复杂河床坝基岩体盖重固结灌浆关键技术

Consolidation grouting methods for riverbed rock mass coverings of complex dam foundations

采用无盖重灌浆技术存在表层岩体灌浆效果难以保证、混凝土盖重灌浆与混凝土施工工序干扰等难题,该文结合白鹤滩坝基复杂地质条件,通过预留岩体盖重、控制灌浆压力与浓度、采用分孔分序灌浆方法及材料等,提出"预留岩体盖重+低压浓浆封闭+盖重固结灌浆"的关键技术,不仅解决了常规固结灌浆技术存在的问题,还有效保护了白鹤滩坝基薄层角砾熔岩,解决了柱状节理玄武岩因固结灌浆裸露而进一步卸荷松弛的难题,白鹤滩水电站河床坝段固结灌浆工程实践表明:灌后检查孔透水率合格率99.3%,各岩性的高波速测点占比91.8%~93.3%、低波速测点占比2.0%~2.9%,总体满足设计要求。研究结果对同类工程的固结灌浆设计与施工具有借鉴意义。

Effective surface rock grouting and effective coupling between the concrete-cover grouting and concrete construction are difficult problems,especially with complex geological conditions.This study analyzed the complex geological conditions of the Baihetan dam foundation to develop a consolidation grouting method using the reserved rock mass cover weight,a low pressure thick slurry seal and consolidation grouting by the cover weight by controlling various parameters including the reserved rock mass cover weight,the grouting pressure and concentration,and the grouting method and materials.This method not only avoids the problems of conventional consolidation grouting methods,but also protects the crane beach dam foundation thin layer breccia lava and stabilizes the basalt columnar joints by consolidation grouting bare unloading relaxation.The practice of the riverbed dam section of the Baihetan dam engineering showed that the pass rate of the permeability rate of inspection holes is 99.3%,the high wave velocity of all kinds of lithology measuring point was 91.8%-93.3%,and the low wave velocity measuring point accounted for 2.0%-2.9%,which met the overall design requirements.The results can be applied to the design of consolidation grouting methods in similar projects.