Laboratory Model Test of Rock-Socketed Pile Groups in Steep-Inclined Bedrock Under a Reduced Constraint

Improving the deformation coordination ability of unequal length pile groups is a key point in the application of pile foundation engineering. This study proposed a new concept of rock-socketed pile (RSP) with reduced constraint part, and developed a laboratory model test device to explore the horizontal bearing capacity of unequal length pile groups under various rock inclination angles and reduced constraint part length. Thus, this device revealed the mechanism of decreased RSP group stiffness with the reduced constraint. The results indicated that a smaller inclination angle resulted in a longer unconstrained part of the pile and a larger overall horizontal deformation. The reduced constraint part can significantly adjust the overall displacement of the piles for the same inclination angle. The larger the length of the reduced constraint part, the larger the displacement of the RSP pile top. Under the same loading conditions, increasing both the pile and RSP part lengths of the reduced constraint can reduce the pile bending moment. The use of the reduced constraint part is equivalent to an increase in the length of the piles after adjusting the stiffness of the relatively short piles. This research offers a basis for designing reduced constraint measures for an RSP group in an inclined bedrock stratum.