Effect of loading rate on fracture characteristics of rock  

作　　者：周小平 钱七虎 杨海清 

机构地区：[1]School of Civil Engineering,Chongqing University [2]PLA University of Science and Technology

出　　处：《Journal of Central South University》2010年第1期150-155,共6页中南大学学报（英文版）

基　　金：Projects(50490275, 50621403, 50778184) supported by the National Natural Science Foundation of China;Project(NCET-07-0911) supported by Program of New Century Talents of Ministry of Education;Project(CSTC, 2009BA4046) supported by the Natural Science Foundation of CQ CSTC

摘　　要：The three-point bending experiments were applied to investigating effects of loading rates on fracture toughness of Huanglong limestone. The fracture toughness of Huanglong limestone was measured over a wide range of loading rates from 9 × 10-4 to 1.537 MPa.m1/2/s. According to the approximate relationship between static and dynamic fracture toughness of Huanglong limestone, relationship between the growth velocity of crack and dynamic fracture toughness was obtained. The main conclusions are summarized as follows. （1） When the loading rate is higher than 0.027 MPa-ml/2/s, the fracture toughness of Huanglong limestone increases markedly with increasing loading rate. However, when loading rate is lower than 0.027 MPa-ml/2/s, fracture toughness slightly increases with an increase in loading rate. （2） It is found from experimental results that fracture toughness is linearly proportional to the logarithmic expression of loading rate. （3） For Huanglong limestone, when the growth velocity of crack is lower than 100 m/s, the energy release rate slightly decreases with increasing the growth velocity of crack. However, when the growth velocity of crack is higher than 1 000 m/s, the energy release rate dramatically decreases with an increase in the crack growth velocity.The three-point bending experiments were applied to investigating effects of loading rates on fracture toughness of Huanglong limestone. The fracture toughness of Huanglong limestone was measured over a wide range of loading rates from 9×10-4 to 1.537 MPa·m1/2/s. According to the approximate relationship between static and dynamic fracture toughness of Huanglong limestone, relationship between the growth velocity of crack and dynamic fracture toughness was obtained. The main conclusions are summarized as follows. (1) When the loading rate is higher than 0.027 MPa·m1/2/s, the fracture toughness of Huanglong limestone increases markedly with increasing loading rate. However, when loading rate is lower than 0.027 MPa·m1/2/s, fracture toughness slightly increases with an increase in loading rate. (2) It is found from experimental results that fracture toughness is linearly proportional to the logarithmic expression of loading rate. (3) For Huanglong limestone, when the growth velocity of crack is lower than 100 m/s, the energy release rate slightly decreases with increasing the growth velocity of crack. However, when the growth velocity of crack is higher than 1 000 m/s, the energy release rate dramatically decreases with an increase in the crack growth velocity.

关 键 词：fracture toughness of rock three-point bending round bar loading rate velocity of crack growth 

分 类 号：TU45[建筑科学—岩土工程]