Resin Bolts Research Articles

Experimental Study on Durability and Bond Properties of GFRP Resin Bolts.

Glass fiber-reinforced polymer (GFRP) anchor bolts are a new type of high-performance nonmetallic anchor with significantly higher tensile strength, a lighter weight, better corrosion resistance, and a lower cost than steel bars. Therefore, exploring the durability and bonding performance of GFRP anchor systems is of great importance for the structural design of protective engineering, especially in coastal environments. However, insufficient research has been conducted on the durability of GFRP resin bolts in seawater conditions, with no universal standard on the pullout testing of GFRP bolts. To study the durability and bonding performance of GFRP resin bolts, durability experiments were conducted in this work using artificial seawater, and the pullout tests were conducted using a large-scale concrete platform with different compressive strengths (21.2, 40.8, and 61.3 MPa). The results of the durability experiments indicated that the strength variations of the GFRP rods and epoxy resin materials in artificial seawater environments were less than 5%. Subsequently, indoor pullout tests using steel tubes filled with epoxy resin were conducted, and the test results indicated a critical anchor length value. Pullout tests of the GFRP resin bolts embedded in large-scale concrete blocks were also conducted with different strengths. According to the test results, all GFRP resin bolts embedded in the three concrete blocks with different compressive strengths exhibited rod fracture failure. The failure mode was not controlled via the compressive strength of the concrete blocks due to the high bonding strength between the resin and the rod, as well as between the resin and the concrete. Therefore, this GFRP resin anchor system could fully utilize the tensile strength of GFRP rods. This research offers significant practical value in verifying the safety and reliability of GFRP resin bolts in corrosive marine service environments, and it contributes to the application and development of GFRP materials in the engineering field, serving as a valuable reference for the structural design and further study of GFRP bolts.

Study on propagation characteristics of ultrasonic guided wave and detection of the defect in resin bolts

The nondestructive testing of the bolt anchoring quality based on ultrasonic guided wave technology is significant to ensure project security. In this paper, an improved Legendre polynomial method (ILPM) is presented to study the longitudinal axisymmetric guided waves in a full-length bonding resin bolt which is a typical bilayer structure. The ILPM employs analytical integral calculation instead of numerical integral in the traditional Legendre polynomial method (TLPM), leading to superior computational efficiency. The effectiveness of the ILPM is validated, and the convergence and computational efficiency are also discussed. The attenuation and group velocity curves of guided waves are solved for the resin bolt. Through the theoretical analysis of dispersion characteristics, the optimal excitation frequencies for experimental detection can be found. Meanwhile, the guided wave detection system of a resin bolt is established to verify the theoretical results. Based on the Self-Sending and Self-Receiving experiment, the resin bolts with different anchoring defects (debonding length and incision size) are studied. The influences of L-mode defect detection ability and defect size parameters on the amplitude of the guided wave signal are analyzed. The experimental results show that L-mode can be used to detect the defects in the bolt, and the defect size can be characterized by the defect echo amplitude.

Theoretical and experimental study on guided wave characteristics in bonded bolts

An analytical integration Legendre polynomial series approach (AILPSA) is proposed to study guided waves in a resin bolt, which is a typical layered cylindrical structure. Compared with the conventional Legendre polynomial series approach, the AILPSA can save the abundant numerical integration calculation time and dramatically improve the computational efficiency. The attenuation and group velocity curves of the resin bolts are calculated. The errors of group velocity between the theoretical and the experimental are analyzed, and the contrast diagrams between amplitude curves of end reflection and attenuation curves are given to illustrate the law between these curves.

Research on Deformation Control Measures of Surrounding Rock in Soft Rock Tunnel

In order to study the control measures of soft rock tunnel surrounding rock deformation, based on the restraint effect of shotcrete anchor support on it, a support model was constructed, and numerical simulation was used to compare and analyze the restraint effects of different bolts controlling the surrounding rock deformation. The results show that: With the reduction of the bolt spacing (d), the resin bolt has a significant supporting effect compared with the mortar bolt support, the maximum displacement of the surrounding rock is reduced by 70.69%, and the maximum stress is reduced by 58.81%. With the increase of bolt length (L), compared with mortar bolt support, resin bolt has a more obvious restraint on surrounding rock deformation. The maximum displacement of surrounding rock is reduced by 57.89% and the maximum stress is reduced by 40.23%. When 4.5m <L< 6.m, 0.6m< d< 0.7m, the resin bolt has a significant effect on controlling the deformation of surrounding rock. In other cases, the use of mortar bolts or resin bolts to support the surrounding rock deformation has little significant difference.

Evaluation of Rock Bolt Support for Polish Hard Rock Mines

The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead “Olkusz – Pomorzany” mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt “Olkusz – 20A” is able to overcome the load.The second purpose of the study was to obtain load – displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

Mine controls bad roof with trusses bolted on cycle : Barish, K Coal AgeV90, N5, May 1985, P62–66

Roof conditions deteriorated in a drift mine in Pennsylvania, and timber, steel, 10 ft roof bolts and resin bolts used in combination proved unsuccessful for roof control. A truss system of rods in tension was finally found satisfactory and was installed on-cycle using modified roof-bolting machines. An account is given of the application of the method.

New method allowss for anchorage check for rock bolts : Min Engng V37, N4, April 1985, P320–322

Tests have indicated that a high proportion of rock bolts are not performing satisfactorily, often without this being obvious to the operator. A table shows possible reasons for unsatisfactory installation for different types of bolt. Resin bolts provide the biggest cause for concern. Tests to determine the integrity of rock bolt installations are being developed. A new type of bolt is described which provides anchorage on installation and allows for follow-up checks when required.

Mechanism and application of M-1 type resin bolts : Zheng Zhongyuan; Huang Naijiong Proc International Symposium on Rock Bolting, Abisko, 28 August–2 September 1983P403–406. Publ Rotterdam: A. A. Balkema, 1984

Mechanism and application of M-1 type resin bolts : Zheng Zhongyuan; Huang Naijiong Proc International Symposium on Rock Bolting, Abisko, 28 August–2 September 1983P403–406. Publ Rotterdam: A. A. Balkema, 1984

Inorganic cement for mine roof-bolt grouting : Simpson, R E; Fraley, J E; Cox, D J US Bureau of Mines report RI 8494, 1980, 32P

Beginning in 1972, fully grouted resin bolts were used in underground mines. An estimated 20 million resin bolts will be installed in 1980 owing to their apparent support improvement in most roof-bolt applications. Inorganic cements were tested to replace the resin at a lower cost while retaining the advantages of a grouted bolt. Although other inorganic materials were considered, all but portland and gypsum cements were rejected for reasons of availability, performance, or cost. Portland and gypsum-type cements were tested by the Bureau of Mines to select a fast-hardening, low-cost material that would anchor a roof bolt adequately to meet safety standards. An alpha-gypsum cement, accelerated with potassium sulfate, was selected as the best material because it had adequate pull strength at a desired set time of less than 5 minutes and was readily available.

Reinforcement mechanisms of untensioned full-column : USBM RI 8439, 1980, 37P resin bolts

Reinforcement mechanisms of untensioned full-column : USBM RI 8439, 1980, 37P resin bolts

Reinforcement mechanisms of untensioned full-column resin bolts : USBM RI 8439, 1980, 37P

Reinforcement mechanisms of untensioned full-column resin bolts : USBM RI 8439, 1980, 37P

Roof reinforcement using wood resin bolts (in Polish) : Bednarek, W; Papierz, A Wiad Gorn, Oct 1976, P305–311

Roof reinforcement using wood resin bolts (in Polish) : Bednarek, W; Papierz, A Wiad Gorn, Oct 1976, P305–311

Comparative evaluation of conventional and resin bolting systems : Karabin, G J; Debevec, W J US Mining Enforcement and Safety Administration informational report 1033, 1976, 22P

Over the past few years, the use of fully grouted bolts to support the roof of underground openings has increased dramatically. While conventionally anchored bolts effectively reinforce the strata of over 80 percent of mine workings, the use of resin grouted bolts in areas of severe roof conditions has resulted in a substantial reduction in roof falls and an overall improvement in both safety and production. Specially developed strain-gaged resin bolts, compression pads and differential sag stations installed during the mining cycle have generated data reflecting the loading characteristics and resulting roof stability associated with each type of support. Additional investigations have produced optimum installation parameters of the two systems including the effectiveness of thrust/torque controls for conventional bolts and various bolt/hole diameter combinations for fully grouted rods. Theoretical analyses, coupled with the actual field and laboratory findings and numerous observations of installations, have facilitated basic comparisons of the working mechanisms and failure modes of both resin and conventional systems.

The improved performance of resin bolts. Congress. Discussion. -Summary of results obtained from finite-element studies on performance of fully grouted resin bolts.

The improved performance of resin bolts. Congress. Discussion. -Summary of results obtained from finite-element studies on performance of fully grouted resin bolts.

The role of bolts and full column resin bolts in mine openings. Congress. Discussion. In French

The role of bolts and full column resin bolts in mine openings. Congress. Discussion. In French