Study on Influence of External Earth Pressure on Stress and Deformation of Prestressed Double-layer Lining
In order to explore the influence of different external earth pressure on the prestressed double-layer lining structure,based on a hydraulic shield tunnel project in the Pearl River Delta,numerical simulation was carried out by using ABAQUS,and the deformation law and mechanical characteristics of double-layer lining under five earth pressure conditions were analyzed by mathematical statistics.The results show that:the deformation of double-layer lining in the construction period and operation period are all"horizontal duck egg"ellipse;the ellipse degree,circumln order to explore the influence of different external earth pressure on the prestressed double-layer lining structure,based on a hydraulic shield tunnel project in the Pearl River Delta,numerical simulation was carried out by using ABAQUS,and the deformation law and mechanical characteristics of double-layer lining under five earth pressure conditions were analyzed by mathematical statistics.The results show that:the deformation of double-layer lining in the construction period and operation period are all"horizontal duck egg"ellipse;the ellipse degree,circumferential pressure and contact stress of prestressed lining in the construction period are basically not affected by the change of external earth pressure;the transverse ellipse degree,circumferential pressure and contact stress of outer lining in the construction period increase with the increase of external earth pressure;the ellipse degree,circumferential pressure and contact stress of double-layer lining in the operation period increase with the increase of external earth pressure,but the contact stress at the arch waist is almost not affected by the earth pressure;the tensile stress of prestressed lining in the operation period appears and dein order to explore the influence of different external earth pressure on the prestressed double-layer lining structure,based on a hydraulic shield tunnel project in the Pearl River Delta,numerical simulation was carried out by using ABAQUS,and the deformation law and mechanical characteristics of double-layer lining under five earth pressure conditions were analyzed by mathematical statistics.The results show that:the deformation of double-layer lining in the construction period and operation period are all"horizontal duck egg"ellipse;the ellipse degree,circumferential pressure and contact stress of prestressed lining in the construction period are basically not affected by the change of external earth pressure;the transverse ellipse degree,circumferential pressure and contact stress of outer lining in the construction period increase with the increase of external earth pressure;the ellipse degree,circumferential pressure and contact stress of double-layer lining in the operation period increase with the increase of external earth pressure,but the contact stress at the arch waist is almost not affected by the earth pressure;the tensile stress of prestressed lining in the operation period appears and decreases with the increase of external earth pressure,but there is no risk of tensile cracking;the maximum circumferential compressive stress of prestressed lining in the operation period shifts from the anchorage groove in the construction period to the arch waist;the outer lining of the segment is still fully pressed in the operation period;due to the offset effect of internal water pressure on external earth pressure during operation,the ellipse degree,circumferential stress and radial stress of double-layer lining are reduced compared with those in the construction period.
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