Modern Transportation and Metallurgical Materials

This paper discusses the subgrade diseases of interchange project of expressway in a deep soft soil area. Based on the foundation treatment construction scheme and monitoring data, the causes of differential settlement of road and bridge connection positions and instability of high-filled subgrade are analyzed, the secondary treatment scheme is put forward and verified by the monitoring data during the secondary treatment construction period. The research shows that vacuum combined surcharge preloading method is an effective method to treat deep soft foundation. The settlement amount after foundation treatment depends on the relationship between the load during the service period and the load during the construction period. In order to make the settlement after construction under control, the load during the construction period should not be less than the load during the service period. In deep and thick soft soil areas, in order to reduce differential settlement and make a smooth transition between rigid pile foundation and soft soil foundation, it is necessary to set up a transition section. In addition, monitoring is indispensable for the construction of high-filled roadbeds in deep soft soil areas.