杭州市青山水库低弹模混凝土防渗墙应变观测资料分析

Observation Data Analysis of Strain in Low Elastic Modulus Concrete Impervious Walls of Qingshan Reservoir in Hangzhou

通过杭州市青山水库防渗墙应变观测资料分析,获得低弹模混凝土防渗墙温度和应变变化规律。分析结果表明,低弹模混凝土防渗墙应变计的初始基准值取48~72 h左右时的读数为宜。防渗墙顶部一定范围内受外界气温影响较大,墙体内部温度变化滞后于气温变化;防渗墙中下部温度变化较小。拉应变主要出现于初期防渗墙上部,随着墙体温度稳定和库水位升高,逐渐向压应变转化,并逐渐趋于稳定。防渗墙顶部应变受温度影响较大,防渗墙下部应变受库水位影响较大;一般防渗墙应力应变计算分析可忽略温度影响。

Analyzing observation data of strain in low elastic modulus concrete impervious walls of Qingshan Reservoir in Hangzhou,the paper studies variation rules in temperature and stress strain of these walls.Results indicate that it is appropriate to set reading of 48 hours as the initial reference value of the strain gauge.The interior temperature variation inside the impervious walls lags behind 2 to 5 months compared to that in the atmosphere,and the change is limited to the top 10 m of the walls.Tensile strain mainly occurs in the upper part of walls in initial stage,then compressive strain gradually prevails with the stability of temperature and the increase of water level,and finally offset each other.The strain in the upper part of walls is more responsive to temperature change while the lower part is more likely to be affected by water level.Temperature variation is negligible in the calculation of stress strain of impervious walls in general terms.