Anchorage is an effective way of reinforcement in the rock and geotechnical engineering, such as slopes, underground caverns, tunnels and foundations, etc. The study of the effectiveness and the mechanism of the anchorage is always one of the hottest topics in the field of geotechnical engineering. In this paper, on the basis of comprehensive understanding of ULAC(Unified Lagrangian Analysis Code), a kind of serial Lagrangian Element program, and PULAC(Parallel ULAC),which are coded previously in the institute of ourselves, the reinforcement module for the two programs is developed, which can be used to model the effect of a variety of reinforcing elements, such as rock bolts, anchors, and nails. They are verified by some numerical examples, and the results obtained from ULAC and PULAC are consistent with the results of analytical method and the well known code of FLAC3D.
Anchorage is an effective way of reinforcement in the rock and geotechnical engineering. The study of the effectiveness and the mechanism of the anchorage is always one of the hottest topics in the field of geotechnical engineering. Lagrangian analysis program is widely used in the field of geotechnical engineering in recent years. Many scholars analyze the problem of anchorage in geotechnical engineering by ripe commercial Lagrangian analysis programs like FLAC & FLAC3D. Yang Guihua etc.  used FLAC in the calculation of bolt support on coal goaf, and contrasted the deformation of surrounding rock between before and after the bolt support. The result shows that the anchor is useful in the controlling of the vertical deformation of surrounding rock. Qi Taiyue etc.  modified the model of bolt element in FLAC3D 3.3, and made it can simulate the process of damaging and softening of rock bolts. Feng Guangming etc.  researched the anchorage effects in primary anchoring force by using FLAC program. The Lagrangian analysis and the commercial software like FLAC and FLAC3D is universally accepted and widely used in the field of geotechnical engineering, but the literature about the realization of algorithm and the further research is rarely seen, which brings difficulties in the development of algorithm and software. In this paper, on the basis of ULAC (Unified Lagrangian Analysis Code) and PULAC (Parallel ULAC) which are coded previously in the institute of us, we researched the mechanism of rock bolt element in Lagrangian analysis, developed the anchorage module for the two programs, and carried on the confirmation with the numerical example. ULAC is a kind of serial Lagrangian element program compiled in C language . ULAC makes a uniform treatment in two-dimensional and three-dimensional Lagrangian analysis program.