Analysis Method for Ground Settlement Induced by Ultra-Deep Excavation in Hangzhou Soft Clay Considering Time-Space Effect

doi:10.16183/j.cnki.jsjtu.2023.199

Abstract

Abstract:

The PLAXIS 3D software and the soft soil creep model were used to establish a 3D numerical model of the B2 excavation within an ultra-deep excavation group, allowing for analysis of the effects of time-space factors on ground settlements. Then, the complementary error function and trilinear model were introduced. After that, the numerical results were used to correct the complementary error function. Finally, a rapid approach was proposed for predicting ground settlements while accounting for the temporal and spatial influences. The results indicate that soft soil creep not only causes additional wall deflections resulting in soil settlements but also induces soil settlements independent of these deflections. The impact of ignoring soft soil creep on prediction of ground settlement is not weaker than that of wall deflections. The excavation area determines the construction duration when the excavation depth and rate are identical, impacting ground settlements induced by soft soil creep.

Key words: soft clay, ultra-deep excavation, ground settlement, time-space effect, complementary error function

CLC Number:

TU478

XIONG Yifan, YING Hongwei, ZHANG Jinhong, CHENG Kang, LI Binghe. Analysis Method for Ground Settlement Induced by Ultra-Deep Excavation in Hangzhou Soft Clay Considering Time-Space Effect[J]. Journal of Shanghai Jiao Tong University, 2025, 59(1): 48-59.

Figures/Tables 17

Fig.1

Tab.1

Tab.2

Soil calculation parameters

本构模型	土层	l/m	γ/(kN·m^-3)	c'/kPa	φ'/(°)	λ^*	κ^*	μ^*
SSC	②软黏土	20.4	17.8	5	25	0.06	0.006	0.002 5
						$E 50 r e f$ /MPa	$E o e d r e f$ /MPa	$E u r r e f$ /MPa	$G 0 r e f$ /MPa	γ_0.7	m
HS-Small	①填土	6.5	17.0	5	28	4.5	3.8	22.7	79.4	0.000 2	0.80
	③粉质黏土	13.5	19.3	25	30	6.5	5.4	32.4	113.4	0.000 2	0.80
	加固土	23.7	19.3	60	25	15.0	15.0	85.0	170.0	0.002 0	0.12
						E/MPa	υ
MC	④圆砾	2.2	19.0	1	18	36	0.30
	⑤强风化砂岩	6.9	21.0	30	20	90	0.25
	⑥中风化砂岩	20.5	22.0	50	30	3 600	0.25

Tab.2

Fig.2

Fig.3

Fig.4

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Fig.15

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工况	施工内容	时长/d
1	开挖至-8.3 m,第2道支撑形成强度	30
2	开挖至-13.8 m,第3道支撑形成强度	37
3	开挖至-17.9 m,第4道支撑形成强度	43
4	开挖至-22.1 m,第5道支撑形成强度	32
5	开挖至-26.3 m,第6道支撑形成强度	31
6	开挖至-30.2 m,底板形成强度	57