uniaxial compressive strength less than 20 MPa.