超深软土地基大功率振冲加固技术参数分析与研究

Analysis and research on technical parameters of high-power vibro-vibration reinforcement for ultra-deep soft soil foundation

拉哇水电站上游的围堰坝高60 m,地基由堰塞湖相沉积厚约50 m的低液限黏土和粉土层组成。为了确保围堰建设的安全可靠,需要对深厚软土地基采用振冲碎石桩进行加固处理。本研究基于物联网远程施工控制平台收集的1.58亿条实测数据,测算了振冲碎石桩的体积置换率和成桩桩径,并初步评估了振冲碎石桩的复合地基加固效果。测算结果表明,振冲碎石桩的桩间距对体积置换率有显著影响,当间距为2.5 m时,平均桩径为1.16 m,体积置换率为15.10%;当间距为3.0 m时,平均桩径为1.09 m,体积置换率为10.87%。研究还发现,地层的软硬和施工操作水平会影响成桩桩径尺寸,软弱夹层处易发生局部缩径,应严格控制加密段长度在0.5~1.0 m范围内,同时控制加密电流和留振时间满足施工标准。本研究基于智能化施工监测系统的应用,为深厚软土地基振冲碎石桩加固处理质量控制和检测,以及复合地基加固效果综合评价提供科学论证的初步成果,可为振冲碎石桩的加固设计提供参考。

The cofferdam in the upper reaches of Lawa Hydropower Station is 60 m high and its foundation is composed of low liquid limit clay and silty soil layers about 50 m thick deposited by barrier lake sediments.In order to ensure the safety and reliability of cofferdam construction,it is necessary to strengthen the deep soft soil foundation by utilizing vibro-replacement columns.Based on 158 million measured data collected by the remote construction control platform of the Internet of Things,this study estimated the volume replacement rate and column diameter of the vibrio crushed stone column,and initially evaluated the reinforcement effect of the composite foundation of the vibrio crushed stone column.The results show that the column spacing has a significant effect on the volume replacement rate.When the spacing is 2.5 m,the average column diameter is 1.16 m and the volume replacement rate is 15.10%.When the spacing is 3.0 m,the average column diameter is 1.09 m,and the volume replacement rate is 10.87%.The study also found that the hardness of the stratum and the level of construction operation will affect the diameter of the column,and local diameter reduction is easy to occur at the weak interlayer.The length of the encryption section should be strictly controlled within the range of 0.5-1.0 m,and the encryption current and vibration retention time should be controlled to meet the construction standards.Based on the application of intelligent construction monitoring system,this study provides preliminary results of scientific demonstration for the quality control and detection of vibro-replacement stone column reinforcement treatment on deep soft soil foundation and comprehensive evaluation of the reinforcement effect of composite foundation,and can provide reference for the reinforcement design of vibro-replacement stone column.