The invention relates to a
model test device for a high-speed railway
subgrade passing through a karez. The device is mainly characterized in that a test box body is mounted below a cross beam of a reaction frame, and
organic glass plates are arranged at the front part and the rear part of the test box body; the box body is filled with model soil in which tracer particles are buried; and a PVC vertical
pipe and a PVC longitudinal
pipe are arranged in the model soil; a railway
subgrade is arranged on the top surface of the model soil; multiple
layers of stiffened strips are arranged in the railway
subgrade, a concrete base plate is laid on the upper portion of the railway subgrade, and a jack on the cross beam is arranged over a concrete plate; a
vibration exciter and a displacement meter are arranged on the concrete base plate; three strain gauges are arranged on the model geogrids of the stiffened strips; three soil pressure boxes are vertically arranged on the railway subgrade, and three lateral soil pressure boxes and two strain gauges are arranged on the PVC vertical
pipe; and a particle image velocimeter is arranged on the outer side of the test box body. According to the invention, the mechanical properties of the subgrade and the karez foundation under the
train load can be obtained, so that a test basis is provided for reinforcement design and construction of the subgrade and the foundation of the high-speed railway in the karez region.