Esterhuizen G S, Gearhart D F, Tulu I B
NIOSH Pittsburgh Mining Research Division, Pittsburgh, PA 15236, USA.
West Virginia University, Morgantown, WV 26506, USA.
Int J Min Sci Technol. 2018 Jan;28(1):43-51. doi: 10.1016/j.ijmst.2017.12.013.
A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia. Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry. Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation, stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site. During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation. As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10-15 m of the instrumented locations. After reaching the peak loading at about 50-75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports. The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed. The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems. It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location. The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries.
在西弗吉尼亚州的一个长壁采场回风巷入口处，开展了一项全面的监测计划，以测量岩体位移、支护响应和应力变化。在巷道入口开拓几天后开始监测，并在回风巷两侧的长壁采面通过期间持续进行。监测内容包括岩体初始应力的套芯应力测量、锚索加载变化、永久支护压力、顶板变形、煤帮变形、煤柱应力变化，以及监测点周围六个位置岩体内部三维应力张量的变化。在第一个长壁采面通过期间，对岩石和煤体的应力测量检测到加载的微小变化，同时在顶板变形中也检测到微小变化。由于应力和地质条件相对有利，直到第二个采面接近仪器监测位置10 - 15米时，支护系统才经历严重的加载或岩石变形。在顶板下沉约50 - 75毫米达到峰值加载后，锚索开始卸载，荷载转移到永久支护上。永久支护系统能够在掩护支架内侧维持足够的空间，以便按设计为采面内侧的第一个横贯巷道提供通风。这些结果用于将锚索响应模型校准到现场数据，并验证已开发的用于评估巷道支护系统的数值建模程序。得出的结论是，支护系统足以控制回风巷直至长壁采面位置的顶板。监测结果为长壁采场回风巷入口支护设计策略的制定和验证提供了有价值的数据。
