大断面矩形顶管掌子面支护力对土体影响及其合理取值

Influence of Supporting Force of Large-Section Rectangular Pipe Jacket on Surrounding Soil & Reasonable Value Range

掌子面的支护力是顶管施工过程中的重要控制参数,对掌子面周围土体具有直接影响。以深圳轨道交通L12某地下车站通道工程为依托,通过FLAC(3D)软件进行数值模拟对掌子面处的变形及应力变化率等进行分析,得出顶进过程中掌子面的最大变形位于距掌子面底部约1/3h(h为管片高度)的位置,而最大应力变化率则位于中心位置,对掌子面前方土体的影响范围约为1.2h。支护力对顶管两侧地表土体的影响范围约为5h,而地表的最大变形发生于掌子面前方约0.6h处。通过将开挖面所在土层的应力变化率控制在30%以内作为支护力合理取值区间的划分标准,得出该工程的合理支护区间为0.8σ0~1.3σ0(σ0为掌子面中心处静止土压力)。

The supporting force of the face is an important control parameter in the process of pipe jacking construction, which has a direct impact on the soil around the face. Based on the tunnel project of L12 underground station of Shenzhen Rail Transit, the deformation and stress change rate of the face of the palm are analyzed by numerical simulation with FLAC(3D) software. It is concluded that the maximum deformation of the face of the palm is located about 1/3 h from the bottom of the face of the palm(h is the height of the segment), while the maximum stress change rate is located in the center of the face, and the influence range of the soil in front of the face is about 1.2 h. The influence range of support force on the surface soil on both sides of pipe jacking is about 5 h, and the maximum deformation of the surface occurs about 0.6 h in front of the face. By controlling the stress change rate of the soil layer where the excavation face is located within 30% as the dividing standard of the reasonable value range of support force, the reasonable support range of the project is 0.8σ0 ~1.3σ0(σ0 is the static earth pressure at the center of the face).