As a construction method for cut-off walls and retaining walls, mixing self-hardening slurry in-situ with native soil (SMW) is also called column-type concrete wall construction method. After reaching the predetermined design depth, cement slurry is injected into ground through swivel device in drive unit and hollow stem whilst multi-shaft auger is withdrawn, making cement slurry to be fully mixed with native soil. With in-situ forced mixing of cement slurry & native soil and insertion of reinforced elements such as H beam into not fully hardened soil mixing wall, a continuous structure like diaphragm wall will be formed after the hardening of soil mixing wall, which can be used as a retaining and lateral waterproof structure of foundation pits with the advantages of high water resistance and strength of reinforced elements. Reinforced elements can be retrieved for reuse after the construction.
- Comparied with conventional deep mixing pile (DMP) construction method, the equipment used for SMW and pile-forming mechanism are both different. Conventional DMP adopts single-shaft agitating rig, with cement slurry injected into spacings of native soil, while SMW adds high-pressure air when injecting cement slurry, replacing large amount of native soil with fully mixed slurry. Pile strength and uniformity of pile body are obviously better than those of coventional methods. The most important thing is that the parallelism & overlapping between piles of adjacent panels are both excellent, not only achieving reliable waterproof effect, but also good for insertion & retrieval of reinforced elements.
- Comparied with coventional diaphragm wall & bored pile construction methods, SMW has the following advantages:
- Good retaining performance, suitable for the situation of dewatering inside pit but not dewatering outside.
- Little impact on surrounding buildings and pipelines.
- Low environmental pollution in terms of noise, dumping mud and vibration.
- Short duration and low cost.