变径水泥土搅拌桩加固桥头软基的试验分析

Experimental study of T-shaped soil-cement deep mixed column in soft subsoil treatment

变径水泥土搅拌桩是一种新型的水泥土搅拌桩技术,它针对传统水泥土搅拌桩的弊端进行了改进,取得了良好的工程效果。介绍了变径水泥土搅拌桩在高速公路桥头软基的应用情况,并对其施工机械和施工工艺进行了详细说明。试验结果表明,变径水泥土搅拌桩保证了桩体中的水泥掺入量,提高了水泥浆分布的均匀性,从而保证了桩身质量,特别是深部桩体的质量;28 d龄期桩体的强度和均匀性较7 d均有较大提高;桩身水泥土芯样的电阻率与其强度之间存在着较好的线性相关关系;在其他试验条件相同时,扩大头高度越高,变径搅拌桩的单桩极限承载力越高;在保证质量的同时,变径水泥土搅拌桩能相对节约了工程成本,经济效益明显。

T-shaped soil-cement deep mixed column is a new type of soft soil foundation treatment method. Since special modifications have been made towards those drawbacks which exist in traditional deep mixed columns, the T-shaped soil-cement deep mixed column exhibits good performance and thus has been widely used recently. The application practice of T-shaped soil-cement deep mixed column in soft foundation at bridge head was briefly described. The corresponding construction equipments and techniques were explained in detail. The results show that the strength of the column adopted bidirectional mixed technique is uniform, that the soil cement with longer curing time is more homogeneous and has higher strength, and that there exists a good linear relationship between the strength and the electrical resistivity. As a result, the strength of the core samples can be evaluated from their electrical resistivity. The length of the upper column part increased under the same condition with the bearing capacity of the single column. T-shaped soil-cement deep mixed column has the superior engineering characteristics and cost-effective in the soft subsoil treatment.