摘要
针对土石坝心墙土在初次蓄水前为饱和度高于80%的非饱和土,提出了研究心墙水力劈裂问题的非饱和土固结简化计算的有效应力分析方法。该方法不仅可反映孔隙中气体对水压上升的影响,还可合理分析心墙土的渗透性、初始饱和度和蓄水速度等心墙水力劈裂的影响因素。以糯扎渡堆石坝为例,研究发现:填筑竣工时,尽管心墙中部水压很高,但心墙仍处于非饱和状态;初次蓄水时,上游水压力不能及时渗入心墙内部,形成了心墙内外的水压力突变,可导致心墙水力劈裂的发生。同时研究发现:提高心墙的渗透系数、提高心墙填筑土的初始饱和度、在初次蓄水时,放慢蓄水速度等均可防止心墙水力劈裂的发生。因此非饱和土固结简化计算的有效应力方法分析水力劈裂问题是合理的,它可为实际心墙土石坝预防水力劈裂问题提供科学依据,并可进一步提高土石坝设计水平。
A new simplified method of consolidation theory of unsaturated soils is put forward to study the hydraulic fracturing of core walls of rock-fill dams with the degree of saturation of the soils higher than 80%. The method can reflect the interaction between the pore-air pressure and the pore-water pressure, and can also study three influence factors for hydraulic fracturing： the permeability of core soils, the initial degree of saturation of core soils, and the rising speed of reservoir water levels. Conclusions are drawn from the analysis of Ruzadu Rock-fill Dam. First, the core wall is in a state of unsaturated soils after the completion of construction in spite of high pore-water pressure in the core wall. Second, the catastrophe of pore water pressure is formed because the upper water pressure can not infiltrate the core wall in time for the initial impounding, and the hydraulic fracturing of the core wall may occur. Third, hydraulic fracturing in the core wall can be prevented by the improvement of the permeability of core soils, the increase of the initial degree of saturation of core soils, and the slowing down of the rising speed of reservoir water levels. Therefore, the new simplified method of consolidation theory of unsaturated soils is reasonable and can provide scientific suggestions for the design and construction of rock-fill dams and further raise their design level.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2009年第12期1851-1857,共7页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金委员会
二滩水电开发有限责任公司雅砻江水电开发联合基金项目(50639050)
关键词
心墙土石坝
水力劈裂
非饱和土固结
简化计算
影响因素
rock-fill dam with core walls
hydraulic fracturing
consolidation of unsaturated soils
simplified method
influence factor
