中风化砂页岩中抗浮锚杆极限抗拔力和有效锚固长度的研究

为了探究辽宁西部地区抗浮锚杆的极限抗拔力和有效锚固长度的取值,以辽宁阜新玉龙时代广场抗浮锚杆为工程背景,对抗浮锚杆进行现场抗拔试验,通过6根抗浮锚杆在连续荷载作用下的破坏性抗拔试验,测试锚杆杆体的抗拔力,并进一步利用公式推算锚杆轴力和剪应力,并绘制出锚固深度与轴力、剪应力的变化曲线。分析结果表明,注浆体与锚杆杆体间的轴力、剪应力分布是不均匀的,自孔口到杆底端呈逐渐递减的分布模式;当锚杆杆体的内力(轴力和剪应力)达到某一临界值时,锚杆杆体变形由弹性变化为塑性,这一临界值接近于杆体的极限抗拔承载力,锚杆抗拔时并非全长同时受力,而是分阶段受力;经分析此项目中抗浮锚杆极限抗拔力为270～330kN,抗浮锚杆的有效锚固长度约3. 6m,可为辽宁西部地区的中风化砂页岩中抗浮锚杆的使用提供参考依据。

Study on ultimate pull-out capacity and effective anchorage length of anti-floating anchor rod in moderately weathered sand shale

In order to study the value of the ultimate pull-out capacity and effective anchorage length of anti-floating anchors in the western part of Liaoning Province,field pull-out test of anti-floating anchors was carried out on the background of anti-floating anchors in Yulong Times Square in Fuxin,Liaoning Province.Through destructive pull-out tests of six anti-floating anchors under continuous loads,the pull-out capacities of anchors was tested.Furthermore,the formula was used to calculate the axial force and shear stress of the anchor rod,and the curves of the axial force and the shear stress changing with the anchorage depth were drawn.The analysis results show that the distribution of axial force and shear stress between grouting body and anchor rod body is not uniform,and the distribution pattern decreases gradually from the orifice to the bottom of the anchor rod;When the internal force( axial force and shear stress) of anchor rod body reaches a certain critical value,the deformation of anchor rod body changes from elasticity to plasticity,the critical value is close to the ultimate pull-out bearing capacity of the anchor rod.The pull-out capacity of the anchor rod is not a full-length force at the same time,but is subjected to it in stages.The ultimate pull-out capacity of anti-floating anchor rod in this project is 270~330 k N,and the effective anchorage length of anti-floating anchor rod is about 3.6 m,which can provide a reference for the use of anti-floating anchor rod in weathered sand shale in the western part of Liaoning Province.