**5. Conclusions**

Relying on marine soft soil foundation of complex drainage conditions, the continuous drainage boundary conditions are introduced into the double-layer soil consolidation theory model. Combined with the Laplace transform and Stehfest algorithm, the equations of the improved double-layer soil consolidation theory are deduced and solved. The degradation model of the theory is validated and analyzed by the perfectly permeable boundary conditions and the semi-permeable boundary conditions, respectively. Then, the consolidation analysis of coastal soft soil in Guangxi is carried out. We made some useful conclusions:


**Author Contributions:** D.C. and J.L. conducted the calculation analysis and wrote the paper. D.M., X.L. and L.X. motivated this study with good and workable ideas.

**Funding:** This research was funded by the Guangxi traffic science and technology project ("Research on standardization of soft soil foundation treatment technology in Guangxi highway" Grant No. 20140203). And The APC was funded by the Guangxi traffic science and technology project ("Research on standardization of soft soil foundation treatment technology in Guangxi highway" Grant No. 20140203).

**Acknowledgments:** This work was supported by the Guangxi traffic science and technology project ("Research on standardization of soft soil foundation treatment technology in Guangxi highway" Grant No. 20140203). We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

**Conflicts of Interest:** The authors declare no conflicts of interest.
