Abstract
The naturally formed aeolian sand dunes in northern Shaanxi exhibit unique engineering characteristics. Several challenges, such as the poor self-stabilization ability of the surrounding rock, difficultly in injecting grout, and insufficient construction experience, restrict the construction of road tunnels under this stratum. Therefore, in this study, a case study of the Shenmu No. 1 tunnel was conducted to investigate the engineering characteristics of aeolian sand tunnels, compare the grouting effects of commonly used grouting materials, and discuss the reinforcement effects of different construction schemes in aeolian sand tunnels. Based on a field grouting test, it was determined that it is difficult to inject ordinary cement grout into an aeolian sand layer. Furthermore, it was determined that superfine cement grout and modified sodium silicate grout can be injected, but the former exhibits a poor reinforcement effect. Additionally, results of numerical analysis indicated that an approach based on a concept of “horizontal jet grouting pile + benching partial excavation method with a temporary invert” is suitable for the construction of tunnels in aeolian sand in China.
Highlights
Geological characteristics of aeolian sand for Shenmu No 1 tunnel
This study aims to solve technical problems in aeolian sand tunnel grouting and construction technology, and to ensure the construction safety and engineering quality of aeolian sand tunnels
The particles were mostly composed of fine sand (0.075–0.25 mm), followed by very fine sand (0.01–0.075 mm), and medium sand (0.25–0.5 mm)
Summary
Geological characteristics of aeolian sand for Shenmu No 1 tunnel. Physical properties. The starting and ending pile numbers of the left line are ZK90 + 998–ZK91 + 360, and the length is 362 m. The aeolian sand in this location is generally brownish-yellow, loose, and slightly wet. It is primarily composed of feldspar (73%) and fine quartz sand (23%), followed by silt sand and silty soil, which are concentrated at the tunnel exit and in the surface above the tunnel. They exhibit a covering layer thickness in the range of 15–35 m. The uneven coefficient Cu was 3.5, and the curvature coefficient Cc was 0.64, thereby indicating poor gradation
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