Anchor Cable Research Articles

Experimental Investigation of the Influence of the Anchor Cable Inclination Angle on the Seismic Response Characteristics of Anchored Piles

Studies show that prestressed anchor cable antislide piles have good antiseismic characteristics. As an important parameter in the design of anchor-cable piles, the effect of anchor-cable inclination on the seismic response of the anchor-cable pile system has been rarely studied so far. In the present study, the seismic response characteristics of the anchor-pulled pile under different cable inclinations are studied using a large-scale seismic model test platform and numerical methods. The obtained results show that the inclined angle of the anchor cable has a great influence on the seismic response of the pile-anchor system. It is found that under the same seismic conditions, the axial force of the anchor cable becomes smaller as the anchor dip angle increases, while the pile top displacement becomes larger. The dynamic earth pressure behind the pile changes from the sliding surface to the pile top, indicating that the earth pressure near the sliding surface and the pile top is of active and passive earth pressure types, respectively. This pressure decreases with the increase of the anchor dip angle, thereby affecting the performance of the antisliding pile.

Analysis on Evolution Law of Small Structure Stress Arch and Composite Bearing Arch in Island Gob-Side Entry Driving

At present, the theory of supporting the surrounding rock small structure of gob-side entry driving has been widely used, but there is no specific quantitative analytical formula for the bearing strength and bearing characteristics of the structure. Construct a small structural stress arch mechanical model based on the arch axis equation, and divide the width of coal pillars (fractured zone-plastic softening zone-plastic hardening zone) and small structural stress arch height. According to the relationship between the stress arch height and the size of the roadway, the anchor cable length is determined to be 7.3 m, and the “anchor mesh + ordinary long anchor cable + grouting anchor cable” coordinated support plan is proposed: anchor net support is used for the first support, and long anchor cable and grouting anchor cable are used for the second support. Combined with the supporting parameters, a mechanical model of the surrounding rock composite bearing stress arch is proposed, and the composite bearing stress arch structure is derived using elastoplastic mechanics to obtain the ultimate bearing strength relationship expression. The results show that the ultimate bearing capacity of the haulage gateway of 17236 island working-face in the north of Zhangji coal mine can reach 29.193 MPa after the composite bearing stress arch support. The feasibility of the supporting scheme is verified, and field monitoring showed that the deformation zone of the surrounding rock of the transportation haulage gateway is stable after being supported by the composite bearing stress arch structure, the maximum shrinkage of the top and bottom of the roadway is 287 mm, and the distance between the two sides is 640 mm.

Efficient Excavation and Support Cooperation Technology for Surrounding Rock of Deep Buried Long-Distance and Large Section Gob-Side Roadway: A Case Study

The gob-side roadway technology is widely used in coal mining in China, as it can improves the recovery rate of coal resources and alleviate the shortage of mining replacement. However, it is still difficult to control the stability of surrounding rock in gob-side roadway under deeper mining depth and more complex stress environment. With the auxiliary transportation roadway 30207 (ATR 30207) of the Muduchaideng Coal Mine as engineering background, this paper introduces the engineering case of gob-side roadway characterized by deep buried, long-distance, and large section. Through comprehensive methods, we studied and put forward the efficient excavation-support cooperation technology for surrounding rock of gob-side roadway. The research shows that the head-on cutting of gob-side roadway causes the stress to transfer and gradually adjust in the heading face to form a steady-state advanced abutment stress field. The coupling effect of the advanced abutment stress and the lateral abutment stress of goaf are the main reasons for repeated hole collapse of anchor cable drilling in solid coal rib, development and expansion of the roof separation fracture, and the low excavation speed. Supposed that upon the heading face support is completed, the next excavation-support cycle is quickly started during the early stage of stress adjustment, and the time effect can be fully utilized to alleviate the disturbance intensity of the advanced abutment stress in the heading face, as well as reduce the damage of rock mass. This paper puts forward the time-effect collaborative control countermeasures of the roof and rib in gob-side roadway of “hole collapse anchor cable of solid coal rib lag construction and waits for pressure relief and rapid excavation-support cycle in the heading face.” Engineering practice shows that the mine pressure behavior of roadway roof and solid coal rib is effectively controlled, and the roadway forming speed is greatly improved, which can provide reference for the efficient excavation-support design of gob-side roadway under the conditions of deep buried, long-distance, and large section in similar deep mines.

Performance of a U-shaped anchoring system for cable-stayed bridges

An innovative U-shaped anchoring system was previously proposed to prevent the cracking of cable-pylon anchorage zones of concrete pylons in long-span cable-stayed bridges. The anchoring system transfers the cable force to the concrete pylon in the form of radial pressure, which fundamentally prevents the tension cracking of the concrete pylon column. In this study, the mechanical performance of the U-shaped anchorage system was investigated using finite element analysis. Subsequently, the fatigue performance of the steel strand in the U-shaped saddle, the anti-sliding performance of the U-shaped saddle, and the corrosion resistance of the steel strand were experimentally studied. The results of finite element analyses indicate that the U-shaped anchorage system significantly avoids concrete cracking in the cable anchorage zones provided that the strength grade of concrete filler is no less than C30. The experimental results show that the steel strand with polyurea coating has sufficient fatigue resistance as well as adequate anti-corrosion performance, and the anti-sliding performance of the anchoring system is sufficiently good. These critical studies validate the superiority of the U-shaped anchoring system with polyurea-coated steel strands, which should observe wide engineering applications in long-span cable-stayed bridges.

Anchorage performance of a modified cable anchor subjected to different joint opening conditions

In tunnelling engineering, the cable anchor is usually used to reinforce the surrounding rock mass. Site observation shows that the cable anchor may be subjected to different joint opening conditions. However, little study has been launched to study the influence of the joint opening on the anchorage performance of cable anchors. This paper conducted the laboratory Short Encapsulation Pulling Test (SEPT) to study the anchorage performance of a modified cable anchor subjected to different joint opening conditions. During the test, the joint opening was simulated with the bearing plate whose central diameter was different. The results showed that when the joint opening size increases, the maximum load-carrying capacity of cable anchors decreases. This was observed under both unconfined and confined boundary conditions. Moreover, under the confined condition, there was a threshold for the joint opening size. Once the joint opening size was beyond that threshold, further increasing the joint opening size had marginal effect on the capacity of cable anchors. Additionally, under the confined condition, the maximum load-carrying capacity of cable anchors was apparently higher. Furthermore, under the confined condition, cable anchors showed apparent residual load-carrying capacity in the post-failure stage. By contrast, under the unconfined condition, after the peak, the load-carrying capacity of cable anchors dropped dramatically. This leaded to negligible residual load-carrying capacity.

Lightning Transients of the Overhead Catenary System Pillar and its Adjacent Grounding Systems in a High-Speed Railway Depot

We have surveyed a signaling equipment failure caused by the spread of ground potential rise (GPR) between the overhead catenary system (OCS) pillar with two anchor cables and the trackside equipment due to lightning strikes to the pillar in a high-speed railway depot. Also, we evaluate the lightning currents on these conductors and their GPR considering the effect of soil conductivity <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">σ</i> and distance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> between the trackside equipment grounding rod and the anchor cable grounding system by using the 3-D finite-difference time-domain method. The simulation results show that the lightning current on the OCS pillar is shunted by anchor cables, and the distribution of currents on these conductors is influenced by soil conductivity. With the increase of soil conductivity, the current on the pillar increases, and the current on the anchor cable decreases. The GPR of the grounding systems is affected by the soil conductivity, and the GPR increases with the decrease of soil conductivity. Moreover, the GPR of trackside equipment grounding rod decreases with the increase of distance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> .

Failure Characteristics and Deformation Control Methods of the Bottom Drum of Roadways during Repeated Mining of Multiple Coal Seams

As the problems of serious bottom drum and roadway broken surrounding rock are influenced by repeated mining in multiple coal seams, the factors affecting the surrounding rock deformation of a +980 m roadway in Faer coal mine by analyzing the rock composition and obtaining borehole video data are investigated. The mechanism of the overburden caving affected by repeated mining of multiple coal seams is analyzed theoretically, and the numerical simulation is conducted to evaluate the deformation mechanism of roadway bottom drum. A combined support technology is proposed consisting of bolts, anchor cables, grouting, and pressure relief grooves. The measurements obtained during a 50 d monitoring period indicate that the deformations of the roof, floor, and both sides of roadway in the repaired and reinforced section are only 26, 56, and 26 mm, respectively. The fissures filled with slurry in the rock surrounding roadway can prevent further deformation of the rock mass.

Parameter Estimation and Tracking of an Expandable Cable-Driven Parallel Mechanism for Minimally Invasive Interventions

Conventional catheter-based procedures suffer from inaccurate device steering, and navigation limitations as the long and flexible devices are manipulated remotely from outside the patient body. A recently developed approach aims to overcome these limitations by using an expandable cable-driven parallel mechanism for local device manipulation and tracking relative to the anatomy. However, as the frame of this system is flexible and may be constrained by unknown anatomical constraints inside the patient body, accurate system identification is a key and critical step which would ultimately determine the accuracy in device steering and tracking. In this paper, we present an optimization approach to identify the parameters of an expandable cable-driven parallel mechanism deployed in an unknown environment, merely based on measurements of the cable length variations that would be available outside the patient body. We have verified and validated the proposed approach in terms of accuracy in the prediction of the frame shape and cable anchor locations, as well as its tracking accuracy. Both simulations and experimental studies have been performed, and we have demonstrated that the proposed method allows for rapid frame shape and anchor position estimation with unknown anatomical constraints and permits localized device tracking and steering with submillimeter accuracy.

Mechanical properties and field application of constant resistance energy-absorbing anchor cable

During the construction of underground engineering projects, it is often confronted with complex conditions such as high stress, extremely soft rock, and strong disturbance, resulting in stress concentration and energy accumulation in the surrounding rock. Due to insufficient elongation and low safety margin, it is difficult for common anchor cables to effectively absorb the energy released from the rock deformation, which often results in the failure of the supporting structure. To this end, a new material constant resistance energy-absorbing anchor cable (CREAC) is developed with high elongation and high energy absorption properties. To study the mechanical and energy absorption properties of the new anchor cable, the static tensile and dynamic impact tests are conducted. The results between CREAC and structural constant resistance and large deformation anchor cable (CRLDC) are compared. In terms of static mechanical properties, the maximum elongation of CREAC is 16.2%. Based on the commonly used cable length of 10 m in the field, the maximum elongation and the energy absorbed by CREAC are 2.21 times and 2.76 times that of CRLDC, with good static deformation and energy absorption capabilities. In terms of dynamics properties, the average single impact deformation of CREAC is reduced by 88.7% compared to CRLDC, and the energy it can absorb is 7.43 times that of CRLDC, showing advantages in impact deformation resistance and energy absorption. The design method of the constant resistance energy-absorbing support is proposed and the field application of CREAC is carried out. The monitoring results confirm that this new material anchor cable can effectively control the deformation of the surrounding rock.

Laboratory Model Tests of Seismic Strain Response of Anti-Seismic Anchor Cables

Under the impact of seismic forces, the strain of conventional anchor cables tended to increase sharply in an instant, which could easily cause the anchor cables to fail due to stress overload. This study aimed to optimize the design of rock supporting methods under dynamic disaster events such as earthquakes and rock bursts. A scale model specimen with a mechanical sliding device was designed based on an anti-seismic anchor cable. The working mechanism and seismic strain response of anti-seismic anchor cables were studied using static and shaking table model tests. The results show that under a static force, the anti-seismic anchor cables undergo in sequence a first elastic deformation stage, a slipping stage, a second elastic deformation stage, a plastic strengthening stage, and a brittle failure stage. In the slipping stage, the anchor cables start frictional sliding while keeping the axial force unchanged so as to adapt to the large deformation of the rock mass. The anti-seismic anchor cables exhibit the three situations of no-slip, instantaneous slip, and gradual and accumulative slip under seismic excitation. With a large constant resistance to slippage, the anchor cables do not slip, which can easily cause the anchor cables to break due to stress overload. With a small constant resistance to slippage, the reserved slipping distance is instantly exhausted; a step-shaped jump appears in the time history curves of the strain of the anchor cables. In the engineering design, a preset constant resistance to slippage is needed to match the seismic force for the anchor cables to exhibit the mechanism of multiple accumulated slips. During each slipping process, the strain of the anchor cables first decreases and then increases, with the peak strain decreasing significantly. This mechanism effectively cushions the instantaneous impact force of the earthquake, releases rock deformation, and dissipates seismic energy.

A Case Study on Surrounding Rock Deformation Control Technology of Gob-Side Coal-Rock Roadway in Inclined Coal Seam of a Mine in Guizhou, China

Surrounding rock deformation control of gob-side coal-rock roadway in inclined coal seams (GCRICS) is a major problem in gob-side entry technology application practice. This paper describes a case study of the surrounding rock deformation characteristics and control technology of a typical GCRICS in Guizhou, China. As according to data obtained during a field investigation, the reasons for the deformation and failure of 151509 tailentry and the shortcomings of the original support scheme were analyzed. In combination with existing theory and field experience, the “anchor cable + U-shaped steel + shotcreting + grouting” (CUSG) support method was proposed. The plastic zone distribution, displacement, and stress evolution law of the roadway-surrounding rock under the four support modes were analyzed and compared by numerical simulation. The results show that the supporting effects of several support methods varied from good to poor; CUSG was the best, followed by anchor cable support, U-shaped steel support, and then no support. Based on the previous seepage grouting theory, a slurry diffusion model of hollow grouted anchor cable (HGC) was established and the calculation formulas of slurry diffusion radius and grouting time were deduced, which provided guidance for field construction. Finally, the CUSG surrounding rock control technology was applied to 151509 tailentry subsequent roadway support. Through drill holes, analysis of the surrounding rock of the non-grouting area and the grouting area was conducted. It was found that the surrounding rock of the grouting area was high in integrity and strong in bearing capacity. Throughout the excavation period to the end of roadway mining, the roadway did not have to be repaired. This case study has high practicability, high popularization value, and provides a useful reference for the engineering support design of the GCRICS.

Deformation and Failure Characteristics and Control Technology of Surrounding Rocks in Deep High-Horizontal Stress Rock Roadways in the Wanbei Mining Area

Taking the engineering conditions of the Zhujixi coal mine and Hengyuan coal mine in the Wanbei mining area as the background, based on the investigation of the deformation and failure status of the surrounding rock of the two mines, the deformation and failure characteristics of the surrounding rock of the deep rock roadway in the Wanbei mining area are systematically studied by using the comprehensive research methods of the surrounding rock mechanical parameter test, in situ stress measurements, and numerical simulation. The results show that the measured value of the intermediate principal stress is slightly less than the theoretical value, which is obviously affected by the tectonic stress. The lateral pressure coefficients of the two mines calculated according to the theory are between 1.06 and 1.24 and 1.18 and 1.24, respectively. The simulation shows that when the lateral pressure is higher than 1.5, the arrangement of drilling holes with a depth of 5–10 m and a diameter of 200–300 mm can effectively transfer the stress concentration, proposed using Ф22 L = 2800 mm anchor rods, row spacing 800 × 800 mm, specification Ф 22. For the anchor cable with a length of L = 6,300 mm, the row spacing between anchor cables is 1,600 ± 100 mm, and the coordinated support technology of the reinforcement support and grouting is added. The technology can fully mobilize the deep stable rock stratum when it is applied from the slope change point of 11 coal belt roadways in the east wing of the Zhujixi coal mine to the machine head chamber of 11 coal belt roadways in the west wing, and the field application is good.

Anti-explosion and reinforcement effects on a cavern with a new prestressed anchor cable

Traditional cavity reinforcement technology is difficult to effectively protect the cavity from damage caused by modern large-yield explosions, and the anti-explosion performance of prestressed anchor cables needs to be improved urgently. The design of a new prestressed high-elastic fully adhesive anchor cable for the enhancement of the anti-explosion effects of the anchor cable is presented in this paper. A constitutive model of the anchor cable is established in FLAC 3D and used to restore an equal scale field anti-explosion test. The reinforcement effects of the new anchor cable are compared with the conventional one’s. Results show that the stresses of the anchor cables differ at different locations: the anchor cable at the arch crown of the cavern is the one mainly under pressure with the compressive strain of the new anchor cable reduced by 25 %; while the anchor cable at the arch foot of the cavern is the one mainly under tension and the tensile strain of the new anchor cable is reduced by 26.3 %. The vertical displacement of the arch crown is reduced by 16.2 % with the reinforcement of the new anchor cable. The new anchor cable performs much better on the reinforcement of the cavern than the conventional one in the aspects of stress, strain and displacement, which provides a basis for the design of new anchor cables and their applications in engineering.

A New Prestress Loss Calculation Model of Anchor Cable in Pile–Anchor Structure

Pile–anchor structures are widely used in foundation excavation and slope reinforcement due to their safety and reliability. However, the pile–anchor structures have the common problem of the prestress loss of anchor cables, which may reduce the stability of the structures. To accurately predict the prestress loss of anchor cables, a new prestress loss calculation model was established, and the availability of the prestress loss calculation model was verified through engineering cases. Meanwhile, aiming at the long-term prestress loss of anchor cables, the coupled creep behavior of anchor cable–rock and soil was studied and an anchor cable–rock and soil coupled creep model suitable for pile–anchor structures is proposed. The model test confirms that the coupled creep model could accurately describe the coupled creep behavior of the anchor cable and the rock and soil mass. The models provide a theoretical basis for the study of the prestress of anchor cables in pile–anchor structures, and have a guiding significance for the design and construction in foundation excavation and slope engineering.

Evaluation of failure risk for prestressed anchor cables based on the AHP-ideal point method: An engineering application

This research is focused on the evaluation method of failure risk of prestressed anchor cable, and an accurate evaluation method with a simple operation is proposed. The analytic hierarchy process are used to determine the weight of each evaluation element, the closeness degree of each indicator is determined based on ideal point method. The results show the following: (1) the evaluation method better integrates the effects of multiple factors on the failure risk of the prestressed anchor cable, and the evaluation results are accurate and consistent with the actual situation of the project; (2) the evaluation result is intuitive, and the correlation degree obtained can not only reflect the failure risk grade of prestressed anchor cable, but also the possibility of deterioration of the failure risk of the evaluated anchor cable to a higher level could be obtained; and (3) the rationality and practicability is verified by comparison with field situation and other several methods. In addition, this method has good applicability in solving the other uncertain problems.

Stability of expansive soil slopes reinforced with anchor cables based on rotational-translational mechanisms

Expansive soil slopes are usually characterized with conspicuous fissures. Pre-stressed anchor cables are effective techniques in improving the slope stability. Explicit considerations of the fissures and the suction effect become crucial in producing more realistic solutions. Based on the kinematic limit analysis theorem, this paper performs a limit analysis of the stability for expansive soil slopes stabilized by anchor cables. The upper bound solution to the slope stability was optimized and compared with the published solutions, demonstrating the applicability of the proposed method. An illustrative slope reinforced with two different reinforcement patterns was investigated to show the role of soil suction and anchor reinforcement in the safety assessments of expansive soil slopes. The results indicate that the slope stability and anchor reinforcement relate closely to the fissures. A threshold value of the fissure height exists, beyond which the slope stability is significantly reduced. An optimum inclination angle (ξopt) of anchors exists universally and is reduced as the anchor height, the internal friction angle and the surcharge load increase.

Analysis on Construction Technology of Prestressed Anchor Cable for High Slope in Road and Bridge Construction

Analysis on Construction Technology of Prestressed Anchor Cable for High Slope in Road and Bridge Construction

Influence of Internal Rubber Damper on Cable External Viscous Damper Effectiveness

In practice, the internal rubber dampers are widely installed inside the cable guide pipe between the external viscous damper and the cable anchorage. In order to study the effect of the internal damper on the performance of the external viscous damper, the theoretical analysis model of a taut cable with an internal rubber damper and an external viscous damper is established in this paper, where the internal damper is assumed to be a high damping rubber damper with a flexible support and the external damper is considered to be a linear viscous damper. Then, the numerical iterative formula and approximate solution expression for the cable modal damping ratio are derived. Based on the approximate solution, the parameters of the internal rubber damper are analyzed comprehensively, and its influence on the cable modal damping in cable multimode is studied as well. Results show that, except for the support flexibility of the internal rubber damper, other parameters will have a negative effect on external viscous damper effectiveness. From the perspective of cable multimode vibration control, the installation of an internal rubber damper significantly weakens the modal damping, and this effect is more pronounced in lower frequency modes.

Investigation on the key techniques and application of the new-generation automatically formed roadway without coal pillars by roof cutting

The first-generation automatically formed roadway without coal pillars by roof cutting (AFRCPRC) technology has achieved significant technical and economic benefits in the period 2009–2019. However, it adopts shaped charge blasting for roof cutting, which is not only unsafe but also troublesome with respect to explosive approval. Besides, the installation procedure of macro-negative Poisson's ratio (NPR) anchor cable is rather complicated. To overcome these drawbacks, the second-generation AFRCPRC technology was developed in 2020. It employs a non-explosive blasting method, i.e., instantaneous expander, forming a single fracture (IESF), and thus its safety is greatly improved. In addition, micro-NPR anchor cables, which are easy to operate and have the characteristics of large elongation, high strength, strong impact resistance and no obvious necking phenomenon, are used for roadway support. In this paper, the basic principles, key techniques and main processes of the second-generation AFRCPRC technology are introduced, and experiments that were conducted in a coal mine are described. The experimental results show that IESF has excellent directional roof-cutting ability which can replace the explosive energy-focusing blasting, and the micro-NPR anchor cable boasts superior supporting performance which can effectively control roof deformation. The automatically formed roadway deforms insignificantly and satisfies the requirement of the next working face, illustrating the success of the second-generation AFRCPRC technology. Compared with the first-generation AFRCPRC technology, the remarkably improved second-generation one will have greater application potential in the mining field.

Study on Monitoring Methods of Stone Cultural Relics - Taking Shaoxing Yangshan Statue as an Example

In recent years, due to the structural factors of the rock mass itself, many rock masses are in an unstable state, and there are many structural fissures in the rock mass.There is a serious seepage phenomenon inside the cave, and the weathering diseases on the surface of the rock mass have appeared to varying degrees. Its cultural, artistic and scientific values need to be continued. Through modern instrument and scientific testing scheme, the horizontal displacement, crack and stress of reinforced anchor cable of dangerous rock mass are monitored in real time. After material reinforcement and repair, continuous monitoring is carried out to check the repair effect and ensure that the repair scheme is effective. Keywords : unstability; crack; weathering; monitoring DOI: 10.7176/CER/14-2-04 Publication date: April 30 th 2022