必威体育精装版基坑降水引起的相邻建筑物直接经济损失预测研究.ppt

Presume ψ comply with the standard normal distribution * ， Take ψ as 0.29, then the settlement calculation error No. Modified calculation settlement (mm) S=ψS1 Monitored settlement (mm) error 1 26.49 27 1.88% 2 25.82 24.9 3.69% 3 29.25 33.6 2.94% 4 33.06 33.8 2.19% 5 36.42 35.5 2.60% 6 34.78 29.7 1.71% 7 35.41 34.8 1.77% 8 35.04 36.3 3.47% 9 36.40 37.5 2.94% * 4 Building loss results from ground settlement 4.1 Main assumption Only direct loss is taken into consideration * * 4.2 Algorithm The ground near the construction pit is divided into a series of donuts. (2) Equation (3.1) is employed to determine the settlement of each donut (the middle line of each donut is taken as target). (3) Settlement gradient between bordered donuts is obtained. (4) Economic loss rate vs. ground settlement gradient is set up. (5) A certain scope around the pit is chosen, all buildings loss in the scope is accumulated. * 4.3 Donuts 4.3.1 Usually, the geometric center of pit is set as the center of all donuts 4.3.2 The affecting scope (taken as 5Sw, Sw-the depth of water table falling beneath the pit ground ) is divided into a series of donuts with the increment as 0.2Sw * 4.4 ground settlement gradient No. G1 G2 G3 G4 G5 G6 G7 G8 Gi 0.32 0.3. 0.27 0.25 0.23 0.22 0.20 0.19 No. G9 G10 G11 G12 G13 G14 G15 G16 Gi 0.18 0.17 0.21 0.22 0.20 0.19 0.18 0.17 No. G17 G18 G19 G20 G21 G22 G23 G24 Gi 0.16 0.15 0.14 0.22 0.24 0.25 0.22 0.18 * Ground settlement gradient in the Case Project * Generally, the further the distance from the pit edge is, the smaller the ground settlement gradient is. * However, if a donut runs across over the soil surface which is below and above the water table before and after pumping, the gradient here is likely to leap significantly. * For the sake of security, 1‰ is taken as the threshold of ground settlement gradient. 4.5 The threshold of difference settlement building * 4.6 The relationship between ground settlement gradient (G) and economic los