Study On Grouting Reinforcement Method And Trenchless Repair Pretreatment Of Urban Underground Rubble Masonry Drainage Main Channel

A large number of urban drainage main canals were built in China from 1950s to 1960s.The canal structure has exceeded the service life of the canal structure.The aging of pipe and canal materials has caused corrosion damage and leakage of pipe and canal,and even caused deformation,uneven settlement,collapse and other diseases of pipe and canal,affecting urban function and safety.The survey found that most of the early canal structures used masonry arch culverts and precast concrete slab culverts,and their side walls and foundations generally used mortar rubble.In the rubble masonry,the deterioration of rubble is very slight,and the mortar joint is seriously damaged,resulting in the lack of mortar joint and even the loosening and falling off of rubble.The rubble masonry is reinforced by grouting method.On the other hand,when the reliability of the original structure of the main drainage channel is insufficient,the section increase method is generally used for reinforcement,and the existing structure needs to be pre repaired before reinforcement.This study has carried out the following research work on these two aspects:(1)The mechanical properties of rubble masonry after grouting are studied by comparing the compressive properties of 6 grouted and 3 non grouted rubble masonry specimens.The test results show that the cracking load of non grouted rubble masonry is slightly earlier than that of grouted rubble masonry.The vertical cracks of non grouted rubble masonry mainly develop along the mortar joint,while the vertical cracks of grouted rubble masonry develop along the rubble and mortar joint.The compressive strength,elastic modulus and Poisson’s ratio of grouted rubble masonry are 4.23 times,25.3 times and 12.3%of that of non grouted rubble masonry respectively.The test results show that the mechanical properties of rubble masonry are greatly improved after grouting reinforcement,and the grouting reinforcement method can be used for Rubble Masonry reinforcement.(2)Through the grouting reinforcement test of large-scale ground full-scale model with turning canal section,the process of construction preparation,drilling arrangement,drilling method and grouting material modulation in the construction of rubble masonry grouting reinforcement is studied,and the acceptance method of grouting quality in the grouting reinforcement method is put forward.(3)Based on the field investigation of the main drainage channel of Changsha Hongqi Canal and relevant literature at home and abroad,the failure characteristics and influencing factors of masonry pipe culvert are summarized.Combined with the failure characteristics,the pretreatment method of the original structure of the main channel during trenchless reinforcement and repair is put forward.