岩石断裂尺寸效应测试装置研制及实验研究

面向岩石断裂尺寸效应研究的实验装置需求,针对现有技术中三点弯曲装置对多组尺寸岩石试件适应性差、最小跨距的测试量程不足等问题,研制了一种可灵活用于岩石断裂尺寸效应测试的三点弯曲装里.装置采用"两体分离式"的设计,三种不同型号的滚子与压头体、支座体配合使用,有效避免了不同尺寸试件采用同一直径滚子测试带来的实验精度问题;同时...

The development of testing device and experimental study on size effect of rock fracture

To meet the needs of experimental equipment for the study of size effect of rock fracture,a three-point bending device which can be flexibly applied to the testing was developed,for solving the problems of poor adaptability of three-point bending device to multi-size rock specimens and insufficient testing range of minimum span in the existing technologies.The design of“two-body separation”was adopted for this device,and three different types of rollers were used in combination with the indenter body and the supporting body to avoid the test accuracy problems caused by using rollers with the same diameter for specimens with different sizes.At the same time,the device realized the setting of different experimental spans with 4 mm~100 mm,which simultaneously satisfied the needs of fracture testing of multiple groups of specimens with large size changes.With the help of this device,three-point bending fracture tests and the relevant numerical calculation of shale specimens with different sizes were carried out.Fracture parameters such as apparent fracture toughness of modeⅠand nominal strength of shale specimens with different sizes were obtained.The study results indicated that the rock fracture size had a significant effect on apparent fracture toughness of modeⅠand nominal strength of shale.The calculated results were in good agreement with the Size Effect Law(SEL)proposed by Bazant.It can be concluded that the fracture strength of shale can be predicted effectively by SEL curve,and the device has the advantages of high experimental efficiency and high precision.