Definition
Bolt pull-out meter is a special testing equipment used to determine the tensile performance of anchor members or systems under stress. It evaluates the bond strength or load-bearing capacity between the anchor, anchor cable, or other similar fixing element and the substrate material by applying an axial pulling force. The instrument is widely used in construction engineering, geotechnical engineering, rail transit and infrastructure maintenance, providing key data support for structural safety assessment.
How it works:
The bolt puller works on the principle of mechanical balance and hydraulic transmission. The instrument usually consists of a loading unit, a hydraulic pump, a pressure sensor, a displacement measurement device and a control system. When working, the hydraulic pump drives the piston to generate thrust, which transmits the force to the end of the bolt through a rigid support, forming an axial tensile load. The pressure sensor monitors the load value in real time, and the displacement sensor records the displacement change of the bolt under the action of tension. After processing the load and displacement data, the load-displacement curve can be drawn to analyze the mechanical properties of the anchoring system.
The core mechanical relationship can be expressed as:
F = P × A
where F is the applied tensile force, P is the hydraulic system pressure, and A is the effective working area of the piston.
Measurement method
The measurement process must follow relevant technical standards, such as national standards GB/T standards or ASTM international standards. The operation steps mainly include: first, install the bolt puller at the test point to ensure that the axis of the instrument coincides with the axis of the bolt; Then the tensile force is applied in stages through the hydraulic system, and the load of each stage is maintained for a certain time and the displacement value is recorded. Stop loading when the predetermined maximum load is reached, the displacement exceeds the standard, or signs of failure appear. After the test, the linear segment, yield point and peak of the load-displacement curve should be analyzed, and the ultimate bearing capacity and deformation characteristics of the anchorage system should be calculated.
Influencing factors
The accuracy of the measurement results is influenced by several factors. The characteristics of the anchor include material strength, diameter and surface treatment; matrix material properties such as concrete strength, rock integrity or soil compactness; The construction process involves the diameter of the borehole, the fullness of grouting and the curing conditions; Instrument factors include calibration status, loading rate control and fixture alignment accuracy. Environmental conditions such as temperature and humidity may also play a role in bonding properties. Operators need to evaluate these factors before testing and account for them in the report.
Applications:
Bolt pullers are suitable for a wide range of industrial and engineering applications. In construction engineering, it is used to test the pull-out performance of anchored steel bars and bolts after concrete structures. evaluate the reliability of slope support bolts and tunnel lining anchors in geotechnical engineering; check the installation quality of bridge cable anchors and track fixings in traffic engineering; In addition, it is also widely used in power facilities, ancient building reinforcement and industrial equipment foundation testing. The instrument provides a quantitative basis for project acceptance, regular maintenance and accident diagnosis.
Key points of selection
When choosing an anchor puller, technical parameters and usage needs should be comprehensively considered. The range of measurement should cover the design load of the bolt to be measured, and the common models cover tens of thousands of Nm. to thousands of KiloN; The accuracy level should meet the requirements of relevant standards for measurement errors; The instrument should have the function of automatic data collection and export to facilitate subsequent analysis. Portability and site adaptability include weight, size, and ease of installation in different space conditions. In addition, equipment durability, maintenance intervals and supplier technical support capabilities are also aspects that need to be paid attention to when selecting. It is recommended to choose according to the actual application scenario and refer to the current technical specifications.