On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution──origin and evidences of the strong body earthquake──generating model

According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific problems whichmust be studied i, the elucidation emphasizes that the core of this project is to study the conditions and processesof the generation of strong earthquakes. The paper first outlines the origin and development of the'strong-bodyearthquake-generating model' proposed by the author in the 1980;and then proves the reasonableness of themodel from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. Bystudying the tomographic image for the northern part of North China, it can be seen that the sources of strongearthquakes are all distributed in high-velocity bodies,or in the contact zone between high-velocity and lowvelocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical modelsof hard and soft inclusions that the existence of a hard inclusion is an imPOrtant condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability,sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmentalstiffness.

Fractured zone height of longwall mining and its effects on the overburden aquifers

As mining depth becomes deeper and deeper,the possibility of undermining overburden aquifers is increasing.It is very important for coal miners to undertake studies on the height of fractured zone during longwall mining and the effects of longwall mining on the underground water while mining under surface water bodies and underground aquifers.In order to study this problem,piezometers for monitoring underground water levels were installed above the longwall panels in an American coalmine.Large amounts of pre-mining,during mining and post-mining monitoring data were collected.Based on the data,the heights of fractured zones were obtained and the effects of longwall mining on the underground water were studied.The results demonstrate that when the piezometer monitoring wells had an interburden thickness of less than 72.7 m,the groundwater level decreased immediately to immeasurable levels and the wells went dry after undermining the face of longwall.The height of the fractured zone is 72.7-85.3 m in the geological and mining conditions.The results also show that the calculated values of fractured zones by the empirical formulae used in China are smaller than the actual results.Therefore,it is not always safe to use them for analyses while mining under water bodies.

Effect of BMI on outcomes of surgical treatment for tibial plateau fractures： A comparative retrospective case series study

Purpose： Tibia plateau fracture （TPF） treatment aims at achieving a stable, aligned, mobile, painless knee and preventing post-traumatic osteoarthritis. To achieve this goal, surgeons consider criteria such as patients＇ characteristics, severity, risk of complications, fracture displacementJdepression, degree of soft tissue injury. However, body mass index （BMI） is not considered as a risk factor in literature. Our study was conducted to find out any possible correlation between BMI and functional scores or radiological score separately. Methods： Retrospective analysis of case series between 2011 and 2014 was done on the database of a tertiary hospital in Istanbul. There were 67 TPF patients （54 males, 13 females） in the study. Relationship between BM1 and functional knee scores or radiological score was compared statistically. Closed fractures with both high-energy and low-energy injury were included in the study. Patients with open fracture, multi-trauma presence, meniscus and/or ligamentous injury, increased co-morbidity, inadequate records （25 cases in all） were excluded. Surgery type, Schatzker classification, injury side, trauma energy, and gender were considered as possible risk factors. Binary regression analysis was done for possible factors affecting functional knee scores and radiologic score. Results： Model summary calculations were done as Nagelkerke R2 test for Knee Society score, Lysholm knee score, and Ahlback and Rydberg radiologic scores, which were 0.648, 0.831, and 0.327 respec- tively. Homer-Lemeshow test values were 0.976, 0.998, and 0.362, respectively. There is negative correlation between BMI and both knee function scores. There is no correlation between BMI and radiologic score. Conclusion： An increase in BMI has a negative effect on functional knee scores after surgical treatment of TPFs. Therefore, BMI should be considered as a risk factor for surgical treatment of TPFs.