A New Residual Subsidence Prediction Method of Short Working Face Goaf for Safety Construction of Urban Viaduct.

The planned viaduct in Jining, Shandong is a priority project in the city. However, the 63 working faces of a mine in Jining is only 3 m away from the planned viaduct, posing a serious threat to the safety of the viaduct's construction. Consequently, it is essential to evaluate the stability of the planned viaduct's goaf area under the influence of the 63 working faces. However, the 63 working faces are short faces, and there is a lack of corresponding prediction of surface residual subsidence. To address this issue, this paper employs theoretical analysis and numerical simulation to uncover the foundation deformation mechanism and characteristics of fractured rock and soil mass in the short goaf. Subsequently, a residual subsidence prediction method for the short goaf was proposed for the viaduct mined-out area. This new approach was implemented for the planned viaduct in Jining, and its effectiveness was validated through InSAR and leveling monitoring results. The research findings offer technical support for viaduct construction in areas affected by underground mining.

[The clinical results of combined periodontal-orthodontic treatment on patients with periodontitis and labial displacement of incisors].

PURPOSE: To evaluate the clinical effects of combined periodontal and orthodontic method in treating labial displacement of anterior teeth caused by periodontitis. METHODS: 21 cases with periodontitis and fly-out of anterior teeth were selected. After the inflammation was controlled by essential periodontal therapy, the anterior teeth were allied by edgewise appliances; meanwhile, periodontal care and occlusal adjustment were conducted to control inflammation and occlusal trauma, until normal occlusion was established. A total of 74 teeth were treated, the periodontal probing depth and the degree of alveolar ridge resorption was recorded before and after treatment, respectively. All the data were statistically analyzed by Ridit test and Chi-square test. RESULTS: After 1-2 years of follow-up, all cases under 40 years got satisfactory effects, with significantly decreased periodontal probing depth (P<0.01) and alveolar ridge (P<0.05). CONCLUSIONS: Combined periodontal and orthodontic treatment was effective in the management of periodontitis, occlusal trauma and teeth alignment, and the effects were stable for a relatively long period. But patients over 40 years was not suitable for the treatment.