Laboratory simulation experiment is an important method for studying roadway deformation condition and mechanism.Based on the theory of solidification pressure,we built a vertical experimental model used by low strength material.This model,which initial strain energy equaled zero,simulated the solidification pressure.And this model made up for the deficiency of displacement field of horizontal solidification method.According to similarity theory,the material is desirable.In solidification process,this experimental model simulated physical and mechanical property in different depth.The simulated object was ore-body in 14-exploration line used two-sublevel mining under self-weight stress.Experiment results matched numerical simulation.Roadway deformation mechanism has been analyzed based on experiment results and numerical simulation.

The occurrence of ground subsidence induced by backfill mining method becomes a new threat to many mines.The current paper presents a typical example in the Jinchuan mine in China.Based on actual situations of mining subsidence and damage, GPS monitoring networks were successively established in three neighboring mine fields in the Jinchuan mine at the beginning of 2001.An integrated monitoring network composed of 848 monitoring points to study mining subsidence was eventually set up in the entire mining area in the first half of 2005.Based on combined field investigation and monitoring, it revealed the characteristics of mining subsidence in the Jinchuan mine.In addition, the mining subsidence mechanisms, comparison between the monitoring results and the ground subsidence, correlations with the damage of underground facilities and the extracted ore tonnage were discussed.Furthermore, several countermeasures were proposed according to the mining subsidence and damage situations.

Based on numerical simulation method,the ground movement laws and evolution pattern of displacement field caused by underground backfill mining in high tectonic stress area were studied.The numerical results indicate that the shape,range,central position and magnitude of ground movement are changing regularly caused by backfill mining in high tectonic stress area.The deformation of the ground surface in the hanging wall is obvious larger than that in the foot wall.The surrounding rock deformation form changes from roof convergence and floor heave at an early stage to wall convergence in the later.The magnitude of the displacement in the hanging wall is larger than that in the foot wall.This result is beneficial to the study of the ground surface movement and surrounding deformation caused by backfill mining the steep orebody in high tectonic stress area.

This paper presents a case study investigation into the hydrogeological characteristics and permeability of rock mass in a seabed mine. Following an introduction to the geology and hydrogeological conditions in the Xinli mine area, we reveal the features of the preferred structural planes, dynamic characteristics of mine water seepage, and the permeability of the fractured rock mass in the pit. The permeability of the pit rock mass shows varied characteristics at different geotectonic locations because of the different degrees to which the structural planes developed. The fractured rock mass generally shows low permeability, and the main composition of water seepage is high-salinity brine. Future large-scale undersea mining may induce rock mass movement, destroy water-resistant layers, and enhance water transmissibility and the probability of water gushing into the pit. Thus, strengthening the quality of the filling mass, protecting the stope roof and the water-resistant layers, as well as regular monitoring of water seepage discharge and identification of water sources are critical to work safety and the prevention of seawater gushing in the mine.

The vertical shaft plays an important role in underground tunnel mining mines. However, few attempts have been done on the deformation and failure mechanics of shafts suffering from rock mass movement in metallic mines undergoing mining activities. Numerical simulation methods and geomechanical methods are applied in the study of deformation, failure and stability of the line No. 14 ventilating shaft in Jinchuan No. 2 Mine under the conditions of different kinds of mining design. The results show that the shaft is seated in the scope of the depression induced by the underground mining, and the displacement of rock mass keeps increasing. Therefore the underground mining is the main factor for the safety and stability of the shaft. Moreover, whether mining of the rich ore body or combined mining of the rich ore body and lean ore body, the distribution regularities of displacement and stress of the shaft are similar, and the section of the faults is still the vulnerable zone of the shaft in which it influences the size and distribution of the displacement and stress greatly. Consequently, it is the faults which cross the shaft and lead to reactivation due to underground mining are the trigger factor, and the rock mass movement, rupture and fall are the primary form of the shaft deformation and failure mechanism, and this kind of fault effects will be aroused again in the future under the present circumstances of mining.

As an advanced mining technology, cut-and-fill mining was successfully applied in the Jinchuan Nickel Mine over 18 years until the end of 1999 when ground fissures occurred above the ore body. Since the first field investigation of the ground fissures in 2000 and the establishment of GPS monitoring network in 2001, ground deformation and damage has been continuously monitored and researched for the last 10 years. By the end of 2010, the maximum vertical displacement reached 1,720 mm and accompanied by the rapid development of ground fissures. This study considers the effects of large-scale stress adjustment and redistribution, hysteretic backfill, low strength of filling body, unfilled void space, as well as repeated mining activities concurrently caused ground deformation and ground fissures. Besides, the hysteretic mechanisms of ground response relative to the mining operations and the mechanisms of displacement variations are discussed from different perspectives. The results provide invaluable information on designing and building mines with the cut-and-fill method.

The ground deformation due to the relative position between the underground excavation and the fault was studied by the means of simplified numerical method. The results show that, when the fault located in the compressive region of ground surface incurred by underground excavation and the excavation in the footwalls, the likelihood of discontinuous deformation of the ground is tiny; when the fault located in the compressive region of ground surface incurred by underground excavation and the excavation in the hanging walls, the ground surface cracks where the fault located tend to get close ; when the fault located in the tensile region of the ground caused by underground excavation, the horizontal tension is so severe that there will be tension cracks where the fault outcrop exposed, the characteristics of normal fault slip will be displayed along with the mining depth and size increases, no matter the excavations lie in the hanging walls or in the footwalls.

To trace the potential hazards of open-pit slope in Longshou mine, global positioning system (GPS) is applied to monitoring ground movement and deformation induced by transition from open-pit to underground mining. Through long-term monitoring from 2003 to 2008, huge amounts of data were acquired. Monitoring results show that large-scale ground movement and deformation have occurred in mining area, and the movement area is ellipse-shaped. The displacement boundary of settlement trough is 2.0km long along the exploratory line, and 1.5km long along the strike of ore body. GPS monitoring results basically agree with the practical deformation state of open-pit slope. It is indicated that the long-term GPS monitoring is an effective way to understand the mechanism of ground movement and deformation in mine area.

The stability of the underhand drift cemented filling body is analyzed by using stress arch theory and beam theory,and a simple judgment formula of the stability is obtained.A filling scheme with equal cement-sand ratio is firstly proposed,and the feasibility of the new scheme is proved in a case of Jinchuan No.2 mining area.The high concentration cement filling method with the equal cement-sand ratio of 1∶6 can meet the requirements on strength,and about RMB 1.4 million yuan of costs can be saved each year.

The distribution of land subsidence caused by both high-rise building loading and exploitation of groundwater is increasingly complex in urban area.This paper examines the land subsidence in Tanggu area.It considers the equilibrium condition,the elastic constitutive condition,the deformation compatibility condition of solid,and the continuity condition of water flow in soil consolidation.It then develops a three-dimensional land subsidence model for Tanggu area.The model is also based on the Biot's consolidation theory and takes into account both high-rise building loading and exploitation of groundwater.The finite element method is applied to the numerical calculation of the ground subsidence.The results indicate that there will be a considerable ground settlement in 3～4 years after construction of high-rise building.The settlement under the condition of both high-rise building loading and the exploitation of groundwater is lower than the sum settlement under he two single conditions.The model has a good convergence property and its computing results conform to actual data well.

Take the - 510 level and - 555 level as the example, statistical models of rock mass discontinuity characteristics are obtained based on site data via Matlab. Then the Monte-Carlo network simulation of rock fissures is achieved. Based on the fractal theory, the fractal dimension is decided. The study shows that the stability of north of F3 is better than that south of F3, with regard to the two levels. And both qualitative and quality analysis are given, which provide some proofs for mine security.

Being a water yielding accident,water disaster in a mine happened suddenly when mine shafts or mining faces got close or connected to aquifers,surface water,water-filled fracture zones or karst caves.It often set back mine productivity or even caused flooding because of its sudden break-out and enormous quantity.As the fracture zone was generally a low strength region in the rock mass,mining the ore body often made a fault active,which probably formed a pathway for water bursting.Based on the geological conditions of submarine mining in Xinli mining area of Sanshandao Gold Mine and the practical working conditions,the paper analyzed the status of fracture zone's activation and of the subsidence deformation of the upper clay confining beds by the use of numerical simulation.The results showed that the contact zone between the fracture zone and the upfaulted wall rock would be strongly disturbed by mining.The watertight capacity of the upper clay confining bed decreased as the stope shifted up.When mining to-165m,the fracture zone and its accompanied fractures on both sides would spread and connect to the upper confining bed and sandy soil layer,forming an aquiduct for seawater to the stope.The safety of undersea mining would be threatened by seawater pouring.

Aiming at the problem of surface subsidence induced by underground backfilling of steep orebody in Jinchuan Nickel mine,we elucidate the current status of ground surface movement in No.3 mining area on the east of F17 based on GPS monitoring data,studied the correlativity between the extracted ore tonnage and the volume of surface subsidence basin,and analyzed the development characteristics of ground stress field and displacement field of surrounding rock under different mining conditions by using ADINA software.The results show that the ground surface subsidence basin is now developing in No.3 mining area and its geometric shape obviously affected by ore-controlled fault.There will be some correlativity between the volume of surface subsidence basin and extracted ore tonnage in a period of time if orebody's geometric shape and mining mode keep stable.The major factors affecting surface subsidence are convergence displacement of the surrounding rock during the period from forming mining drift to the finish of filling and caving the pillars between two roadways.The settlement is larger in the condition of multi-drift mining than that of single drift.

Based on geological investigations and GPS monitoring data, this paper presents ground movement phenomena and characteristics for Jinchuan Nickel Mine, China. The results show that ground subsidence occurred with increasing mining depth. The greatest accumulated subsidence reached 1287.5 mm between 2001 and 2008, and 37 considerable fissures were found at the ground surface. By establishing a mining-geological model, and by applying a numerical computation method, a short-term forecast of rockmass movement is proposed. The results show that the rate of ground subsidence and deformation will intensify further, and the distribution of subsidence and degree of damage to the mine roadway and shaft induced by ground subsidence and deformation will also extend in the following several years.

After the No.14 shaft was repaired in Jinchuan No.2 mine,two big cracks were formed in the new shaft well.Therefore,further reinforcement program was put forward on the repaired shaft.Based on GPS monitoring data of ground surface movement,this paper evaluated the feasibility of the reinforcement program of No.14 shaft by numerical simulation.The results show that the shallow reinforcement measure did not change the extent of mining impact on the shaft,and the reinforcement method did not achieve the desired effect.Then,the prestressed cable reinforcement was used for inspecting the adaptability of this strengthening program.It was further found the level and distribution of shaft wall displacement and stress did not change significantly before and after the reinforcement.This shows that only shallow reinforcement program was not effective for the shaft which located in the severely affected region of rock movement induced by underground mining.It was a useful guide for engineering design and had practical significance in mining production.Finally,further reinforcement program was suggested after considering damage reasons of No.14 shaft,problems in the former inforcement program,as well as trends of rock movement.

To enhance understanding of the mechanism of slope stability,this paper investigates some of the mechanical characteristics of the slope mass only subjected to its self-weight body force.It uses the FLAC numerical simulation software and similarity law.It studies the relationships between them and the related physical or mechanical parameters.At the ground surface,the principal stresses must be either parallel or normal to the topography in the absence of surface loads.As the depth increases,the principal stress directions approach either vertical or horizontal.There are tensile stress and compressive stress at the slope surface.And the tensile stress in the toe of a slope is also very high.These are some general characteristics for the distribution of stresses in a slope,shown both in this paper or some other articles.This paper emphasizes that when the angle of a slope increases linearly,the changing velocity of maximum tensile stress on the top of the slope behaves fastly,then slowly and then fastly.The tensile stress decreases linearly with the depth on a line from the top of the slope downward vertically to the inner of the slope.Under the condition of small deformation,the stress field does not depend on the Young's modulus value.When meeting the similarity law,the magnitudes of displacement ratios at the corresponding points are square times of their sizes' ratios of a slope.This paper complements to existing knowledge.It further offers a base for further studies on more complicated slopes.It is meaningful in both theory and practice.

Taking the supporting program for repairing Shaft No.14 in Jinchuan No.2 mine area as the research object,we firstly analyzed the mechanism of its shotcrete-bolting technique under the condition of high stress and cracked rock mass in Jinchuan Nickel mine.Furthermore,we analyzed its reinforcement performance by numerical simulation.The result showed that the supporting program took effect to restrict movement and deformation of the rock mass,but its performance is fair.As the mining depth and scale increase,the surrounding rock of the shaft would be deformed further or even be destroyed.

No.14 shaft is the key to the Jinchuan mine safety production.Three single prediction models were developed,a combined prediction model with optimum weight for No.14 shaft which contains effective informations of single model was built based on the optimal combined theory and prediction precision were improved accordingly.The precision and weight distribution are related to the selection of single model.As a short-term prediction model,the result shows that stable deformation instead of saltation will occur in the next two semesters.