Numerical modeling of non-deformable support in swelling and squeezing rock

Choosing the support system in swelling and squeezing rocks is one of the challenges for rock engineers. There are many factors that need to be considered such as support type, performance of the support, the support element, rock parameters, condition of the rock structure, and creating an appropriate support strategy. TH-type steel supports, which have long been used in deep underground mine headings, have recently started to be used as yield-control support system in tunnels. However, sliding ability of the TH steel support allows cross-section contractions. If the amount of convergence can not be calibrated, re-shaping studies have to be done at the excavated areas due to the occurrence of time-dependent creeps, especially in swelling and squeezing rocks. Also, numerical model studies for highly swellable and/or squeezable rocks must represent the time-dependent creep behavior of the rock. Simple stiffness parameters such as time-dependent creep, swelling index, and compression index should be addressed into the model. It is possible to constitute a high performance support system in this swelling and squeezing types of rocks by choosing appropriate round interval, using a non-deformable and heavier I profile and using sufficient parameters obtained by analysis. The present paper presents in-situ measurements and the analysis of time-dependent numerical model of non-deformable support system at the T-13 tunnel which is applied to one of the 39 tunnels at Eskişehir–Köseköy high-speed railway route.

► In this study, swelling and squeezing rock behavior was analyzed. ► Determined time-depended deformation behavior of rock and tunnel. ► Defined the deformation problem. ► Designed a new support system. ► Solved the problem with numerical modeling. ► Compared the numerical model results and in-situ measurements.