Question

Question 2 (a) A 4 m high masonry retaining wall of width 1.8 is built to retain a 2-layered soil profile shown in Figure 2 on Bonham Road on Hong Kong Island with a surface sucharge of 20 kPa. The soil parameters are given in the figure. During raining season, ground water rises to interface between Soil 1 and Soil 2. Assume that there is no friction between the vertical wall and the soils. The sliding friction angle between the base and the soil is 25°. The unit weight of stone is 23.5 kN/m3 (i) Plot the effective earth pressure and water pressure the retaining wall at active failure (ii) Taking moment at Point A, find the total thrust acting on the wall. (ii) Find the maximum and the minimum base pressures on the wall (iv) Find the factor of safety against sliding (8 marks) (3 marks) (2 marks) (2 marks) Surface surcharge 2 kPa Soil 1 ?.-280 y-17kN/m3 W.T. c-6 kPa ?,-31° 2mSoil 2 Road gure 2A (b) On July 22, 2015, a Chinese Banyan tree of over 16 m fell down from a masonry wall on Bonham Road, injured a 54 year old lady. On August 7, Highways Department removed four healthy Banyan trees on the same masonry wall, and caused some protests from environmental group. In this part, you are asked to check the stability of the wall in Part (a) again if the Banvan tree on Bonham Road were now on this wall

Answer 1

a) p _ a _ a = K _ a _ 1 times q = 0 . 36 times 2 = 0 . 72 k P a k a _ 1 = 0 . 36 c =) k P a phi = 28 degree r = 17 k N/m ^3 P _ a _ b t = K _ a _ 1 times equivalent sur change - D . 36 X [2 + 17 times 2] = 12 . 96 k P a P _ a _ b _ b = K a _ 2 times equivalent surcharge - 2 C squareroot K a _ 2 = 0 . 32 times 36 - 2 times 6 squareroot 0 . 32 = 4 . 73 k P a P _ a _ c = 0 . 32 times [2 times 17 + 2 + [20 - 10] times 2] - 2 times 6 squareroot 0 . 32 = 11 . 13 k P a Total Active force = [0 . 72 + 12 . 96 times 2 + 4 . 73 + 11 . 13/2 times 2] = 13 . 36 + 15 . 86 = 29 . 22 K N/m \r\n taking moment @ A = 13 . 38 times ((2 a + b)/3 (a + b) times h + 2] + 15 . 86 [(2 a + b)/3 (a + b) times h]
please provide then additional details weight of tree, that counts as additional surcharge on the wall.Provide in the comment section.Tough it wont hamper the stability of the wall,as it will add in the weight of the wall.

please provide the details ,i will solve in the comment section