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Solution Piam Tunnel

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Fiam Tunnel Rock & Soil Shed

On the road where 70% of the land was inevitably built for a long time in mountainous conditions, during the rainy season and thawing season, due to landslides or rock sliding due to the transition of the incision surface, a lot of property, casualties, and a lot of damage caused by road control every year. National and personal losses are occurring. Therefore, damage that occurs every year should be minimized by installing piam tunnels in steep slopes and areas where sliding may occur.

As a general method that can be applied, the rebar and concrete pouring method is applied at the site. However, there is the inconvenience of having to control traffic for a long time due to the long construction period, and sudden sudden surges that may occur due to natural disasters during the construction period are inconvenient. Special measures should be prepared for safety accidents due to sliding of rocks and soil. The construction cost does not secure competitiveness with pre-fabrication products pre-fabricated at the factory.  

Solution  Corrugated steel sheet is a construction method that is generally made with the balance of soil and soil on both sides, and when an eccentric action is applied from one side, many problems may occur in the stability of the structure of the corrugated steel sheet. Accordingly, when designing a corrugated steel sheet in a Piam tunnel, FEA analysis (MIdas GTS NX, Midas Civil) is performed based on the ground data that has been pre-examined for stress and response conditions on one side (soil and rock slide) to calculate member force. , selection of the corrugated section of corrugated steel sheet that can cope with it (from 2016, the application of the super-frame type, in which the secondary moment of section increased more than 3 times compared to the existing rib type, is advantageous for stability), steel type, thickness, presence or absence of reinforcement, and reinforced concrete retaining walls and sidewalls Design the foundation.

In addition, since the Piam Tunnel is mainly installed on the existing road on a steep slope, it has excellent field applicability by applying the 'Built-up Beam to the Elbow' manufactured in the factory in advance according to the road alignment.

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​For all safety factors (SF: Safety Factor) corresponding to design stability, design review is performed with SF: 150%~200% or more, which is higher than the safety factor of general corrugated steel sheets (SF: 120%, 100% or more is OK). (Considering the stress exceeding the design requirement in case of continuous increase in precipitation and fall due to climate change) In addition, FEA Simulation (retaining wall construction, backfill stage, Concrete pouring pressure, live load conditions for each compaction equipment, etc.), the structural safety factor (SF) of the corrugated steel sheet used in the past was sufficiently secured by applying the 'extra corrugated steel sheet (EXSCor)', and the economic feasibility In terms of constructability, it has sufficient competitiveness to satisfy customers. 

1. Design Workflow


2. FEA Modeling

FEA Modeling
Properities Specification

3. FEA Modeling based on Construction Procedure

시공단계별 모델링
시공단계별 모델링
시공중 장비하중 & 타설압
Dead Loading & Live Loading

4. FEA  Result

FEA Result

*For detailed structural invoices and FEA reports, please request the structural analysis team of ChungAmE&C. 

5. Construction Status_October 2018 ~ May 2019 

연하급경사지 피암터널 현황
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6. Upper plan of corrugated steel plate Fiam tunnel

The plan is to horizontally flatten the upper part of the Fiam Tunnel with soil and to construct a slope in advance to move the soil and rocks coming down from the steep slope to the opposite side (cliffs and rivers) from the upper part of the Fiam Tunnel. Recently, in overseas sites, when the upper part of the Fiam Tunnel is leveled horizontally, it cannot withstand the stress of sliding down soil and collapse or repair and reinforcement is frequently required. As a solution, the 'upper inclination angle of up to 30 degrees' was requested. Accordingly, as shown in Figures 1 & 2, our company planned the condition to flow down to the opposite side even if the soil and rocks slide by configuring the inclination angle of the upper soil up to 30 degrees , and the corresponding structural design service was completed.  

In Korea, a 20 degree slope was designed in the 'Piam Tunnel of Gangwon-do Yeonha-grade Slope' designed in 2016, and a supplementary plan for additional sliding was established and construction was completed. 

Flat & Inclination Angel Cover

7. Case Study

Case Study
Case Study
Case Study
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