Highway Construction Project, Highway No. 1388 (Huai Nam Khun - Doi Tung) KM. 4+600 and KM.7+400
Location
Chiang Rai, Thailand
Client
LAMpang road construction center
project type
temporary Soil nail & Horizontal drain
CHALLENGES & INNOVATIVE SOLUTIONS
CHALLENGE
High-Angle Excavation in Constrained Mountainous Terrain
Excavating a very high slope to accommodate a permanent MSE Wall near the Doi Tung Royal Palace presented severe geotechnical and spatial challenges. The necessity to secure the massive cut prior to the permanent wall's installation required precise execution within a highly restricted footprint.
-
Extreme Excavation Heights: The design required a exceptionally high slope cut, significantly increasing the risk of soil failure before the permanent retaining structure could be built.
-
Prohibitive Work Envelope: The steep hillside location provided a severely limited working area for heavy earthmoving and drilling machinery.
-
Hydrostatic Pressure Risks: Subsurface water accumulation behind the newly cut slope threatened to compromise the global stability of the excavation.
-
Construction Sequencing Hazards: The eventual bottom-up construction of the MSE wall would expose workers to critical safety risks if the high cut above remained unreinforced.
SOLUTION
Sequential Geotechnical Support and Subsurface Drainage
To mitigate the extreme excavation risks and accelerate the project schedule, the engineering team implemented a top-down temporary stabilization strategy coupled with active drainage systems.
-
Targeted Deep Stabilization: Deployed temporary soil nails to artificially reinforce the high slope cut immediately during the excavation phase.
-
Sequential Excavation (Benching): Applied a benching and nailing technique to safely stage the earthworks, which drastically reduced construction time while maximizing site safety.
-
Hydrostatic Pressure Relief: Installed horizontal drains deep into the earth mass to lower the groundwater level and eliminate destabilizing water pressure behind the cut.
-
Secured Work Environment: Established a fully stabilized temporary earth retaining system that allowed for the safe, unhindered bottom-up assembly of the permanent MSE Wall.
THE OUTCOME
Secure and Efficient High-Wall Construction in Restricted Terrain
Despite the severe spatial limitations and significant geotechnical risks, the engineering team executed the temporary slope stabilization flawlessly. The strategic integration of benching, temporary soil nailing, and horizontal drains successfully neutralized the threats of slope failure and hydrostatic pressure. This rigorous site preparation allowed the permanent MSE Wall to be constructed smoothly, safely, and efficiently from the bottom up through to the project's successful completion.
