The Helical Anchor Type with Application as a Horizontal Drainage Equipment for Slope Protection

Helical anchors, sometimes referred to as screw anchors, screw piles, and helical piles, are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are manufactured using varying sizes of tubular hollow sections for the pile or anchor shaft. This paper presents an innovation of the helical anchor for horizontal drains, a form of subsurface drainage systems for slope protection. To address the adverse effect of groundwater, an expansion of the application of the helical anchor structure in civil engineering is needed, and new drainage solutions are being considered. The features of the helical anchor type for horizontal drainage equipment, analyses of some of its advantages, and conditions of application are presented. Generally, a helical anchor for horizontal drainage is convenient for installation, maintenance, or removal, and is effective for both horizontal drainage and for anchoring the revetment. It is also a typical construction in drainage works, generally performed by a cranking handle or a rotary-percussion-type drilling machine. The helical anchor pipe for horizontal drainage has many segments with joints using a cranking hand for installation and is quite effective where the installation space is narrow or there is no machine. In particular, the installation of this equipment differs significantly from other drilling methods because it can be driven into a sand layer without a hole wall.

The influence of bottom-up anchors pre-tension optimization on the prediction of pit walls rockfall displacements

Introduction. Currently in Russia, innovations in urban subsoil facilities construction are among the key factors of economic development. To improve the efficiency of holding a pit wall in restraint urban conditions and prevent soil loosening around the pit, it is proposed to optimize the pre-tension forces of the bottom-up anchors. It has been determined that the pre-tension forces of the active anchors create extra retention forces in the sliding wedge and, in some specified sense, reinforce the walled soil. Research methodology. When modeling the complex calculation of a pit wall, 4 main stages of the pit excavation and 3 stages of preliminary level tensions of anchor ties were preset. The numerical solution of the beam bending problem is the basic method of calculating the walling strength; the beam laying on the elastoplastic base and retained by the anchors as bonds. The bottom-up anchor structure is modeled in the operating environment of GeoWall software. The values of bottom-up anchors pre-tension are set following the ordinates of forces in the anchors, obtained from the walling stability calculation by the deterministic approach. Experimental research was carried out of the impact made by pit opening stages on the walling stress strained state. Results. Analysis and discussion. The efficiency of bottom-up anchors optimal pre-tension, according to the research results, is obtained by constructing the diagrams reflecting the correlation dependence between the anchors loading and the walling displacement. An obvious advantage of the software is the opportunity to calculate walling and retaining structures stage by stage ignoring their construction technologies. Experimental calculation in GeoWall has shown a high bearing capacity of the bottom-up anchor support. Summary. The nature of the obtained dependence between the anchor longitudinal forces and the pit walling horizontal displacement reflects the actual situation. Thus, for a quiet expectable value of horizontal displacement, it is required to correct the optimal value of pre-tension using the empiricalformula dependences.

Investigation of Mechanical Properties for Group Anchors

Prestressed anchor support is one of the most important support methods for coal mine roadways. As the coal mining depth increases, the adaptability of existing prestressed anchor has become weaker and weaker, which is mainly reflected in the current anchor prestress is much smaller than the support resistance required for the stability of the roadways and makes it difficult to effectively control the roadways. In order to solve the problem, a group anchor structure was proposed to realize higher prestressed anchor support technology and improve the support status of deep roadways. For coal mine roadways, group anchor structure is a new technology and new topic, and the design method and theoretical basis of the group anchor support are lacking. Therefore, the paper studied the bearing capacity of the group anchors through physical tests and numerical simulations. Among them, a special set of group anchor drawing tooling was designed and processed to match the physical test. The test results show that the group anchor structure can double the bearing capacity and bearing rigidity compared with traditional anchors, and the group anchor support can further optimize the support parameters to improve the bearing capacity of the surrounding rock. Therefore, the group anchor support is helpful to the stability control of the surrounding rock of the deep roadway.

Back analysis of pile and anchor retaining structure based on BOTDA distributed optical fiber sensing technology

In order to understand the deformation law and internal force distribution characteristics of the pile-anchor retaining structure in deep foundation pit engineering, the stress of the pile-anchor retaining system in the process of foundation pit excavation was tested by using the distributed optical fiber sensing technology of BOTDA. It uses the supporting pile cloth to set up the strain cable to collect the strain from the excavation process to the stability of the foundation pit, which analyzes the stress and internal force distribution. The results show that the overall deformation of the foundation pit is small and in a stable state. It uses the monitoring strain energy to truly reflect the distribution and transmission law of the pile internal force. It is shown that the bending moment is the maximum at the action position of the anchor cable on the pile anchor structure and 2.5m below the bottom of the pit. The design needs to reinforce the construction of such locations. At the same time, the distribution form of earth pressure calculated in reverse is different from the conventional one. When there are multiple rows of prestressed anchor cables, the earth pressure applied on the support is less than the calculated value of classical earth pressure theory. This pile anchor structure design theory and engineering application has reference value.

The manufacturing of a surface anchor structure for the electroless plating of a three-dimensional antenna integrated with a mobile device case

This study proposes a method to improve the manufacturing process of a surface anchor structure for the injection molding along with bonding properties of the plating layer for antennas, which can be applied to the Laser Direct Plating (LDP) process for the production of a three-dimensional antenna integrated with a mobile device case. By adjusting parameters such as the output of the laser processing, scanning speed, and pulse recurrence frequency, a micro anchor structure was developed on the surface of the injection mold. The measurement of the surface roughness using a 3D surface profiler showed that the roughness improved by approximately 3.6 times, from 0.96 to 3.24 µm. In addition, the zigzag arrangement of the micro anchor structure was improved by 1.2 times compared to the even arrangement. Furthermore, if the micro anchor structure contained a wall after laser processing, the bonding strength of the plating solution was 69%; with no wall, it was 94% or higher. Thus, the existence of walls resulted in a difference of 1.4 times in the bonding strength. The laser processing improved the bonding strength of the plating solution on the micro anchor structure by approximately 19 times.

Experimental Study on Distribution of Landslide Thrust in Pile-Anchor Structure based on Photoelastic Technique

This paper aimed to perform systematical study on the distribution of landslide thrust in pile-anchor support system, which has been a widely applicable treatment method in landslide control with safety, highly efficiency and adaptation. The advantage of photoelastic technique is visualization of strain and stress fields, therefore photoelastic model tests are conducted to show the distribution of landslide thrust in pile-anchor structure before failure in landslide. The effects of different materials and pile lengths are investigated by 6 photoelastic test cases under different loading conditions. It can be found from quantitative analysis of experimental results that load proportion of anchor would increase gradually with the decrease of pile embedded depth or the increase of landslide thrust force. Meanwhile, landslide thrust distribution in pile-anchor structure is directly affected by the stiffness of piles. The pile-anchor structure is significantly better at reducing bending moment value and optimizing bending moment distribution of pile. Finally, some theoretical analysis and design suggestions are proposed based on the experimental study.