Ultimate Pullout Force Research Articles

Grouting sleeve/bird’s nest anchor cable anchoring capacity characteristics and numerical simulation study

With the deepening of coal mining resources, the safety issues of broken soft coal seams become increasingly prominent, severely affecting the safety of deep mining operations and workers. Traditional anchoring methods alone are ineffective in achieving secure anchorage. Therefore, the grouting anchor cable composite structure is explored to address the safety of roadway excavation in deep broken soft coal seams. Indoor grouting anchorage tests and pull-out tests for grouted anchorages are conducted to study their bearing characteristics and failure mechanisms. Discrete element numerical simulation methods are employed to verify the findings from indoor tests. Research indicates that the ultimate pull-out forces at grouting pressures of 0.5, 1.0, 1.5, and 2.0 MPa are 87, 104, 118, and 131 kN, respectively. The pull-out force of the grouted anchorage is positively correlated with the grouting pressure. At the loading end, shear stress and axial force reach their maximum values of 1.8 MPa and 106 kN, respectively, under 2.0 MPa grouting pressure. The distribution patterns of shear stress and axial force decrease gradually with increasing anchoring depth. Microscopic analysis reveals that the failure of the anchor body model is primarily due to the tensile cracks formed by the particle flow code in two dimensions. This finding is consistent with the failure mode observed in indoor tests, which involves the slip and debonding failure of the anchor cable. Crack evolution is categorized into three stages: initiation, continuous propagation, and anchor failure. As the inter-particle contact forces within the anchor body model decrease, the region of chain fracture expands. These results provide technical support for understanding the bearing characteristics of grouting anchor cable composite structures.

Mechanical performance analysis of double-dovetail joint applied to furniture T-shaped components

T-shaped mortise and tenon members are the main structure of traditional Chinese furniture. In this paper, the double-dovetail joint used for face-to-face joint of rubber wood (Hevea brasiliensis Muell. Arg) is transformed into a new type of double-dovetail joint and rounded double-dovetail joint for T-shaped members of point joint structure. The ultimate pull-out test and bending strength test were carried out on the two structures and three structures of oval mortise, round rod mortise and right angle mortise. The results show that the ultimate pull-out force of the round double-dovetail joint is 39% higher than that of the double-dovetail joint, and the bending resistance capacity is 8.9% higher, and the strength and stability are better than those of other split mortises and tenons, which proves that this structure can be used in actual production, and also proves that the mortise and tenon connected by the surface has the possibility of transforming into a point connection structure. The concave structure of the rounded double-dovetail joint makes the mortise and tenon fit well, the tenon squeezed tight, and a good bonding effect was achieved. This structure can also provide greater friction and resistance, delay rubber adhesive failure and improve the stability.

Experimental study on the interface characteristics of geogrid-reinforced gravelly soil based on pull-out tests

The factors influencing geogrid–soil interface characteristics are critical design parameters in some geotechnical designs. This study describes pull-out tests performed on gravelly soils commonly encountered in the Xinjiang region and reinforced with two types of geogrids. The factors affecting the geogrid–gravelly soil interface properties are investigated with different experimental loading methods (pull-out velocity, normal stress), geogrid types, and soil particle size distributions and water contents. The ultimate pull-out force increases with the normal stress and pull-out velocity. Furthermore, with increasing coarse particle content and water content, the ultimate pull-out force increases and then decreases sharply. Based on these research results, this paper provides reasonable parameters and recommendations for the design and pull-out testing of reinforced soil in engineering structures. In reinforced soil structure design, the grid depth should be increased appropriately, and the coarse particle content of the overlying soil should be between 30 and 40%. During construction, the gravelly soil should be compacted to the maximum compaction at the optimal water content, and the structure should have a reasonable waterproofing system. According to the calculation results of the interface strength parameters, the uniaxial geogrid–gravelly soil interface has a high cohesive force csg, which should not be ignored in reinforced soil structure design.

Field experimental study on the pull-out characteristics of a new type of expanding shell bolt

Rock bolt foundation is becoming increasingly popular for transmission line engineering in mountainous areas due to the ability to maximize rock foundation bearing performance, reduce foundation size and burial depth, and save investment. However, failure modes such as pull-out of bolt can lead to insufficient utilization of bearing capacity of rock bolt. To overcome this problem, a new form of expanding shell bolt is proposed and the effect of several variables including grouting materials, bolt diameter, site weathering degree, and anchoring depth are investigated in this study. The results indicate that the new expanding shell bolt may significantly increase the pull-out bearing capacity compared to common rock bolts, due to the built-in effect between the bottom part of bolt and the rock on the hole wall. The effect of grouting material and anchoring length on the shell anchor's uplift bearing capacity is minimal. Considering that the ultimate tensile strength when the anchor bar breaks depends on the diameter of the steel bar, increasing the diameter of the anchor bar will effectively improve the pull-out characteristics of the bolt. The failure mode of anchor rods is also influenced by the rock layers. Rock layers with lower weathering levels have stronger embedding force, and the expansion head can effectively play a role. Due to the group anchor effect, the ultimate uplift bearing capacity of group anchor foundation in rocks is not simply the sum of the bearing capacity of each one, but must be multiplied by the group anchor coefficient. This coefficient is close to 0.9 in moderately weathered and strong-medium weathering sites. Finally, the calculation method for ultimate pullout force of expanding shell bolt is established. The feasibility of this method is verified by comparing on-site test values and calculated values.Author keywords: Rock bolt; Expanding shell bolt; Pull-out bearing capacity; Failure mode; Group anchor effect.

Study on the Style Design and Anchoring Mechanism of Enlarged Head Anchors

To resolve insufficient traditional bolt supports due to the complexity of geological conditions, the optimal design of an expanded head bolt was investigated by using theoretical calculations and experiments. The results show that the drawing capacity of an expanded head bolt is affected by the bearing capacity of front and rear ends, side bearing capacity, and side friction resistance. For a circular anchor bolt, stepped anchor bolt, and semi-ellipsoidal anchor bolt, with an increase in the front section’s radius, the lateral friction resistance of the inner anchor section is gradually shared by the bearing force of the front end of the inner anchor section; the bearing effect of the front end of the inner anchor section is enhanced; and the pulling performance of the anchor bolt is enhanced. Therefore, the pulling force of the circular anchor bolt is at the maximum, followed by the stepped anchor bolt, and the semi-ellipsoidal bolt is at the minimum. The increase in the rear section can provide greater lateral friction resistance and end-bearing force. Compared with cylindrical enlarged head anchors, the circular, stepped, and semi-elliptic enlarged head anchors have a smaller front section but a larger rear section, and the reduction in the front section’s bearing capacity is less than the increase in the side bearing capacity and rear-end bearing capacity; thus, the cylindrical bolt has the lowest pulling force. Compared with the front radius, the back radius has more influence on the drawing ability of the enlarged head anchor. The longer the inner anchorage section, the larger the distribution range in the compression zone that is formed in the soil body and the smaller the range in the tension zone that is formed in the rear. The increase in the length of the inner anchorage section is conducive to improving the reinforcement effect of the soil in front of the anchorage section in the bolt. Therefore, this parameter plays an important role in the redistribution of the soil in front of the force. The ultimate pull-out force of a circular table-shaped tensile bolt is the highest, followed by the stepped bolt, and the semi-elliptic bolt comes in third, with the cylindrical bolt exhibiting the lowest pull-out force; the circular table-shaped enlarged head anchor constitutes the best style design.

Experimental Study on Lap-Spliced Performance of High-Strength Stainless Steel Wire Mesh in Engineering Cementitious Composites.

To investigate the mechanical properties of high-strength stainless steel wire mesh (HSSSWM) in Engineering Cementitious Composites (ECCs) and determine a reasonable lap length, a total of 39 specimens in 13 sets were designed and fabricated by considering the diameter of the steel strand, spacing of the transverse steel strand, and lap length. The lap-spliced performance of the specimens was tested through a pull-out test. The results revealed two failure modes in the lap connection of steel wire mesh in ECCs: pull-out failure and rupture failure. The spacing of the transverse steel strand had little effect on the ultimate pull-out force, but it restricted the slip of the longitudinal steel strand. A positive correlation was found between the spacing of the transverse steel strand and the slip amount of the longitudinal steel strand. With an increase in lap length, the slip amount and 'lap stiffness' to peak load increased, while the ultimate bond strength decreased. Based on the experimental analysis, a calculation formula for lap strength considering the correction coefficient β was established.

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.

Study of the Load-Bearing Characteristics of Bolts under Asymmetric Freezing Conditions

To investigate the load-bearing characteristics of anchor rods under asymmetric freezing conditions such as those in cold regions and the effect of frost swelling, a model test device was developed using a controlled-temperature environmental box and a hydraulic actuator. Laboratorial pull-out model tests of anchor rods in soil layers were conducted at different moisture contents and freezing temperatures, the changes in anchor rod pull-out force before and after freezing were quantitatively described, load–displacement relationship curves were prepared, and the frost swelling displacement of anchor rods under asymmetric freezing conditions and the stress evolution of surrounding soil were observed and recorded. The shear strength of the anchor–soil interface increased with decreasing temperature, and the ultimate values of the pull-out force at 0, −3 and −7 °C were 4, 17.04 and 18.1 times greater than those at room temperature, respectively, for 10% water content. The pull-out force of the frozen anchor increased with increasing water content. The bolts were displaced by the freezing expansion force. Their lateral displacements at 0, −3 and −7 °C were 2.9, 3.2 and 3.5 mm, respectively, and their vertical displacements were 0.2, 3.5 and 4.3 mm, respectively, for 10% water content. The total displacement increased with increasing moisture content, and the maximum transverse displacements were 3.5, 3.65 and 3.8 mm for 10, 12 and 14% water contents, respectively, and 4.3, 5.1 and 5.5 mm in the vertical direction, respectively. The ultimate pull-out forces after freezing and thawing were 71, 68 and 52% of that before freezing for 10, 12 and 14% water, respectively.

Anchorage weakening effect of coal roadway sidewall with different destressing borehole diameters

AbstractThe pressure relief with large‐diameter boreholes is one of the effective methods to prevent coal bumps in deep coal roadway. An unreasonable pressure relief design can cause the rockbolt support failure and aggravate the deformation of the surrounding rocks. In this paper, a coupling model of roadway sidewall considering borehole pressure relief and rockbolt support was established. The influence of the destressing borehole diameter on the rockbolt located in the plastic zone and the roadway deformation was studied by theoretical calculation and numerical simulation. The results show that there is a critical zone of the borehole diameter for the influence on the rockbolt normal stress and roadway convergence. When the destressing borehole diameter exceeds the critical zone, the rockbolt normal stress decreases sharply. Considering the existence of the broken zone in the surrounding rock, the bolehole diameters in the critical zone increase with the increase of the distance between the borehole and the rockbolt, the residual strength, and decrease with the increase of initial stress. In the engineering analysis, with the increase of the destressing borehole diameter, the ultimate pullout force of rockbolt decrease, and the plastic zone of surrounding rock, the roadway deformation, the maximum axial force, and slippage of the rockbolt all increase. Therefore, to better keep the stability of the surrounding rock in coal roadway, the borehole pressure relief needs to be coordinated with the rockbolt support. The destressing borehole diameter in the pressure relief design should not be greater than the critical zone.

Experimental study of dynamic bond behaviour between corroded steel reinforcement and concrete

Corrosion damage of steel reinforcement is detrimental to the load-carrying capacity of reinforced concrete structures because it not only reduces the cross sectional area and strength of reinforcement bars, but also weakens the bond between reinforcement and concrete. Many studies have investigated the effects of corrosion on reinforcement loss and static bond strength between reinforcement and concrete, but no study of the influence of corrosion damage on dynamic bond strength has been reported yet. In this study, laboratory tests were conducted to investigate the effect of corrosion on the bond behaviour between steel reinforcement and concrete subjected to high rate dynamic load. Accelerated corrosion damage was induced to steel bars embedded in concrete specimens under laboratory condition. The bond parameters of steel reinforcement and concrete including the ultimate bonding load and bond-slip relationship corresponding to the various strain rates and corrosion degrees were obtained through dynamic pull-out tests. The empirical formulae of dynamic increase factors (DIFs) of the ultimate bonding strength corresponding to different corrosion levels and strain rates were proposed. The experimental results show that the strain rate effect on bonding behaviour is prominent irrespective of the corrosion level. The increase in the ultimate bonding strength with strain rate for the heavily corroded reinforcement (η = 5 %-10 %) is more prominent than that for the slightly corroded reinforcement (η = 0 %-5%). The decrease in the ultimate pull-out force caused by the corrosion damage at high strain rate is more pronounced than that at low strain rate. Corrosion-induced crack and the tensile strength of concrete have significant effect on both the static and dynamic bond behaviours. The results presented in the paper can be used for better modelling and prediction of the responses of corroded reinforced concrete structures subjected to dynamic loads.

A novel plastic failure model of prestressed anchor cables for upper bound stability analyses of rotational reinforced slopes

In the existing upper bound limit analyses (UBLA) of rotational slopes reinforced with prestressed anchor cables, the mobilized axial forces of all cables are assumed to be equal to the ultimate pullout force. However, such an assumption overestimates the mechanical contribution of prestressed anchor cables, resulting in excessively high safety factors. In this technical note, we aim to tackle this issue by proposing a pseudo-plastic design concept, in which soil masses and prestressed cables are treated as plastic and elastic-plastic, respectively, when slopes collapse. A pseudo-plastic failure model of prestressed anchor cables is proposed, where the variation of tension forces and movement of anchor heads are accounted for. Several interesting conclusions are drawn as follows: (1) Contrary to the conventional plastic failure mode of cables, upper bound solutions obtained by the proposed model are much closer to the exact solutions. (2) Variation of factors of safety (FSs) against the accumulated rotational displacement can be explained by the force-displacement curve obtained in the pullout test of prestressed anchor cables. (3) The sliding slope reinforced with cables may turn out to be stable after a slight rotational movement, which can be utilized in the economical design.

A new bone adhesive candidate- does it work in human bone? An ex-vivo preclinical evaluation in fresh human osteoporotic femoral head bone

IntroductionThe fixation of small intraarticular bone fragments is clinically challenging and an obvious first orthopaedic indication for an effective bone adhesive. In the present study the feasibility of bonding freshly harvested human trabecular bone with OsSticR, a novel phosphoserine modified cement, was evaluated using a bone cylinder model pull-out test and compared with a commercial fibrin tissue adhesive. MethodsFemoral heads (n=13) were collected from hip fracture patients undergoing arthroplasty and stored refrigerated overnight in saline medium prior to testing. Cylindrical bone cores with a pre-inserted bone screw, were prepared using a coring tool. Each core was removed and glued back in place with either the bone adhesive (α-tricalcium phosphate, phosphoserine and 20% trisodium citrate solution) or the fibrin glue. All glued bones were stored in bone medium at 37°C. Tensile loading, using a universal testing machine (5 kN load cell), was applied to each core/head. For the bone adhesive, bone cores were tested at 2 (n=13) and 24 (n=11) hours. For the fibrin tissue adhesive control group (n=9), bone cores were tested exclusively at 2 hours. The femoral bone quality was evaluated with micro-CT. ResultsThe ultimate pull-out load for the bone adhesive at 2 hours ranged from 36 to 171 N (mean 94 N, SD 42 N). At 24 hours the pull-out strength was similar, 47 to 198 N (mean 123 N, SD 43 N). The adhesive failure usually occurred through the adhesive layer, however in two samples, at 167 N and 198 N the screw pulled out of the bone core. The fibrin tissue adhesive group reached a peak force of 8 N maximally at 2 hours (range 2.8-8 N, mean 5.4 N, SD 1.6 N). The mean BV/TV for femoral heads was 0.15 and indicates poor bone quality. ConclusionThe bone adhesive successfully glued wet and fatty tissue of osteoporotic human bone cores. The mean ultimate pull-out force of 123 N at 24 hours corresponds to ∼ 300 kPa shear stress acting on the bone core. These first ex-vivo results in human bone are a promising step toward potential clinical application in osteochondral fragment fixation.

Three‐dimensional upper‐bound limit analysis of ultimate pullout capacity of anchor plates using variation method

AbstractThe uplift bearing capacity of anchor plates has been the focus of geotechnical engineering research. In this study, based on the upper‐bound limit analysis theory and considering the nonlinear characteristics of geomaterials, the three‐dimensional uplift behavior of a shallow horizontal anchor plate was analyzed. Based on the variational principle, virtual power principle, and equilibrium equation, the ultimate pullout forces of rectangular and circular anchor plates were derived, and the dimensionless breakout factor and failure mechanism of the overlying soil were obtained. The ultimate pullout forces were in good agreement with the existing research results, and the principal stresses along the rupture surface agreed well with that obtained by numerical analysis, which could demonstrate the effectiveness and accuracy of the proposed method. Moreover, the effects of the nonlinear coefficient, anchor size and aspect, embedment ratio, and surface overload on the breakout factor were investigated. Meanwhile, the shape modification factors of rectangular and circular anchor plates were obtained. The findings of this study can provide a useful reference for anchor plate design.

A semi-analytical model for a compaction-grouted soil nail with double grout bulbs considering compaction effect in sand

A soil nail with double grout bulbs has excellent pullout resistance, and the model for calculating the pullout resistance is an important reference for the design of soil nail with double grout bulbs. A modified hyperbolic model for a compaction-grouted soil nail with double grout bulbs was proposed based on energy equilibrium method, in which the compaction effect derived from the grouting was also considered. Then, the calculated pull-out force using the hyperbolic model was verified by the test results. Then, the difference in pull-out force under two typical failure patterns was discussed. Finally, parametric studies regarding different spacing/diameter ratio (Sd/D2), dry density, initial compression modulus and overburden pressure were conducted under the two failure patterns. The results show that the bulb resistances from the cylindric surface and the curved surface contribute most to the pull-out forces under the first failure pattern and the second failure pattern, respectively. The pull-out force of the back section is linearly increase with the Sd/D2 and it is larger under the second failure pattern than that under the first failure pattern. The dry density and the initial compression modulus influence the initial increase rate of the pull-out force, while the overburden pressure not only influences the mobilization rate of the pull-out force but also the ultimate pull-out force.

Microstructure and Macromechanical Properties of Retaining Structure of Near-Water Reinforced Soil under Dry-Wet Cycle

Reinforced soil-retaining structures that have been working in near-water environments for a long time are likely to affect their own mechanical properties due to the dry-wet cycle caused by changes in water level. In response to this problem, this paper uses a combination of macro- and microtests, selecting reinforced soil samples with four water content conditions, five overburden pressure conditions, three sets of dry-wet cycle conditions, and a total of 60 working conditions for testing. Scanning electron microscopy was used to observe the microscopic characterization of the reinforced soil particles under different times of the dry-wet cycle, and the pull-out test was used to study the mechanical properties of the interface of the reinforced materials and soils. The analysis results of the test show that the dry-wet cycles increase the porosity of the reinforced soil and the number of pores, among which the proportion of micro and small pores increases, the abundance and fractal dimension of reinforced soil particles increase, and the roughness of the particle surface is reduced. The change of the microstructure of the reinforced soil causes the cohesion of the soil to decrease in the macroscopic view. The friction coefficient and the ultimate pull-out force of the interface between the reinforced materials and the soils decrease with the increase of times of dry-wet cycle.

Experimental Study of the Failure Mechanism of the Anchorage Interface under Different Surrounding Rock Strengths and Ambient Temperatures

In order to study the anchoring instability mechanism of surrounding rock in deep roadway, the failure mechanism of the bolt‐anchoring agent interface was studied by simulating different strength rock mass and ground temperature environment, using C20, C40, and C60 strength concrete and steel pipe to simulate different surrounding rock strength environments. Indoor pull‐out tests were carried out to study the pull‐out load displacement relationship, ultimate pull‐out force, residual anchoring force, the distribution law of axial stress and tangential stress along the bar, and the energy consumption value of drawing failure at 20, 50, and 70°C. The test results show that, with the decrease of surrounding rock strength or the increase of ambient temperature, the pull‐out force, residual anchoring force, and energy consumption value of anchorage interface gradually decrease; under different axial forces, the axial force distribution of the rod body decreases exponentially from the anchoring end to the opposite end; and the shear stress transfers to the deep part of the anchor body with the increase of the load. According to the failure phenomenon of the specimen, the failure modes of the bolt bolt‐anchorage agent interface can be divided into shear slip mode and shear expansion slip mode. The shear expansion slip formula of anchorage interface is derived. Using high‐strength and temperature‐resistant resin anchoring agent for comparative test, the rationality of the mechanism analysis is proved, which provides more clear guidance for the construction of anchor support.

Effect of Mortar Constraint Conditions on Pullout Behavior of GFRP Soil Nails

Glass fiber reinforced polymer (GFRP) bars are safe, light, and environmentally friendly and, hence, have emerged as desirable alternatives to traditional steel reinforcements in soil nailing wall reinforcement. The loads experienced by GFRP soil nails are transmitted through bonding with mortar and the surrounding soil mass. Constraints of the soil mass on mortar affect the pullout performance of the nails. This paper presents a laboratory test study on the influence of different mortar constraint conditions on the pullout behavior of GFRP soil nails. The results indicated that single loading or cyclic loading has a negligible effect on the failure modes of specimens under different constraints. Therefore, all specimens underwent the same mode of failure, i.e., splitting failure of the mortar. The ultimate pullout force associated with single loading under strong constraint conditions was 77% higher than that under unconstrained conditions, and the anchorage depth increased from 0.6 m to 1.0 m. The load‐slip curves obtained for unconstrained conditions and strong constraint conditions were approximately straight lines and double broken lines, respectively. The ultimate tensile stress of GFRP soil nails exceeds the tensile strength of ordinary steel bars, indicating that these nails have sufficient strength reserve.

A Comprehensive Review of the Mechanical Behavior of Suspension Bridge Tunnel-Type Anchorage

The recent surge of interest towards the mechanical response of rock mass produced by tunnel-type anchorage (TTA) has generated a handful of theories and an array of empirical explorations on the topic. However, none of these have attempted to arrange the existing achievements in a systematic way. The present work puts forward an integrative framework laid out over three levels of explanation and practical approach, mechanical behavior, and calculation method of the ultimate pullout force to compare and integrate the existing findings in a meaningful way. First, it reviews the application of TTA in China and analyzes its future development trend. Then, it summarizes the research results of TTA in terms of load transfer characteristics, deformation characteristics, failure modes, and calculation of ultimate uplift resistance. Finally, it introduces four field model tests in soft rock (mainly mudstone formations), and some research results are obtained. Furthermore, it compares the mechanical behavior of TTA in hard rock strata and soft rock strata, highlighting the main factors affecting the stability of TTA in soft rock formation. This paper proposes a series of focused topics for future investigation that would allow deconstruction of the drivers and constraints of the development of TTA.

A limit analysis of the ultimate pullout capacity of a shallow horizontal strip anchor plate embedded in slope

Aiming at calculating the ultimate pullout capacity of a shallow horizontal strip anchor plate embedded in complicated topographical regions, e.g., mountainous areas, a kinematic admissible velocity field of the curved failure mechanism is constructed for the shallow horizontal strip anchor plate embedded in slope, based on the upper bound limit analysis theorem, the nonlinear Mohr-Coulomb failure criterion as well as the associated flow rules. The ultimate pullout force and failure mechanism are deduced using the variation minimum principle. Influences of the inclination angle and embedded depth on the ultimate pullout force are discussed in detail. The results show that the ultimate pullout force of the anchor plate decreases with the increasing inclination angle and the failure planes of the above ground are no longer symmetrical with an obvious shifting to the down side of the slope. Along with the increasing embedded depth, the ultimate pullout force of the anchor plate increases with a larger failure scope of the above ground. The inclination angle has a greater impact on the ultimate pullout force of the anchor plate with a smaller embedded depth. This effect should be taken into account for reasonably characterizing the ultimate bearing feature of a shallow horizontal strip anchor plate embedded in slope.

Pullout Behavior of GFRP Anti-Floating Anchor Based on the FBG Sensor Technology

Building anti-floating anchors have been increasingly used in recent years, but conventional steel anchors under service conditions are easily subjected to chemical erosion. Glass fiber reinforcement polymer (GFRP) is a promising solution to this problem. In this study, field pullout tests were conducted on three full instrumented GFRP anti-floating anchors in weathered granite. Specifically, the GFRP anchors during pultrusion were innovatively embedded with bare fiber Bragg grating (FBG) sensors to monitor the axial force distribution along depth. It was found that the embedded FBG could reliably monitor the axial force distribution of GFRP anchors. The ultimate pullout force of a GFRP anchor with diameter of 28 mm and anchorage length of 5 m was up to 400 kN. The GFRP anchor yielded at 0.8 m underground. Force distribution and field photos at failure indicated shear failure occurred at the anchor/bolt interface at the end of the tests. The feasibility of the GFRP anti-floating anchor was also verified in civil engineering. Finally, an elastic mechanical model and Mindlin’s displacement solution are used to get distribution functions of axial force and shear stress along the depth, and the results accord with the test results.