Abstract:Based on the analysis of the technical difference of horizontal jet grouting for tunnel arch between China and the developed countries,it is easy to find some construction problems,such as the quality control,serious deformation and waste grout discharge during tunnel horizontal jet grouting in China. In order to master the key technique of tunnel horizontal jet grouting,a large advanced drilling rig and a patented seal equipment have been developed;furthermore,a new construction method of horizontal jet grouting with invented seal equipment for the tunnel pre-support has been proposed. By a full-scale field testing executed by the above- mentioned construction method,the useful technique,its matching drilling rig and its equipments,and the relative construction parameters are introduced. Additionally,all test results which include the geometric form of the horizontal jet grouting arch of tunnel,the connection thickness of pile to pile,the minimum thickness of horizontal jet grouting arch,the strength of piles in 28 days,and the 6 m long excavation of tunnel under pre- support system as well,are well demonstrated. The results of full-scale testing show that the new technique to be safe and reliable,having the advantages of reasonable construction sequence,cost effective and environmental protection. It is believed that this new construction technique has successfully solved the existing problems of horizontal jet grouting in China,and it will have a good prospect for future sub-horizontal treatment ahead of the tunnel excavation face.