非荷载因素作用下的轴力修正计算

Correction Calculation of Axial Force under Non Load Factors

基坑支撑轴力监测的准确性通常较低,例如引用的工程案例,其支撑轴力远大于预警值甚至设计值,但基坑以及支撑均未发生破坏。为了分析轴力过大的原因并比较各种影响因素的作用,考虑混凝土收缩与徐变等非荷载因素的作用,应用现有的收缩与徐变公式对基坑监测所得支撑轴力数据进行修正,得到修正后的支撑轴力,并分析收缩与徐变效应对轴力的影响;对修正结果分析并与预警值比较,其结果表明:徐变产生的轴力对监测所得轴力值影响较大,占总轴力值的45%~54%;收缩产生的轴力对监测值的影响较小,占总轴力的3%~10%;修正后轴力约为预警值的60%~70%。但修正后的个别轴力仍然存在大于预警值的情况,因此还需对修正公式进一步进行研究。

The accuracy of foundation pit support axial force monitoring is usually low.For example,in the engineering case cited in this paper,the support axial force is far greater than the early warning value or even the design value,but the foundation pit and support are not damaged.In order to analyze the causes of excessive axial force and compare the effects of various influencing factors,this paper considers the effects of non load factors such as concrete shrinkage and creep,modifies the support axial force data obtained from founda‐tion pit monitoring by using the existing shrinkage and creep formula,obtains the corrected support axial force,and analyzes the influence relationship between shrinkage and creep effect on axial force.The results show that the axial force produced by creep has a great influence on the monitored axial force,accounting for 45%~54%of the total axial force.The axial force produced by shrinkage has little effect on the monitored value,accounting for 3%~10%of the total axial force.The corrected axle force is about 60%~70%of the early warning value.However,the corrected axial force is still greater than the early warning value,so the modified formula needs to be further studied.