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目前,许多工程都使用弹塑性有限元方法来分析基础中有软弱夹层的混凝土坝的失稳过程和安全度。然而计算结果表明:由于在用这种方法求出的荷载与位移的关系曲线上,临界荷载的位置往往难以确定,同时从应力成果也很难看出坝基中塑性区的发展以及塑化带逐步贯通的明确过程,因而难以为设计提供准确的安全系数。 本文建议用弹粘塑性有限元法求解抗滑稳定安全系数。在简述弹粘塑性有限元理论的基础上,本文把弹粘塑性本构关系作为非线性应力的计算手段引入坝体及其基础的抗滑稳定分析中,并把计算结果和弹塑性方法的结果进行了比较。比较表明:在用弹粘塑性方法求出的荷载与位移的关系曲线上,一旦超过临界荷载,对荷载的微小增量来说,位移增长幅度明显,因而能够为设计提供较精确的安全系数值,同时该法求出的塑性区及塑化带的发展贯通过程也更为合理。
At present, many projects use the elasto-plastic finite element method to analyze the instability process and safety of concrete dams with weak sandwiches in the foundation. However, the calculation results show that the position of the critical load is often difficult to determine because of the load-displacement curve obtained by this method. It is difficult to see from the stress results that the plastic zone development in the dam foundation and the plasticization zone gradually pass through. The clear process makes it difficult to provide an accurate safety factor for the design. This paper proposes to use elastic-viscoplastic finite element method to solve anti-sliding stability safety factor. Based on the elasto-viscoplastic finite element theory, this paper introduces the elasto-viscoplastic constitutive relation as a non-linear stress calculation method to the anti-sliding stability analysis of the dam body and its foundation, and the calculation results and the elasto-plasticity method The results were compared. The comparison shows that in the curve of load and displacement obtained by the elasto-viscoplastic method, once the critical load is exceeded, the increase of the displacement is significant for the small increment of the load, thus providing a more accurate safety factor value for the design. At the same time, the development of the plastic zone and the plasticization zone obtained by this method is also more reasonable.