FLAC3D的锚杆拉拔数值模拟试验

为研究锚杆锚固力主要影响因素、锚杆拉拔过程中的整体失稳的规律等,采用三维显式有限差分法,建立锚杆拉拔数值仿真模型,进行一系列计算机模拟.结果表明:数值模拟计算的结果和现场试验得到的结果基本吻合,表明数值模拟锚杆拉拔过程是可行的;锚杆拔出的过程是慢慢滑移到突然整体失稳过程;锚杆锚固效应随着锚固剂的摩擦角、粘结力和有效围压的增加而增强;锚固剂所受的剪切应力分布规律随锚杆拉拔过程而改变,在拉拔初始时,自由端至锚固端,自由端锚固剂处的剪切应力为最大,锚固端处的剪切应力为最小接近为零,随着锚杆拉拔的进行,自由端处锚固剂与锚杆的界面屈服点首先达到,造成自由端处锚固剂与锚杆出现滑移现象,而随着锚杆拉拔的进一步进行,锚固剂所受的剪切应力慢慢呈现均匀分布,均都达到了最大值,均达到了锚固剂与锚杆界面的屈服点,锚杆出现整体失稳;在锚杆的拉拔过程中,锚杆的变形规律是自由端处的变形量最大,自由端至锚固端锚杆的变形量逐渐变小,同时锚固剂变形的规律与锚杆的变形规律相同.

Numerical simulation on pull-tests of a cable by FLAC3D

To study major influential factors of cable anchorage force and the law of the whole instability in pull-tests for a cable,a numerical simulation model was established by 3-D explicit finite difference method. It is proved that results of numerical simulation agree with field results of pull-tests.The pull-tests of the cable is a process in which the slow slippage turns abruptly into the whole distability.The anchorage effect of the cable boosts up along with the augment of friction angle,adhesion stress and effective pressure.The shearing stress distribution regularities of anchorage agent change with the pull-tests process of the cable.At the initial stage of pull-tests,the shearing stress of anchorage agent in free end is maximum,while that in anchorage end is minimum.Cable grout yield points of free end are obtained firstly along with pull-tests,resulting in the slippage of the cable and anchorage agent of free end.Shearing stress of anchorage agent takes on slowly homogeneous distribution along with the further operation of pull-tests and reachs cable grout yield points from free end to anchorage end,so as that the whole cable becomes instable.The maximum deformation occurs in the free end during the pull-tests,the deformation amount of the cable is diminished gradually from free end to anchorage end,and the deformation law of anchorage agent is uniform with that of a cable.