双矩形钢模管互导干作业地下连续墙

Research on dry diaphragm trenching with self-guided double-rectangular-casing

地下连续墙常采用泥浆护壁、水下灌注混凝土进行施工,槽壁稳定和槽段接头防渗一直是施工控制的难点。泥浆本身易于造成环境污染,而泥浆制备的水耗和废料处置也增加了工程造价。为解决这些问题,开发了一种新技术———双模管互导干作业地下连续墙技术。该技术采用钢模管护壁和双矩形模管导向沉管挤土或沉管干取土的成墙工艺(分别适用于墙厚300～500mm和600～1 000mm),不需要泥浆和水下灌注墙混凝土,可以在同一平面内成墙、实现墙单元无缝连接。实践表明,该技术墙体防渗性能好,成墙效率高,连接质量可靠,不仅适用于深厚软粘土地层的基坑围护工程,也可应用于类似地质条件下水库工程的防渗加固。

It has been a pinch point to control the trench stability and panel joint permeability in the conventional underground diaphragm concrete wall. It is prone to high construction cost because of environmental pollution due to bentonite slurry and waste of water consumption plus debris disposal treatment. A new technology, i.e. dry diaphragm trenching with self-guided double-rectangular-case, is developed in this paper in order to avoid these problems. Through this technology, two pieces of rectangular steel casing are driven in sequence and guided each other and trench is made by squeezing the soft soil, if wall thickness ranges from 300mm to 500mm; or by dragging soil out of the casing, if wall thickness ranges from 600mm to 1 000ram as in the normal condition. Panel alignment and straightness are assured without any joints due to dry concrete pouring instead of influenced by bentonite slurry. Compared to regular diaphragm wall, it is a new environment-friendly, less emission and energy conserved technology by eliminating the slurry pollution with low cost. Engineering practice shows that the quality of panel connection is reliable; in the meanwhile, the permeation-proof performance due to jointless interlocking is superior with high efficiency in wall-erecting. This technology can be applied not only to the retaining system of foundation pit in soft strata but also to the infiltration prevention and reinforcement of reservoir in the similar conditions.