As one of the largest coastal wetlands in northern China, the ecological function of Caofeidian wetland has gradually degraded due to the influence of climate and surrounding environment. In order to regulate and repair the water area of the wetland, it is necessary to study and analyse the historical changes and influencing factors of the water area of Caofeidian wetland This paper extracts the water area of Caofeidian Wetland in 1984~2013 from the images collected by Landsat satellites using the normalized difference water index (NDWI), and analyzes the causes of water area variation in the wetland according to the climate data of Caofeidian Meteorological Station and the Tangshan Statistical Yearbook. The main conclusions are as follows: (1) the water area of Caofeidian wetland had been fluctuating in 1984~2013, showing a slow upward trend. (2) Considering the water area variation and the climate data of Caofeidian Meteorological Station, it is concluded that the mean precipitation of Caofeidian Wetland showed a slight decrease while the annual mean temperature exhibited a slow increase. The correlation analysis reveals that the water area variation is not highly correlated with annual precipitation or annual mean temperature. Thus, the natural factors have a slight impact on the water area variation in Caofeidian Wetland. (3) Based on the water area variation and the data in the Tangshan Statistical Yearbook, the author discovered a prominent growth in resident population in Caofeidian District, and a huge increase in the local aquaculture area. The correlation analysis shows that the water area variation in the wetland is highly correlated with the resident population and strongly correlated with aquaculture area. Because Caofeidian wetland is located in the underdeveloped areas of industry and economy, local people have built a large number of breeding ponds in the wetland, so the main influencing factor of the wetland water area is the breeding area, followed by the permanent population.

This paper establishes the physical model of the prototype tailings pond using the similarity theory by taking a heightened and expanded project of tailings reservoir in Chengde, Hebei Province as an example and studies the process and mechanism of partial failure of the tailings reservoir when the drainage system fails by adopting the model test of the dam failure. The result shows that the dam damage can be divided into three categories: soil flow damage, gully damage and collapse damage. In addition, this paper analyzes the reasons for the three categories of damages.

Abstract-This Based on the stope in HeBei province, the sliding failure mode and treatment measure after the excavation of the stope is discussed. The RMR methods and the GS I methods are both used to estimate the mechanical parameters of the rock mass, and the smaller parameters are selected for the stability calculation. The numerical simulation of the slope excavation by finite element is carried out, and the development of the displacement and plastic zone during the excavation are analyzed. Furthermore, the stability analysis of the excavated slope is carried out, and the results showed the safety factors cannot meet the standard requirement. Then the bolt support are used to reinforce the excavated slope, and the calculation results show that the safety factors of the reinforced slope can meet the requirement of the relative standards.Keywords-mine stope; stability of the slope; plastic zone; bolt support I. INTRODUCTION Stability analysis of rock slope is a systematic engineering, including influence factors of slope instability, stability prediction, the value of shear strength parameters of rock, stability analysis and prevention measures, et al [1][2][3][4][5] . The individual qualitative analysis or quantitative analysis cannot completely reflect slope status. This paper takes the actual project as an example, carried out preliminary study fro m field measurement about main influencing factors of instability, qualitative judgement of instability, laboratory test and the occurrence of structural plane, the value of shear strength parameters of rock and finite element analysis, in detail introduced the process of stability analysis, using energy method for stability analysis of slope that divided sliding soil into multiple-b lock mode, then based on Mohr-Coulomb failure criterion and associated flow rule, structure a coordinated displacement field, and according to principle of virtual work, obtained upper limit of slope safety factor, and gave governance suggestions.

Based on the actual tailings reservoir project, a model test study on the evolution pattern of dam-breaking debris landslide is carried out. According to the similarity criterion of water flow and mud-sand movement, coal dust satisfying the similar relationship is selected as model sand. By analyzing the dam-breaking debris landslide’s range, propulsion speed, submerged depth distribution and particle deposition characteristics, the movement pattern of the landslide is obtained. In the short time after the dam break, the submergence range and advancing speed of the debris landslide increase rapidly. During the propulsion process, due to the increase of the debris landslide in the downstream of the valley, the debris landslide is diffused and the energy consumption during the flow is made. The advancing speed decrease until the landslide stops; The final submerged depth distribution of the dam breach has obvious randomness and non-uniformity, which is mainly related to the downstream terrain; According to the particle size grading analysis of the soil sample at the characteristic location, the further away from the dam toe, the finer particle content in the debris landslide.

Due to different soil strengths, drilled bored piles and slurry-supported bored piles affect the side friction. Through the application of post grouting technology, the friction resistance and bearing capacity of piles can be improved. In this paper, an analysis was conducted on the strength increasing rule of the side drilled bored hole and the side slurry-supported bored pile after post grouting at different ages, by means of chemical reinforcement. The results show that: the post grouting technology has better effect on the slurry-supported bored piles, especially in poor ground conditions, and that the strength on the 120th day can be used as the design strength. Our research achievements can provide a theoretical basis for the post-grouting technology in engineering work.