To strengthen underground arch structure, the method with near-surface bonded carbon fiber reinforced polymer (CFRP) strips is proposed. A nonlinear finite element program is built to analyze concrete arch structure strengthened with CFRP. Factors that influence the strengthening effect are discussed. After arch strengthened with near-surface bonded CFRP strips, the cracking load, the yield load and the ultimate load has been greatly improved, the stiffness has also been greatly improved. The bearing capacity and the stiffness of arch structure increase with the layer quantity of CFRP increasing, increase with the strip quantity of CFRP in units increases. In the condition of the layer quantity and the strip quantity of CFRP being identical, the increasing ratio of load decreases with the reinforcement ratio increasing.

Theory equations and specification equations are currently main methods to calculate wall rock pressure. These equations are created in certain backgrounds, and are applicable in certain ranges, not fit for deep-buried or large span tunnels. Analysis methods combined with actual project are used, and measured data are contrasted with the theoretical results. Common used calculation equations are discussed from the aspects including calculation accuracy, the relationship with buried depth and the relationship with span of underground structure. Revised calculating equation for wall rock pressure of deep-buried and large-span tunnel are put forward, and is proved to be better on the aspects above. It has significance in theory and practice.

Numerical simulation method was used to study the problems on critical anchorage length of bolts. 3-D calculation model was built by FLAC program. By numerical simulation calculations, the conclusion could be drawn: the frictional resistance contribution had nothing to do with drawing forces, and was relevant to the bond stiffness of anchor mortar. And comparative analysis results of one engineering example showed that the calculated values by the presented method agreed well with the measured data.

To control thermal cracks of concrete of thick arch lining of tunnel of big pan, based on basic assumption, the formula calculating thermal stress of arbitrary position and the maximal stress in arch lining restricted by surrounding rock is deduced. Moreover, the formula of thermal stress of arbitrary position, the maximal thermal stress is also presented, when the thick of arch lining varies according to the law of cosine. The change of temperature of concrete of arch lining in practical engineering is monitored. The maximal thermal stress in arch crown surface and the thermal stress in surface along the axis of arch are calculated using the formula deduced above is presented and is contrasted with its real strength. Conclusions show that the thermal stress in arch crown is the maximal stress, concrete lining do not crack under the condition of thermal stress less than its strength.