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The article analyzes the influence about backwater side sand piling of a Pile-based frame Seawall along the east coast of Zhejiang on the stability and deformation. When sand is not piled on the backwater side of the Seawall, the overall safety factor of the Seawall is 1.619∼2.941, which meets the specifications and design requirements; when the backwater side is piled with sand or sand piling+vehicle driving, the overall safety factor of the Seawall is respectively 1.119∼1.617, 1.107∼1.599, and the safety factor of some working conditions is less than required 1.20, which does not meet the specifications and design requirements. According to the simulation results of the MIDAS finite element software, the settlement of the Seawall within 3 months of sand piling is 22.0mm, and the horizontal displacement is 7.9mm, indicating that the sand piling on the back side has a great influence on the deformation of the Seawall. The settlement and horizontal displacement of the Seawall are too large, resulting in a large reduction in the vertical and horizontal bearing capacity of the pile foundation, which has a huge impact on the overall stability and safe operation, severely disrupting the stress balance of the Seawall structure, and causing landslides on the water-facing side risk.

The article analyzes the impact of a constructing sewage treatment plant on the built seawall nearly by PLAXIS finite element software, located on the coast eastern Zhejiang. As the construction carrying on, the settlement and horizontal displacement are gradually increasing on the top and backwater slope of the seawall. The settlement on the top of Seawalls is 35.91 cm, the horizontal displacement is 50.76 cm; the settlement on the back slope is 71.45 cm, the horizontal displacement is 48.54cm. During the construction process, settlement increase rate at the foot of the backwater slope was significantly larger than that at the top of the seawalls. The horizontal displacement increase rate at the top of the seawalls was slightly larger than that at the foot of the backwater slope. The settlement and horizontal displacement of the seawall exceed the normal allowable deformation, which threatens the safety of the seawall. It is necessary to take reinforcement measures for the seawall to ensure safe operation.

In order to improve water quality, to ensure the capacity of normal flood discharge and river transport, it carried out a lot of dredging work across the country recently. For harmful sediment’s second pollution and recycling use, this study selected five kinds of sediment. And point A was determined as the research object by using the geo-accumulation index to evaluate the heavy metal. Then the sediment was mixed with lime, fly ash, kaolin clay, sodium silicate, sodium carbonate and polyvinyl alcohol as mud stabilizing materials. Experimental research shows that, copper loss of stabilized soil’s toxicity leaching agent reaches more than 95%, and the permeability coefficient was 10-5 cm/s orders of magnitude. In this paper, it ensures GW7 as the best choice of plants experiments, which are 5% fly ash, 1% lime, 3% kaolin clay, 3% sodium silicate, 3% sodium carbonate and 1% polyvinyl alcohol, through the ways of permeability, water retention, SEM and XRD. The scheme effectively stabilizes copper, and keeps the plants as better form than others. But it has different effect on different plants. Thus it should consider planting varieties optimization in actual applications.