锚索与锚杆联合锚固支护岩坡的有限元分析

针对广东某高速公路74 m高的7级挖方边坡，采用三维弹塑性有限元数值计算方法分析山区路堑开挖岩质边坡的锚固支护的受力情况。分别计算了坡体无锚和3种不同的锚固方案。通过坡体无锚方案的计算确定坡体的滑动面并为锚固方案的设计提供依据。3种锚固方案中的预应力锚索和锚杆按不同方式进行了组合。所建立的锚固坡体三维有限元分析模型对锚固坡体进行了合理简化并节约了计算量。计算中锚索的预应力采用预先施加应变的方式施加。计算分析表明，边坡加锚后可显著减少边坡塑性区。实际工程中采用预应力锚索和锚杆交错布设方案进行边坡锚固支护可较好地达到安全与经济并重的边坡处治原则。现场监测结果表明，锚固边坡有限元分析合理可行。

Finite element analysis of rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt

Pointed to a seven-grade 74 meters high rock cutting slope in an expressway of Guangdong Province in China, three-dimensional elastoplastic finite element method is applied to analyze the rock cutting slope reinforced by combined action of prestressed anchor cable and anchor bolt in mountainous area. Anchorless scheme and three anchoring schemes of the cutting slope are analyzed respectively. Analysis of anchorless scheme identifies the slide face of the cutting slope and furnishes reasons to the anchoring schemes. In three anchoring schemes, prestressed anchor cable and anchor bolt are distributed by three different regulations in the cutting slope. The three-dimensional finite element analysis model of anchored slope simplifies the real anchored slope reasonably and thus the efficiency of computation is improved. In the finite element computation, the prestress of anchor cable is implemented by applying initial strain on the anchor cable elements as the loads. Computation results show that the combined action of prestressed anchor cable and anchor bolt can decrease the plastic zone of the slope effectively. Analyses show that the scheme with interlaced disposal of prestressed anchor cable and anchor bolt in each slope grade is the best scheme in three anchoring schemes for both safe and economical; and this scheme is applied to the practice of reinforcement for the above slope. Comparisons with the monitored displacements of the reinforced slope confirm the behavior predicted by the finite element analysis.