Behavior and Simulation of Deep Cement Mixing (DCM) and Stiffened Deep Cement Mixing (SDCM) Piles Under Full Scale Loading

Abstract

Professor in Geotechnical Engineering Program, School of Engineering and Technology, Asian Institute of Technology, Thailand (bergado＠ ait.ac.th).iii) M. Eng. Graduate, ditto. iv) Doctoral Graduate, ditto. v) Regional Technical Manager of PLAXIS Asia. The manuscript for this paper was received for review on January 29, 2010; approved on December 7, 2010. Written discussions on this paper should be submitted before November 1, 2011 to the Japanese Geotechnical Society, 4-38-2, Sengoku, Bunkyo-ku, Tokyo 112-0011, Japan. Upon request the closing date may be extended one month. ABSTRACT A new kind of Deep Cement Mixing (DCM) pile called StiŠened Deep Mixing Pile (SDCM) is introduced to mitigate the low ‰exural strength and unexpected failures of DCM piles. A jet grouting method with a jet pressure of 22 MPa, was utilized in the installation of DCM piles. The SDCM pile consists of a DCM pile with a precast reinforced concrete core pile inserted at its center. Pile and embankment load tests were conducted, and then the results of theˆeld load tests were simulated by a 3Dˆnite element method (FEM) to back-analyze and conˆrm the related design parameters. These parameters were then used further in numerical experiments. Theˆeld test results showed that the settlements and lateral movements of the SDCM pile using a prestressed concrete core pile with area ratio (A core /A DCM ) of 0.17 and a length ratio of 0.85 was less than those of the DCM pile by 40z and 60z, respectively. Moreover, the SDCM pile foundation increased the bearing capacity by as much as 2.2 times. The average lateral pile capacity of the SDCM piles was 15 times higher than the DCM piles. A strength reduction factor of 0.40 was obtained at the concrete core and the DCM interface from the full scale pullout test. The behavior of both the DCM and SDCM piles was conˆrmed from the subsequent 3D FEM simulations. From the 3D FEM simulations, the length of the concrete core pile had more in‰uence on the settlements of the SDCM pile than its cross-sectional area. However, both the length and cross-sectional area of concrete core pile aŠected the lateral resistance of the SDCM pile.

Strength properties of an epoxy resin and cement-stabilized silty clay soil

“…The DMM is based on mixing binders, such as cement, lime, fly ash, gypsum and other additives, with the soil by the use of rotating mixing tools in order to form columns of a hardening material due to the pozzolanic reactions that occur between the binder and the soil grains (Porbaha, 1998(Porbaha, , 2002Sukontasukkul and Jamsawang, 2012;Voottipruex and Jamsawang, 2014). These DMM piles act as ground reinforcements, thereby increasing the load bearing capacity of the ground (Jamsawang et al, 2011;Voottipruex et al, 2011aVoottipruex et al, ,2011b. The DMM method is often applied in many geotechnical and foundation applications, such as the stabilization of deep excavations or high embankments, slope stability, tunnel support, the reduction of settlement or the increase of bearing capacity of soft compressible soils for building foundations, and water retention (Bergado et al, 1999;Lin and Wong, 1999;Moseley and Kirsch, 2004).…”

Numerical study on load transfer effect of Stiffened Deep Mixed column-supported embankment over soft soil

“…Under the embankment load, both the negative and positive unit skin frictions were generated along the shaft of concrete core pile. The distribution of unit skin friction was different from that obtained from the plate loading test on a single SDM column (Voottipruex et al, 2011a), along which there was no negative unit skin friction occurred. In the plate loading test on a single SDM column, the load was applied through a rigid steel plate placed on the top of SDM column to the SDM column, thus there was no relative displacement between concrete core pile and soil-cement due to the rigid loading plate.…”

“…Zhao et al (2010) presented two failure modes of SDM column under plate loading test, namely the core pile failure and the interface failure between concrete core pile and DM column. Zhao et al (2010) and Voottipruex et al (2011aVoottipruex et al ( , 2011b indicated that the length of core pile had more significant influence on bearing capacity than diameter of core pile. Jamsawang et al (2011) and Raongjant and Jing (2013) experimentally found that the lateral bearing capacity of SDM column was 11 to 15 times and 3 to 4 times greater than that of DM column under static load and cyclic load, respectively.…”

Long-term reinforcement strains for column supported embankments with viscous reinforcement by FEM

“…Columns installed by the deep-mixing-method (DMM) have been widely acknowledged as a cost-effective and speedy means of supporting roadway embankments constructed over soft soil (e.g., Bergado et al, 1999;Lin and Wong, 1999;Igaya et al, 2011;Chai and Carter, 2011;Jamsawang et al, 2011;Voottipruex et al, 2011a;Chandra, 2012;Dahlstr€ om and Wiberg, 2012;Kamruzzaman et al, 2012;Bruce et al, 2013;Chai et al, 2015;Liu et al, 2015). To minimize column construction costs and improve embankment stability, geosynthetic reinforcement is increasingly used as basal reinforcement in combination with columns to control embankment deformations including both vertical and horizontal displacements (e.g., Forsman et al, 1999;Parmantier et al, 2005;Lai et al, 2006;Pooranampillai et al, 2012;Borges and Gonçalves, 2016;Chen et al, 2016;Zhang et al, 2016).…”