How does a tunnel boring machine (TBM) control the subsidence of the ground above the trenchless installation?

土壤沉降，也称为沉降，被定义为地面的向下垂直运动，通常由土壤内应力的变化引起。沉降通常被描述为地面的沉没或塌陷。过度的垂直地面运动可能导致附近结构的失真，最终导致发展cracks和, in some cases, total failure or collapse of the structure.

subscan either be instantaneous, occurring almost immediately after soil disturbance, or it can take place over several years.

subsis especially an issue during trenchless construction activities, such as tunneling. As the隧道镗床（TBM）沿着预期进步bore path, it removes the surrounding soil. This activity loosens the ground while leaving soil layers directly above the bore path unsupported. As a result, the strength and stability of the soil matrix are affected, causing the earth to shift in a downward direction.

TBMs control ground subsidence by employing a construction technique known as the顺序挖掘方法（SEM）。在SEM期间，隧道分开，挖掘，并在几个相对较小的段中支持。随着隧道建设向前发展，剪头at the face of the tunnel boring machine loosens the surrounding soil. The cuttings are then removed by a system of screw and belt conveyors to the入口坑地点。

一旦切割头已经向所需距离推进隧道，precast concrete liner segments被馈送到TBMS旋转环形竖立器系统。该机制使用真空将每个预制段抬起到安装位置。衬垫段围绕圆周一个逐个安装，直到隧道部分完成。

This completed tunnel segment possesses strength properties which allow it to support the layers of soil above the bore path.

Thehydraulic jack system然后向前推动切割头，重复衬里过程。使用专用设备仔细监控每个挖掘的段，以确保土壤运动不超过允许的限制。TBMS和SEM技术允许长而复杂的隧道构造，而不会引起由过度的土壤干扰引起的沉降。