Construction Of Vertical Shafts Research Articles

Impact of excavation footage on vertical shaft lining deformation and surrounding rock stress in Xiyu conglomerate

The Xiyu conglomerate, which is extensively distributed in Xinjiang, China, presents challenges for vertical shaft construction owing to its poor cementation and low strength. The selection of an appropriate footage length is paramount for ensuring safe construction. Based on the shaft pipeline construction project of the Xinlongkou Hydropower Station on the Kuitun River, this study investigated the impact of footage length on the stability of vertical shafts within the Xiyu conglomerate strata using finite element simulation and measurement data to analyze the lining displacement and change in stress in the surrounding rock. The results show that the excavation footage has little effect on the lining’s horizontal displacement during vertical shaft excavation. A mathematical model was developed to describe how the vertical displacement of the lining varies with the excavation footage and vertical shaft depth. Below a critical threshold, the stress in the surrounding rock cannot be effectively alleviated, leading to a concentration of stress; above that critical threshold, an excessively large excavation increases the load on the surrounding rock. Based on the simulation results and factors such as economic benefits, construction speed, and safety, an excavation footage of 4 m is judged to be appropriate.

Failure Characteristics of the Water-Resisting Coal Pillar under Stress-Seepage Coupling and Determination of Reasonable Coal Pillar Width

Groundwater inrush hazard has always been a great threat to the construction of vertical shafts in coal mines. Generally, the failure of the water-resisting coal pillar under coupled stress-seepage conditions around the vertical shaft is the main reason for the generation of the water inrush channel. In order to understand the mechanical behaviors of the water-resisting coal pillar, the strength of typical coal affected by the size and water content was investigated, and the stress sensitivity of permeability was investigated by a stress-seepage coupling test. The stress field and deformation of the water-resisting coal pillar were investigated by numerical simulation, the stability of the water-resisting coal pillars with different widths was evaluated, and the reasonable width of the coal pillars under coupled stress-seepage condition was determined. Results show that the water content and coal pillar width have a great influence on the mechanical characteristics of coal samples. Under the conditions of lower water content and larger coal sample width, the coal sample presents higher strength, smaller axial deformation, smaller permeability and porosity, and weak sensitivity to stress. The simulation results show that the boundary of the main roadway at the end of the coal pillar is dominated by tensile stress, and fractures can significantly contribute to the destruction of coal pillars. With the increase in the width of the water-resisting coal pillar, the internal damage variable, maximum tensile stress, porosity, and average water flow velocity of the coal pillar decrease, which reduces the risk of water inrush and improves the safety of the water-resisting coal pillar. An evaluation model of the reasonable width of the water-resisting coal pillar under the stress-seepage coupling was proposed, and the model was verified by the shear slip law and experimental results. This study provides theoretical and experimental guidance for the risk management of groundwater inrush disaster during the construction of vertical shafts in coal mines.

Behavior of large shaft sinking headframe subjected to uneven foundation settlement

Deep mining is an inevitable trend in China and the world, for which the construction of deep and large vertical shafts is the primary task. A shaft sinking headframe is a basic structure for supporting various hoisting and sinking equipment during vertical shaft construction. The design of the shaft sinking headframe is challenging due to the significant differences in the geometry and working load compared to conventional steel structures. Recently, the effect of uneven foundation settlement on the shaft sinking headframe has been of great concern when sinking shafts by the freezing sinking method or in permafrost soil areas. In this study, finite element calculations were performed to investigate the mechanical behavior of the SA-3 shaft sinking headframe under uneven foundation settlement (0.001–0.006 L) and normal working-load conditions. The results indicate that the most unfavorable condition for the stress of members is the diagonal double foundation settlement, and in the view of the geometric offset, the most unfavorable condition is the same-side double foundation settlement. The corner members near the settled foundation were changed from a state of compression to tension. Uneven foundation settlement of less than 0.001 L is acceptable for the safety and service performance of the shaft sinking headframe. These criteria can be used for reference in engineering practice.

Monitoring of construction-induced urban ground deformations using Sentinel-1 PS-InSAR: The case study of tunneling in Dangjin, Korea

The construction of underground tunnels can prime or trigger ground subsidence, and thus surface deformation monitoring is required during and post-construction. Freely available satellite data allow significant possibilities for the use of remote sensing techniques, particularly multi-temporal interferometric synthetic aperture radar (Mt-InSAR), for surface deformation monitoring. However, track records and field demonstrations of InSAR-based tunneling-related deformation monitoring are limited, particularly in identifying the spatiotemporal evolution of ground deformation and causal factors thereof from construction activities. Therefore, this study explores the feasibility of using satellite SAR data to monitor the surface deformation associated with different tunnel construction phases. Tunneling-related surface deformation was analyzed using the persistent scatterer InSAR (PS-InSAR) technique and Sentinel-1B SAR data; the PS-InSAR results were compared with those from the conventional leveling method. The velocity map of the study site revealed a localized subsidence trough associated with the construction of vertical shafts and shield tunneling. The cumulative time-series displacement map successfully tracked the spatial and temporal progression of ground deformations related to the phases of tunnel construction activities. The maximum subsidence rate in the radar line-of-sight direction was estimated to exceed 40 mm/yr, with maximum cumulative subsidence of ∼ 200 mm. The results clearly showed that dewatering during tunneling aggravated the subsidence phenomenon. The consequent compaction and consolidation of the compressible soil layers due to the lowered groundwater table were the main causes of subsidence. Our results demonstrate the viability of the PS-InSAR technique based on the C-band Sentinel-1 product as a monitoring method to examine the spatiotemporal evolution of ground deformation patterns during tunneling activities and as a possible preliminary surveying tool to identify ongoing abnormal settlement prior to tunnel construction.

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.

Study on triaxial creep behavior and the damage constitutive model of red sandstone containing a single ice-filled flaw

The freezing method is widely used in the construction of vertical shafts in water-rich strata. The formed frozen rock wall is often involved in the creep process, and in particular, the creep behavior of frozen fissured rock mass poses a great threat to construction safety. To better understand the creep instability law of ice-filled, fractured red sandstone under freezing and triaxial stress conditions, a series of triaxial creep tests on frozen red sandstone specimens containing a single, pre-existing flaw at −10°C and under a confining pressure of 4 MPa were carried out with a self-developed DRTS-500 subzero rock triaxial testing system. The multistage loading creep curves were obtained, and the evolution laws of deformation and damage for the frozen specimens in the primary (instantaneous), secondary (steady-state) and tertiary (accelerating) phases were analyzed. The nonlinear visco-elastoplastic constitutive model of red sandstone with a single ice-filled flaw was established according to the fractional calculus theory and the Kachanov damage theory. The results show that the initial creep property, unstable creep property and creep failure mode of frozen single-flaw red sandstone are significantly affected by the flaw dip angle. The proposed creep damage model can accurately describe the complete creep curves of frozen red sandstone with a single ice-filled flaw, especially in the unstable creep stage. The influences of the stress level and flaw dip angle on the creep parameters were analyzed, and sensitivity analyses of the characteristic creep parameters were carried out to verify the reliability and rationality of our creep model. This research can be applied to the assessment of collapse, cracking and other long-term failures and hence can be used as a theoretical basis of design in the freezing engineering of coal mine shafts.

Vertical Shaft Excavation Shaping and Surrounding Rock Control Technology Under the Coupling Action of High Ground Stress and Fracture Formation

AbstractThe stability discrimination method of surrounding rock in vertical shaft construction and the safety technology of shaft construction under the geological condition of a super-thick crush ...

МОНИТОРИНГ УСТОЙЧИВОСТИ ВЕРТИКАЛЬНЫХ СТВОЛОВ КАЛИЙНЫХ РУДНИКОВ

As a result of experimental and theoretical studies, the regularities of the interaction of vertical shafts of potash mines with the rock mass were clarified, which allows predictive assessment of the consequences of violations of construction geotechnology projects and to develop effective measures to restore lining and ensure safe operation of shafts. At the same time, during the construction of vertical shafts, deviations from projects occur without modeling the possible consequences of such violations of projects. However, for a predictive assessment of the consequences of violations of construction geotechnology projects and the development of effective recommendations for the restoration and ensuring the safe operation of shafts, it is necessary to use a system of control and measuring monitoring of the support material, and mathematical modeling of its stress-strain state.

Experimental investigation of physical and mechanical properties of processes accompanied with phase transition in water-saturated soil

Nowadays, in view of increasing occurrence depth and complication of hydrogeological conditions in mineral deposits, the construction of vertical shafts is conducted using the artificial freezing technology. Therefore, mechanical processes mechanical behavior of water-saturated rock layers during freezing and thawing processes require a deep analysis.The paper considers the possibility of using a fiber-optic system for recording a temperature decrease during a soil freezing process and deformations arising in water-saturated soil due to frost heave. The features of the freezing front propagation and moisture redistribution are discussed. Two types of experiment were carried out all-round freezing and one-side freezing. It is important that the experiments simulate different direction of freezing front propagation. To analyze the experimental data a thermo-hydro-mechanical model is proposed. The model takes into account non-instantons kinetics of water crystallization, residual moisture content contained in the soil under temperature below the freezing temperature, moisture migration to the freezing front and an evolution of a stress-strain state of the soil caused by thermal strain and volumetric expansion due to the phase change of water into ice and the moisture flow. Results of the performed study have been shown that the numerical prediction of temperature change are in good agreement to the measurements, but there is qualitative difference between the frost heave deformation given by the model and registered by the sensors.

ВЗАИМОДЕЙСТВИЯ ВЕРТИКАЛЬНЫХ СТВОЛОВ С ПОРОДНЫМИ МАССИВАМИ ПРИ ВОССТАНОВЛЕНИИ КРЕПИ И АРМИРОВКИ

As a result of experimental and theoretical studies, the patterns of interaction of vertical shafts with rock masses were clarified when restoring support and reinforcement to improve the geotechnology of construction of vertical shafts of potash mines in the specific conditions of the Verkhne-Kama potassium-magnesium salt deposit. The system for monitoring the dynamics of deformations and normal tangential stresses in the concrete lining of the cage and skip shafts of the Ust-Yaivinsky mine of Uralkali Company during the replacement of destroyed tubing to determine the critical time period ensuring the non-emergency replacement of tubing segments is advisable to be implemented in the form of an automated stationary monitoring systems for engineering structures.

ОБ ОПЫТЕ И ПЕРСПЕКТИВАХ ПРИМЕНЕНИЯ ТЕХНОЛОГИЙ ПРОХОЖДЕНИЯ ВЕРТИКАЛЬНЫХ СТВОЛОВ В УКРАИНЕ

Purpose. Analysis of production experience, scientific and technical developments and assessment of the prospects for the application and development of technologies for the construction of vertical shafts in Ukraine in the context of the need to restore the coal mining industry to preserve the energy independence of the state. Methodology. The methods of analysis of the accumulated production experience of shaft sinking in Ukraine, in the post-Soviet space and in the leading mining countries, as well as scientific and technical literature were used. Results. The classification of technologies and methods of vertical shaft sinking is considered and supplemented, technological schemes and equipment used and promising for Ukraine for the construction of shafts by conventional and special methods are analyzed, the production experience of the Donetskshakhtoprokhodka and Spetsshakhtobureniie trusts is generalized from the point of view of applicability in the construction of shafts of block No. 12 of PJSC Shakhtopravlenie Pokrovskoe”. The possibility of using a modified parallel technological scheme of shaft sinking has been substantiated. The prospects of mechanized shaft sinking in Ukraine – by drilling and with the use of shaft-sinking machines – are assessed. The characteristics of the conditions for the construction and operation of shaft lining, the final element of the shaft, as a structure and functional complex are given. Variants of combined lining, including those with the use of fiber-reinforced concrete, are considered. Scientific novelty. The results of the analysis of technological schemes and methods of vertical shafts sinking, accumulated production experience and scientific and technical developments are generalized, trends and prospects for the development of technologies are considered. Practical value. The analysis of technological schemes and methods of sinking vertical shafts was carried out on the basis of domestic and foreign production experience. Key words: vertical shaft, sinking technology, shaft sinking flow chart, drilling and blasting operations, shafts drilling, shaft-sinking machine.

Unloading Creep Characteristics of Frozen Clay Subjected to Long‐Term High‐Pressure K0 Consolidation before Freezing

Artificial ground freezing has been widely applied in the construction of vertical shafts in deep and thick alluvia. As an important factor, the in situ creep behavior of deep, frozen soil affects the mechanical properties of frozen walls and the safety and stability of shaft linings. Acquiring creep characteristics and deep soil parameters by methods that ignore the engineering and geological situations is currently inadvisable. A series of triaxial unloading tests were conducted with frozen clay subjected to long‐term high‐pressure K0 consolidation before freezing to research the unloading creep characteristics, creep strength, and other parameters of the clay, and the results indicated the following: (1) The creep behaviors of frozen clay are affected by the consolidation time and consolidation stress. Long‐term high‐pressure K0 consolidation reduces the creep strain and creep rate of frozen clay. (2) The decrease in the ice and the unfrozen water contents of frozen clay caused by the prolongation of consolidation time result in an increase in the long‐term strength and instantaneous strength. Consolidation time has an obvious effect on long‐term strength and weakens the creep property of frozen clay. Consolidation stress significantly affects the instantaneous strength. (3) The deformation resistance capability of frozen clay is enhanced by compaction; thus, E1, η1, and η2 increase with prolonged consolidation, and the nonlinearity of the accelerated creep increases.

Общие проблемы управления геотехническими рисками на примере строительства вертикальных стволов метрополитена в городе Мо скве

Общие проблемы управления геотехническими рисками на примере строительства вертикальных стволов метрополитена в городе Мо скве

Small-diameter vertical shafts constructed in the shallow space of steep mountainous areas

Japan is a mountainous country comprising several islands, in which mountains occupy 70% of the entire land. Therefore, numerous transmission line towers have been constructed in the shallow space of steep mountainous areas. In such construction, monorails and/or cableways are generally used to transport materials and equipment to the construction site instead of using a construction road, as the former method is more economically viable. However, with this method, drill rigs or vertical shaft sinking machines cannot be transported to the site. Four small-diameter vertical shafts of 2.5 or 3.0 m as the foundation for high-voltage transmission line towers in mountainous areas are traditionally constructed manually in Japan. Over the past two decades, however, dangerous and poor environmental conditions for workers regarding the manual construction of these small-diameter vertical shafts have become a major problem. Meanwhile, owing to the poor environmental conditions of small-diameter vertical shafts to be constructed in the shallow space of steep mountainous areas, a decrease has occurred in the number of young workers entering these projects. Namely, the construction of transmission line towers with using the manually traditional small-diameter vertical shafts is becoming difficult in Japan from abovementioned problems. Hence development of a new technology to solve the problems is necessary for Japan’s economic growth. With this knowledge, the authors have developed a new small-diameter vertical shaft construction system, in which workers do not have to enter the vertical shaft during construction, as machines are used instead. The applicability of the proposed system was confirmed by means of the construction of three actual vertical shafts at two construction sites, as well as in factory and field tests. The applicability and details of the final proposed system are summarized in this paper.

Non-standard equipment for construction of vertical shafts

The article deals with the modern problems of construction and reconstruction of vertical shafts of mines, which require innovative technical solutions in the mechanization of mining operations. The examples developed by the authors of the original equipment and technologies, are successfully implemented for the mining industry in Russia.

Assembling of Steel Angle Headframe of Multifunctional Purpose

The article reviews new technical solution on equipment provision of vertical shaft utilizing steel headframe of multifunctional purpose. Practice of construction of coal and ore mines provides application of various designs for steel angle headframes which are divided into separate large assembly blocks and constructive elements during assembling operations. Design of these blocks and elements, their weight and dimensions effect the chose of the method of assembling on which economic and technological indicators, as well as duration of down-time, depend on during performance of construction operations in shaft. The technical solution on equipment provision for mine vertical shaft using headframe of multifunctional purpose will allow changing the management construction of vertical shaft. The proposed headframe combines the functions of sinking and operation that eliminates costs for assembling/dissembling of temporary headgear. The constructive design of the headgear allows application of the effective method of assembly and thus to provide improvement of the technical and economic indexes, and high calendar time rate of the shaft construction due to reduction of duration of works on equipment provision for the shaft and to refurbishment of the shaft in order to carry out horizontal mining.

Design and construction of shaft for rock caverns in Singapore

Access shaft is of critical importance to the construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, the design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative III: plain shaft, are proposed based on a simplified geological profile of the Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls.

Lateral earth pressures acting on circular shafts considering soil-structure interaction

Nowadays, there is a significant demand on developing and expanding the existing infrastructure which necessitates the implementation of fast and cost effective construction methods such as the secant pile walls. The secant pile walls constructed in a circular plan layout to form a vertical shaft provide unique advantages such as compression ring behaviour. Compression rings act as a single-unit system in resisting lateral earth pressure and converting loads from all directions to compressive forces which can be resisted only by low concrete strength. Secant pile walls require stringent drilling tolerances to be achieved in order to behave as a compression ring and to perform as an effective groundwater cut-off wall. This paper presents a parametric study that investigates various aspects of the behaviour of circular shafts constructed using secant pile walls. The aspects that are studied include the identification of the magnitude and distribution of earth pressures exerted on circular shafts by the retained material. The distribution of surcharge pressures on the shaft walls is also studied. The results showed that the surcharge pressures on the wall increased with increasing width of surcharge area; for example, the maximum surcharge pressure increased by at least 60% when surcharge width increased from W = 3 m to W = 48 m. In addition, the results indicated a decrease of the maximum surcharge pressure on the wall by almost 22% when shaft radius decreased from R = 5 m to R = 3 m for Soil 1. Unlike what is observed in plane strain conditions, distance between the surcharge and shaft wall was seen to have a small effect on the magnitude of maximum pressures. The results also showed that the theoretical estimate of pressures underestimated the calculated values at larger depths and that the horizontal extent of the spread of pressure around the shaft was significantly influenced by the type of soil as well as width of surcharge. The outcomes of this study address practical design concerns and are considered to be of interest to those involved in design and construction of vertical shafts.

New Technical Solution for Vertical Shaft Equipping Using Steel Headframe of Multifunction Purpose

The article reviews a novel approach to the design of steel angle headframe for vertical shafts of coal and ore mines on the basis of rational design solutions. Practice of construction of coal and ore mines provides application of various designs for steel angle headframes which are divided into separate large assembly blocks and constructive elements during assembling operations. Design of these blocks and elements, their weight and dimensions effect the chose of the method of assembling on which economic and technological indicators, as well as duration of down-time, depend on during performance of construction operations in shaft. The technical solution on equipment provision for mine vertical shaft using headframe of multifunctional purpose will allow changing the management construction of vertical shaft. The constructive design of the headgear allows application of the effective method of assembly and thus to provide improvement of the technical and economic indexes, and high calendar time rate of the shaft construction due to reduction of duration of works on equipment provision for the shaft and to refurbishment of the shaft in order to carry out horizontal mining.

Results of studies of shaft boring machine operation in vertical shaft construction at Upper Kama Potash Deposit

Results of studies of shaft boring machine operation in vertical shaft construction at Upper Kama Potash Deposit