为了研究冲击荷载下地铁隧道盾构管片的破坏特性,采用轻气炮试验和动力有限元数值模拟相结合的研究方法,对冲击荷载下盾构管片的破坏情况进行分析,通过分析管片单元的应力状态研究了冲击荷载下盾构管片的破坏机理。结果表明:以冲击位置为中心,盾构管片试件表面径向主要受压,环向主要受拉,相同位置压应变大于拉应变;不同速度子弹冲击下,管片正面冲击坑水平方向及竖直方向尺寸相差不大;随着子弹速度的增加,管片正面冲击坑尺寸不断增大,冲击坑的深度不断增加,冲击坑等效直径增长随子弹冲击速度增加呈“三段式”;沿着子弹冲击方向,盾构管片试件单元应力状态从三向受压变化到三向受拉,盾构管片冲击正面混凝土受压破碎,盾构管片冲击背面发生受拉破坏。研究结果可为管片抗冲击设计提供一定的理论基础。
To investigate the damage characteristics of the shield segment of the subway tunnel under impact loading, the combined research method of the light gas gun experiment and the numerical simulation were adopted. The damage conditions of the tunnel shield segments subjected to impact loading were analyzed. By analyzing the stress states of shield segment elements, the failure mechanism of shield segment under impact loading was studied. Results show that with the impact position as the center, the surface of the shield segment specimen is mainly subjected to compression in the radial direction and tension in the circumferential direction, and the compressive strain is greater than the tensile strain at the same monitoring position. Under the impact of bullets with different velocities, the horizontal and vertical dimensions of the impact crater on the front of the segment are not much different. With the increase of bullet velocity, the size of the impact crater on the front of the shield tunnel segment increases and so does the depth of the impact crater. The equivalent diameter of the impact crater increases in a "three-stage pattern" with the increase of the impact velocity of the bullet. Along the bullet impact direction, the element stress state of the shield segment specimen changes from triaxial compression to triaxial tension. When impacted by the bullet, the concrete in the impact side of the tunnel shield segment will be crushed by compression and the concrete in the back of the tunnel shield segment will be damaged by tension. The research results can provide a certain theoretical basis for the impact resistance design of shield segment.
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