# Experimental Study on Engineering Properties of Cemented Soil with High Water Content
## 1 Introduction  
Deep cement mixing (DCM) columns are widely used in soil treatment all around the world. The physical and mechanical properties of cemented soil have been investigated by many researchers [1; 2; 3]. The experimental results indicate that cemented soil strength grows with the cement content and curing time. Moreover, an optimum water content for cemented soil was found for a certain cement content. [PERSON] et al. analyzed the influence of water content, cement content, curing time, and porosity rate on the cemented soil strength based on a series of laboratory tests, and a formula was proposed to predict the strength of the cemented soil [4; 5]. The influence of confining pressure on the stress-strain development law of the cemented soil was also studied by some scholars through triaxial compression tests [6; 7; 8]. The test results showed that the deviatoric stress of cemented soil was positively correlated with confining pressure, while the growth rate was very limited. The consolidated undrained shear tests for cemented soil showed that when the confining pressure is small, the shear strength of the cemented soil is mainly provided by the strength of cement-solidified soil. When the confining pressure exceeds the yield strength of cement-solidified soil, the confining pressure is the dominant factor of the shear strength [9]. The peak deviatoric stress increases with the confining pressure when the cemented soil is in the unsaturated state [10]. [PERSON] et al. established a model that could describe the mechanical behavior of cemented unsaturated loess and found that it was also suitable for the mechanical behavior of unsaturated cemented soil [11]. [PERSON] extended the Mohr-Coulomb model through the peak strength index and residual strength index,and suggested that the peak strength index would decrease to the residual strength index with a linear trend in the softening process [12].  
In recent years, a new kind of composite pile foundation, called the pre-bored grouted planted (PGP) pile, has been developed in China. A pre-stress high concrete (PHC) pile was inserted into the cemented soil column, and was surrounded by the cemented soil when the PGP pile was installed [13]. Moreover, the water content of the cemented soil should be very large, which guarantees that the cemented soil column could be stirred homogeneously in the construction process. In the load transfer process of the PGP pile, the load applied on the pile head was transferred from the PHC pile to the surrounding cemented soil through the PHC pile-cemented soil interface, and then transferred to the surrounding soil through the cemented soil-soil interface [14]. The compressive and uplift bearing capacity of the PGP pile was demonstrated to be better than that of the conventional bored pile [15; 16; 17]. Moreover, the pile-soil interface shear test results showed that the strength of the cemented soil had a great influence on the shaft resistance at the PHC pile-cemented soil interface [18]. Hence, the properties of the cemented soil would also affect the behavior of the PGP pile.  
In this research, a series of unconsolidated-undrained triaxial tests and UCS tests of cemented soil with different ratios were conducted. The mechanical characteristics of cemented soil were further analyzed based on the test results. The experimental results could offer a basis to the design of the DCM pile, jet grouting pile, and PGP pile.