Influence of Underpinning Pile Drilling Construction on the Bearing Behavior of Existing Loaded Foundation Piles: Case Study

Table 1

Physical and mechanical parameters of soil.

Layer number	Name of soil layer	t (m)	γ (kN/m^3)	c (kPa)	φ (°)	Es (MPa)	μ	N63.5 values
①2	Plain fill	5.1	17.7	9.0	12.0	20.0	0.35	55
③2	Mucky silty clay	11.5	17.9	11.2	19.5	17.5	0.35
③3	Mucky clay	6.0	17.1	19.6	7.0	15.0	0.35
④3	Clay	5.0	19.0	37.0	14.5	36.5	0.35
⑤	Silty clay	5.0	18.9	35.0	16.0	35.0	0.35
⑥1	Clay	5.4	18.0	52.5	9.0	22.5	0.35
⑧1	Highly weathered andesite	—	22.0	450	53	150.0	0.25

Note. t is the thickness of soil layer; γ is the unit weight of soil layer; c and φ are the cohesive and internal friction angle, respectively; E_s is the compression modulus; μ is Poisson’s ratio; N_63.5 values are the blow counts received from the heavy dynamic penetration test.