No abstract

The aim of this study was to clinically compare the therapeutic effects of internal fixation using a third-generation Gamma Long Nail (TGLN) with that of INTERTAN in the treatment of Seinsheimer Type V subtrochanteric femoral fractures in elderly patients. The therapeutic effect of internal fixation with TGLN, compared with that with INTERTAN, was retrospectively analyzed in elderly patients diagnosed with Seinsheimer Type V subtrochanteric fracture. Twenty-five cases were divided into 2 groups based on the fixation devices: the TGLN group (13 cases; 5 men and 8 women) and the INTERTAN group (12 cases; 5 men and 7 women). Patients were followed up postoperatively, and their clinical history, intraoperative blood loss, fracture healing, Harris Hip Scores, and postoperative complications were recorded and compared. Patients in the TGLN group had shorter operation time and less intraoperative blood loss, compared with those in the INTERTAN group ( P < .05). There were no significant between-group differences in postoperative complications, fracture healing time and Harris Hip Scores during the follow-up ( P > .05).

The fracture of rocks surrounding the floor roadway during the mining of the working face of a coal mine is a complicated spatiotemporal process due to the superimposed action of multiple stress fields on the surrounding rock mass. Using the surrounding rock of a floor roadway in the working face of the Huainan Pan’er Mine as the research subject, we conducted real-time monitoring using geoelectric field monitoring technology, and found the spatiotemporal response law of the geoelectric field in the process of regional rupture and damage of engineering rock masses under a complex stress field environment. The results show that (1) the time series response characteristics and spatial distribution of the geoelectric field signal are closely related to the stress distribution and damage evolution of the surrounding rock mass; (2) the rupture and damage degree of the goaf floor significantly increased when the working face was pushed through the monitoring area for 20–40 m. During this process, the excitation current dropped by 4–12 mA, and the self-potential pulse fluctuation amplitude was greater than 400 mV; (3) from the beginning of the monitoring process to the end of the monitoring, the self-potential in the damaged area decreased by 250 mV, and the self-potential in the mudstone layer below the damaged area increased by 140 mV. The electrons released into the environment around the damaged rock mass during the severe impact phase of mining did not flow back to the damaged area, and the positive charge in the damaged rock mass gradually accumulated in the complete rock mass in units of rock strata; (4) when superimposed and supported by anchor rod and cables, the bearing capacity of the shallow bearing circle of the roadway was enhanced, and the excitation current presented a step-like overall increase during mining of the working face with a small drop after every significant increase. This result is of significance in monitoring the evolutionary process of real-time failure of rock masses under complex stress environments using geoelectric field information and in improving the quality of geoelectric field monitoring technology testing applications in the future.

A 3D joint inversion of 2D electrical prospecting data can effectively solve the shortcomings of the 2D electrical method in detecting the spatial forms of anomalous bodies. However, the direction and interval between 2D electrical prospecting survey lines can affect the workload of field prospectors and the accuracy of the subsequent 3D inversion. This study established a physical model of an indoor water tank. Multiple sections of 2D electrical survey lines were laid and survey line data was acquired. The intersection angles between 2D electrical survey lines and anomalous bodies as well as the relations between the 3D inversion characteristics and 2D electrical prospecting data for different line intervals were studied. The results of this study indicate that the electrical response of cylindrical anomalous bodies tends to become weaker, first slowly and then faster, with a decrease in the angle. When the intersection angle is between 60° and 90°, the inverted forms of the anomalous bodies are unchanged. When the interaction angle is less than 60°, there is a significant twisting of the bodies and the electrical response is obviously weaker. The 3D joint inversion imaging using multi-section resistivity data can effectively improve the recognition on the spatial forms of objects. However, the joint inversion obtained with different survey line intervals varies in how precisely the objects are depicted. The increase in the interval between survey lines can be divided into four main stages in terms of the 3D joint inversion. To maintain the efficiency of practical prospecting and because survey data forming shallow strata are affected by external interference, it was found experimentally that the optimum interval for the effective depiction of the locations and forms of objects ranges from 8 cm to 12 cm. Specifically, the least number of 2D survey lines can be deployed while ensuring the overall accuracy and reliability of the survey result when the survey line interval/2D electrical prospecting inversion depth ranges from 8/17 to 12/17. The study results may help us to guide the arrangement of electrical survey lines in field prospecting and improve construction efficiency and the accuracy of joint inversion.

Aiming at the difference of hidden danger identification of embankment dams by different arrays of high-density electrical method, a combined inversion method of wenner data volume is proposed to improve the resolution capability of target. The response characteristics of α, β and γ array to the preset model are presented by constructing the geoelectric model of the dam body and the potential leakage hazard in the contact zone. According to the simulation results, different arrays have different detection effects on the same target and the same array has different detection effects on different targets. β array reflects better effect of low resistance area, and γ array is more suitable for dividing dam body boundary, but both have weak anti-interference ability. In addition, the spatial feature information of the target by multiple-wenner inversion is more for the preset model and can effectively compensate for the limitation of a single array. The inversion results based on a priori model can suppress boundary interference and improve the effective identification of preset hidden dangers and boundary. The field test also shows that the anomaly determined by multiple-wenner inversion technology is highly consistent with the leakage site, which effectively improves the accuracy of hidden danger diagnosis.