深基坑围护结构局部逆作施工技术

Construction Method of Deep Foundation Pit Enclosure Structure Combined with Grouting Anchor and Punching Pile

改革开放以来,我国经济高速发展,迎来了城市地铁的建设大潮,地下既有管线侵入地铁基坑施工范围的情况屡见不鲜。既有管线的侵入对基坑支护造成了很大的难题。既要保护既有管线,又要保证基坑开挖过程的安全。深基坑内管线下方施工围护结构的设计及施工方法的研究目的,是在深基坑开挖范围内有管线无法迁改或迁改困难的情况下导致管线经过范围内围护结构无法施工而采用逆作法施工,为了解决深基坑逆作围护结构在随开挖深度的增加,逆作部分内支撑支护主要受力在支撑点上,逆作部分所受土压力主要横向分布,在内支撑受力面积以外逆作处土压力会集中,无法竖向分散土压力,逆作支护处易发生坍塌事故,影响基坑安全。

Since the reform and opening up, China’s rapid economic development has ushered in the tide of urban subway construction. It is not uncommon for underground pipelines to invade the construction of subway pits. The intrusion of existing pipelines has caused great problems for foundation pit support. It is necessary to protect both existing pipelines and to ensure the safety of the foundation pit excavation process. The purpose of the design and construction method of the construction envelope under the pipeline in the deep foundation pit is that the pipeline can not be rebuilt or the relocation is difficult within the excavation scope of the deep foundation pit, so the reverse construction is used. In order to solve the increase of the deep excavation depth of the deep foundation pit, the internal support of the reverse part is mainly supported by the support point, and the earth pressure of the reverse part is mainly distributed horizontally. The earth pressure will be concentrated in the reverse of the inner support stress area, and the soil pressure cannot be dispersed vertically. The collapse of the support site is prone to collapse and affect the safety of the foundation pit.