Definition
Anchor tensile gauge is a special measuring device used to measure the axial pull-out bearing capacity of anchor members. It evaluates the mechanical properties and installation quality of anchor systems such as anchors and anchor cables by applying and measuring pull-out force, and is widely used in on-site testing and acceptance in geotechnical engineering, construction engineering, transportation facilities, and geological disaster prevention and control.
How it works:
The bolt tensile gauge works based on the principle of force balance and hydraulic transmission. The equipment is mainly composed of hydraulic pump, hydraulic cylinder, pressure sensor and display unit. During operation, a manual or electro-hydraulic pump injects hydraulic oil into the hydraulic cylinder to push the piston to generate an axial pulling force, which is evenly transmitted to the bolt under test through the pressure plate. The tensile force value is converted into an electrical signal by the pressure sensor, which is displayed in real time on the display unit after processing. If the system satisfies Hooke's law and the static equilibrium conditions, the relationship between the tension F and the system pressure P can be expressed as:
F = P × A
where A is the effective working area of the hydraulic cylinder piston. In the elastic deformation stage, the bolt displacement and tensile force usually have a linear relationship, and the working state of the bolt can be judged by displacement monitoring.
Measurement method
Before measurement, it is necessary to confirm that the exposed length of the bolt meets the installation requirements, and check whether the connecting parts of the equipment are reliable. Put the tensile gauge into the bolt to ensure that the pressure plate is in smooth contact with the support surface. After installing the displacement measurement device, the pulling force is applied at a uniform speed, and the loading rate is generally controlled within 10% of the maximum test force designed per minute. The graded loading and loading mode is used to record the tensile value and corresponding displacement of each stage. When the set maximum test force is reached, the bolt has obvious slippage or the displacement increases sharply, the loading is stopped, the pressure is slowly relieved and the residual deformation is recorded. The test process should follow relevant engineering technical specifications to ensure data accuracy and operational safety.
Influencing factors
Measurement results are influenced by a variety of factors. The rock and soil properties, grouting density and bonding strength of the anchor section directly affect the uplift bearing capacity. In terms of equipment, the tightness of the hydraulic system, the accuracy of the pressure sensor and the condition of regular calibration determine the reliability of force measurement. Under the installation conditions, the contact angle and flatness of the pressure plate and the rock surface may cause eccentric loading. Changes in ambient temperature can affect hydraulic oil viscosity and sensor sensitivity. Improper control of the operator's load rate or inconsistent timing of readings can also introduce human error. These factors need to be considered in the experimental design and results analysis.
Scope of application:
This equipment is mainly used in the quality inspection and safety assessment of geotechnical anchoring engineering. In the slope reinforcement project, it is used to check whether the uplift performance of the anchor meets the design requirements. During tunnel support construction, the installation quality of the system anchor can be detected. In the monitoring of foundation pit support, the long-term working status of the anchor cable can be evaluated. In addition, it also plays an important role in the anchor detection of power tower foundations, wind turbine foundations and other structures, as well as the periodic inspection of anchor structures in geological disaster prevention and control projects. Its on-site fast testing feature provides direct data support for engineering safety.
Key points of selection
The selection should comprehensively consider the measurement range, accuracy requirements and site conditions. First, the maximum range of the equipment is determined according to the design pull-out force, usually with a safety margin of 1.2 to 1.5 times. The accuracy level should meet the engineering testing standards, and the error of the value should not be greater than ±1% of the full scale. The on-site power supply conditions determine the choice of manual hydraulic pump or electric pump model. The weight and size of the equipment need to be adapted to the on-site handling and installation space. In terms of function, it is advisable to choose a model with peak hold, data storage and output interfaces to facilitate data recording and analysis. In addition, the environmental adaptability of the equipment, such as waterproof and dustproof ratings and operating temperature ranges, also needs to match the actual usage conditions. It is recommended to refer to the relevant national or industry testing instrument standards for comparison and selection.