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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。
Aiming at the unsaturated soil with the degree of saturation higher than 80% before the initial impoundment, an effective stress analysis method for simplifying unsaturated soil consolidation is proposed to study the hydraulic fracturing of the core wall. The method not only can reflect the influence of the gas in the pore on the hydraulic pressure rise, but also can reasonably analyze the influencing factors of the hydraulic fracturing of the core wall, such as the permeability of the core wall, the initial saturation and the water storage velocity. Taking Nuozhadu CFRD as an example, it is found that when the filling is completed, the core wall is still in a non-saturated state despite the high water pressure in the middle of the core wall. When the water is impacted for the first time, the upstream water pressure can not penetrate into the interior of the heart wall in time , Forming a sudden change in the water pressure inside and outside the heart wall, can lead to the occurrence of hydraulic fracturing of the heart wall. At the same time, it is found that the hydraulic fracturing can be prevented by increasing the permeability coefficient of the core wall, increasing the initial saturation of the core wall filling soil, and slowing the water storage rate during the initial impoundment. Therefore, it is reasonable to analyze the hydraulic fracturing problem by simplifying the calculation of effective stress method for unsaturated soil consolidation. It can provide a scientific basis for the prevention of hydraulic fracturing of core earth-rock dam and can further improve the design level of earth-rock dam.