Chapter 11 A full-scale study on cement deep mixing in soft Bangkok clay

Abstract

Abstract A case history of full-scale deep mixing improved soft clay ground overlain by a 6.0 m high reinforced test embankment is presented. The deep mixing piles were constructed in the ground using the jet mixing technique with cement slurry employing a jet pressure of 20 MPa. Comparison was made to another reinforced test embankment of almost the same height constructed previously on unimproved soft clay foundation. Excess pore pressure buildrup during soil-cement pile installation by jet mixing was monitored. The surface and settlements as well as lateral movements were monitored during and after embankment construction. The deep mixing improvement has effectively reduced the settlement and lateral movement of the foundation soil by as much as 70% and 80%, respectively. The local differential settlement between deep mixing pile and its surrounding soil amounted to 8–20% of the average total settlement of the improved ground, and could induce downdrag skin friction on the pile.