【摘要】 通过地质力学模型试验方法,研究洞室在开挖与超载过程中自由式锚索和全长黏结式锚索的预应力变化特征。给出锚固洞室在开挖与超载过程中锚索预应力变化的展开图,并给出锚固洞室中锚索预应力的变化特征:在洞室开挖过程中,两种锚索的预应力都普遍减小,但自由式锚索减小的较少(15%左右),全长黏结式锚索减小的较大(20%左右),减小的幅度平均为15%～22%。不同部位的单根锚索,其预应力减小的数值大小及所对应的部位都具有很强的随机性。在洞室超载过程中,锚索预应力普遍增加,增加较大的部位与侧压系数N有关,在N<1时主要是洞室两侧拱脚部位增加较大,拱顶和地板部位增加较小。无论是开挖过程中锚索预应力的减小,还是超载过程中锚索预应力的增加,都是锚索初始预应力较小的,锚索预应力相对改变量较大;否则则较小。因此,在确定锚索超张拉比值时,对不同吨位的锚索应取不同的比值。对吨位较大的应取较小值,对吨位较小的应取较大值。对锚固工程设计和现场施工具有重要参考价值。更多还原

【Abstract】 By geomechanical model tests,the variation characteristics of tension in non-bonded prestressed anchor cable and fully grouted anchor cable during the underground opening excavation and overloading are given. Based on the analysis of the developed charts of the variation of tension in cables,it is found that the tension in the two types of cables generally decreases and the average range is 15%22% during the underground opening excavation. The variation magnitude of tension decreases and the corresponding position of each anchor cable in different places obviously show randomness. In overloading process of the model test,the tension generally increases and the position where the tension increases is relevant to the coefficient of horizontal pressure of the model. The tension in anchor cables installed in the arch ends increases more and that in anchor cables installed in the arch crown and the floor increases less when the coefficient of horizontal pressure is less than 1(N<1) . Whether the tension in anchor cables decreases during the opening excavation or increases during the opening overloading,the relative increment of tension is more for anchor cables with low initial tension,otherwise,the relative increment of tension is less. Consequently,the different ratio of tension in anchor cables should be taken for anchor cables with different initial tension load. A low ratio should be taken for anchor cables with high initial tension and a high ratio should be taken for anchor cables with low initial tension load. Several suggestions are provided for the design and field construction of anchor cable.更多还原