一种连续-非连续方法验证及矩形隧道围岩垮塌模拟

提出了一种适于模拟岩石材料变形、开裂、接触、摩擦及转动的连续-非连续方法。该方法借鉴了拉格朗日元法、变形体离散元法及虚拟裂缝模型的有关原理。首先,针对弹性滑块沿固定斜面下滑及三点弯梁开裂问题进行了模拟,以检验该方法的正确性。然后,针对矩形隧道围岩模型位移控制加载条件下的变形、开裂及垮塌过程进行了模拟。结果表明:位于隧道两帮、顶部和底部的最大主应力低值区(最大主应力值下降区)的形状呈半圆形;随着加载的进行,位于隧道顶、底部的任一个最大主应力低值区被分化成“双耳形”;随后,隧道顶、底部发生开裂,冒落及底鼓发生,隧道两帮也发生开裂;最终,松散的岩块几乎充满了半个隧道,隧道围岩整体垮塌。

Verification of the Continuum-discontinuum Method and Modeling of Collapsing of the Surrounding Rock of a Rectangular Tunnel

A continuum-discontinuum method was proposed to model a serious of complex mechanical behaviors of rock materials, such as deformation, cracking, contact, friction and rotation. The method introduced the Lagrange element method, the discrete element method and the fictitious crack model. Firstly, the sliding of an elastic block along an inclined plane and the cracking of a three-point-bending beam were modeled to verify the proposed method. Then, the deformation, cracking and collapsing of the surrounding rock of a rectangular tunnel under the constant velocity were modeled. Results show that, firstly, the regions with lower maximum principal stresses are semi-circular at two sides, the roof and floor of the tunnel; as deformation proceeds, two ear-shaped regions with lower maximum principal stresses at the roof or floor of the tunnel are formed; then, cracking appears at two sides, the roof and floor of the tunnel so that the roof caving and the floor heave are found; finally, the half of the tunnel is almost filled with loose rock blocks, meaning overall collapsing of the surrounding rock.