覆盖型岩溶地基控制旋喷成桩质量的施工技术

Construction Technology for Ensuring Quality of Jet Grouting Pile in Covered Karst Foundation

覆盖层较厚时,覆盖型岩溶地基经处理后形成复合地基,复合地基具有较高的承载力,可作筏板基础等浅基础持力层。在采用高压旋喷注浆技术处理的施工中,常会出现不返浆等影响成桩质量的异常现象,通过对这些异常现象发生的原因进行分析,从施工程序和预处理、调整工艺参数等方面提出了避免异常现象产生的施工技术,从而有效控制了成桩质量。工程实践表明,采取综合的施工技术可有效控制旋喷注浆成桩的质量,使整个复合地基满足设计要求。

The composite subgrade formed after treatment of covered karst foundation with thick covering layer has higher bearing capacity and may be used as bearing stratum of shallow foundation such as raft foundation. Some abnormal phenomena, such as no slurry returning, often appear in the course of construction with high pressure jet grouting technology to affect the pile quality, through which the causes are analyzed; furthermore, some measures with respect to construction procedure, pretreatment and technical parameters adjustment are suggested in order to prevent these abnormal phenomena and ensure pile quality effectively. It is showed by engineering practice that the quality of jet grouting pile could be controlled effectively by taking some comprehensive measures so that the composite foundation as a whole could meet the design requirement.