Research On Novel Miniature Auger-bore Pipe-jacking Technology

With the rapid development of China’s economy,urban infrastructure is constantly improved and improved,the use of urban underground space is the main trend of the development of major cities.The development of China’s urbanization needs a lot of planning of various underground pipelines.The aging of old underground pipelines provides a broad prospect for the development of trenchless technology.Compared with the "open cut" construction technology,the micro pipe jacking technology has the advantages of less environmental interference,no impact on traffic,no need to transport and pile up miscellaneous soil,small noise,small ground settlement and stratum structure disturbance,short construction period and obvious social and economic benefits.This paper mainly studies the calculation formula of miniature pipe-jacking force at present and combines with the measured data of jacking force of the equipment after the transformation of the project,the earth pressure and lateral earth pressure on the pipe jacking and the normal stress caused by them are analyzed.According to the characteristics of hard plastic soil with high strength and poor flow plasticity,a new flow model of miniature auger-bore pipe-jacking spiral dumping was established,and it was used to guide equipment development and pipe jacking construction.Through the relevant technical research,laboratory test and field demonstration,the following main technological innovation achievements have been formed:1.According to the characteristics of high strength and poor flow plasticity of hard plastic soil layer,the soil pressure above and below pipe jacking and lateral soil pressure are analyzed.Furthermore,the calculation formula of jacking force in the process of pipe jacking is deduced.The theoretical derivation of thrust and torque of pipe jacking is carried out,and Compare with the data of field monitoring to verify the accuracy of the above theoretical derivation formula.2.A new type of micro auger pipe jacking machine with independent intellectual property rights has been developed.3.In order to better meet the needs of various complex formation conditions,the micro pipe jacking machine is equipped with corresponding residue soil improvement equipment,and the laboratory test and field effect verification are carried out.The novel miniature auger-bore pipe-jacking method proposed in this project solves many defects and problems existing in the construction method of small diameter gravity flow pipeline.This novel miniature auger-bore pipe-jacking technology belongs to dry drilling construction with little or no mud,and is more in line with the general trend of green construction method selection in the future.It is a construction technology method worthy of further study and promotion.