采矿工程中英文对照外文翻译文献Word文档格式.docx

1、Soft rock engineering is a difficult topic which has received much attention in the field of rock mechanics and engineering. Research and practical work have been carried out, but much of the work has been limited to solving problems from the surface. For overcoming the difficulties of large deforma

2、tions, long duration time-dependent effects, and difficulties in stabilizing the soft rock, the problem should be tackled more radically, leading to a more effective method of achieving optimization of the engineering system in soft rock. A summary of the optimization procedure is made based on engi

3、neering practice. 1. Introduction There are many soft rock engineering problems around the world, involving engineering for mines, highways, railways, bridges, tunnels, civil subways, buildings, etc. Engineering losses have occurred because of volumetric expansion, loss of stability of the soft rock

4、, etc. This has been an important question to which much attention has been paid in engineering circles, and in the field of academic rock mechanics. Since the 1970s, considerable research and practical efforts have been made in the field of soft rock engineering in various countries, but the major

5、efforts were concentrated on such aspects as the method of construction, the design and reinforcing of the supporting structures, measurement and analysis of the rocks physical and mechanical properties, its constitutive relations and engineering measurement. It has been found that the soft rock eng

6、ineering problem involves complex systematic engineering including such subsystems as classification of soft rocks, judgement concerning the properties of soft rock, project design and construction. Only by considering the integral optimization of the system can we obtain an improved solution to the

7、 problem. Hopefully, a radical approach can lead to engineering feasibility, lower costs and engineering stability in order to achieve the engineering objectives. 1.1. Mechanical properties of soft rock and associated engineering Soft rock is an uneven and discontinuous medium. Its strength is low,

8、with a uniaxial compressive strength usually lower than 30 MPa. Some soft rocks expand when they are wet. Cracks in some soft rocks will propagate easily which makes them exhibit volumetric expansion. Large deformation and creep can occur in soft rocks. Many soft rocks are compound ones which have c

9、omposite properties formed from two or more sets of constituent properties. Soft rock can be graded into divisions according to its properties. After engineering has occurred, soft rock can deform rapidly and by time-dependent deformation, owing to its low strength and sensitivity to the stress fiel

10、d. With the effect of water, the expansive minerals in soft rocks volumetrically expand, which causes large convergent deformations, which leads to damage of the surrounding rock. The mechanical properties of soft rocks appear so various and different that it is difficult to express them with mathem

11、atical formula, which is the technological challenge for soft rock engineering. 1.2. Engineering in soft rock and its optimization Because soft rock engineering can induce large deformations, the maintenance of the engineering can be difficult. Moreover, volumetric expansion and loss of stabilizatio

12、n of the surrounding rock often causes damage to supporting structures. If we use strong supports to control the deformation of the surrounding rock, the engineering cost will be high, and the construction time will be increased by repeated installation of support, sometimes the support itself has t

13、o be repaired. In order to obtain the benefits of easier construction and lower cost, the integral optimization of the system must be carried out and managed in a systematic and comprehensive way. Design and construction are the two important steps in soft rock engineering. These must begin by under

14、standing the physical and mechanical properties of soft rock, in the context of the stress field, hydrogeology and engineering geology. The engineering design plan is conceived as a whole according to the theory of rock mechanics and combining practical data from adjacent or similar projects, includ

15、ing integrating the many factors. The establishment of the correct soft rock engineering system should come from practice, basing on a full mastery of the factors. The scheme is shown in Fig. 1. Fig. 1. Engineering system for soft rock. Optimization of soft rock engineering is achieved by making the

16、 surrounding rock interface with the supporting structure such that the engineering will be stable. The key technological strategy is to avoid a high stress field and enhance the supporting ability of the surrounding rock. Feasible measures are as follows: reducing the external load; optimizing the

17、engineering structures size and shape, improving planar and cubic layouts of engineering; choosing better strata, and structure orientation, etc., as shown in Fig. 2. Fig. 2. The principle of the optimization process. According to these ideas, take the development of a coal mine in soft rock as an e

18、xample. Integrated optimization of the development system of the mine should take the relevant factors into account: existing information; an overall arrangement for optimal development and production; eliminate adverse factors; and deal with the problems of soft rock by a simple construction method

19、. The content of the first part of the optimization includes: choosing the mine development method; deciding on the mining level; and determining layers in which the main roadways are to be located. Also important is arranging a reasonable layout of the pit bottom and chamber groups and seeking to r

20、educe the deviator stress caused by mutual interference of the openings. Openings perpendicular to the direction of horizontal principal stress should be avoided when choosing the driving direction of roadways. Optimizing the layout of the mining roadways reduces the damage to support caused by movi

21、ng loads introduced by mining. Further optimization is related to the geometry and size of the roadway sections, the supporting structure, and the method and technology of construction. Finally, by measuring and monitoring during construction, feedback information can be obtained to ensure that the

22、engineering is running on the expected track and, if there is any deviation, corrective action can be implemented. The system is shown in Fig. 3. Fig. 3. Systematic optimization of coal mining in soft rock. 2. Engineering examples 2.1. Mine No. 5 in Youjiang coal mine, China The mine is situated to

23、the east of Baise Coalfield, in the West of Guangxi Zhuang Autonomous Region. It belongs to the new third Period. The mine area is located at the edge of the south synclinal basin. There are three coal layers; the average thickness of each seam is 12m; above and below the coal layers are mudstone, w

24、hose colours are grey, greyish white, and green. There are minerals of mixed illite and montmorillonite in the rock, montmorillonite 58%, and illite 720%. The rocks uniaxial compressive strength is 45 MPa, the average being 4.8 MPa. There are irregular joints in the rock, but distributed irregularly

25、, and the rocks integral coefficient index is 0.55. Most of the cracks are discontinuous, without filling matter in them. The surrounding rock is a soft rock subject to swelling, with low strength, and is quite broken. The strike of the coalfield is NEE, the dip angle of the coal layers is 1015. The

26、 mine area is 6km long along the strike, and 1km long along its inclination, its area is 6km2, the recoverable reserves are 4,430,000 tons. In the adjacent mine No. 4, the maximum principal stress is NNESSW, approximately along the seams inclined direction. A roadway perpendicular to this direction

27、has convergence values of 70100mm, the damage of roadway supports is 51%. A roadway parallel to the direction of maximum principal stress has convergence values of 2040mm, the damage rate of supports is 12%, and the average damage rate of the mine is 40%. In the design of the mine, a pair of incline

28、d shafts were included. The level of the shaft-top is +110m, the elevation of the main mining level is located at 120m. Strike longwall mining is planned, arranging with uphill and downhill stope areas, as shown in Fig. 4. Fig. 4. Development plans for Mine No. 5 in Youjiang. The first optimization

29、measure is to weaken the strain effect of the surrounding rock in the mine roadway caused by the stress field. Roadways are arranged as far as possible to be parallel with the maximum principal stress （that is, approximately along the inclined direction） so as to reduce the angle between them. The s

30、trike longwall mining is changed into inclined longwall mining, the mine is mined upward by using the downhill stope area, the main mining level is elevated by 20m, 1131m of roadways are saved and the cost of the roadway construction and facilities is saved 2,760,000 （$336,600）. The new system is sh

31、own in Fig. 5. Fig. 5. Development system plans after optimization for Mine No. 5 in Youjiang. The second optimization measure is to change the layout of the pit bottom and openings to be parallel with the maximum principal stress as far as possible. The total length of roadways initially designed w

32、as 1481m, and 30.11% of them were arranged to be perpendicular to the maximum principal stress. After amendment, the total length of roadways is 1191m, which is a decrease of 290m, and with only 24.69% of roadways that are perpendicular to the principal horizontal stress, roadways are easier to maintain. As shown in Fig. 6 and Fig. 7. Fig. 6. Layout of the pit bottom and chamber initially designed for Mine No. 5 in Youjiang. Fig. 7. Layout of the pit