Xingyi Normal University for Nationalities Retaining Wall Reinforcement

Time:2023-09-21View:

Project Background

In the picturesque town of Dingxiao, nestled within the heart of Xingyi City, lies Xingyi Normal University for Nationalities. A place of learning and inspiration for many, this institution boasts a striking campus landscape. Among the topographical features of the campus are two significant slopes. The upper slope houses the teachers' dormitories, while the lower slope is earmarked for a proposed teaching building. The critical issue that led us to intervene in this project was the perilous condition of the retaining wall constructed in 2013.

The 11-meter high retaining wall, initially built with mortar-masonry, had deteriorated over time and was teetering on the brink of collapse. A comprehensive assessment revealed the urgent need for reinforcement and repair. However, executing this task posed formidable challenges. The primary challenge was the height of the slope, towering at 11 meters, and the need for a 9-meter wide road on top.

The original plan to utilize φ25 reinforcement bars in this project had to be altered due to equipment restrictions and unstable ground conditions. Consequently, after careful consideration, the R32 self-drilling anchor system from Sinorock was selected as the most suitable option to ensure a secure and efficient solution for this project.

project overview

Project Overview

Project Duration:	September 2020 – October 2020
Service Scope:	Anchoring materials, anchoring rigs, and on-site technical services
Application:	Reinforcement and repair of retaining wall of building slope
Application Structure:	Self-drilling anchor bars used as permanent soil nails
Quantity Consumption:	Approximately 3000 meters of self-drilling anchor bars
Geological Conditions:	The slope featured a composition of plain fill, red clay, strongly weathered dolomite, and moderately weathered dolomite. The top of the slope consisted of a gentle slope with a soil layer, transitioning into a rocky slope further down. The proposed site also exhibited structured dissolution slow slope landform characteristics.

Questions and Challenge

Design Conundrum: Given the complex geological conditions, the project's designer initially proposed a reinforcement plan involving anti-slide piles and anchor support. The plan included the installation of three rows of steel pipe anti-slide piles at the foot of the slope, reinforced anchors on the slope for additional support, and the subsequent placement of steel meshes with concrete spraying. However, during the construction phase, a formidable challenge emerged. Drilling through the fill layer behind the retaining wall proved to be exceedingly difficult, despite numerous attempts, leading to project suspension.

providing technology support

Solutions

Faced with this impasse, our technical team quickly came up with a breakthrough solution adopted by the construction team - using R32 self-drilling anchor bars as soil nails, each with a length of 1.5 meters. These anchor bars were equipped with ESSF R32/76 drill bits, capable of drilling to a depth of 9 meters. During construction, the self-drilling anchor bar was drilled through the 4-meter retaining wall first, then penetrating the 5-meter fill layer and ultimately anchoring into the bedrock.

To facilitate this, a special adapter coupling was designed by our technical team to connect the anchor rod and drill bit to the pneumatic DTH drilling rig. This adaptation allowed for precise drilling and ensured the effectiveness of the self-drilling anchor system. Additionally, grouting was performed simultaneously with drilling, enhancing the quality of the surrounding soil and bolstering the anchoring force.

The self-drilling anchor system utilized a range of components, including a hollow anchor bar, coupler, centralizer, drill bit, plate, and nut. This comprehensive system seamlessly combined drilling, grouting, and anchoring functions into one cohesive process, with the anchor bar serving as both a drill rod and reinforcement body.

self drlling anchor bolt system

Construction Process

Materials prepared → Erect scaffolding → Drilling rig in place → Connect hollow anchor bar and drill bit → Percussive rotary drilling → Couple next anchor bar → Repeated drilling and grouting → Drilling completion → Install next row anchor bar → Installation completion

Construction Equipment

Drilling Rig

The electric DTH drilling machine JVD-100, equipped with a QCZJ90 impactor, played a pivotal role in executing the drilling tasks with precision and efficiency.

Construction Efficiency

The construction efficiency achieved during this project was nothing short of remarkable. With an average net drilling time of just 25.6 minutes per hole, even at a substantial depth of 9 meters. Each drilling rig completed over 50 meters of drilling per shift, spanning eight hours of continuous work. This efficiency was a testament to the effectiveness of Sinorock's self-drilling anchor system in addressing the complex challenges presented by the project.

Conclusion

The Xingyi Normal University for Nationalities Retaining Wall Reinforcement project stands as a testament to the capabilities and effectiveness of Sinorock's self-drilling anchor system in addressing even the most challenging slope stabilization tasks. By adopting innovative techniques and state-of-the-art equipment, this project not only ensured the safety and stability of the campus but also served as an inspiring example of engineering excellence in action. As we continue to push the boundaries of what is possible in slope stabilization, Sinorock remains committed to providing innovative solutions that safeguard lives and infrastructure, one project at a time.

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