采用挤压边墙技术的高面板坝裂缝成因分析

为加快施工进度,国内很多高面板堆石坝都采用了挤压边墙技术,用上游坡面的挤压边墙代替传统的垫层.挤压边墙的施工特点决定了其与上覆面板之间的结构关系将与传统的面板-垫层有很大差别.虽然目前面板坝的施工技术和施工水平较以前有较大的提高,但少数工程仍然出现了比较严重的面板裂缝,而采用挤压边墙技术的面板坝施工期出现的裂缝分布规律与采用面板-垫层施工方法有明显的不同.面板裂缝的产生与面板施工期的应力变形状态密切相关,目前面板堆石坝计算中采用的整体模型方法对面板的概化较多,得到的面板应力精度较差.根据挤压边墙实际的施工特点,提出采用子模型法分析面板的应力变形,对某面板坝工程裂缝成因的分析结果表明,温降和上游坡面局部高程不平整引起的面板与挤压边墙之间的局部约束过大是导致面板裂缝的主要原因.

Cause analysis of cracking of concrete slab for high CFRD based on concrete crushing-type side wall technology

In order to simplify the construction procedure and shorten the construction period, the concrete crushing-type side wall(CSA) technology is widely adopted during constructing many concrete face rockfill dams(CFRD), in which the CSA replaces the traditional cushion as the contact interface with concrete slab. The construction specificity of CSA decides that the larger difference will exist between the contact relation between CSA and concrete slab and the one between cushion and concrete slab. Although recent construction technology has greater development than before, concrete slabs’ cracks of a few CFRD still occur seriously. Distributing rule of cracks for CFRD with CSA is not same with ones which adopt traditional cushion. The cracking of concrete slab has great relation with its stress state during construction period. At present the whole computation method of concrete slab stress analysis exists more simplification assume, which results in pour stress accuracy of concrete slab from computation results. Submodeling method is presented to compute the stress and deformation of concrete face slab considering CFRD constructed by stages. A contact friction element with no thickness based on coulomb friction model is applied to simulate the special boundary between CSA and concrete face slab. The actual project analysis result shows that the temperature decrease and the intense constrain with not flattening of upstream slope at some altitude bring about cracking of concrete slab.