Abstract: Rock mass physical model test is widely used in the study of rock mass engineering stability because it can
visually reproduce the engineering failure process. As an important means to monitor the internal strain of surrounding rock,the
accuracy and reliability of strain brick method are particularly important. In order to explore the influence of pouring method on
the stress-strain characteristics and measurement accuracy of strain bricks,and clarify its microscopic mechanism,the strain,
stress and failure characteristics of specimens under direct pouring and concrete slab pouring were systematically analyzed by
combining laboratory test with numerical simulation,and the mechanism of contact seam and contact surface on strain bricks
and specimens was revealed. The results show that under the action of axial stress,the contact seam generated by direct pouring
will lead to the dislocation of the samples on both sides,which makes the axial measurement data of the strain brick too large
and easy to damage. The specimens poured on the concrete slab are significantly constrained by the slab body,and the stress
and strain are small. With the increase of the curing time of the concrete slab,the bonding force between the post-cast concrete
and the slab body is weakened,and the bearing capacity is obviously reduced. Material heterogeneity will increase the uncertainty
of strain transfer,and the change of contact seam width and depth,temperature and humidity will reduce the measurement
accuracy of strain brick. Comprehensive analysis,under the direct pouring method,the strain brick measurement method is suitable
for the measurement under low-level loading. The strain brick measurement method is suitable for the measurement under
high-level loading conditions when the pre-cast concrete slab with 8 d curing is used as the reference slab. The research can
provide guidance for the measurement of rock internal state in rock mass physical model test.

Key words: physical model test,pouring method,strain brick measurement,contact joints