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In order to study the fire detection method of cable tunnel. We carried out physical experiments in the cable tunnel test section, using the heater pyrolyze PVC so that its pyrolysis as the ignition source obtained a total of 17 fire source location points in the horizontal and vertical directions of seven different fire detectors, and only processed the response time data of the alarm detector obtained the response time and the analysis results were drawn. With the increase of the distance from the fire source, the response time of each type of detector increases in different forms. It is found that the detection distance of the grating fiber temperature sensor is shorter, and the response time near the fire source is more stable. The detection performance of the point pyrolytic particle detector is more affected by the detection distance, which is advantageous for the detection point to have better response performance. The intelligent active suction detector is also affected by the detection distance, which is less affected than the point detector, the response time curve is more stable, and the detection performance is better at each test point. Clc number: X Document Identification Code; A.

Smoke mass flow rate (SMFR) is an important factor for smoke control in tunnel fire. The presence of bifurcation structure can lead to the flow redistribution and distinctive characteristics. In the current study, a relational expression for the SMFR in branched tunnel was theoretically derived. A series of numerical simulations with Fire Dynamics Simulator(FDS) were conducted to investigate the effects of multiple factors on the smoke mass flow and validate the predictions. The results indicated that for a T-shaped tunnel, the amount of smoke flowing into the branch is mainly depends on the thickness and temperature of the incoming smoke flow from mainline, affecting by heat release rate(HRR) and tunnel section size, while the influence of the bifurcation angle and longitudinal position of fire source is unremarkable. Fairly good agreement was achieved between the predictions and simulation results. This research can be instrumental in estimating the SMFR in T-shaped tunnel fire scenarios and offer valuable insights for smoke management strategies.