弯曲试验确定岩石单轴抗拉强度的新方法

A New Method for Determination of Uniaxial Tensile Strength of Rock through Bending Test

岩石的单轴抗拉强度是岩石的一个重要力学参数。四点弯曲试验法是获取岩石单轴抗拉强度的一种间接方法,但四点弯曲试验的传统公式计算出来的单轴抗拉强度往往比实际的单轴抗拉强度大得多,有时甚至是直接拉伸试验抗拉强度的2～3倍。因此,需要对传统公式进行改进,得出新的抗拉强度计算公式,并在四点弯曲试验中获得与实际比较符合的单轴抗拉强度。在岩石拉压模量不同的基础上,考虑岩石破坏前的塑性变形行为,通过弹塑性力学的方法精确地推导出四点式弯曲试验的单轴抗拉强度计算公式,并分析了新的抗拉强度计算公式的结果,获得与实际情形比较符合的岩石单轴抗拉强度。

The uniaxial tensile strength of rock is an important mechanical parameter. The four-point bending test method is an indirect method for obtaining the uniaxial tensile strength of rock. But the uniaxial tensile strength calculated by the traditional formula of the four -point bending test is often much greater than the actual uniaxial tensile strength,and sometimes is even 2 ~ 3 times the tensile strength of the direct tensile test. Therefore,it is necessary to improve the traditional formula to derive a new tensile strength calculation formula,and obtain a uniaxial tensile strength that is in line with the actual one in the four-point bending test. On the basis of different tension and compression modulus of rocks,the plastic deformation behavior before rock failure is considered,and the uniaxial tensile strength calculation formula of the four-point bending test is accurately deduced by the elasto-plastic mechanics method. The results of the new tensile strength calculation formula were analyzed and the uniaxial tensile strength of the rock,which was in line with the actual situation,was obtained.