Please solve only part 5
Extracted text: The figure below shows a soil profile located at a site for a bridge construction. The profile consists of a layer of normally consolidated clay with thickness of 5.0 m laying over the bedrock and overlain by layer of sand with thickness of 5 m. The water table is observed to be at 2.0 m below the ground surface. A shallow foundation is designed to support the bridge pier at this site. The vertical load imposed on the foundation is Q = 850 kN. A 2.5 cm maximum settlement criterion was set for the foundation. A square footing with B=L=1.0 m was proposed to be constructed at the ground surface to sunnort the pier. 1. Assumi g that consolidation settlement is the onl ulement conouting to the tal settlenent of the fou dation, does the fo ation et uesignpeciie 2. To ens ire tha the fou dation meea sign conso date he clay yer. Thalickn ss the son is 1.0r and the dry ur weight of the soil is 17 N/m ification a layer of soil fill is y ll placed to pre- Ho much es the soil settle nder the f1. Updthe pil profile after fill is re noved at the end of corolidation. what the over-consolidati ratio of he clay layer in thew soil profile. 3. Hov much is the undation expect d settle in hec currenoll profile. 4. Afte the soil has n pre-conso dated, n table has ential to nne top of the clay layer. n change at this point. 5. Two alternative solution drop, a. Increasing the dimensions of the footing supporting the pier, to reduce the increase in stress nie uric reading indicated th the ground water e bridge pier settlement are proposed to mitigate the settlement that may occur due to the GWT due to the impose load from the pier. b. Replace a portion of the sand layer with geofoam' (p=11kg/m³) to reduce the overburden stress on the clay layer. As an engineer you need to decide on which is the most suitable approach to use and provide the supporting calculations. GL Gs=2.65 e=0.55 2.0 m Sand 3.0 m Gs=2.78 w=25% 5.0 m Cc=0.28 Clay Cs=0.056 Bedrock Note: using a spreadsheet to perform you calculations will help in editing and revising. Make sure the formulas used in your calculations are included in your solution.
Extracted text: Foundation B X L B 2 vertical to 2 vertical to I horizontal I horizontal Ao B+ z• FIGURE 8.9 2:1 method of finding stress increase under a foundation 9, × B × L (B + z) (L + z) Ao = (8.15)