基于原型监测的特高拱坝软弱带置换效果评价

Evaluation and research on replacement reinforcement quality at abutment of ultra-high arch dam based on prototype monitoring

特高拱坝蓄水后所受的总推力巨大,坝肩是关键受力部位,合理评估置换体加固效果将直接影响到工程的安全性和经济性。以原型监测为基础,采用实测值分析与理论推导相结合的方法,对小湾特高拱坝坝肩回填效果进行分析和评价。结果表明:接触带压应力过程线经历了增大和稳定2个阶段;接缝开合度过程线经历了温升压密、温降张开和稳定3个阶段,开合度与温度分段线性相关;围岩呈稳定态势,变形主要集中在前3个月,离洞口6m范围受开挖影响较大,16m为围岩松动圈范围。钢筋温度应力的理论值与实测值偏差较小。综合分析认为:回填体与围岩结合良好,有很好的传力性能;回填体及围岩应力、变形正常;回填效果好。

The prototype monitoring and derivation were integrated to study the reinforcement quality of replacement at abutment of the ultra-high arch dam in Xiaowan Project,China.The principles of monitoring layout and design are introduced in detail.According to the prototype monitoring,several facts are found：there is a compressive stress between the replacement body and surrounding rock mass,and two typical stages are found in the hydrograph of contact stress,namely increasing stage and stable stage.The joint opening hydrographs also show subsection characteristics,with three typical stages,namely compression stage,opening stage and stable stage.It seems that the joint opening and temperature have a sub-linear correlation relationship.The surrounding rock mass is stable.The surrounding rock mass within 16m from the wall is the loose zone caused by excavation,and the displacement increases very quickly in the first 6m.The theoretical calculated thermal stress of reinforcing bar steel well accord with the monitoring data.It may conclude that,the geology weakness bodies are well replaced,and the abutment is safe.