Mechanical compaction and chemical grouting are the two most widely used methods in geotechnical engineering for ground improvement. However, the disadvantages of the methods including high cost, high energy consumption, and potential environmental pollution are obvious. A new ground treatment technique, i.e., microbial induced carbonate precipitation, was developed recently. Review of ground improvement using microbial induced carbonate precipitation technique was performed in this study. The mechanism of microbial induced carbonate precipitation-treated soils was first introduced followed by the review of many aspects of the microbial induced carbonate precipitation technique. Thereafter, the related engineering applications were presented and summarized. Moreover, some problems existing in current theoretical and experimental studies as well as the possible solutions for future development were also discussed. Some recommendations were proposed for a wider application of this technique.

Wind erosion phenomenon is commonly encountered in desert areas, which is harmful to engineering constructions and environment. This study proposed an innovative microbial‐induced calcium carbonate precipitation (MICP) technique to reinforce sands for mitigating natural hazards caused by the wind erosion. A series of small‐scale laboratory experiments were performed to evaluate wind erosion resistance of MICP‐treated sands with different treatment cycles. The spraying method was used to treat sand specimens, and unconfined compression (UCC) strength tests were also conducted to assess the performance of the MICP technique. Experimental results revealed that the bulk density of treated sand was slightly increased with the number of MICP treatment cycles. Additionally, the wind erosion rate of treated sands was significantly decreased, and the UCC strength was increased (maximum to 4 MPa) with the number of treatment cycles, which was mainly attributed to the bonding effect from the microbial‐induced CaCO₃ crystals among sand particles based on the scanning electron microscopy (SEM) analyses. Such effect also facilitated to form a hard protection layer on top of the sand specimen in order to improve the wind erosion resistance of MICP‐treated sands. This technique provides an alternative method to mitigate and prevent the aggravation of desertification.

Embankment is vulnerable to scouring and erosion during heavy rainfall events in most coastal areas in China. In this study, microbially induced calcium carbonate precipitation (MICP) technique was applied for sand embankments for scouring/erosion control. Three small-scale MICP treated sand embankments and one untreated embankment were first prepared using the injection method. Then, a series of laboratory scouring/erosion experiments were performed to investigate the slope failure process. The total erosion mass, the soil detachment rate and the content of MICP induced calcium carbonate (CaCO₃) were also measured to evaluate the effectiveness of MICP treatment in sand embankments. Experimental results revealed that the average CaCO₃ content was increased by 2% with each increment of MICP treatment cycle. The anti-scouring/erosion performance of MICP treated sand embankments was significantly improved as compared to the untreated one. Scanning electron microscopy (SEM) technique was also used to further study the micro-mechanism of the MICP treatment. The results revealed that the MICP induced CaCO₃ was formed at the contact points among sand grains that increased the bonding strength, resulting in an improvement of scouring/erosion resistance of the treated embankment. This study preliminarily investigates the feasibility of using the MICP technique to mitigate scouring/erosion of sand embankment in coastal areas. More complicated environmental factors need to be considered for field implementation in the future.

Plate anchors are embedded into the ocean floor to provide holding capacity for offshore structures. Anchor holding capacity is a function of both the anchor and soil properties. Although plate anchors have been widely studied experimentally and numerically, there is still no universally agreed-upon design approach, indicating that the problem physics remain elusive. In this work, discrete-element method (DEM) simulations were used to investigate the behavior of plate anchors during pullout in an effort to elucidate some of the microscale physical processes that influence overall system behavior. Macroscale assembly response was compared to published experimental results and empirical solutions. The influence of embedment ratio, anchor roughness, soil density, and anchor size on holding capacity was investigated, and system-scale results reasonably agreed with previously published work. Thus, observations of the simulated contact force network and particle velocity during uplift were used to provide insight into anchor failure mechanisms. Finally, the model was used to briefly explore the response of a cyclically loaded plate anchor embedded in a granular assembly.