Influence of Existing Defects on Mechanical Properties of NC Lining

Abstract

The mechanical properties of the lining are directly affected by defects such as voids behind the lining and insufficient thickness of the lining. In order to quantitatively evaluate this effect, the mechanical behavior of the lining under the influence of the void behind the lining, the insufficient thickness of the lining, and the combination of the two kinds of defects are adopted by the 1/5 scale model test. Based on the experimental research, numerical calculation models based on the CDP model for defect lining are established, with the effects of load direction, stratum stiffness, defect location, defect type, and degree on the mechanical behavior of the lining analyzed by the numerical simulation. The experimental and numerical results show that the void weakens the stiffness of the lining. As the void range increases, the lining becomes more deformable and its bearing capacity decreases with the “S” curve. Thinning significantly reduces the deformation properties of the lining and the bearing capacity and stiffness of the thinned section. The lining bearing capacity decreases linearly with the increase of the thinning ratio, when the load is applied at the thinning. With the influence of combined defects on the load-displacement curve of the lining fluctuating drastically, the mechanical properties of the lining are significantly reduced. The bearing capacity of lining decreases with the increase of composite defects in a “S” shape. The effect of void and lining thinning on the lining bearing capacity increases with the increase of the stiffness of the formation. The loss rate equation of the concrete lining bearing capacity under the influence of existing defects is established by using the L-M nonlinear regression analysis, a provision of scientific guidance for the safety evaluation of the defect lining.

Finite Element Analysis Model Design on the Mechanical Properties of Prefabricated Shear Wall Structure

“…According to Figure 6, it can see that with the increase of the displacement, the hysteretic curve of the specimen tends to be full and the energy consumption increases gradually. The energy dissipation capacity of the specimens under high axial compression ratio is relatively large, whether it is the connecting steel or the connecting steel plate in the prefabricated shear wall structure [22][23][24].…”

Numerical Investigation on the Mechanical Properties of Vault Void Lining and Steel Plate Strengthening

“…The results showed that the stress state of the lining changed from an axial thrust to a bending moment due to the existence of the void. Zhang et al [ 17 ] considered the voids caused by insufficient thicknesses and established a numerical model for strengthening the lining based on a CDP model. By analyzing the influence of void location, void type, and degree on the mechanical properties of the lining, the results showed that the stiffness of the hollow lining had a weakening effect.…”

Numerical Investigation of Longitudinal through Voids in Tunnel Secondary Lining Vaults and Steel Plate Strengthening

“…It was found that the void significantly reduced the bearing capacity of the lining, as well as increased the local deformation, and significant lining cracking showed at the void location. Zhang et al [ 20 ] verified the effect of voids on lining in Ding’s test [ 19 ] by building a numerical model of CDP. The results showed that the bearing capacity of the lining decreased in an ‘s’-shaped curve with the increase in void.…”