| Great attention has been paid on mining technology of ore deposit with difficult environmental condition along with the increasing requirement on mineral resources. Qualified mining technology and equipment of ore deposit below railway, river and buildings (shortly, DRRB) are limited because of complicated existence condition of ore body and different features of rock deformation. Influence degree of mining activities and surrounding disturbance on surface buildings or structures should be estimated and correspondent preventive measures should be considered, based on evaluation of underground engineering works, in order to extract safely DRRB.Xinqiao Mining Corporation, Ltd. (XMC), Tongling, Anhui province, China, is one of the largest pyrite mines in China. Eastern part of ore deposit located below a railway and a small river and is a kind of typical DRRB. Because safe mining process of ore deposit under dynamic load and water body is a open, dynamic and non-linear system, function and influence of mining activates and surrounding disturbance on railway, river and slope of open-pit are studied in detail using such comprehensive researching means as theoretical analysis, field measurement, laboratorial experiment and numerical simulation in this paper. Main conclusions and creative results are summarized as follows:(1)Improved clay cementing mixture was developed and used in curtain grouting practice in XMC. The mixture is good in crush-resistance, low in material cost (81% lower than that of conventional cement slurry), high in concretion rate (nearly 100%) and excellent in water-blocking result. Clay slurry-making technology characterized in effective transportation, automatic crushing and fast mixing system was also invented. The new technology could not only raise slurry-making capability and effectiveness by 60% and 80% respectively, but also improve slurry quality and system reliability.(2)Grouting drill holes were arranged in varying large space and improved clay or fly ash cementing slurry (10% in proportion) was poured into drill hole so that fault and cave could be filled. Number of drill hole was reduced by 36% and water-block rate was increased by 78%, respectively, compared to conventional hole design with fixed space. Water inflow from open-pit was obviously reduced and serious surface subside within railway and river area was avoided as a result of curtain grouting.(3) Computation method of geometrical dip by three dimensional simulation soft 3DEC was improved. Geometrical slope of dip open-pit was automatically represented by 3DEC soft using triangular pyramid approaching method, according to coordinate data of slope roof and bottom. The numerical model of the slope could meet reliability and accuracy requirement for subsequent numerical simulation.(4)Three dimensional model of ore deposit and related development works below dynamic load and water body was established by 3DEC soft. Overall arrangement of development works and structural size of stope were evaluated, response of development works to influencing factors were simulated, and stress, displacement and velocity of surrounding rocks around DRRB, based on analysis of the model.(5)Curtain grouting engineering based on results of theoretical analysis, field investigation, mechanical parameters measurement, dynamic load survey and CT goaf detection is useful for safe mining of DRRB. Mining model of DRRB based on numerical simulation is helpful to optimize development works including shaft and tunnel.
|
PDF Full Text Request