外文翻譯---土壓力理論在薄煤層回填支柱設(shè)計中的應(yīng)用

1、翻譯部分 翻譯部分英文原文 英文原文Design of backfilled thin-seam coal pillars using earth pressure theory1. IntroductionThe Self-Advancing Miner has been designed to extract coal from seams less than 90 centimeters thick. The SAM allows

2、 for extraction of the full seam height while minimizing waste rock, and utilizes remote operation that allows the miner to advance up to 180m (600ft) into the seam. However, the coal seams are so thin that the recovery

3、rates of this mining method will be fairly low and will decrease rapidly with the depth of mining. In order to increase the recovery from thin-seam mines, pillars must be designed as small as possible without compromisin

4、g the stability of the mine. Backfill can provide the support necessary to maintain the integrity of the underground workings while allowing for increased extraction. The placing of backfill underground has predominantly

5、 been a practice employed in cut-and-fill mines (Thomas, 1979). Backfill material is introduced underground into previously mined stopes to provide a working platform and localized support, reducing the volume of open sp

6、ace which could potentially be filled by a collapse of the surrounding pillars (Barret et al., 1978). The presence of fill in an opening prevents large-scale movements and collapse of openings merely by occupying voids l

7、eft by mining (Aitchison et al.1973).Therefore, the placement of fill in open spacesunderground tends to prevent the unraveling/spalling of the surrounding rock mass into the mined-out space, effectively increasing the s

8、trength, or load bearing capacity, of the surrounding rock mass. This type of support mechanism not only helps provide support to pillars and walls, but also helps to prevent caving and roof falls, minimize surface subsi

9、dence, and enhance pillar recovery (Coates, 1981). Although the support capability of backfill is well known it still remains fairly difficult to quantify. Models and equations for the determination of backfill support h

10、ave been proposed (Cai, 1983; Guang-Xu and Mao-Yuan, 1983) and pillar-backfill systems have been modeled using laboratory set-ups in order to correlate the actual support behavior of fill with proposed models (Yamaguchi

11、and Yamatomi, 1989; Blight and Clarke, 1983; Swan and Board, 1989; Aitchison et al., 1973). But in general these models and lab tests are dependent on local experience and empirically derived relationships between backfi

12、ll support, material properties, and mine left at the ends of the panels to protect the cross-cuts. Figure 2 is a cross-sectional view of the cutting face. The face evokes the highwall mine comparison; the coal seam runs

13、 through the middle of the panel and a portion of the panel ‘material’ is left above and below each cut. The cut width is 3m (10ft) and the cut height is equivalent to the seam height (less than 90cm (36in)). It is inten

14、ded that as the SAM retreats from each cut, backfill will be either hydraulically or pneumatically placed in the mined-out void.3. Application of earth pressure theoryThe idea that the backfill support mechanism describe

15、d in the previous section can be quantified using principles taken from soil mechanics is not new. A broad understanding of fill behavior has always been dependent on knowledge of earth pressures. However, earth pressure

16、 theories and concepts have not generally been considered adequate in properly quantifying the magnitude of fill support in underground mines. Limited understanding about the transfer of loads from the surrounding rock t

17、o the fill and frictional effects, along with mine geometry, have made it difficult to apply the concepts of earth pressure theory to backfill support (Thomas, 1979).What makes the case of the SAM operating in a thin-sea

18、m coal mine different is the concept of ‘designed failure’ of the pillars so that deformations capable of mobilizing the passive resistance of the backfill will occur. From civil engineering design of retaining walls it

19、has been shown that the movement required to reach maximum passive earth pressure within in a loose sandy soil is 4% of the wall height (Clough and Duncan, 1971). The denser the soil, the less movement required. Applying

20、 this guideline to the thin-seam coal mine; for a pillar height of 90cm lateral deformation of the pillar must be at least 3.6cm for a loose, sandy backfill to reach maximum passive earth pressure conditions. The initial