Study On Inversion Of Standard Bollard Moorning Force And Optical Fiber Monitorning Method

The bollard of the port engineering facility is a key facility for transmitting the mooring force of the ship to the wharf structure.Affected by many factors,such as the enlargement of the ship,the irregular mooring of the ship,and the effect of abnormal wind and waves,the force state of the bollard is extremely complicated.Under the coupling effect of multiple factors,once the mooring force of the bollard exceeds the design value,it will not only cause damage to the structure of the bollard itself,but also bring serious consequences for the destruction of the wharf structure.The safety monitoring of the mooring bollard structure under complex mooring conditions has become a major safety issue that needs to be urgently resolved during the operation of the wharf.The existing technology mainly realizes the online assessment of the safety of the mooring bollard structure through the monitoring of the mooring line force.However,through research,it is found that the mooring force value is only a very shallow structural safety control index.The same mooring force value,under the influence of mooring angle,mooring direction,mooring position and other factors,has a The safety impact is very different.It is not a very effective method to directly monitor the mooring force to evaluate the safety of the bollard structure.With the support of Ningbo Transportation Science and Technology Project,a safety monitoring method for the mooring bollard structure using the standard condition inversion of the mooring force of the bollard structure surface strain is proposed.Research has been carried out in terms of aspects,the main research contents of this article are as follows:(1)The structural characteristics and stress characteristics of the bollard structure are analyzed,and the standard conditions for the setting of the mooring force are proposed based on the relevant specifications such as the "General Instructions for the Design of Bollard Components".(2)The force analysis model of the bollard structure under the mooring force is established,the formula for calculating the surface strain of the bollard is derived,and combined with the standard mooring conditions,the standard mooring based on the twopoint strain on the surface of the bollard is derived and established Force inversion model.Taking the 1500 k N single-sided eaves cast steel bollard as the generalized research object,the three-dimensional finite element sub-model of the bollard is established,the mechanical characteristics of the bollard under the action of the mooring force are simulated and analyzed,and the mooring boat is verified and optimized The calculation formula of the column surface strain and the standard cable force inversion model,the standard cable force is retrieved based on the measured point strain calculated by the finite element method,and the maximum strain is used as the basis for judgment.The results show that the maximum error between the inversion maximum strain and the finite element calculation result 7.704 * 10-6,the error ratio is 4.6%,which proves that the force state of the bollard structure under the standard mooring force is consistent with that before the inversion,and the inversion model is accurate.(3)According to the stress characteristics of the bollard and the characteristics of field operations,a five-point strain measurement scheme for the root of the bollard is proposed,and the method for monitoring the force state of the bollard structure based on the fiber grating sensor technology is designed and optimized.According to the number of bollards and the characteristics of the wharf structure,the networking method of optical fiber strain sensors and the layout of optical fiber links are proposed,and a cluster monitoring system for bollards that integrates data collection,analysis,storage is built.(4)Conducted field tests on typical bollards of Daxie China Merchants International Terminal,verified and optimized the construction process of bollard structure monitoring,continuously recorded mooring data under different mooring conditions,and performed real-time real-time standard mooring force and maximum strain Inversion,the maximum error of the inversion maximum strain is 11.01 * 10-6 compared with the measured result,and the error ratio is 8.39%.Considering the limited number of sensors,it is not guaranteed that the maximum strain can be measured every time.The inversion accuracy meets the requirements and proves the standard The force state of the bollard under the mooring force is consistent with that before the inversion.The inversion model is accurate and reliable.Substituting the inversion results into the bollard grading early warning mechanism can realize the safety assessment of the bollard,indicating that the monitoring method proposed in this paper can Achieve long-term,reliable and accurate safety monitoring of the bollard structure,without affecting the normal mooring work,without changing the original structure of the bollard,suitable for promotion on the built dock..