水闸混凝土结构关键部位温控防裂研究

由于水闸底板结构属于薄板结构,层厚较薄,其混凝土内部温度随年气温呈周期性变化,无稳定温度,给其最高温度控制标准的制定带来了一定困扰。为此采用有限元仿真分析方法,以某水闸为例,就水闸结构的最高温度温控标准、关键部位防裂重点及防裂措施进行了重点分析。通过计算可知,该水闸混凝土的最高温度控制标准按照32℃控制为宜;低温季节混凝土浇筑完成后及时保温可降低拉应力19%,上下层温差按照15℃控制,安全系数1.65。结果表明:水闸结构最高温度控制标准按照基础温差加闸底板结构各浇筑层第二年温度的最低值确定为宜;低温季节混凝土浇筑完成后应及时保温;闸墩与底板混凝土的上下层温差控制是闸墩结构防裂的重点之一,需从严控制。

Study on temperature control and crack prevention for key positions onconcrete structure of sluice

As the structure of the bottom slab of sluice belongs to thin plate structure with a thinner thickness,while the internaltemperature of its concrete presents a cyclic change along with the annual temperature without a constant value,certain difficultyis brought to making the control standard for its maximum temperature. By taking a sluice as the study case,the temperature con-trol standard for the maximum temperature of sluice structure and both the major points of the crack prevention and the anti-crack-ing measures for its key positions are emphatically analyzed herein with the method of finite element simulative analysis. Throughthe relevant calculation,it is known that the maximum temperature standard for the concrete of the sluice is appropriated to becontrolled with the temperature of 32 ℃ . During the lower temperature season,the tensile stress therein can be lowered by 19%through the timely insulation,while the temperature difference between the upper and the lower layers can be controlled by 15 ℃with the safety factor of 1. 65. The result shows that the maximum temperature control standard for the sluice structure is appropriate to be determined in accordance with that the basic temperature difference plus the lowest value of the next year temperature ofeach concrete placing layer for the bottom slab of the sluice. The timely insulation must be made after the concrete placement inthe lower temperature season,furthermore,the control of the temperature difference between the upper and lower concrete layersof both the pier and bottom slab is one of the major points of the crack prevention of the pier structure,thus must be strictly con-trolled.