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采用透明土材料和粒子图像测速法(PIV)技术,通过物理模型试验研究锚杆拔出机理。在模型试验中采用A、B两种不同尺寸的连续球体锚杆锚固段,试验获得各锚杆锚固段上移对周围土体的扰动规律、锚杆位移与锚固力变化曲线以及拔出破坏时破裂面的位置及形状。通过分析连续球体锚杆锚固段的极限承载力和锚固段破坏机理,推导出连续球体锚杆抗拔力的计算公式。试验结果分析表明:本文试验条件下,锚杆拔出时竖向位移最大影响范围与连续球体的半径和间距有直接关系;A、B型连续球体锚杆的极限承载力,分别比普通圆柱型锚杆提高52%和117%;连续球体锚杆锚固段在上拔破坏过程中抗拔力的贡献可分为3个部分:直杆与土层的黏结、肩部端承力和黏土黏聚力。
Transparent earth materials and particle image velocimetry (PIV) were used to study the mechanism of bolt pullout by physical model test. In the model test, A and B two different sizes of continuous ball anchors were used to test the perturbation law of the upper anchorage section of the anchorage section to the surrounding soil, the change curve of anchor displacement and anchorage force, and the pullout failure The location and shape of the rupture surface. Through the analysis of the ultimate bearing capacity and the failure mechanism of anchor segment of continuous spherical anchor, the formula for calculating the pullout force of continuous spherical anchor is deduced. The test results show that the maximum vertical displacement of anchor rod is directly related to the radius and spacing of continuous spherical ball when the bolt is pulled out. The ultimate bearing capacity of A and B continuous spherical anchor is higher than that of normal cylindrical The anchor rod increases by 52% and 117%. The contribution of the anti-pull force of continuous spherical anchor segment in the process of ascending and descending can be divided into three parts: the bond between the straight rod and the soil layer, the bearing capacity of the shoulder and the cohesion of the clay force.