Tka-sds-1 tunnel model test system is to place the tunnel model on the steel structure reaction frame, and install two hydraulic jacks (6 jacks in total) on the top and both sides of the frame. The jacks simulating vertical load are placed on both sides of the upper part of the model, and apply load through the force transfer plate (frame). The vertical stress is applied and simulated by using 2 jacks and the horizontal stress is mainly calculated according to the lateral pressure coefficients of different surrounding rocks. The load applied to the model is basically similar to the prototype.
1. Reaction frame:
Steel structure reaction frame size: length × width × height =0.8 m×3.0 m×2.4 m.
The reaction frame is composed of the base, integral frame, front and rear limit plate, front and rear tunnel mouth baffle and top cover. The base and the integral frame are welded as a whole, and the front and rear limit plate, front and rear tunnel mouth baffle and top cover are connected to the integral frame through high-strength bolts.
The reaction frames are made of high strength i-beams and steel plates.
2. Hydraulic servo control loading system:
It includes hydraulic pump station, hydraulic cylinder, servo valve, servo controller, signal line, oil pipe, hydraulic jack, transmission plate and acquisition system.
The top part is fixed with two top hydraulic jacks, and two side hydraulic jacks are fixed on both sides of the overall frame.
With the help of pump station, servo controller and tubing, the oil pressure is output for the hydraulic jack. With the change of oil pressure, the expansion and stable state of the hydraulic jack is controlled. At the same time, the tunnel model is loaded and unloaded through the pressure plate
The force transfer plate shall have sufficient strength to ensure that the deformation of the force transfer plate shall be controlled within the range of 0.1mm during loading and unloading. The finite element calculation of the force plate model should be carried out in advance to ensure that the jack can provide even pressure through the force plate.
Hydraulic jack: single maximum load 200kN, cylinder maximum shape distance 150mm. Each jack is independently connected with a transmission plate to facilitate the installation and debugging of the whole system.
The acquisition system realizes the control of the test process and the collection of real-time information to ensure that the test is carried out in a predetermined way.
Control mode: each test is loaded according to a certain proportion of the prototype stress, and the output pressure of the servo controller and the oil pump is changed at the same time or single change. At this time, the jack output has different loading and unloading tests on the model, providing a variety of tunnel loading tests under the boundary.
3. Observation system:
Position of observation hole:
A:Without affecting the stress of the tunnel model, observation holes should be reserved for the transmission plate to facilitate the observation of surrounding rocks and supporting conditions of the tunnel, and to record the occurrence and development process of cracks.
Method 2:Without affecting the force of the tunnel model, observation holes are reserved between the transmission plates.
4. Supporting measuring equipment
(1) displacement measurement device around the tunnel. The electrical displacement meter with a precision of 0.001mm can be considered to be equipped with a high-precision displacement meter and a conversion interface meter to automatically collect the displacement. Its range and accuracy are required to be 30mm±0.1%.
(2) internal force measuring device. The strain measuring system can be composed of several poisons rubber base resistance strain gauges, corresponding static resistance strain gauge and other auxiliary equipment. The system error is less than 1%.
(3) contact pressure force measuring device. A 0.5 grade precision earth pressure sensor may be considered to be equipped with the above-mentioned strain variable measurement system. The system error is less than 1%.
5. Track and flat car
The system shall be equipped with rail and flat car, and the height of the rail and flat car shall be consistent with the lower reaction frame of the tunnel test system, so as to facilitate the transportation of the tunnel model.
6. Other parts
2 jacks and steel track installation positions should be reserved for the lower reaction frame, and the positions of jacks on both sides of the frame should be considered to facilitate the system upgrade in the future.