Study On The Construction Technique Of Luotuochang Tunnel In Aeolian Sand Formation

Aeolian sand tunnels’ construction is difficult, and has high risk. This often becomes abottleneck restricting full line of project. Using theoretical analysis，numerical simulation andfield tests, this paper studies systematically Luotuochang aeolian sand formations tunnels’reasonable supporting form and parameters, construction methods and technology, and theend of the tunnel root pile construction technology.The main thesis and conclusions of the paper are as follows:1. It conducts a numerical simulation calculation on advanced support of big and smallpipe in aeolian sand formulation, and proposes reasonable engineering practice parameters.During the construction process, we improve the existing pipe shed drilling and propose theconstruction method of the second drilling. This method gives the solution to the problem ofthe pipe roof collapsing into the hole under the condition of aeolian sand formation throughhigh pressure fengqing hole. This ensures the safety of hole tunneling.2. This paper analyzes and summarizes the collapse treatment experience of the aeoliansand formation tunnels, and gives an improvement on the three step reservation core oilexcavation method. It proposes the “Four Step Reservation Core Oil Excavation Method”,and quantifies the space and time between each process, which ensures the stability of tunnelface soil and the rapid closure of the support. The paper also discusses the problem of thecontrol, convergence and settlement of the aeolian sand tunnel, which can provide a referencefor similar construction.3. It determines the reasonable parameters of root piles through single and group rootpile test. The project manual uses Luoyang shovel into the hole, makes mace reaming, anduses gravel grouting filling into the root pile successfully. The application of the root pilesmakes the construction rapidly, and ensures the tunnel safe.