Efficiency assessment of L-profiles and pipe fore-poling pre-support systems in difficult geological conditions: a case study
| Autor: | Saeid Parnian, Akbar Mousazadeh, Taher Moradi, Javad Moharrami, Sepideh Nasseh, Ayub Elyasi |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Mechanical Engineering
Poling 0211 other engineering and technologies Numerical modeling Drilling Excavation 02 engineering and technology Building and Construction 010502 geochemistry & geophysics 01 natural sciences Instability Overburden Adit Mechanics of Materials Support system Geotechnical engineering Geology 021101 geological & geomatics engineering 0105 earth and related environmental sciences Civil and Structural Engineering |
| Zdroj: | Structural Engineering and Mechanics. 57:1125-1142 |
| ISSN: | 1225-4568 |
| DOI: | 10.12989/sem.2016.57.6.1125 |
| Popis: | Tunneling is one of the challenging tasks in civil engineering because it involves a variety of decision making and engineering judgment based on knowledge and experience. One of the challenges is to construct tunnels in risky areas under shallow overburden. In order to prevent the collapse of ceilings and walls of a large tunnels, in such conditions, either a sequential excavation method (SEM) or ground reinforcing method, or a combination of both, can be utilized. This research deals with the numerical modeling of L-profiles and pipe fore-poling pre-support systems in the adit tunnel in northwestern Iran. The first part of the adit tunnel has been drilled in alluvial material with very weak geotechnical parameters. Despite applying an SEM in constructing this tunnel, analyzing the results of numerical modeling done using FLAC3D, as well as observations during drilling, indicate the tunnel instability. To improve operational safety and to prevent collapse, pre-support systems, including pipe fore-poling and L-profiles were designed and implemented. The results of the numerical modeling coupled with monitoring during operation, as well as the results of instrumentation, indicate the efficacy of both these methods in tunnel collapse prevention. Moreover, the results of modeling using FLAC3D and SECTION BUILDER suggest a double angle with equal legs (2L100x100x10 mm) in both box profile and tee array as an alternative section to pipe fore-poling system while neither L80x80x8 mm nor 2L80x80x8 mm can sustain the axial and shear stresses exerted on pipe fore-poling system. |
| Databáze: | OpenAIRE |
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