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采用振动碾压填筑堆石坝的过程中,堆石料会发生大量的颗粒破碎,导致粗粒含量减小,细颗粒含量增加,碾压后的级配与设计级配已经不再相同。然而,目前在可研和初设阶段,开展现场碾压试验难度大,而有限元计算大坝变形时采用的堆石料计算参数往往都是设计级配(未考虑碾压)的三轴试验结果。实际上,设计级配的变形模量比碾压后级配(相同密度条件下)的试验结果高。本文参考已建大坝碾压时颗粒破碎的实测结果,采用考虑颗粒破碎的状态相关的堆石料弹塑性本构模型,开展了大坝施工和蓄水的有限元分析研究,计算结果表明:是否考虑碾压过程中的颗粒破碎对大坝变形计算结果有着较大的影响,如果在三轴试验或计算分析中不考虑这个因素,会明显地低估大坝的变形,对大坝的安全性评价是十分不利的,这可能是目前有限元计算的高坝沉降变形比实测偏小的主要原因之一。
During the process of vibrating and compaction rockfill dam, a large amount of particle crushing occurs in the rockfill material, resulting in the decrease of coarse particle content and the increase of fine particle content. The gradation and design gradation after rolling are no longer the same. However, at present, it is very difficult to carry out on-site roller compaction test in the feasibility study and initial stage. However, the calculation parameters of the rockfill materials used in the finite element calculation of the dam deformation are often the design grade (without considering the rolling) triaxial test results . In fact, the deformation modulus of the design grade is higher than the test result of the graded mix (under the same density). In this paper, with reference to the measured results of granulation when the dam is being crushed, the finite element analysis of dam construction and storage is carried out by using the elasto-plastic constitutive model of rockfill considering the state of particle crushing. The calculation results show that: Considering the particle crushing in the process of rolling has a great influence on the calculation results of the dam deformation. If this factor is not considered in the triaxial test or calculation analysis, it will obviously underestimate the dam deformation and evaluate the safety of the dam Which is very unfavorable. This may be one of the main reasons why the settlement of high dam is smaller than the actual measured value by finite element method.