Xiang Fu

Storm surge is one of the primary causes of marine disasters in China, especially tropical storm surges. Numerical model forecasts serve as a critical reference in storm surge operational prediction. The precision of the storm surge simulation is largely contingent upon the accuracy of the input driving forces. The prevailing typhoon storm surge numerical models typically utilize a model wind field derived from tropical parameters as the driving force, ensuring both accuracy and timeliness. However, these statistical models based on the classical wind-pressure relationship or the principle of gradient wind often fail to capture the true asymmetry of the tropical wind field, particularly when the tropical structure is distorted by coastal topography or interactions with other atmospheric systems. Therefore, we upgraded the GPU version of the high-precision operational storm surge forecasting model for the China Sea, by incorporating remote sensing wind data from HY-2B、2C and 2D satellites to assimilate and correct the model wind driven field. Hindcast and forecast cases demonstrated the improvements of calculation results, especially in areas impacted by the right half of the tropical.

In view of the current situation where most studies on gas desorption characteristics are limited to the atmospheric pressure desorption environment, we have independently developed a coal methane desorption instrument to test the nonatmospheric pressure desorption characteristics for coal particle gas beneath the condition of desorption damage. The instrument can arbitrarily adjust the gas pressure in the range of measurement while controlling the instantaneous release of excess gas to keep the desorption environment pressure constant. We measured the methane desorption amount of coal samples with different desorption times within 3 h and calculated the desorption velocity. The results show that the final desorption amount and desorption velocity of gas scale up with the increase of times, and the final desorption amount of coal sample W-01 increases the most, which is 18.5%. With the passage of time, the diffusion coefficient decreases gradually, and the number of desorption times is directly proportional to the diffusion coefficient. Its relative deviation of diffusion coefficient between different desorption times of the same coal sample can reach up to 40%, and the desorption time in the range of 5 to 30 min is the area with high relative deviation. A quantitative index K_i of a double-parameter damage model based on desorption conditions and adsorption pressure is proposed, and the damage extent of each sample is evaluated. The damage quantitative index of coal sample W-01 is the highest, which is 0.87. The methane desorption model of coal under the condition of desorption damage is constructed, and more than 30 groups of experiments are verified.

There is a positive feedback mechanism of desorption, pulverization, and redesorption in the process of coal and gas outburst. The coal pore structure changes to some extent in the process of coal pulverization and has a related impact on the dynamic parameters of coal particle gas desorption. To understand the impact of desorption damage on the dynamic characteristics of coal particle gas desorption, in this paper, a self-developed coal particle gas desorption test device is used to measure the amount of methane desorption of different coal samples repeatedly desorbed under the same adsorption equilibrium pressure. The results show that the methane desorption kinetic curves of the four coal samples based on desorption damage basically have the same trend. Nie's diffusion model can better describe the methane desorption characteristics of coal particles. After desorption, the methane desorption amount, initial desorption velocity, diffusion ability, and ultimate amount of methane desorption of the coal samples are greater than those before desorption. The desorption damage affects the relevant dynamic parameters of the coal particle gas diffusion model, and its impact on the outburst coal is greater than that on raw coal. In addition, the pore size distribution and change characteristics of the coal samples before and after desorption are analyzed quantitatively via a low-temperature liquid nitrogen adsorption test and fractal dimension-related theory. It was found that the pore volume peak area of the coal samples affected by desorption damage within each pore size range was significantly larger than that before desorption. Among them, micropores have the most significant impact on the desorption damage of coal samples, and the peak area of the pore volume of protruding coal is greater than that of raw coal, indicating that the internal pores of coal after desorption damage are more developed than those of raw coal.

A storm surge hazard indicator was developed based on the storm surge index and high-water index. Based on this indicator, the storm surge hazard along the Chinese mainland coast was evaluated. Storm surges were simulated by the GPU-based high-resolution 2-D hydrodynamic operational storm surge model, driven by ERA5 reanalysis data. High waters were calculated from coastal warning water. The results show that the storm surge hazard of more than 80% of the mainland coast are moderate and low. The coast with a high-level storm surge hazard was distributed at the top area of Hangzhou Bay, in the Pearl River Estuary, along the eastern coast of the Leizhou Peninsula and in the coastal area of Guangxi Province, representing less than 20% of the total coast. In future work, different sea level rise scenarios will be considered in this indicator and method.

As the infrasound signal has the advantages of slow energy attenuation, strong ability to cross obstacles and no need of contact acquisition, it is of great significance to take advantage of the infrasound signal in the process of deformation and failure of rock and soil mass to realize remote rapid monitoring and early warning of geological disasters. The infrasound signal characteristics of soil slope failure and rock under different stress states (compression, shear and tension) were compared by indoor and outdoor tests. The results showed that there was an obvious waveform of infrasound signal at the site of soil slope damage. The infrasound signal appeared mainly in elastic and plastic deformation stages under the compression state, the peak frequency of the infrasound signal was about 7 Hz. The concentration of signal power was slightly less than that under the compression state, and the peak frequency was about 8 Hz. The infrasound signal always associated with the whole loading process under tension state, and there were two bands of frequency center, in which the lower frequency was close to that of the compression test specimen, and the higher frequency was 3 Hz larger. On this basis, using the infrasound characteristics of rock and soil mass failure, the infrasound and other monitoring methods were carried out for Xinpu landslide in Fengjie, Chongqing, China. After the occurrence of the landslide, the infrasound signal characteristics of rock and soil failure were basically the same as those of indoor tests. The low-frequency signals were mainly monitored. At the same time, the monitoring results showed that the peak value of the infrasound signal reached before the mechanical signal, and the mechanical signal was monitored prior to the displacement signal. The infrasound signal can be 3-5 hours ahead of displacement signal. This regularity has important scientific and application value for landslide monitoring and prediction.