膨胀土基坑回填处理方法

The Backfill Treatments of the Expansive Soil Foundation Pit

南水北调中线总干渠工程穿渠建筑物布置较多,且设计类型各异多样。在膨胀土岩渠道长约400km范围内,因其遇水膨胀、失水干缩及强度衰减的工程特性,加上复杂的土体结构、不同类型地下水、独特的破坏机理、基坑的多样化及施工环境的影响等都会给基坑开挖、回填处理带来相当大的困难。鉴于上述多种因素夹杂并存,设计对不同的基坑采用的工程处理措施及回填材料有所不同。若对基坑开挖、回填处理不当,可能会对膨胀土渠坡或渠堤稳定产生不利影响,若不利现象的长期不断发展,甚至会引发渠坡失稳或渠堤不均匀沉降,最终给工程带来危害。以淅川段膨胀土渠道为例,对施工开挖基坑及其回填处理进行了详细分析研究,为今后膨胀土地区基坑施工开挖、回填处理提供一定的参考借鉴。

The channels of the middle line of the south-to-north water transfer project have many architectural layouts of different designs.In the expansive soil and rock channel within 400 km range,water expansion,dehydration shrinkage and engineering properties of strength make it difficult for the excavation and backfill treatment of the foundation pits . Therefore we considered different engineering treatments and backfill materials for different designs .If the excavation or the backfill treatment goes wrong ,it may have negative influence on the expansive soil-based slopes or embankments ,the slopes may be unstable , the embankments may get ground subsidence , which eventually endanger the construction .We use the expansive soil of Xichuan segment channel for an example ,to give detailed analysis and research ,which can be used for reference on future expansive-soil-based excavations and backfill treatments .