The Behavior of Braced Excavation in Silty Clay Soil under El-Centro Seismic

Braced excavation is one of the important systems used to support soil from collapse during excavation. A braced excavation system may be exposed to seismic load and undergoes more forces through the significant vibration of the surrounding soil in addition to the static and lateral loads of soil and nearby structures. The investigation of the braced excavation under the effect of earthquake behavior is still limited or poorly described. Further, this paper presents a numerical study to evaluate the vertical settlement and horizontal displacement of sheet pile wall embedded in silty clay soil in Baqubah city under the influence of the acceleration time history of the 1940 El-Centro earthquake. The study utilized the software PLAXIS 3D. A three-dimensional analysis of the braced system with dimensions of 14m×6m and an excavation depth of 7m was achieved. Three levels of strut and wale layers were used, and five struts for each level. The penetration depth for the sheet pile wall was 9m. The study showed that the El-Centro earthquake laterally moved the braced excavation system as a block mass due to the existence of the excavation system in soft silty clay. The lateral displacement reached approximately 150mm. The differences in lateral earth pressure on sheet pile wall depth a few seconds before and after the earthquake were very small.