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提出一种用于岩石材料I/II复合断裂韧度测试的新试件——单边切槽深梁(SENDB)试件,使用有限元法对新试件I(II)型无量纲应力强度因子YI(YII)及无量纲T应力T*进行系统研究和数值标定。研究结果证实SENDB试件可方便地通过调整裂纹倾角?、裂缝长度a和支座间距2S实现从纯I型到纯II型任意I/II复合度荷载作用下的岩石断裂韧度测试。与现有弯曲类试件对比分析表明:(1)SENDB试件与经典的单边切槽梁(SENB)试件在几何尺寸和岩石复合断裂韧度测试方法上存在显著差异,SENDB试件是通过调整裂缝倾角实现复合加载,而SENB则是通过移动裂缝位置(无法实现纯II型加载)或四点弯曲试验(加载装置复杂)实现复合加载;(2)因可方便地加工系列尺寸(包括大尺寸)的试件,新构形相比圆盘类试件在尺寸效应研究方面略有优势;(3)与国外学者新近提出的ECT试件相比,SENDB试件可选择的量纲一的裂缝长度和量纲一的支座间距范围要更宽泛;(4)为了实现从纯I型到纯II型整个区间的复合断裂测试,对SENDB,SCB和ECT三种试件,均应使用较小的支座间距或较长的裂缝。
A new specimen, SENDB, for I / II composite fracture toughness test of rock material is proposed. The dimensionless stress intensity of new specimen I (II) Factor YI (YII) and dimensionless T stress T * were systematically studied and numerically calibrated. The results of the study confirm that the SENDB specimen can be conveniently used to test the fracture toughness of rocks under any I / II complex load from pure Type I to Type II simply by adjusting the crack dip, the crack length a and the abutment spacing 2S. The results show that: (1) There are significant differences between the SENDB specimen and the classical SENB specimen in the geometrical size and rock composite fracture toughness test method. The SENDB specimen is The composite loading is achieved by adjusting the dip angle of the fracture, whereas SENB is the composite loading by moving the fracture location (pure Type II loading is not possible) or the four-point bending test (loading device is complex); (2) Large size), the new configuration is slightly superior to the disc type in terms of size effect research; (3) Compared with the newly proposed ECT specimens by foreign scholars, SENDB specimens can be selected in dimension one (4) In order to achieve the composite fracture test from the pure type I to the pure type II, the three specimens SENDB, SCB and ECT should be used to compare the length of the support and the distance between the two. Small bearing spacing or longer cracks.