Anchor Cable Research Articles

Rap1 coordinates cell-cell adhesion and cytoskeletal reorganization to drive collective cell migration in vivo

Collective cell movements contribute to tissue development and repair and spread metastatic disease. In epithelia, cohesive cell movements require reorganization of adherens junctions and the actomyosin cytoskeleton. However, the mechanisms that coordinate cell-cell adhesion and cytoskeletal remodeling during collective cell migration invivo are unclear. We investigated the mechanisms of collective cell migration during epidermal wound healing in Drosophila embryos. Upon wounding, the cells adjacent to the wound internalize cell-cell adhesion molecules and polarize actin and the motor protein non-muscle myosin II to form a supracellular cable around the wound that coordinates cell movements. The cable anchors at former tricellular junctions (TCJs) along the wound edge, and TCJs are reinforced during wound closure. We found that the small GTPase Rap1 was necessary and sufficient for rapid wound repair. Rap1 promoted myosin polarization to the wound edge and E-cadherin accumulation at TCJs. Using embryos expressing a mutant form of the Rap1 effector Canoe/Afadin that cannot bind Rap1, we found that Rap1 signals through Canoe for adherens junction remodeling, but not for actomyosin cable assembly. Instead, Rap1 was necessary and sufficient for RhoA/Rho1 activation at the wound edge. The RhoGEF Ephexin localized to the wound edge in a Rap1-dependent manner, and Ephexin was necessary for myosin polarization and rapid wound repair, but not for E-cadherin redistribution. Together, our data show that Rap1 coordinates the molecular rearrangements that drive embryonic wound healing, promoting actomyosin cable assembly through Ephexin-Rho1, and E-cadherin redistribution through Canoe, thus enabling rapid collective cell migration invivo.

The Retention and Control Technology for Rock Beams in the Roof of the Roadway: A Case Study

Background: Coal mining requires safe and effective roadway support to ensure production and worker safety. Anchor support is a common method used for controlling the roof of coal seams. This study aims to analyze the effectiveness of different anchor support schemes and provide a theoretical basis for designing safe and effective roadway support. Methods: The authors used a computer simulation tool called FLAC3D to simulate and analyze the spacing between anchor bolts, anchor bolt length, anchor cable length, and effective roadway roof control, and support the schemes at the western wing roadway in the no. 15 coal seam of no. 1 mine of Ping’an Coal Mine. Results: The study found that using different combinations of anchor bolts and cables with varying lengths could effectively control the deformation of the roadway surrounding rock, depending on the spacing between layers of the coal seam. The most effective support schemes were recommended depending on the specific conditions. Conclusion: The study provides a theoretical basis for the design of anchor support in coal mines, which can ensure the safety of production and improve roadway stability. The results could be useful for other mining operations facing similar challenges in roadway support and stability.

Supporting Mechanism of Pile-Anchor Systems for Deep Foundation Pits in Alpine Regions during the Spring Thaw

This study investigated the supporting mechanism of the retaining piles and prestressed anchor cables of a deep foundation pit in alpine regions during the spring thaw. A numerical model was developed based on a subway project in Changchun City. Field monitoring data and the numerical model were used to analyze the variations in the ground settlement, horizontal displacement of the pile tops, and axial force of the anchor cables during the spring thaw under different working conditions. The results demonstrated that changes in the ground settlement primarily occurred in the late stages of the spring thaw with no obvious settlement phenomena because of the thaw. The pile top displacement of most piles remained stable. The axial force of the anchor cables gradually decreased and then sharply increased early in the spring thaw and then slowly decreased in the middle and late stages. Increasing the pile length decreased the pile top displacement to a certain point. Moreover, increasing the pile length increased the axial force of the first anchor cable but decreased the axial force of the lower four anchor cables. Furthermore, increasing the pile spacing increased the pile top displacement and axial force of the five anchor cables. Increasing the incident angle of the anchor cables decreased the pile top displacement and increased the axial force of the first, third, and fourth cables. The axial force of the second cable was minimized at an incident angle of 14°, and the axial force of the fifth cable was minimized at incident angles of 16° and 18°.

Cross-Scale Analysis on the Working Performance of Micropile Group and Talus Slope System

Micropile groups (MPGs), combined with the advantages of the anti-slip pile and anchor cable, offer an efficient support system that can be used as countermeasures for stabilizing the talus slopes. However, the performance of MPGs in stabilizing the talus slopes is rarely numerically investigated from the continuous-discontinuous viewpoints. To fulfil this knowledge gap, a numerical method coupled with the discrete element method (DEM) with the finite element method (FEM) is proposed first, and validated to be with good accuracy by the centrifuge model tests. A series of cross-scale analysis cases are then adopted to assess the behavior of MPG in the talus slopes, in which the influencing factors are also taken into account. The numerical results indicate that the MPGs reinforcement can significantly improve the stability of the talus slopes, avoiding the potential progressive shallow slip. For the MPGs with different pile spacing, the distribution laws of deformation and internal force are rather similar, but the one whose pile spacing is four times the pile diameter shows better performance. Moreover, the effective anchorage length of MPG is approximately 1/3 of the pile length, and the axial force distribution is influenced by the type of pile bottom constraint and the tangential contact between the micropile and the bedrock. Finally, the “bidirectional anchorage” attributed to the platform and the bedrock can greatly improve the performance of the MPG, which is a non-negligible part of the anti-slip mechanism of the MPG. This study is of great significance for facilitating the design of MPG in stabilizing the talus slopes.

Study on Failure Mechanism of Roadway Surrounding Rock and Hierarchical Continuous Support Technology in Unidirectional Fault Area

A fault is a common geological structure in coal mining. Large deformation or even instability and collapse often occur in roadways in fault areas, which restricts the safe and efficient production of mines. With the track roadway of the 5206 working face of Xin’an Coal Mine as the engineering background, this study aims to explore the failure mechanism of surrounding rock under the influence of fault structures. Field investigation and numerical simulation were used comprehensively to analyze the failure characteristics of the surrounding rock under the influence of a unidirectional fault structure. Based on the principle of thick-layer transboundary anchorage, the hierarchical continuous support technology of transboundary anchoring in the fault structure area was proposed. The results show that the stress near the fault area is relatively concentrated, and the rock mass strength is low, which may easily cause the deformation and failure of the surrounding rock under the dynamic stress response. Using the new technology to reconstruct the bearing structure of the broken surrounding rock mass, the deformation of the surrounding rock can be effectively restrained. According to the monitoring feedback, the roadway deformation in the roof and two sides is reduced by 68.5% and 35.4%, respectively; and the maximum evolutionary depth of the roof crack is reduced to 3.5 m from 7.5 m in the original support scheme. Moreover, this study also explored the necessity of wedge anchorage for corner anchor cables and the deformation characteristics of surrounding rock at different fault dip angles. These results provide an important reference for the maintenance and control of coal roadways under the influence of unidirectional fault structures.

Model test on deformation and failure mechanism of tunnel support with layered rock mass under high ground stress

To control the large deformation of the Changning Tunnel, based on the constant resistance and energy absorption characteristics of the NPR anchor cable, first, through the physical model test, the mechanics of the NPR anchor cable controlling the deformation of the floor heave was studied, including the temperature field, strain field, and displacement field during the tunnel excavation and loading process. Then, through field tests, the control effect of NPR anchors was studied. The results of the model test show that under the support of NPR anchor cables, with the increase of geostress, the asymmetric deformation of the vault and floor is obvious. During the loading process, the shallow rock mass pressure strain area at both ends of the floor is larger, squeezing the floor and causing strong temperature changes and floor heave failures of the rock mass, while the deep rock mass strain value changes smoothly and is relatively stable. After the axial force of the NPR anchor cable transitions from the growth stage to the stable state, the rock mass deformation converges and stops growing. In the field test, the NPR anchor cable can reduce the primary support deformation from more than 2000 mm to 108 mm, and reduce the stress on the support structure, which is helpful in avoiding the risk of initial support deformation and secondary lining damage in the deep-buried, layered rock mass tunnels.

Comparative analysis of anchor cables in pullout tests using distributed fiber optic sensors

The interaction mechanism between grouted anchor cables and the surrounding rock mass or soil are complicated and difficult to investigate using conventional monitoring technologies. This study focuses on the in-situ pullout behavior of grouted anchor cables using Brillouin Optical Time-Domain Analysis technique. A series of pullout tests were conducted on anchor cables with five different anchor lengths and three grouting methods. Distributed fiber optic sensors were used to measure the strain distribution of cable bolts from tip to top. The in-situ pullout test results show that both ultimate pullout resistance and ultimate displacement at the ultimate pullout resistance increase with anchor length. The bond strength suffers a slight variation with an increase in anchor length. Both ultimate pullout resistance and the ultimate displacement for Type-B grouting (grouting with reaming) and Type-C grouting (secondary grouting) are larger than those for Type-A grouting (one-time grouting). The shear bond strength of Type-C grouting is greater than that of Type-A grouting. Results from Gaussian functions analysis show that it is feasible to use the function to characterize the axial stress of anchor cables. Furthermore, the overall mobilized percentage η was evaluated. The anchor cables with smaller anchor lengths will result in greater η. The η for the anchor cables of 6 m reaches 92% at the last load, whereas the anchor cables of 18 m were mobilized by only 29% at the last load. The grouting method has a negligible effect on the η, increasing from 22% to 29% in process of the pullout test.

Corrosion Damage Evolution Study of the Offshore Cable-Stayed Bridge Anchorage System Based on Accelerated Corrosion Test

The cable-stayed bridge anchorage system is prone to serious corrosion problems in the offshore environment, threatening its service safety. Based on the copper accelerated salt spray (CASS) test, the anchorage system was subjected to accelerated corrosion and then dissected along the axial direction to study the corrosion damage evolution of the internal structure. This revealed the evolution of corrosion damage in the anchorage system of offshore cable-stayed bridges. The results show that in the offshore environment, a large number of corrosion factors enter the interior of the cable anchorage system through the splicing seam at the junction of the anchor cup and the connecting barrel, and spread to both ends, thus causing corrosion damage to the anchor cup, connecting barrel, filling medium and cable steel wires. Inside the cable of the anchorage system, cross-sections with a higher corrosion level on the outer circle steel wires will also have a higher overall corrosion level. The outer circle steel wires are less able to meet the strength requirements, because they withstand most of the corrosion effects, and the corrosion pits on the surface of the steel wires will render them much weaker than the design tensile strength and fracture. After the CASS test, the ductility of cable steel wires decreases from the inner circle to the outer circle, and the higher the corrosion level of steel wires, the more obvious the brittle indications; the steel wires tend to undergo brittle failure. In the design and manufacture of the cable-stayed bridge anchorage system, special attention should be paid to the corrosion protection of the splicing seam, as well as the corrosion condition and residual strength of steel wires in the outer circle of the cable, to delay the degradation of the mechanical properties and brittle damage of the anchorage system.

An early warning method for a slope based on the increment ratio of anchor cable internal force

An early warning method for a slope based on the increment ratio of anchor cable internal force

Analytical model for reinforcement effect and load transfer of pre-stressed anchor cable with bore deviation

Anchors have been widely used in slope engineering, mining engineering and foundation pit engineering, but their stabilities are significantly affected by anchor cable bending which could be contributed by complicated geological conditions and technical limitations. Theoretical analysis in this paper leads to the establishment of the stress model for the bending anchor cable, and the mathematical expression of the relationship between the ultimate pull-out force and the curvature of the bending anchor cable. Numerical simulation is used to evaluate the effect of the anchor cable curvature on the reinforcement effect. The results suggest that the stress distribution and reinforcement effect are affected by different curvatures, the bigger curvature corresponds to the smaller deformation and the larger pull-out force. The rate of decrease in the anchor cable displacement with the burial depth is linearly related to the pull-out force. In addition, the anchor cable curvature affects the response of the surrounding rock mass to stress and strain: The greater the curvature, the larger the area of the responsive rock mass and the higher mobilization of the strength of the rock mass itself. The anchor cable curvature also influences the reinforcement effect of multiple anchor cables. The results are applied to foundation pit engineering, and it is found as follows: The appropriately bending anchor cable (00-0.50 of curvature) with the same length can make wall stress and deformation more reasonable, and better control foundation deformation; however, with the increase in curvature, the effective anchoring length and the anchor cable depth decrease, and the reinforcement effect declines. The study results can provide reference for anchorage engineering.

A Long-Term Monitoring Method of Corrosion Damage of Prestressed Anchor Cable

Based on high-stress characteristics of prestressed anchor cables, this paper develops an axial-distributed testing method to test corrosion damage of prestressed anchor cables. The positioning accuracy and corrosion range of an axial-distributed optical fiber sensor is studied, and its mathematical model between corrosion mass loss and axial fiber strain is established. The experimental results show that the fiber strain from an axial-distributed sensor enables one to reflect the corrosion rate along a prestressed anchor. Moreover, it has a greater sensitivity when an anchored cable has a higher stress. The mathematical model between corrosion mass loss and axial fiber strain is determined to be ε=4723.64ρ+2592.95. The corrosion location along the anchor cable is characterized by axial fiber strain. Therefore, this work provides an insight for cable corrosion.

Dynamic Characteristics of Rock Holes with Gravel Sediment Drilled by Bit Anchor Cable Drilling

Gravel and sediment frequently build up in holes during the anchor cable installation process, which makes it harder to install the anchor cable and causes reinforcement to fail, which can lead to accidents. In this paper, a bit anchor setup approach is proposed to set up a drill bit at the front of the anchor cable to aid the anchor cable drilling. The feasibility of this approach is established with the aid of DEM-MBD joint simulation and proves the correctness of the simulation model. The major elements affecting drilling effectivity have been studied by the use of ‘check + simulation’. The effects exhibit that the axial velocity and working aperture are negatively correlated with the drilling resistance of the anchor cable; the feed price is positively related to the anchor cable drilling resistance; with the increase in anchor cable pitch, the drilling resistance of the anchor cable changes into a hump shape. When the bit is 0.2 m from the backside of the hole, the particle pace vector at the decrease stop of the bit gives a conical distribution. This paper is of fantastic magnitude in relation to the environment-friendly setup of anchor cables and protection against disasters.

Shaking table test on dynamic response of a deposit slope with a weak interlayer reinforced by the pile-anchor structure

Owing to its low shear strength, the presence of a weak interlayer frequently plays an adverse role on slope stability. Through a shaking table test, this study investigated the dynamic response of the deposit slope with weak interlayer at the exit of the Zheduo Mountain Tunnel reinforced by pile-anchor structures. The acceleration field of the slope, peak value of the dynamic earth pressure of the pile, deformation of the pile, anchor cable tension and load-sharing ratio were considered. The findings demonstrate that as an earthquake intensifies, the slope soil behind a pile gradually becomes compressed; subsequently, tension cracks emerge at the back edge of the slope and expand significantly, eventually forming a penetrating sliding surface. Under various earthquake intensity levels, the acceleration amplification coefficient of the slope increases with the elevation. A weak interlayer can amplify the amplitude of the Fourier spectra, which results in a difference in the vibration between the deposit and bedrock and damage to the slope. When the acceleration exceeds 0.3g, the soil behind pile begins to squeeze it, and the peak value of the dynamic earth pressure first increases and then decreases along the elevation of the pile, reaching its maximum near the sliding surface. The load-sharing ratio of the pile-anchor structure steadily decreases as the peak acceleration of the seismic wave, tension of the anchor cable, and limiting effect of the anchor cable on the pile displacement increase. We suggest that the amplification effect of seismic acceleration should be considered in the seismic design of pile-anchor structures, with local reinforcement near the sliding surface of the pile, and the load-sharing ratio of the structure should be flexible.

Slope Stability and Effectiveness of Treatment Measures during Earthquake

Slopes are prone to instability during earthquakes, which will cause geological disasters such as landslides and pose a great threat to people’s lives and property. Therefore, it is necessary to analyze the stability of slopes and the effectiveness of treatment measures during earthquakes. In this study, an actual slope in the creeping slide stage was selected and located in an area where earthquakes occur frequently. Once the slope experiences instability, it will produce great damage. Therefore, a finite difference program, Fast Lagrangian Analysis of Continua in Two Dimensions (FLAC2D), was employed in the numerical simulation to explore the stability of the slope before and after treatment under earthquake action. Different from previous studies, this study explores the effectiveness of various treatment measures on slope stability during earthquake. The computed results show that the stability of the slope is greatly influenced by earthquakes, and the slope displacement under seismic conditions is far larger than that under natural conditions. Three treatment measures, including excavation, anti-slide piles, and anchor cables, can significantly reduce slope displacement and the internal force on anti-slide piles, and improve the stability of a slope during an earthquake. This will provide a valuable reference for the strengthening strategies of unstable slopes. The analysis technique as well as the derived insights are of significance for slope stability and the effectiveness of treatment measures.

Tensile stiffness of perfobond rib connectors in steel–concrete composite pylon of bridges

Perfobond rib connectors (PBLs) are subjected to considerable tensile forces when used as stiffeners in steel panels and force-transfer structures in the cable anchorage zone in the steel–concrete composite pylons of cable-stayed bridges. Determining the elastic tensile stiffness of the PBLs is necessary for a structural analysis of the composite pylons. This investigation aimed to explore the critical parameters affecting the elastic tensile stiffness of PBLs and propose equations for accurately predicting the tensile stiffness of PBLs. Twelve PBL specimens were tested under pull-out load to investigate their elastic tensile stiffness. Thereafter, a parametric analysis was conducted via the finite element approach to examine the influence of the geometric characteristics of the perforated rib, transverse rebar diameter, and concrete strength on the tensile stiffness of the PBL. The results demonstrated that the elastic tensile stiffness of PBLs increased with the increase in the rib thickness, hole diameter, and concrete strength but decreased with increasing embedded depth. The perforated rib width had no influence on the elastic tensile stiffness. Additionally, the elastic tensile stiffness increased slightly as the transverse rebar diameter increased. Subsequently, a theoretical spring model was developed to predict the elastic tensile stiffness of the PBLs, considering the contribution of perforated ribs and concrete dowels. Finally, a comparative analysis was performed, which proved that the proposed equations in the present study based on the spring model were accurate in predicting the tensile stiffness of PBLs. The proposed equations are recommended for application in the structural analysis of composite pylons.

A novel non‐pillar coal mining technology in longwall top coal caving: A case study

AbstractIn longwall top coal caving (LTCC) mining methods, problems such as large deformations, loss of coal resources, and excavation relay out of balance are often encountered with the increased production in single mining panels. To address these problems, a novel non‐pillar coal mining technology in LTCC was used based on the equilibrium mining theory. This approach could cut off the stress transmission, eliminate the coal pillar, and retain the gob‐side entry. In this technology, the entry is first excavated along the roof of the coal, and then four techniques are applied to control the surrounding rock of the retained entry. The constant resistance and large deformation anchor cable are used to maintain the roof stability. The directional roof split blasting technique is adopted to separate the roof between the entry and gob. The blocking‐gangue support system (BGSS) is used to form the gangue rib lagging the mining panel. The temporary support system is applied to prevent the roadway from being affected by the dynamic pressure and prevented the BGSS from falling. Finally, the field monitoring results indicate that the surrounding rock of retained entry is stabilized at 200 m behind the working face. The deformation of retained entry is within a reasonable range at 180–190 m behind the mining panel. The results provide an important reference for the thick coal seam non‐pillar coal mining technology, specifically using this technology in LTCC panels.

Dynamic Response Analysis of Suspended Tunnel under Wave-current Combined Action

The environment in the ocean is complex, and waves and currents produce complex coupling effects on the structures in the ocean. The flow-solid coupling theory and calculation method are applied to establish a three-dimensional model to study the changes in the flow field under the joint action of waves and currents through the comparative analysis of water velocity at the upper and lower near-wall surfaces of the suspension tunnel tube body. The dynamic response of the tension-leg suspension tunnel is calculated using unidirectional fluid-structure coupling. The relationship between different wave heights, different anchor angles, different flow velocities, and different depths and the deformation of the suspension tunnel in the presence of waves is investigated. The results show that the wave height and velocity have a great influence on the floating tunnel, and the displacement changes in both horizontal and vertical directions are large. With the increase of construction depth, the influence of waves on the floating tunnel becomes smaller. When the angle of the anchor cable is changed, the horizontal direction and the vertical direction change in opposite laws, so it is very important to select a suitable angle for the anchor cable. The research results provide a reference for the design of similar floating tunnels.

Experimental and Numerical Studies on Dynamic Response of Parallel Wire Cables Subjected to Close-In Explosions

The recent trend of increasing global terrorist attacks and identified vulnerabilities associated with critical bridges highlights the necessity to protect cable-stayed bridges from terrorist assaults. The cables are the most crucial load-carrying components within the envelope of a cable-stayed bridge, whose failure could result in the progressive collapse of the whole bridge structure with disastrous consequences. However, there is a very limited understanding of the blast effects on cables. This paper presents an experimental and numerical investigation of the blast performance of parallel wire cables under close-in explosions. Field blast tests were conducted on three identical parallel wire cable specimens with varying explosive charge weights. An equivalent beam–shell model was developed in LS-DYNA to reproduce the dynamic response of parallel wire cables subjected to close-in explosions and was comprehensively validated against the experimental results. With the validated numerical modeling techniques, the dynamic behavior of parallel wire cables in a realistic blast scenario of vehicle-borne improvise explosive devices (VBIEDs) detonated on the bridge deck was investigated. The results showed that high bending stress was induced in the cable end near the deck, indicating that the cable-to-girder anchorage zone is the most vulnerable position under the close-in blast scenario. Parametric analyses were carried out to further investigate the effects of cable dimension, prestressing force, cable length, and anchorage angle on the dynamic response of the parallel wire cables. It was found that the cables with smaller dimensions and higher prestressing force are more vulnerable, while the cable length and anchorage angle have limited effects on the performance. The results could be used in the safety evaluation and preliminary protective design of cable-stayed bridges under potential blast threats.

Research on Pillarless Mining by Gob-Side Caving under Soft Rock Roof Conditions: A Case Study

In China, soft rock roof makes up the majority of coal mine roof, yet it is easy to break due to low strength and poor integrity. As such, it is difficult for the traditional pillar-based roadway protection means and pillarless mining techniques to effectively control the roadway roof. In order to solve the problems with pillarless mining under soft rock roof conditions, using the 1510 working face of Xinyi Coal Mine as an example, a gob-side caving roadway forming (GSCRF) technique for broken immediate roof is developed. This paper discusses the adaptability and feasibility of this technology through theoretical modeling and on-site engineering testing. A roadway rock surrounding control scheme based on “cable + steel beams + yielding prop” is further designed, and field tests and monitoring are carried out. Field tests show that, during GSCRF of the 1510 working face, the maximum subsidence of the roof remains within 200 mm. The convergence of the two sides causes stabilization. The tension on the anchor cables is gradually becoming stable. The monitoring results show that the roadway has a good stress environment and the surrounding rock is effectively controlled. Compared with the traditional pillarless mining mode, this technology has the technical advantages of achieving complete elimination of coal pillars, reduced pressure on the roadway roof, and interference-free mining of the working face. The research outcome can provide useful reference for pillarless mining by GSCRF and a solution for pillarless mining under soft rock roof conditions.

System reliability analysis of a slope stabilized with anchor cables and piles under seismic loading

System reliability analysis of a slope stabilized with anchor cables and piles under seismic loading