摘要
水力劈裂的常用计算方法分有效应力法和总应力法,但其计算结果却常有很大差异。本文详细分析了它们产生差异的原因,认为应该用心墙外水压力是否超过心墙上游面处土中的中主应力来判别水力劈裂的发生可能。提出应用有效应力法计算心墙堆石坝初期有效应力和水压力,通过叠加得到总应力,再与心墙前水压力比较来判别是否发生水力劈裂。该方法可以反映心墙渗透性、饱和度、库水位上升速度等对水力劈裂的影响。这样,通过控制这些因素就可避免水力劈裂的发生。最后通过实例计算表明了该方法的合理性。
There are two analysis methods of hydraulic fracture： effective stress method and total stress method. Their computation results are quite different. The fracture criterion of the former is effective stress less or equal to zero. This means to compare the total stress of a point in the core wall with water pressure at the same point. While the total stress method is to compare the total stress of a point in the wall with the water pressure at the point out of the core wall. In the initial stage of reservoir filling, the core material is unsaturated, and its permeability is low. The water pressure has not transferred to the inner part of the core wall. There will be sudden change of water pressure at the upstream edge of core wall. The criterion of effective stress method does not reflect the mechanism of hydraulic fracture. The criterion of total stress method should be adopted. However, the given parameters of constitutive model are often obtained from drained test of saturated soil. This is not suitable for total stress analysis. The proposed method in this paper is that the effective stress and pore water pressure are calculated on the basis of effective stress method, the sum of them is the total stress, an fracture is based on total stress. The calculation of an example project reasonable. The proposed method can reflect the influence of permeab d then the adjustment of hydraulic shows that the proposed method is ility and saturation degree of core material and the rising speed of reservoir water level on hydraulic fracture. Controlling these factors can avoid hydraulic fracture.
出处
《水利学报》
EI
CSCD
北大核心
2006年第11期1348-1353,共6页
Journal of Hydraulic Engineering
基金
国家自然科学基金项目(50479019)
关键词
土石坝
水力劈裂
防渗心墙
有效应力法
总应力法
earth and rock-fill dam
hydraulic fracture
anti-seepage core wall
effective stress method
total stress method
