横泉水库旧坝体强夯加固处理技术与效果

Dynamic Compaction Technique and Effect on the Old Dam Body of Hengquan Reservoir

目前我国对大坝加固的方法较多,但对填筑质量极差、多项关键指标均达不到现行规范要求的旧坝体,常规加固方法投资大、施工期长。本文以横泉水库旧坝体强夯工程为研究对象,探索采用一种处理软弱地基的强夯技术来加固旧坝体的方法。通过采集夯前、设计试夯、施工试夯和强夯施工等各阶段检测数据,结合运行期观测资料,对影响大坝质量的主要指标进行对比分析。结果表明:强夯法对旧坝体加固处理效果显著,各项指标均可达到设计要求,加固深度内的旧坝体湿陷性可全部消除,干密度普遍提高,整体压缩性大幅减弱,特别是较夯前趋于均匀化,渗透系数降低明显。经检测,强夯不会对旧坝体造成有影响的裂缝,通过蓄水运行观测,新旧坝体之间未出现不均匀沉降,大坝运行安全。强夯加固法可在旧坝体和大坝两岸黄土岸坡处理、淤地坝除险加固等工程中推广使用。

There are a number of methods of reinforcing dams, however, for the old dam bodies whose filling quality is terrible and many key indexes do not meet the current qualification, the traditional reinforcement methods take too long time and cost too much. Taking Hengquan Reservoir as a research object, the paper explored an approach to reinforce the old dam body by using the dynamic compaction technique while handling with soft ground. Combining with the observation details during operation, the paper took comparison and analysis by means of collecting data before tamping and trial tamping of design, trial tamping of building and dynamic compaction. The result shows that the dynamic compaction performs well on reinforcing the old dam and all indexes can meet the requirements. The collapsibility of the old dam in the depth of reinforce can be eliminated completely. The dl7 density has been improved generally. The compressibility reduces and homogenizes greatly. The coefficient of collapsibility cuts down much and there is no influential cracks caused by dynamic compaction. There has not any asymmetric sedimentation between new and old dam body by observation after storage operation and the reservoir operates well. The dynamic compaction can be generalized to engineering projects which need to work with old dams and loess bank slopes of both sides of dams and reinforcement of warping dams.