Seismic energy response and damage evolution of tunnel lining structures

Yuan²,

et al. 2020

Shock and Vibration

It has generally been believed that the serious seismic damage of tunnel mainly occurred in portal section and fault dislocation zone. However, the survey of seismic damage showed that the seismic damage of tunnel also mainly occurred in geological section at interface of soft and hard rock. Currently, merely scholars have made some research studies on characteristics of seismic damage and damping technology of tunnel crossing the vertical interface between soft and hard rock in high intensity area, and the mechanism of seismic damage has not been clearly revealed. Therefore, based on the Urumqi Metro Tunnel project in China, a three-dimensional six-degree-of-freedom shaking table model test was carried out. Through comparative analysis of peak ground acceleration (PGA), displacement difference at the interface between soft and hard rock, and structural safety factor under 5 kinds of conditions, the seismic damage characteristics of tunnel crossing interface of soft and hard rock were revealed, and a new damping technology of absorbing joint was proposed. The following findings can be drawn. (1) The seismic damage of tunnel is mainly affected by stratum inertial force under the homogeneous stratum of soft rock. The seismic damage of tunnel is mainly caused by the forced displacement (the displacement difference between the two sides of interface of soft and hard rock), followed by stratum inertial force under the geological condition of interface between soft and hard rock. (2) The conventional type of absorbing joint (only the second lining is set with absorbing joint) is used in tunnel lining structure, and the damping ratios of principal tensile stress, bending moment, and axial force of lining are above 47.5%, 40.7%, and 72.7%, respectively. Compared with conventional type of absorbing joint, the damping effect of new type of absorbing joint (staggered absorbing joints of primary support and secondary lining) is 19.9% higher than that of conventional type. (3) The new type of absorbing joint is recommended for tunnel crossing interface section of soft and hard rock. The specific implementation suggestions are as follows: the setting interval of second lining absorbing joint is the same as the length of lining formwork trolley, and the interval of primary support absorbing joint can be set according to excavation footage length. The filling materials in second lining absorbing joint can be shared with the rubber waterstop set in construction joint, and the primary support absorbing joint can be realized by injecting mixtures of rubber particles and shotcrete.

Section: Introductionmentioning

confidence: 99%

Experimental Study on Characteristics of Seismic Damage and Damping Technology of Absorbing Joint of Tunnel Crossing Interface of Soft and Hard Rock

Yuan²,

et al. 2020

Shock and Vibration

“…In China, the transportation infrastructure in the West has been developed continuously, and the traffic lifeline projects in high earthquake intensity and dangerous mountainous areas have been vigorously carried out. Tunnels crossing active faults have emerged, such as the Lanjiayan Tunnel from the highway of Mianzhu to Maoxian in Sichuan Province (through the Longmen Mountain Branch Fault), the Erlangshan Tunnel on the Yakang highway (through the Baohuang and other active faults), and the series of tunnels on the Jianchuan-Tibet Railway (through the Longmen Mountain, Xianshuihe, Jinsha River, Basu, and other active faults) [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Model Tests on the Antibreaking Countermeasures for Tunnel Lining Across Stick‐Slip Faults

Advances in Materials Science and Engineering

et al. 2020

In order to improve the structural safety and stability of the tunnels crossing stick-slip fault, an indoor model test on the effect of tunnel antibreaking measures under the influence of fault stick-slip movements was conducted. Using contact pressure, longitudinal strain, and safety factor, the antibreaking effect of tunnels was compared and analyzed under 5 kinds of operating conditions, mainly including no measures, structural strengthening, structural strengthening and reducing dislocation layer, structural strengthening and reducing dislocation joint, structural strengthening and reducing dislocation layer, and reducing dislocation joint. The results showed that the longitudinal strain and contact pressure of the tunnel changed markedly (from severe change to more uniform change) when the reducing dislocation measures were adopted in the test, reducing dislocation layer/joint or reducing dislocation layer and reducing dislocation joint. The effect of reducing the fault stick-slip dislocation on the tunnel structure is very limited by only taking structure strengthening measures. The effect of reducing the fault stick-slip dislocation on the tunnel structure is obvious by using the reducing dislocation method, and the minimum safety factor is increased by more than 8 times. The effect of resisting and reducing the fault stick-slip dislocation on the tunnel structure is remarkable by adopting the measures of the structural strengthening and reducing dislocation layer and reducing dislocation joint, and the minimum safety factor is increased by more than 25.45 times. The results can provide reference for the design of antibreaking for the stick-slip fault tunnel in high earthquake intensity and dangerous mountainous areas.

“…In view of the problems of tunnel frost damage in cold areas, the tunnellers have carried out the research work on the temporal and spatial variation law of temperature field [1][2][3][4][5][6][7][8][9], thermal insulation, and prevention measures of frost damage [10][11][12][13][14][15][16]. However, the research on the intelligent evaluation system of tunnel frost damage in cold regions is rarely reported, mainly including as follows: according to the average temperature and freezing depth of the coldest month, the Qinghai-Tibet Plateau, Inner Mongolia, and Northeast China are divided into three cold regions, and the characteristics of frost damage are analyzed according to different cold regions [17].…”

Section: Introductionmentioning

confidence: 99%

Study on the Intelligent Evaluation System of Tunnel Frost Damage in Cold Regions Based on the Fuzzy Comprehensive Evaluation Model

Zhu

Mathematical Problems in Engineering

et al. 2020

At present, the tunnel design specifications in China do not provide a clear and systematic intelligent evaluation system of tunnel frost damage in cold regions. Based on the research results of 122 seasonal frozen soil tunnels in high-latitude areas of China, four key influencing factors of geohydrology, temperature, surrounding rock, and engineering measures were determined, the intelligent fuzzy comprehensive evaluation model was established, the weights of all factors were considered, and the intelligent evaluation technology system of tunnel frost damage in cold areas had been put forward. Meanwhile, the rationality of the intelligent model was verified by a specific engineering case. The research suggests that the intelligent evaluation model of tunnel frost damage proposed in this paper can accurately describe the relationship of influencing factors of tunnel frost damage in cold areas, the weight of each influencing factor is calculated by using analytic hierarchy process, and the main risk sources of tunnel frost damage in cold areas are found out. The intelligent evaluation model is an efficient and practical method for Intelligent prediction of frost damage. By using the subordinate function method, the improvement from qualitative analysis to quantitative index calculation is realized. The blindness of engineering analogy construction is avoided, and the scientificity and accuracy of renovation measures for frost damage have been improved. At the same time, the research results provide a theoretical basis for the improvement of the intelligent evaluation system of tunnel frost damage in cold regions.