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深厚覆盖层坝基中存在弱透水层时,弱透水层往往既是隔水层又是软弱夹层,是利用其作为渗流控制依托层,还是不考虑其防渗作用,关系到防渗工程的成本、进度等。流固耦合能较真实反映出弱透水层对坝基渗流场和应力场的影响,该文以比奥固结理论为基础,结合土体非线性流变理论,将土体本构关系推广到黏弹塑性,同时考虑土体力学参数及水力参数的动态变化关系,借助ADINA进行双场耦合求解,分析上江坝深厚覆盖层坝基中弱透水层对土石坝渗流场、应力场和自身应力应变的影响。研究表明:半封闭式防渗墙和弱透水层可形成坝基内部的联合防渗体系,能达到显著的渗流控制效果,大坝渗流量、坝基出逸坡降和弱透水层自身应力应变均小于其允许值,能保证大坝的安全稳定运行。但同时防渗墙和弱透水层承受的应力应变会相对增加,需要采取合理的工程措施给予辅助。实例中防渗墙深度相比封闭式防渗墙减小近60 m,若方案能给与采用,可大大减少工程造价。因此,坝基内部若存在弱透水层应该给与足够的重视,科学论证后若能加以利用,能做到事半功倍。
When there is a weak aquifer in the deep overburden dam foundation, the impermeable aquifer is often both the aquitard and the weak interbed, whether it is used as the seepage control support layer or not, and the seepage prevention is not considered, which affects the cost of the seepage control project, the progress Wait. The fluid-structure interaction can reflect the influence of aquitard on the seepage field and stress field of the dam foundation. Based on the Biot consolidation theory, combined with the nonlinear rheological theory of soil, this paper generalizes the constitutive relation of soil to viscosity Elastoplasticity, taking into account the dynamic relationship between soil mechanics parameters and hydraulic parameters, the two-field coupled solution of ADINA is used to analyze the seepage field, stress field and stress-strain of the earth-rock dam with the weak permeable layer influences. The results show that the semi-enclosed impervious wall and the impermeable aquifer can form joint seepage control system inside the dam foundation, which can achieve significant seepage control effect. The seepage volume of dam, descend of dam foundation and the stress and strain of impermeable layer are all less than The allowable value, to ensure the safe and stable operation of the dam. However, at the same time, the stress and strain to the impervious wall and the aquitard will be relatively increased, and reasonable engineering measures need to be taken to provide assistance. In the example, the depth of cut-off wall is reduced by nearly 60 m compared with the closed cut-off wall. If the solution can be adopted, the construction cost can be greatly reduced. Therefore, if there is a weak aquifer in the dam foundation, enough attention should be given to it. If scientific proofs can be used, it can be more effective.