盾构隧道渗漏对地表沉降和管片受力影响研究

Study on the Influences of Shield Tunnel Leakage on Ground Surface Settlement and Mechanical Behavior of Segment

盾构隧道管片接缝漏水会引起地表沉降,并对管片的受力造成不利影响。通过数值模拟系统分析了渗漏时间、渗漏程度、渗漏位置和渗漏面积对土体中的孔压分布、地表沉降、管片变形和管片内力的影响。数值模拟结果表明:(1)对孔压分布的影响,盾构隧道渗漏会使土体中的孔压降低,渗漏时间越长、渗漏程度越严重、渗漏位置越靠近拱底、渗漏面积越大,孔压降低的幅值越大。(2)对地表沉降的影响,渗漏引起的孔压降低会使土体竖向有效应力增加,引起地表沉降;渗漏时间越长、渗漏程度越严重、渗漏面积越大,地表沉降越大;渗漏位置会影响地表最大沉降点的位置和最大沉降量。(3)对管片变形的影响,渗漏会使管片发生下沉,由于渗漏点处的总应力减小管片还发生了向渗漏点的偏移以及一定的椭圆化变形。(4)对管片内力的影响,接头2、接头3、全接头和整环渗漏时,由于拱顶竖向应力和拱腰水平应力的差值增大,管片的横向椭圆化变形增大,管片的弯矩增大,拱腰轴力增大,接头1渗漏时,管片的弯矩减小,拱顶轴力增加;渗漏对管片变形和管片内力的影响随渗漏时间、渗漏程度和渗漏面积的增加而增大。

The joint leakage of shield tunnel segment will cause ground surface settlement and adversely affect the mechanical behavior of segment.The influences of leakage time,degree of leakage,leakage position and leakage area on the pore pressure distribution in the soil,ground surface settlement,deformation and internal force of segment are systematically analyzed by numerical simulation.The numerical simulation results show that:(1)The influence on pore pressure distribution:the leakage of shield tunnel caused reduction in pore pressure in the soil.The leakage time is longer,the degree of leakage is more serious,the leakage position is closer to the arch bottom and the leakage area is large,the amplitude of pore pressure reduction is greater.(2)Influence on ground surface settlement:the decrease in pore pressure due to leakage caused an increase in vertical effective stress in the soil,which resulted in ground surface settlement.The the leakage time is longer,the degree of leakage is more serious,leakage area and ground surface settlement is larger.The leakage location influenced the location of maximum settlement point and the maximum settlement value.(3)Influence on the deformation of segment:the leakage caused the sink of segment.The segment also deviated to the leakage point and had a certain ovalization deformation due to decrease in the total stress at the leakage point.(4)Influence on the internal force of segment:when the leakages were occurred at joint 2,joint 3,all joints and whole segment,the difference between vertical stress at arch crown and horizontal stress at arch waist increased,which resulted in the increase in horizontal ovalisation deformation of segment,the increase in bending moment of segment and the increase in axial force of segment at arch waist.When the leakages occurred at joint 1,the bending moment of segment was decreased and the axial force of segment at arch crown was increased.The influences of leakage on the deformation and internal force of segment increased with the increase of leakage time,degree of leakage and leakage area.