A test platform of the earth pressure balance shield is designed and manufactured. Taking a field project as the background, the test model with single cobble strata and two existing tunnels is planned, and the test of shield under-crossing the existing tunnels in the cobble strata is conducted. The surface settlement, the normal earth pressure acting on the existing tunnel, and the circumferential strain of the existing tunnels are measured. During the shield advancing process, two collapse pits are caused on the ground surface directly above the right side walls of the horseshoe tunnel and rectangular tunnel, respectively. Based on the measured surface settlements and the earth pressure on the existing tunnels, collapse mechanism of the cobble soil around the existing tunnel is revealed. Meanwhile, deformation feature of the existing horseshoe and the rectangular tunnels is obtained according to the measured circumferential strain.

设计制造了土压平衡护罩的测试平台。以一个实地工程为背景，设计了单一卵石地层和两条既有隧道的试验模型，并进行了盾构穿越卵石层中现有隧道的盾构试验。测量表面沉降，作用在现有隧道上的法向土压力以及现有隧道的周向应变。在盾构推进过程中，分别在马蹄形隧道和矩形隧道的右侧墙正上方的地面上产生两个塌陷坑。根据测得的地表沉降和现有隧道的土压力，揭示了现有隧道周围的卵石土的坍塌机理。与此同时，