Layered laminated shear model box Laminar Box-III

Under seismic excitation, the soil layer overlying rigid bedrock in nature can be regarded as a shear beam subjected to vertically propagating shear stress. Owing to the mechanical behavior of soil as a semi-infinite free body, determining appropriate boundary conditions for the tested soil and minimizing the interference of the model box effect become critical issues for the success of geotechnical simulation tests such as centrifuge and shaking table tests.

Therefore, a rational model box design must fully consider the influence of soil boundaries to ensure that the tested soil can accurately reproduce the stress and deformation of the in-situ site under seismic loading. The Laminar Box‑III laminated shear model box is designed to meet the above requirements. Compared with rigid model boxes, the shear model box can greatly reduce boundary effects and simulate a free-field environment.

Its main body is formed by alternately stacking lightweight hollow aluminum alloy/carbon steel members and special rubber layers. The interlayer stiffness can be adjusted by modifying the dimensions and material of the rubber layers, and each layer can slide freely along the vibration direction. It can meet the requirements of various geotechnical dynamic model tests, including deep foundations, dams and reservoirs, slopes and retaining walls, underground structures, marine structures, and soil‑foundation‑structure interaction.

Typical features

• Low frictional resistance, allowing free sliding between layers along the vibration direction;

• The height of each layer of the model box can be freely adjusted;

• Large internal space size, which can be designed according to user needs;

• Capable of measuring soil settlement and lateral shear deformation;

• Resistant to high centrifugal force and strong vibration shock interference;

• Has good waterproof and sealing performance, with a pressure bearing capacity of ≥400kPa water head;

The model box is a customized system. The shear model box serves as the main carrier for physical simulation tests of soft soil, and geotechnical seismic tests cannot be conducted without it. The size and number of layers of the stacked model box can be customized. A rubber pad is placed between every two layers to form a stacked structure, which realizes the softened boundary of the model soil and controls the boundary reflection of seismic waves.

Typical applications

• Dynamic centrifuge model test

• Conventional shaking table test

Main Technical Parameters

• The internal space size of the box is designed according to user requirements;

• Centrifugal acceleration resistance ≥ 80g;  Vibration acceleration resistance ≥ 30g;

• Operating frequency range: 10~300Hz;

• Sliding amplitude ≤ 10mm;

• The interior is sealed with a rubber membrane, with a pressure bearing capacity ≥ 400kPa water head;

• It has lateral constraints, and each layer can slide freely along the vibration direction with low frictional resistance;

• Sufficient strength ≥ 10MPa to prevent the box itself from being damaged;

• Maximum deformation of the test box ≤ 1.5mm;

• The test box is reliably connected to the vibration table surface to ensure no slippage between them;

• It can meet the requirements of geotechnical structure model tests such as dry sand, saturated sand, and pile foundations;

• Each layer of the flexible beam frame is provided with threaded holes matching PCB acceleration sensors or MEMS accelerometers;

• A drainage channel is arranged inside the box;

• The configured vertical displacement meter mounting bracket can be used to install the pull rod type or laser displacement meters to measure the soil settlement in the test box or the dynamic displacement change process of pile foundation structures. The mounting bracket can be installed at any position on the test box without sliding;

• The configured lateral displacement meter mounting bracket can be used to install and fix the pull rod type or displacement meters to measure the shear displacement change process of the test box, without sliding during vibration.