连拱隧道动态施工模型试验与三维数值仿真模拟研究

连拱隧道作为公路隧道新的结构型式，理论上还不成熟。以云南省元磨高速公路的一座连拱隧道作为工程背景，按弹性阶段相似原则进行连拱隧道室内模型试验，模拟连拱隧道的施工工况，采用压力盒、数码摄像、沉降板等仪器量测施工过程中隧道围岩应力和位移分布，采用三维连续介质快速拉格朗日元模拟连拱隧道的施工工况，得出施工过程中隧道围岩位移、应力和塑性区分布规律，其结果与模型试验所得结果基本一致。

MODEL TEST AND 3D NUMERICAL SIMULATION STUDY ON EXCAVATION OF DOUBLE-ARCH TUNNEL

Recent years, more and larger, even huge underground projects are under planning, designing and construction in China, as well as in the world. Besides the numerical simulation, physical and geomechanical model tests have been putting on the agenda to meet engineering request. As a new structure form of highway tunnel, the theory of double-arch tunnel is still primary up to now. According to the similar principle of elastic theory, a model test simulating the excavation stage of double-arch tunnel was carried out with the background of a double-arch tunnel being constructed in the Yuanjiang--Mouhei Expressway, Yunnan Province. The model tests for double-arch tunnel, in the past, were mostly two-dimensional or three-dimensional in small size. In those model tests, the displacements were not measured in real deformation field, or even used simply dial indicator, displacement sensor, strain-gauge transducer, etc., which is incomplete because the full deformation field can not be obtained by those methods. In present paper applied with earth-pressure cell, digital camera and settlement plate, the distributions of stresses and displacements in the wall rock mass were measured during the tunnel excavation. 3D fast Lagrangian element method is applied to simulate the excavation of double-arch tunnel. The distributions of stresses, displacements and plastic zones in the wall rock mass of double-arch tunnel were obtained; and the result is in good agreement with that of model test. Some valuable results were concluded finally.