Towards the development of a baseline for surface movement in the Surat Cumulative Management Area

Ground surface movement can result from several natural and anthropogenic processes. Understanding the mechanisms that drive ground surface movement and their contribution to the net movement is crucial in assessing the impact of resource development projects and other human activities. Consequently, there is an interest in understanding ground surface movement in the Surat Cumulative Management Area (CMA), Queensland, and how it is influenced by coal seam gas (CSG) production, if at all. This paper presents the analysis of a large InSAR (interferometric synthetic aperture radar) dataset covering the CMA regions featuring no active CSG wells. These non-production areas were specifically examined in order to develop an understanding of background surface movement and its contributing processes. Of the regional dataset, four focus areas showing measurable changes over time were selected for more detailed investigation. All the focus areas exhibited an overall downward surface movement (subsidence), with three showing cycles of subsidence and uplift that appeared to be very well correlated with rainfall events. The soil types in these three areas were consistent with the hypothesis that the observed surface movement is due to rainfall infiltration-induced consolidation of the shallow soil layers and subsequent moisture-induced shrinkage and swelling. The fourth focus area, however, did not exhibit a strong seasonal fluctuation, and unravelling the mechanisms driving surface movement in this area was more difficult. This investigation resulted in a foundation for further research into the complex problem of surface movement, and in particular, deconvolution of the various contributions that occur at different depths, lengths, and time scales.

Study on the Law of Ground Subsidence for Shallow Buried and Thick Coal Seam by Fully Mechanized Caving Mining Method

In order to master the law of ground surface movement and deformation for shallow buried and thick coal seam under condition of fully mechanized caving mining method, and to gain experience of “mining under buildings, water body and railway”, a ground surface movement observation station was established above 14106 and 14107 working face of No.1 Well which belongs to China Coal Pingshuo Group co., Ltd. Then a series of observation was conducted according to the requirements of relevant technology. After that, process of sorting, calculating, analysis was conducted based on the observation data. As a result, characteristics of surface movement and deformation under this mining and geological condition were mastered by author, the surface subsidence calculation parameters and some surface movement angle parameters was calculated. Based on analysis of ground depression velocity and deflection in the period of ground movement, it is concluded that shallow buried depth with fully mechanized caving mining method has a shorter ground movement active period than that of deep mine, at the same time, its maximum subsidence velocity is big, ground movement and deformation is strenuous and subsidence during ground movement active period occupies a huge proportion of the total subsidence.

Experimental Study on the Law of the Ground Surface Movement on the Old Goaf in Different Mining Conditions

The formation process of goaf was dynamically simulated by similar material simulation esperiment. After mining coal was finished and the goaf was basically stable, deformation regularity of surface migrating was studied under gradual loading in different lacation of goaf . The results show: the residual deformation caused by load arranged on both sides of goaf is bigger than that caused by load arranged in the central of goaf. And the maximum values of residual deformation occur on both sides of goaf. The different mining conditions, load location and size will affect the residual deformation. In single mining conditions, a larger load in the both sides of goaf ,the greater the residual deformation.

Dynamic Response of Pile Groups under Vertical Forces in Saturated Soil

Based on Biot’s wave propagation equation and boundary conditions, this paper builds up pile group and soil system used for calculation in 3 dimension models, though mass conservative and motion equation. The results of ground surface movement are obtained under the effect of vertical dynamic force though Newmark direct integration. Compared with the measured results, the numerical outcomes conform accurately. The calculating results show that vibration of ground surface can be affected by several parameters such as soils’ possion ratio, permeability coefficient, different types of pile groups and so on. Different factors have different effects on ground’s surface vibration in both far field and near field.