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Project Background

Huangshan Zhonghe Agricultural Products Logistics Park is located in High-tech District, Huangshan. PhaseⅠof the project covers an area of 200 acres and a building area of 170,000 m2. It is a regional professional agricultural products wholesale market in Huangshan under the Zhonghe Group and is also an important livelihood project and vegetable basket project in Huangshan City. It’s the key enterprise to ensure supply in key markets of the commerce sector and high-tech zone.

Foundation Support by Self-drilling Rock Bolt

The underground garage area of the comprehensive building of Zhonghe Intelligent Integrated Service Center (D4# Building) is 2077.8m2, the depth of the foundation pit is 5.1m, and the circumference of the foundation is 250m.

Project Overview

Catalog Detail Information
Project Duration: December 2020 – February 2021
Service Scope: Anchoring materials, anchoring rigs, and on-site technical services
Application: Underground parking lot commercial service building
Application Structure: Pile anchor support, self-drilling hollow anchor bar used as temporary soil nail
Quantity Consumption: About 3000m
Geological Conditions: The project is located at the intersection of Binqiyun Avenue and Qingliangfeng Road in Tunxi District, Huangshan City. The proposed site is filled with plain soil, silty clay, round gravel, strongly weathered siltstone, and moderately weathered siltstone from top to bottom within the exploration depth range.

Questions and Challenge

The original design plan A-B and B-C sections are supported by cantilever piles, and the C-A section slope is sprayed with concrete. The instability occurred during excavation, and remedial measures were taken to insert steel pipes, which could not meet the requirements. Due to the presence of round gravel and a strong weathered layer, inserting steel pipe is difficult and the efficiency is low, which can’t meet construction requirements. The project party finally decided to adopt a self-drilling anchor system, using simultaneous drilling and grouting construction process.

round gravel and a strong weathered layer condition


The self-drilling anchor system consists of a hollow anchor bar, coupler, centralizer, drill bit, plate, and nut. It can combine drilling, grouting, and anchoring functions together. The anchor bar can not only be used as a drill rod and reinforcement body but also can be used for simultaneous drilling and grouting. Grouting is common pressure grouting (0.3-0.5MPa). The grouting adopts net cement with a water-cement ratio of 0.5-0.55, and the compressive strength of the grouting body is 20MPa. R38 hollow anchor bar, with a single length of 3m, and R38/90 ESF drill bit are selected. The drilling depth is 12m.

Construction Process

Materials prepared → Drilling rig in place → Connect hollow anchor bar and drill bit → →Simultaneous drilling and grouting→ Flush the hole → Couple next anchor bar → Repeated drilling and grouting → Drilling completion → Install breast beam → Foundation excavation → Install next row anchor bar → Installation completion

Construction Equipment

Drilling Rig: Full Hydraulic Drilling Excavator

Drilling Rig

Construction Efficiency

The average net drilling time for a single hole (12m depth) is 14.4 minutes, and one drilling rig’s drilling length per shift (8h) is more than 360m.