洞桩法边桩变形的荷载-结构模型

掌握边桩的受力变形规律对洞桩法车站的安全至关重要.基于修正的荷载-结构模型研究洞桩法边桩变形规律,并与现场实测结果进行对比.结果表明:边桩顶至底板的边桩侧向位移呈抛物线形,底板以下的边桩侧向位移基本为零;导洞初支体系能够承受大部分自身围岩应力,但在计算模型中忽略导洞围岩应力时,应对导洞底部侧压力系数扩大20%;常规荷载-结构模型计算所得的边桩侧向位移整体偏小,经修正的荷载-结构模型计算所得的边桩侧向位移与现场实测数据较为吻合;修正的荷载-结构模型边桩轴力有大幅缩减,边桩剪力和弯矩基本不变.

Load-structure model of side pile deformation based on pile-tunnel method

Grasping the stress and deformation regularity of side pile is very important for the safety of pile-tunnel approach-based station. Based on the modified load-structure model, the deformation regularity of the side pile is studied and compared with the field-measured result. The result shows that the lateral displacement of the side pile from the top to the bottom plate will exhibit parabolic form and its lateral displacement below the bottom plate will basically be zero, and the initial branch system of the guide tunnel will be able to withstand the stress of largeportion of its surrounding rock. However, the lateral pressure coefficient near the bottom of the guide tunnel should be enlarged by 20 percent if the surrounding rock stress of the guide tunnel was ignored in the calculation model; and the lateral displacement of the side pile calculated with conventional load-structure model will be relatively small as a whole. The lateral displacement of the side pile calculated with modified load-structure model will be in better agreement with the field measured data. The axial force on side pile calculated with modified load-structure model will be greatly reduced and the shearing force in side pile and bending moment on it will bebasically unchanged.