# Effect of Soil Reinforcement on Tunnel Deformation as a Result of Stress Relief
## 4 Conclusions  
This study evaluated the effect of the reinforced soil's Young's modulus and the effect of the reinforcement depth on the tunnel response as a result of a basement excavation, based on back-analyzing a centrifuge model test with no reinforcement. The tunnel heave and diameter change and the stress changes both in the longitudinal and in the transverse directions, were analyzed. The obtained results can provide reference for practical engineering in terms of applying construction measures to control tunnel deformation caused by stress relief. Based on the above analyses, the following conclusions were drawn:  
1. As a result of the stress relief caused by the basement excavation, tunnel heave was observed for the tunnel underneath the basement excavation. The heave was greatly reduced by improving the basement bottom soil's Young's modulus. When a specific soil area S1 was reinforced with a Young's modulus that varied from \(E_{\text{s}}\) to \(5E_{\text{s}}\), the computed tunnel heave decreased by 18%. This was because the reinforced soil blocked the stress transfer and thus reduced the tunnel heave caused by excavation unloading. A further increase of the reinforced soil's Young's modulus did not significantly reduce the tunnel heave. This can be attributed to the fact that obvious stress changes were not observed when the reinforced soil's Young's modulus increased from \(5E_{\text{s}}\) to \(10E_{\text{s}}\). 2. When the reinforcement depth was 0.6 m, the computed tunnel heave decreased by 15% in comparison with the non-reinforced case. However, significant changes were not observed when the reinforcement depth increased further. The further increase of reinforcement depth had no effect and would therefore be uneconomical. 3. As the reinforced soil's Young's modulus varied from \(E_{\text{s}}\) to \(5E_{\text{s}}\), the maximum elongation of the tunnel lining in the circumferential direction changed by 9%. Significant changes were not observed when the reinforced soil's Young's modulus increased from \(5E_{\text{s}}\) to \(10E_{\text{s}}\). Significant changes were not observed when the reinforcement depth increased further. Thus, it was concluded that the reinforced soil's Young's modulus and the reinforcement depth exerted only a slight influence on the diameter change of the tunnel. Conceptualization, H.S. ; methodology, H.S. ; software, H.S. ; validation, W.S. ; formal analysis, H.S. and W.S. ; investigation, H.S. and W.S. ; resources, W.S. ; data curation, H.S. ; writing--original draft preparation, H.S. ; writing--review and editing, H.S. and W.S. ; visualization, H.S. ; supervision, H.S. ; project administration, H.S. ; funding acquisition, H.S. This study was sponsored by the National Natural Science Foundation of China (grant number 51708245), the Natural Science Foundation of Jiangsu Province (grant number BK20160426), the Construction System Science and Technology Project of Jiangsu Province (grant number 2017 ZD124), the Natural Science Foundation for Colleges and Universities in Jiangsu Province (17 KJB130003, 17 KJA560001), the Project with Science and Technology of Huai'an City (HAG201606). We thank [PERSON], Edanz Editing China (www.liwenbianji.cn/ac) for editing the English text of a draft of this manuscript. The authors declare that there is no conflict of interest regarding the publication of this paperData Availability Statement: The computed data used to support the findings of this study are included within the article.