Construction stability and reinforcement technology for the super-large rectangular pipe-jacking tunnel passing beneath the operational high-speed railway in composite stratum

The super-large rectangular underpass of the Putian Railway Station, driven by pipe-jacking method, needs to bore cross under operational Hangzhou-Shenzhen high-speed railway in composite stratum. This paper aims explore construction stability and reinforcement technology tunnel when excavating stratums. Firstly, engineering background, geological conditions are introduced detail. Then, evaluate safety construction, refined numerical models hard-rock ratio for pipe jacking stratum proposed, a risk assessment system comprising twenty factors is established. After that, three schemes employed guarantee railway, effect derived analyzing track stress, settlement, factor, re-assessment results, optimal scheme present project has been obtained. Finally, hand-dug piles + D-shaped beam adjacent automatic investigation thus effectiveness verified.