针对成都砂卵石地层的特殊性给盾构施工带来的刀盘卡停、中心结泥饼、刀盘过度磨损以及螺旋输送机断轴等问题，采用离散元理论及分析方法，通过模拟砂卵石地层盾构掘进过程，对盾构掘进过程中土体运动规律和受力特征进行研究。得出： 1）盾构掘进过程中刀盘掌子面外围土体颗粒运动速度要高于刀盘中心土体颗粒； 2）土舱中心和螺旋轴伸入土舱段左右两侧的土体运动速度较慢； 3）刀盘掌子面土体及土舱内土体压缩力分布与刀盘旋转方向有关。利用EDEM与ANSYS耦合对刀盘及螺旋输送机进行有限元分析，得出： 1）盾构掘进过程中刀盘的最大应力值为123.27 MPa，位于云腿与法兰盘连接处，最大变形量为1.69 mm，位于刀盘最外围的环形梁； 2）螺旋输送机的最大应力值为59.01 MPa，位于土舱后隔板和螺旋输送机筒体连接处，最大变形量为0.49 mm，位于土舱和螺旋输送机筒体连接处附近的螺旋叶片外圈。
The particularity of sandypebble
strata in Chengdu, China introduces problems to shield tunnels, such as
cutterhead jamming, center mud cake, excessive wear of cutterhead, and broken
screw conveyor shaft. Therefore, the discreteelement
theory and analysis method are adopted to simulate the shieldtunneling process in sandypebble strata,
and the law of soil movement and force characteristics of the shield are
studied. It is concluded that (1) the moving speed of soil particles around the
tunneling face of the cutterhead is higher than that of the center; (2) the
soil moving speeds in the center of the soil chamber and at both sides of the
screw shaft extending into the soil chamber are slow; and (3) the compressive
force distribution of soil on tunneling face and soil chamber is related to the
rotation direction of the cutterhead. Finite element analysis is conducted on
the cutterhead and screw conveyor using EDEMANSYS
coupling, and the results show that: (1) The maximum stress on the cutterhead
is 123.27 MPa during shield tunneling, which is located at the junction of the
cloud leg and the flange; the maximum deformation is 1.69 mm, which is located
on the outermost ring beam of the cutterhead. (2) The maximum stress on the
screw conveyor is 59.01 MPa, which is located at the connection between the
rear partition of the soil chamber and the screw barrel, and the maximum
deformation is 0.49 mm, which is located between the outer ring of the spiral
blade near the junction of the soil chamber and the screw barrel.
