Abstract
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.
Highlights
In recent years, more and more tunnels in the world pass through active faults
Only few scholars have made some researches on the antibreaking technique of the tunnel under the influence of the fault stick-slip dislocation. e damage mechanism of tunnel structure was not clear, and failure characteristics as well as damage mechanism of surrounding rock cannot be detected in spite of adopting many different numerical simulation techniques [15]. us, indoor model tests would be the best method to study the mechanical response of tunnel structures and surrounding rock under stick-slip fault circumstances
The increase multiple of the minimum value of the safety factor was 21.16 times, 16.18 times, and 25.45 times. It shows that the effect of resistance to the fault stick-slip dislocation on the internal force of tunnel structures is limited by only adopting the structural strengthening measures
Summary
More and more tunnels in the world pass through active faults. 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. A series of comparative studies on the Koohrangs hydraulic tunnel in Greece were carried out to prove the effect of dislocation joints on secondary lining with different spacing under the influence of the stick-slip fault [17]. Different from the former, a series of model tests were carried out to study the effect of antibreaking joints on the secondary lining to reduce lateral dislocation with the stickslip fault dislocation. Erefore, these series of researches are based on the F8 viscous slip fault of Longxi tunnel on Dujiangyan-Wenchuan highway, deeply studying the antibreaking technology for structural strengthening. It is of great significance to the further development of the antiseismic and disaster reduction technology in the high intensity and dangerous mountainous traffic tunnels
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