超高强混凝土双K断裂参数及断裂能试验研究

Experimental investigation on double-K fracture parameters and fracture energy for ultra-high strength concrete

本文采用尺寸为480 mm×120 mm×60 mm的混凝土三点弯曲梁试件,利用试验测得的起裂荷载P_(ini)、峰值荷载P_(max)及对应的裂缝口张开位移CMOD_c等参数,得到了强度为115.8 MPa的超高强混凝土的起裂断裂韧度K_(IC)^(ini)、失稳断裂韧度K_(IC)^(un)及断裂能G_f,并与其他强度等级混凝土进行了对比。结果表明,超高强混凝土的K_(IC)^(ini)、K_(IC)^(un)与初始缝高比无关;当初始缝高比相同时,K_(IC)^(ini)、K_(IC)^(un)及G_f随着混凝土强度等级的提高而增大。

An experimental investigation on double-K fracture parameters and fracture energy of ultra- high strength concrete is presented. In the tests, the compressive strength was up to 115.8 MPa and the dimensions of three-point bending specimen beams were 480 mm ~ 120 mm x 60 mm. Initial fracture toughness, unstable fracture toughness, and fracture energy were calculated from the data of initial cracking load, peak load, incipient crack opening displacement, etc. The results indicate that no obvious relationship exists between double-K fracture parameters and initial crack-depth ratios of the tested ultra- high strength concrete. At a fixed initial crack-depth ratio, double-K fracture parameters and fracture energy all increase with the increasing compressive strength.