Shaft Lining Research Articles

Research and development of bunton structures of double-row rope-profile guides for movement of lifting cages

The paper studies the existing options of rigid reinforcement of vertical shafts, consisting of buntons and guides of various types, which ensure the movement of vehicles in the shaft reinforcement with double-row rope-profile guides. We have considered various layouts and structures of tiers for various number of vehicles moving in the shaft and their purpose (skips, cages, counterweights), and analyzed their advantages and disadvantages. On the basis of analysis and research, the structures of buntons for double-row rope-profile guides and the legs with grips have been developed that allow the guides to move up and down relative to the tier, to transfer horizontal dynamic forces in the frontal and lateral planes. Research, analysis, development and implementation of bunton structures for double-row rope-profile guides and implementation with connecting rods, frames, which provide greater reliability while maintaining all the necessary clearances (according to the Safety Rules) between the vehicles and the shaft lining, in the "vehicle-reinforcement" system. Using the results of these studies in the development of existing structures will achieve the following results: - increasing the safety level while observing the standard clearances in the elements of shaft reinforcement; - reducing capital costs due to a decrease in the metal consumption of the tier of shaft reinforcement; - reducing the labor intensity of maintenance and repair by reducing the number of buntons and their fastening elements; - reducing the effect of clogging and corrosion on the durability of rope-profile guides and buntons; - reducing the impact of shaft lining violation on the reinforcement; - increasing the reliability level of kinematic connection in the "guide-bunton" system; - providing standard clearances in the shaft section at a safe level; - ensuring a high reliability level and safe operation of the shaft reinforcement with rope-profile guides. The implementation of developed structures of double-row rope-profile guides of the vertical shaft reinforcement will lead to an increase in the level of safe operation, while reducing the metal consumption and the cost of maintenance and operation of the vertical shaft reinforcement.

Stress–strain analysis of vertical shaft lining and adjacent rock mass under conditions of irregular contour

Stress–strain analysis of vertical shaft lining and adjacent rock mass under conditions of irregular contour

Heat exchange modeling between the air flow and the metro ventilation shaft lining in the conditions of St. Petersburg, Russia

Icing of the injection layer in underground tunnels and ventilation shafts leads to wear, destruction of supporting structures and flooding. In St. Petersburg the air temperature in winter can drop to -25 ° C, what can lead to these phenomena in the subway facilities. The article presents the modeling results of a viscous three-dimensional air flow, heat and mass transfer of a metro ventilation shaft in the Ansys CFX program. A numerical model of the ventilation shaft and the surrounding soil consisting of five layers has been developed: air; foam glass concrete; prefabricated cast-iron tubing lining; injection layer; soil massif. The parameters of the computational grid and the boundary conditions of the problem are specified. Two models of the ventilation shaft with an axial length of 1 m and 10 m were built. Temperature plots are constructed for three tasks, where the injection layer consists of water, wet clay soil and average between water and wet clay soil. The choice of overall thermal and technical characteristics of the thermal insulation material during the reconstruction of the existing ventilation shafts in three different sealing space conditions is confirmed.

Impact of ground surface movements on ventilation shaft No. 5 of Taimyrsky Mine at Oktyabrsky deposit

The main resources of Taimyrsky Mine represent the high-grade and impregnated ore. The mine field holds some high-grade massive ore bodies and many impregnated ore bodies which occur everywhere except for the south wing of the deposit. The hydrogeological regime of the deposit is governed by the thick permafrost layer. The accesses to the ore bodies is got via vertical shafts: cage shaft KS-3, skip shaft SS-3, ventilation shafts VS-5, VS-6 and VS-7, a backfill shaft (BS) and an air feed shaft (AFS). In the influence zone of mining operations, there are service shafts SS-5, SS-6 and SS-7, BS and AFS, accordingly, shaft headgears, shaft top works and other facilities. The authors estimate the impact of ground surface movements in the course of mining operations on the behavior of ventilation shaft No. 5. The data of the in-situ, as well as geophysical and geodetic survey observations of the study object are presented. All data analyzed, it is possible to reach a conclusion that all damages detected result from the movements and over-weathering of rocks in the space behind the shaft lining. The incorrect engineering estimate of water influx and seasonal watering during the shaft construction led to a drop in the load-bearing capacity of the lining and to suspension of the lining string in rock mass, which created an extra load and induced partial failure of the lining. At the present time, shaft VS-5 is in the process of the lining reconstruction, complete grating of the space behind the lining and erection of segmental lining from top downward. Based on the research findings, the detected movements are also typical of neighbor shaft VS-6. It is required to undertake a fully integrated survey of the shaft and make provisions for its loadbearing capacity recovery to avoid an adverse situation.

Failure mechanical behaviors and prevention methods of shaft lining in China

The shaft is an essential structure in mining and tunnel engineering. In recent years, the shaft lining is usually subject to deformation and damage with the increasing difficulty of engineering. By investigating shaft lining damage accidents in the Huanghuai area of China, this paper concludes that shaft lining damage has the similarity of the region, the concentration of failure time, and the similarity of geological conditions. In terms of failure mechanics, the primary failure mode of shaft lining is shear failure. To realize the prediction of shaft lining damage, it is necessary to sort out and summarize the load type and stress analysis of shaft lining. Considering temperature stress, earth pressure, self-weight stress, and draining additional force comprehensively, the analytical solution of shaft lining force is obtained using the superposition principle. According to the characteristics of shaft lining shear failure, the Coulomb-Neville criterion is introduced to verify the theoretical calculation of the DS shaft, ZSL shaft, LL shaft, HZ shaft, and BD shaft, which have been damaged. The result shows that the equation has a certain practical application value. Moreover, grouting reinforcement, composite shaft lining with new material, and unloading secondary lining method play an essential role in protecting shaft lining.

Laser Scanning Monitoring of Deformations in Concrete Lining of Mine Shafts

Laser Scanning Monitoring of Deformations in Concrete Lining of Mine Shafts

A Primary Support Design for Deep Shaft Construction Based on the Mechanism of Advanced Sequential Geopressure Release

The construction of 1500 m depth shaft in Xincheng Gold Mine, China, faces complex stress conditions such as high geostress (>50 MPa), high ground temperature (>50 °C), high water-pressure (>9 MPa), and highly corrosive. Traditional deep shafts excavated by the sinking and lining method cannot adapt to high geostress problems, such as rock bursts and large deformations, etc., in the deep shaft construction process. To avoid and adjust the high geostress induced the rockburst and large deformations, the mechanism of the advanced sequential geopressure release (ASGR) has been proposed for the ground control in deep shaft construction. In this paper, the safe distance between the concrete lining and the shaft excavation face is determined based on the ASGR mechanism, which can provide the space for geopressure release, and primary support based on rock mass quality and numerical simulation was employed to control the geopressure and deformation. A new support scheme for the deep shaft is proposed, using long bolts to restrain severe deformations, metal mesh, and a double reinforcement bar to improve the induced stress distribution. According to the results, the construction scheme of deep shaft has been improved, and the safe support distance of the proposed scheme is determined to be 12 m, with an interval of three excavation cycles. Compared to the original scheme of shaft lining after excavation, the proposed scheme based on the ASGR mechanism can effectively improve the geopressure release and benefit from controlling the rockburst and large deformation of deep shaft induced by high geostress conditions. The stress distribution in the lining is more uniform, and safety factor of the lining is increased to 2.0, which is benefit the long-term stability of deep shaft.

Application of FBG Sensor to Safety Monitoring of Mine Shaft Lining Structure.

The use of fiber Bragg grating (FBG) sensors is proposed to solve the technical problem of poor sensor stability in the long-term safety monitoring of shaft lining structures. The auxiliary shaft of the Zhuxianzhuang coal mine was considered as the engineering background, and a test system implementing FBG sensors was established to monitor the long-term safety of the shaft lining structure. Indoor simulation testing revealed that the coefficient of determination (r2) between the test curves of the FBG sensor and the resistance strain gauge is greater than 0.99 in both the transverse and vertical strains. Therefore, the FBG sensor and resistance strain gauge test values are similar, and the error is small. The early warning value was obtained by calculation, according to the specific engineering geological conditions and shaft lining structure. The monitoring data obtained for the shaft lining at three test levels over more than three years reveal that the measured vertical strain value is less than the warning value, indicating that the shaft lining structure is currently in a safe state. The analysis of the monitoring data reveals that the vertical strain increment caused by the vertical additional force is approximately 0.0752 με/d. As the mine drainage progresses, the increasing vertical additional force acting on the shaft lining will compromise the safety of the shaft lining structure. Therefore, the monitoring must be enhanced to facilitate decision-making for safe shaft operation.

Experimental Study on Mechanical Properties of Polypropylene: Steel Fiber Concrete and Loading Characteristics of Shaft Lining

With the rapid consumption of shallow coal resources, the depth of shaft lining construction continues to increase; huge formation pressure and complex geological conditions make the stress condition of shaft lining become more complex. The concrete strength grade is usually enhanced to improve the bearing capacity of shaft lining; however, high strength grades bring high brittleness. In order to solve the problem of high brittleness of high-strength concrete shaft lining in ultra-deep mine construction, a steel-polypropylene hybrid fiber high-performance reinforced concrete (SPHFRC) shaft model was developed. The SPHFRC with various mix proportions was prepared by optimizing the fiber content. The mechanical properties of SPHFRC were tested and compared with the reference concrete (PHSC). The results show that the SPHFRC can be obtained by adding the volume fraction in 1.2% steel fiber and 1.0% polypropylene fiber, which increases the tensile strength by 27.5% and the compressive strength of SPHFRC was similar to the reference concrete. By introducing a new brittleness evaluation index B to evaluate the brittleness of concrete, the results show the fiber greatly improves the brittleness problem of PHSC. Afterwards, a model test of PHSC and SPHFRC shaft lining was conducted, and the circumferential and axial load-stress-strain curves and load-displacement curves of concrete and steel bars are analyzed. Combining the failure characteristics of the two shaft lining models, the following conclusions are obtained: The ultimate bearing capacity of PHSC shaft lining is hardly affected by fibers, but the hoop displacement is significantly reduced and the circumferential stability of shaft lining has been greatly improved, the initial cracks appeared late, the speed of crack’s propagation is reduced, and no obvious concrete peeling and separation appeared during damage. The comprehensive performance of SPHFRC shaft lining is excellent, which has better ductility and anti-deformation ability.

On a Possible Mechanism of Hydrostatic Pressure on Mineshaft Linings in Western China

Reasonable determination of the water pressure on the shaft linings is the key to the optimization design of the vertical shaft of mining. The traditional water pressure calculation model is not suitable for the stratum conditions in western China. A new shaft-surrounding rock seepage model is proposed based on the coordinated seepage conditions of surrounding rock and shaft linings. In the model, the seepage within the shaft depth is assumed happening in a unit thickness confined aquifer. Thereby, the water pressure on the shaft linings is derived by the steady seepage theory, and the water pressure reduction coefficient is defined by normalizing the hydrostatic pressure. The influences of shaft diameter and shaft depth, the permeability coefficient of the surrounding rock, and the seepage flow on the water pressure reduction coefficient are analyzed. After that, the mechanism of reducing water pressure by grouting the surrounding rock is studied by considering the stratum conditions in western China. Finally, a practical equation, which only relating to the depth of the shaft, is fitted on account of the averaged water pressure reduction coefficient from the theoretical model. The effectiveness of the theoretical model and the fitted equation are verified by the measured data and data in the literature.

Permeability evolution characteristics and microanalysis of reactive powder concrete of drilling shaft lining under stress-seepage coupling

This study aimed to solve the problem of drilling shaft support under deep water-rich and weakly cemented stratum conditions. Thus, ultra-high-performance reactive powder concrete (RPC) is proposed as the wall construction material for the drilling shaft lining. The mechanical behavior, permeability, and microscopic characteristics of RPC were tested and analyzed. First, RPC samples were prepared by standard and autoclave curing with strength grades of C110 and C140, respectively, and their quasi-static mechanical properties were tested and compared. Stress-seepage coupling tests were then conducted under different confining and osmotic pressures to analyze the mechanical deformation, permeability evolution, and strength and deformation characteristics. The results showed that autoclave curing significantly improved the strength grade and early strength growth of RPC. Additionally, RPC generally exhibited low permeability characteristics while its permeability evolution law corresponded to the stress–strain relationship under triaxial loading. The permeability was observed to undergo three stages: a gradual decrease, steady development, and rapid increase. Finally, mercury intrusion porosimetry, X-ray diffraction, and scanning electron microscope microscopy analyses were used to determine the mechanism of improving macro mechanical properties and impermeability of RPC by the autoclave curing method based on pore structure characteristics and microstructure formation aspects.

Interface shear behavior of a shaft lining concrete-high density polyethylene material under different pre-imposed normal stresses.

As an important part of a double-layer shaft lining in China, a polyethylene sandwich can reduce or even eliminate the constraint effect on the inner shaft lining, which is confined by the outer shaft lining, thus improving the integrity of the inner shaft lining concrete. To reveal the interface shear mechanism of the concrete-high density polyethylene (HDPE) material, a series of 16 direct shear tests were performed under high normal loads (0.6~4 MPa) with four different surface morphologies. The experimental results showed that the interfaces exhibit a clear strain-softening property during shear, and the shear strength increases linearly with increasing normal stress. Three shearing mechanisms, plowing, localized plastic deformation, and dilatancy, were observed in these experiments. The research results are of great theoretical and practical value for understanding the shear mechanism and predicting the shear strength of a shaft lining concrete-HDPE interface under high normal stress.

Monitoring and Analysis of a High-Performance Concrete Shaft Lining: A Case Study

Shaft lining in ultradeep mines on the coast of eastern China under the complex external environments of “high in situ stress and high osmotic pressure” has the disadvantages of failure; to solve this problem, the field test of high-performance concrete shaft lining structure was carried out in Sha-ling gold mine. The field test study of the high-performance concrete shaft lining was carried out in a −1120 m ingate and a −1114 m to −1124 m shaft. Its stress and deformation were monitored and analyzed. The maximum compressive stress of the HPC shaft lining structure at the level of −1117.7 m of the air intake shaft is 1.91 MPa. Based on the Von-Mises yield theory and the analytical solution of thick-walled cylinder theory, the ultimate limit of the high-performance concrete shaft lining in the Sha-ling gold mine was obtained. The high-performance concrete shaft lining strain changes smoothly, and concrete strain can be divided into three stages: the rapid growth period, the slow growth period, and the stable period. The monitoring results show that the high-performance concrete shaft lining has excellent mechanical properties in the external environment of high in situ stress, which can be used as a reference for the support design of similar projects.

Research and development of structures of single-row rope-profile guides for movement of vehicles in bar reinforcement

The paper studies the horizontal loads arising from the movement of vehicles under the action of dissipative forces (torsion of ropes, aerodynamic forces, loading cages with eccentricity in the frontal and lateral planes), which act on single-row rope-profile guides (hereinafter referred to as RPGs or guides). In the paper, for the case of two moving cages of one lifting unit, in accordance with the current regulatory techniques and Safety Rules, shaft cross-sections for various types of shaft reinforcement were designed, their advantages and disadvantages were analyzed, and their comparative analysis was carried out. On the basis of the research, the structures of single-row RPGs have been developed that have a smaller number of ropes and the structure of an enclosing profile in the form of an elongated hexagon, which makes it possible to increase the reliability of the kinematic link in the "vehicle-guide" system and ensure an increase of safety gaps between the vehicles and the shaft lining. The development of various structural solutions for single-row RPGs for cages makes it possible to achieve: - high reliability of a single-row RPG operation; - increased service life due to a significant decrease in the level of dynamic effects; - reduced labor intensity of maintenance and operation compared to rigid reinforcement; - reduced metal consumption compared to rigid reinforcement; - reduced level of dynamic oscillations at the meeting point of vehicles in the middle part of the shaft by reducing the RPG deflection; - increased reliability of the kinematic link in the "vehicle–RPG" system due to the use of specially designed guide legs; - reduced safety gaps per side (- 500 mm per side) for cage hoists along the entire depth of the shaft compared to flexible reinforcement; - reduced operating costs due to the high service life of a single-row RPG; - elimination of the use of fender ropes; - increased service life of rope-profile guides to the level inherent to guides of rigid shaft reinforcement. The result of the implementation of the developed structures of single-row RPGs with reinforcement is the extension of the service life of the reinforcement, and the reduction in the cost of capital construction and operation in the extraction of minerals from deep horizons.

Laser Scanning Monitoring of Deformations in Concrete Lining of Mine Shafts

Laser Scanning Monitoring of Deformations in Concrete Lining of Mine Shafts

Variation Pattern of the Stress‐Strain Curve of Concrete under Multifactor Coupling

The air shafts of coal mines contain solid, liquid, and gaseous substances that corrode concrete under conditions of relatively high temperature and humidity. The coupling of various factors decreases the concrete strength and thus the bearing capacity of the air shaft lining. In this study, concrete corrosion tests were carried out by simulating the complex environment of a coal mine air shaft lining to study the variation in the concrete stress‐strain curve. For corroded concrete specimens subjected to very low stress, the microcracks and holes were closed, generating a large deformation, indicating severe concrete corrosion. The longer the corrosion time was, the gentler the initial slope of the curve. Finally, the uniaxial compression constitutive model of corroded concrete was established based on the Weibull distribution of three parameters, and the model curve was compared with the experimental curve. This model can not only predict the change of the stress‐strain curve of high‐strength concrete in a coal mine air shaft environment but also provide theoretical reference for the application of high‐strength concrete in an air shaft environment.

Permeability Evolution Characteristics and Microanalysis of Reactive Powder Concrete of Drilling Shaft Lining Under Stress-Seepage Coupling

Permeability Evolution Characteristics and Microanalysis of Reactive Powder Concrete of Drilling Shaft Lining Under Stress-Seepage Coupling

Finite Element Method-based Temperature Field Analysis of Early Age Frozen Shaft Lining with Temperature-Dependent Characteristics

Finite Element Method-based Temperature Field Analysis of Early Age Frozen Shaft Lining with Temperature-Dependent Characteristics

Monitoring and analysis of the stress and deformation of shaft lining and the influence of freezing tube fracture in deep topsoil

Freeze shaft sinking is one of the main methods for the construction of vertical shaft in deep and thick topsoil. Freezing tube, frozen soil wall and shaft lining are the key to ensure the safety of freeze shaft sinking. Based on the on-site monitoring of the freeze shaft sinking project in Yuncheng coal mine in East China, this paper analyzes the variation law of freezing pressure, steel bar stress, concrete strain of the shaft lining, and frost heaving stress inside and outside the frozen soil wall in deep topsoil, and makes an in-depth analysis of the sudden change of the monitoring curves induced by the fracture of freezing tubes. The results show that: the freezing pressure in deep topsoil increases rapidly in early stage, reaching 66% - 86% of its' maximum value in 10 days, and tends to be stable after 30 days; the maximum freezing pressure generally approaches or even exceeds the initial horizontal earth pressure. The accumulation of frost heaving stress aggravates the stress and deformation of the frozen soil wall, freezing tube and shaft lining during shaft excavation, which is an important reason for the maximum freezing pressure to exceed the initial horizontal ground pressure and the fracture of freezing tube. The fracture of freezing tube causes local melting and weakening of the frozen soil wall, significantly affects the stress and deformation of the shaft lining, and induces the mutation of monitoring parameters. By means of monitoring the stress and deformation of shaft lining closely, it is feasible to judge and forewarn the fracture accident of freezing tube in time and take corresponding measures based on the sudden change of monitoring curves captured.

Features of the thermal regime formation in the downcast shafts in the cold period of the year

In the cold period of the year, to ensure the required thermal regime in underground mine workings, the air supplied to the mine is heated using air handling systems. In future, the thermodynamic state of the prepared air flow when it is lowered along the mine shaft changes due to the influence of a number of factors. At the same time, the processes of heat and mass exchange between the incoming air and its environment are of particular interest. These processes directly depend on the initial parameters of the heated air, the downcast shaft depth and the presence of water flows into the mine shaft. Based on the obtained experimental data and theoretical studies, the analysis of the influence of various heat and mass transfer factors on the formation of microclimatic parameters of air in the downcast shafts of the Norilsk industrial district mines is carried out. It is shown that in the presence of external water flows from the flooded rocks behind the shaft lining, the microclimatic parameters of the air in the shaft are determined by the heat transfer from the incoming air flow to the underground water flowing down the downcast shaft lining. The research results made it possible to describe and explain the effect of lowering the air temperature entering the underground workings of deep mines