碾压混凝土拱坝诱导缝等效强度双参数断裂模型

Calculation model of equivalent strength for induced crack in RCC arch dam based on double parameter fracture theory

对两种尺寸碾压混凝土三点弯曲梁进行了断裂试验,获得了荷载和裂缝口张开位移P-M全曲线及荷载和加载点位移P-δ全曲线,分析了碾压混凝土的断裂参数、临界有效裂缝长度和临界裂缝尖端张开位移等一系列空白参数.运用双K和双G断裂理论,分别建立了碾压混凝土拱坝诱导缝等效强度的非线性断裂模型和断裂能量分析模型,从非线性应力场和能量释放率角度明确了诱导缝的起裂、稳定扩展和失稳扩展的计算方法,对两种模型计算结果进行了相互比较,并用有限元和沙牌拱坝的工程实际观测值验证了模型的可靠性.给出了拱坝诱导缝的最佳布置间距、设置位置等.实践证明,该模型可提高碾压混凝土拱坝诱导缝的设计水平,且具有工程实用价值.

By means of fracture testing on RCC three-point bending beams with two different specimen sizes, the P-M complete curve and P-δ complete curve for RCC were gained. Then, the fracture parameters, as well as the critical effective crack length and the critical crack tip opening displacement, were evaluated. Based on the double K and double G fracture parameters above, the fracture energy analysis model and nonlinear fracture calculation model of equivalent strength for induced crack were established, thus the calculation methods on its initiation, stable propagation and unstable fracture were ascertained. These two models were contrasted. Furthermore, the finite element simulation analyses of stress field in Shapai arch dam and the on-site observational splaying points of induced crack at different altitudes validated the reliability of the model. Finally, the crack inducer's optimal setting in RCC arch dam was given. Thus it can improve the design level of induced crack in RCC arch dam and satisfies the necessity of engineering practice.