锚索测力计在预应力锚索加固挡墙监测中的应用

Application of Tendon Dynameter in Monitoring Reinforcement of Retaining Wall Using Prestressed Tendons

由于岩土体本身的复杂性,岩土预应力锚固的监测影响因素和评价也比较复杂。通过一个预应力锚索加固挡墙的工程实例,采用锚索测力计进行预应力锚索的应力损失监测,通过详细的监测数据,分析了油压千斤顶和锚索测力计的工作相关性,锚索锚固的瞬间预应力损失及其影响因素,锚索的长期预应力损失及其影响因素,孔隙水压力和气温对锚索测力计测值的影响,测力计监测值对于施工和设计的指导意义等。明确了依托项目锚索锁定过程中瞬间预应力损失率为2.5%～3.6%。张拉锁定的速度快慢对于瞬间预应力损失没大的影响。温度对于锚索测力计的影响从工程应用角度来看可以忽略不计。孔隙水压力可导致监测力起伏。锚固锁定初期预应力损失较大,一般在锁定后的60 d左右,预应力基本开始趋向稳定。锚索预应力超张拉10%可以达到预期效果等。对于类似重要工程具有借鉴和指导意义。

The influencing factor and the evaluation on monitoring pre-stressed anchorage are complicated because of the complexity of soil-rock mass itself. Many detailed monitoring data are given through a pre- stressed reinforced retaining wall project using tendon dynameter to monitor the loss of prestress. Many questions are analyzed through these data, such as the working association between the tendon dynameter and oil jack, the loss of the momentary pre-stress and its influencing factors, the loss of the long-term pre-stress and its influencing factors, the influence of pore water pressure and temperature on the working of the tendon dynameter, the instructional significance of the monitoring data from tendon dynameter to the construction and the design, etc. From the supported project, it can be seen that （ 1 ） the loss percentage of the momentary pre-stress is in the range of 2. 5% to 3.6% in the anchoring process; （2） the stretch locking speed has less effect on the loss of the momentary pre-stress ; （3） the influence of temperature on the working of the tendon dynameter can be neglected from the point of practical engineering; （4） the pore water pressure can make the monitoring force fluctuation; （5） the loss of pre-stress is a little large at early days after locking, then it tends to stable after about 60 d, and the goal can be achieved when over tensioning 10%. These would be helpful and instructional to the similar important engineering projects.