?The GEOLOGY Formation is generally composed of marine, alluvial,littoral, transitional reef… 1 answer below »

The GEOLOGY Formation is generally composed of marine, alluvial, littoral, transitional and reef members. The soils are loose or soft in consistency and with variable composition of recent deposits. The GEOLOGY Formation at the site consisted of the following strata: (i). Marine Clay; (ii). Estuarine Layer; (iii). Silty/ Clayed Sand Layer (F1); and (iv). Silty Clay Layer (F2). The marine clay layer is the predominant layer within this formation found at site. The maximum thickness encountered in the site investigation is about 30 metres. The silty clay

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7308ENG Computing Laboratory Assignment #2 The major focus of this assignment is on numerical analysis of the ground response in lateral direction during the deep excavation. Task: Provide a 5 to 10 pages report. Carry out a PLAXIS analysis of the stresses and deformations in the sub-soil after the excavation. From your PLAXIS analysis, present the results: (a) The lateral movement profile with depth along E – E; (b) The lateral movement profile with depth along K – K; (c) The factor of safety from Phi-c reduction calculations. Discuss the results as obtained by you in (a) to (c) above. Notes: • The excavation for the main station box is about 18m deep and is 34 m wide. These sections are contained with 800 mm thick diaphragm walls. It extends in longitudinal direction for a large distance, so that a plane strain model is applicable. The sides of the excavation are supported by diaphragm walls with length ranges from 37 to 50 m, which are braced by horizontal struts at an interval of 3 m. • Select Mohr-Coulomb as the Material model. Since only long-term effects of the excavation are considered here, the material type is set to Drained. • For the Interfaces, in the Strength box, select the Manual radio button. Enter a value of 0.5 for the parameter R (for all soil layers). inter • Refine the global coarseness to “Medium”. • The ground water level in the area is generally close to ground level. Current measurements from standpipes and piezometers indicate the general water level is between elevation 100.5m RL and 101m RL. BH K2 BH E2 BH K1 BH E1 Page 1 of 227308ENG Computing Laboratory Assignment #2 The excavation stages are provided in Tables 1 and 2. Table 1: Excavation stages of E-E Section Depth of Excavation Level Strut Level Stages Excavation (m RL) (m RL) (m) 1 100.5 101.0 2.0 2 97.3 97.8 5.2 3 93.5 94.0 9.0 4 89.9 90.4 12.6 5 86.35 86.85 16.15 6 84.38 – 18.12 Table 2: Excavation stages of K-K Section…

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