With the development of the construction of a large number of urban underground space, substations and shopping mall, and with the increase of large-scale building, there is more and more deep foundation pit engineering. The traditional one has not adapted to large underground buildings and the demand of slope’s stability. Especially in the sand gravel stratum, using the traditional method of anchoring, the low probability of pore formation makes it difficult to grout and anchor lately and also increases construction costs.
At this time, self drilling anchor bolt shows its superiority, which can adapt to a variety of complex geological conditions and construction environment, particularly in the soft soil and sand gravel stratum. There are examples of applications in domestic railway engineering. For example, Beijing Metro Line 4 is located in ground floor, which belongs to the sand gravel formations. China Construction Bureau (Group) Co., Ltd. unites design units with hired well-known experts to carry out scientific and technological innovation that has beard fruit, The Construction Technology of self drilling anchor bolt in the Sand Gravel Stratum Retaining Deep Foundation , the leading domestic results. In April, 2007, it passed the validation of Beijing construction method. The project successfully applied this technology, having good social and economic benefits.