降雨入滲對淺埋黃土隧道穩定性的影響

鄧祥輝 曹衛平 楊東升

摘 要： 為了研究降雨入滲作用下黃土力學性質劣化對淺埋黃土隧道穩定性的影響，對隧道圍巖中的黃土進行了不同含水率和不同圍壓的剪切、等壓三軸試驗，結果表明，含水率對黃土力學性質和破壞形態有較大影響。根據試驗結果建立了黃土不同含水率的塑性本構關系，對比了計算結果和試驗結果，證明了該本構關系能較好地描述黃土的應力 應變規律。對不同降雨強度、不同深度的黃土在雨水入滲影響下的含水率分布規律進行分析，并在數值模擬軟件中調用建立的不同含水率的黃土塑性本構關系，計算不同降雨強度下隧道結構的受力和變形，結果表明：考慮降雨入滲后隧道結構變形和受力增加明顯，其中，拱頂沉降增幅達到46%，隧道初期支護應力增加20%～27%。將淺埋黃土隧道結構變形監測數據與數值模擬結果對比，驗證了黃土本構關系的正確性，所模擬的降雨入滲對隧道結構穩定性的影響符合實際工程。

關鍵詞： 淺埋隧道;黃土隧道;降雨入滲;本構關系;數值模擬;穩定性

中圖分類號：U451? ?文獻標志碼：A? ?文章編號：2096-6717（2020）02-0045-11

Stability analysis of shallow loess tunnel considering rainfall infiltration

Deng Xianghui， Cao Weiping， Yang Dongsheng

（School of Civil and Architecture Engineering， Xian Technological University， Xian 710021， P.R.China）

Abstract： In order to investigate the influence of strength reduction of loess induced by rainfall infiltration on the stability of tunnel， direct shear- and triaxial- tests were carried out on loess.The results show that the water content has significant influence on the mechanical behaviors of loess.The elastic-plastic incremental constitutive relation of undisturbed soil was established.By compared with experimental data， the constitutive model was proved to be capable of describing the stress-strain relationship of loess.The distribution characteristic of water content in different depth land under different rain intensity were analyzed.Besides， the constitutive model for loess with different water contents were established so as to calculate the stress and deformation of structure in tunnel under different rain intensities.The results show that when considering rainfall infiltration， the deformation of tunnel and the stress of preliminary support structure are significantly increased.In this situation， the settlement of the tunnel vault increases 46% and the stress of preliminary support structure increases 20%～27%.It is found the elastic-plastic incremental constitutive relation is reasonable and results of the numerical simulation is reliable with comparing the calculated and measured data of tunnel deformation.

Keywords： shallow tunnel; loess tunnel; rainfall infiltration; constitutive relation; numerical analysis; stability

中國黃土分布廣泛，大量建設工程不可避免地要修建在黃土地區。當隧道穿越淺層黃土中的Q4、Q3期黃土時，由于新黃土孔隙率大、濕陷性顯著，隧道施工擾動極易引起各種工程問題[1-2]。特別是降雨產生的地表水入滲后，黃土隧道進、出口段以及淺埋段容易發生大變形、局部坍塌，甚至塌方等工程事故。……