Prediction method for fatigue reliability of cable support in subway tunnel

Abstract

The invention discloses a prediction method for fatigue reliability of a cable support in a subway tunnel. The method comprises: considering nondeterminacy of model parameters, using a response surface method to generate parameter samples; according to the parameter samples, establishing a finite element model, converting a track irregular spectrum to an irregular spatial waveform, used to adjust node coordinates of steel rail nodes in the model; the steel rail node being provided with a vertical pressed non-pulled unit, used to simulate wheel-rail contact; establishing a train-rail model, a tunnel-soil mass model, and a support-cable model and solving, to obtain stress time-history of the node on the root of the support, amplitude of the node being maximum; using a rain-flow counting method to calculate fatigue life; according to the parameter samples and a fatigue life value to fit the response surface and calculating a reliability index; accordingly, a series of fatigue life target values can be assigned, calculating the corresponding reliability index, so as to draw an invalid exceedance probability curve of the support.

Description

technical field [0001] The invention relates to a method for predicting the fatigue life of a cable support, which belongs to the field of structural dynamic response and fatigue life prediction. Background technique [0002] For a typical three-story circular tunnel, the cross-section is divided as follows: the uppermost layer is the exhaust duct, the middle layer is the carriageway, and the lowermost layer is the cable and pipe gallery passage. This kind of tunnel integrates traffic, fire protection, communication and other functions without setting up additional passages, which reduces construction risks and project costs. The heavy-duty power cables are placed in the lower empty box (ie, the lower structure) through the bracket, and the track is installed on the roof of the empty box for running the subway train, so the cable bracket will be directly subjected to the vibration load from the subway. A large number of studies have shown that although the amplitude of this...

AI Technical Summary

Problems solved by technology

However, the actual measurement method has the following three disadvantages: first, the pipeline is generally constructed parallel to the tunnel, and this method is actually carried out after the cable is installed, which cannot provide guidance in the design stage; second, the measurement point is in a closed empty box. This has high requirements on the power supply and communication on site, which increases the difficulty of testing; thirdly, due to the large randomness of subway vibration, especially the uncertainty of geological data and structural parameters, it is necessary to conduct multiple tests at the same point. The appropriate time history curve can only be determined after sampling, which also means that the data of a certain test cannot provide reference for other projects

In addition, considering the randomness of some parameters in the model, if a random sample combination is used to model, it will lead to thousands of repeated calculations, and the process is very cumbersome

Images