Field Experimental Study on Dynamic Response of Soft Foundation During Dynamic Compaction Replacement Construction

To investigate the dynamic response of soft soil foundation, field tests were conducted on a highway project in the mountainous area of Guizhou, where the dynamic replacement (DR) method was applied for foundation improvement. The evolution of excess pore water pressure and ground acceleration response during the compaction process was studied. The results show that excess pore water pressure during the DR process dissipates rapidly, allowing for continuous DR construction. The ground acceleration time‐history curves exhibit 4–6 peaks within 1 s, after which it decays rapidly to zero. The peak ground acceleration decreases as a negative power function with the increase of the distance to compaction point center, and increases with higher compaction energy level and more compaction impacts. The peak ground acceleration in different directions at the same measurement point follows the order: vertical > radial > tangential direction. With the distance to compaction point center increasing, the vertical and radial peak ground accelerations attenuate faster than the tangential one. The peak ground accelerations of all three directions drop below 0.6 m/s 2 at 15 m away from the compaction point center, indicating that the main influence zone of DR method is 15 m approximately. The first dominant frequency of ground acceleration in different directions ranges from 1.5 to 4.0 Hz, indicating that the compaction energy primarily propagates and dissipates as low‐frequency waves within the foundation. The dominant frequency of the ground acceleration is minimally influenced by the distance to compaction point center and the number of compaction impacts.