双拱巷道在梯级扰动下的力学特性及破坏模式

Mechanical Characteristics and Failure Mode of Double Arch Roadway under Step Disturbance

双拱巷道在隧道、采矿等领域中十分常见,许多学者对静载下双拱巷道的力学特性和破坏模式进行了研究。然而,双拱巷道还会受到盾构机或爆破模式开挖等扰动的作用。为此,本文借助ABAQUS数值模拟,展开了梯级扰动荷载下双拱巷道的力学特性和破坏模式研究,并与单、双拱静载条件做了Mises应力、应变和塑性区对比,得到如下结论:(1)双拱巷道梯级扰动荷载下的强度低于静载下的强度,这是由于扰动加载增加了岩体内部的塑性变形,岩体有效承载面积减小而强度下降;(2)单孔砂岩孔径越大,岩体强度越低,塑性变形区越大,压缩应变集中于孔壁左右两侧,相同围压、孔洞布置、加载时长条件,梯级扰动作用下单孔岩体的抗压强度比静载低约3.61%-8.51%;(3)静、扰动加载作用下,均表现为双孔砂岩孔间距越大,峰值轴向应力越小,两孔的应变重叠面积越小,最大塑性应变区域不随孔间距的增加而增加。

Double-arch tunnels are widely used in tunnel and mining engineering.Many studies have been carried out on the mechanical properties and failure mode of double-arch tunnels under static load.However,the double-arch tunnels may also be disturbed by shield tunneling or blasting excavation.To handle this,ABAQUS based numerical simulation has been applied to study the mechanical properties and failure mode of doublearch tunnels under multi-level dynamic load,and the Mises stress,strain,and plastic zone were compared with that based on the static load of single and double-arch tunnels.The conclusions are listed as follows:(1)The strength of the double-arch tunnels under multi-level dynamic loading is lower than that under static load,due to that the dynamic load disturbance increases the plastic deformation inside rock mass,which results in the effective bearing area of rock mass decreases and a decrease in rock mass strength.(2)The larger the pore diameter of single hole sandstone,the lower the rock strength,the larger the plastic deformation zone,and the compressive strain is concentrated on the left and right sides of the hole wall.Under the same confining pressure,hole arrangement and loading time,the compressive strength of single hole rock mass under the step disturbance is about 3.61%~8.51%lower than that under static load.(3)For the static and dynamic load tests,the larger the pore spacing of the double-porous sandstone,and the smaller the peak axial stress,the smaller the strain overlap area of the two holes.It is interesting that the maximum plastic strain area doesn’t increase with the increase of the pore spacing.