粉砂地层盾构近距离侧穿已有建筑的控制技术

依托穗莞深城际轨道太平隧道工程,在其侧穿一多层房屋时,采用控制地层损失与旋喷桩加固土体相结合的方式,很好地保护了现有房屋的安全与正常使用状态。通过分析隧道穿越过程中房屋的实测变形规律,并进行有限元数值分析,比较了有无旋喷桩和地层损失率对土体垂直位移、房屋角点沉降、房屋整体倾斜、土体深层水平位移的变化规律。分析结果表明,设置旋喷桩和控制地层损失均能有效减小沉降和土体位移,但控制地层损失的效果远比设置旋喷桩要明显。随着地层损失的增大,土体水平位移曲线由“勺”型渐变至S型,最大水平位移位置逐渐上移且位于隧道的上边界附近。

Control of Shield Tunneling Passing Through a Nearby Building in Silty Soil

Protection measures including control of ground loss and jet grouting column are adopt during Guangzhou-Dongguan-Shenzhen inter-city rail passing through a nearby multi-story building.Observation on the building shows that the building is in a safe using condition.Finite element method was used to analysis the deformation of building during tunnel excavation and the numerical results were compared with measured results.The analytical results show that both jet grouting columns and reduction of ground loss has the effect of reducing soil deformation,building settlement,and building tilt.However,reduction of ground loss is more effective than installation of jet-grouting columns.With increase of ground loss,horizontal displacement curve of soil changes from " spoon" shape to S shape.Moreover,the depth of maximum horizontal displacement of soil moves up to the upper boundary of the tunnel.