In order to master the creep deformation law of colluvial slope and the stress deformation characteristics of tunnel lining structure under rainfall

the response physical model test of seepage and stress deformation characteristics of tunnel slope parallel system is carried out by using earth pressure cells

strain gauges

dial indicators and hygrometers. The test results indicate that rainfall infiltration depth decreases with increasing slope height and distance from the slope surface. The existence of the tunnel will affect the seepage path of rainwater

accelerating infiltration and increasing peak moisture content on the slope above the tunnel

while decelerating infiltration and reducing peak moisture content on the slope below the tunnel. The slope deformation is positively correlated with the change rate of water content. Slope deformation is concentrated during rapid water content increase

with vertical displacements at the slope top

middle

and foot accounting for 89.6%

96.4%

and 98.9% of the total

respectively. The earth pressure increment at the tunnel top due to slope deformation correlates positively with the tunnel’s buried depth in the accumulation body

with an average increase of 24% per 15 cm. The earth pressure increment at the bedrock end is approximately 2.4 times that at the entrance end

while the increment at the tunnel bottom is smaller than that at the top. The tunnel exhibits the following stress and deformation characteristics: compression at the top

tension at the bottom

overall sinking

local downward bending with the central position as the inflection point

and abrupt strain changes at the bedrock-accumulation layer junction due to shear stress. These characteristics resemble the stress mode of a beam structure with one end hinged and one end anchored. It is recommended to incorporate anti-seepage measures such as sprayed concrete

shallow grouting

or slope ecological protection on the upper slope of the tunnel during the design and construction of similar tunnels. Reinforcement treatment should be implemented in the tunnel entrance area

the middle section with significant deformation

and the rock-soil junction.