Deformation Characteristics of Divided Excavation Groups in Soft Soil

doi:10.16183/j.cnki.jsjtu.2018.02.002

Abstract

Abstract:

With the fast increasing of urban underground space developments in China, a new kind of underground construction, deep excavation group, has been developed, which means a group of adjacent / related excavations constructed at the same time or the super-large excavation divided into small pits. The excavation groups are divided into three kinds according to the special relation of different parts, including the divided, jointed, and adjacent ones. Based on the project of Shanghai International Aviation Centre excavation group, the deformation characteristics of divided excavation groups which is one of the typical types, was studied by statistical analysis method of field measured data in the research. The deformation of partition walls, lateral displacement of underground walls and ground settlement during construction were studied in detail and their differences in different location were analyzed. The differences between traditional excavation and the excavation group were also compared in the research. Research shows that the deformation of partition walls increases first and then decreases, and it is affected by the nearby excavating. In the partition zone, the average maximum lateral displacement of the undergroud wall is 0.16%H, which is smaller than the average of 0.60%H in Shanghai and the average maximum ground settlement is 0.14% H, which is also smaller than the average of 0.40% H in Shanghai. The study provides a very strong reference value for other excavation group construction and protection of sensitive buildings.

Key words: excavation group, partition wall deformation, underground wall deformation, ground settlement

CLC Number:

TU470

FAN Fan, ZHANG Hongbing, WANG Jianhua, CHEN Jinjian, ZHANG Yipeng. Deformation Characteristics of Divided Excavation Groups in Soft Soil[J]. Journal of Shanghai Jiao Tong University, 2018, 52(2): 133-140.

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层号	土层名称	层厚／m	w／％	γ／（kN·m^-3）	e	C_c	p_s／MPa	E／MPa	ν	C／kPa	φ／（°）	ψ／（°）
①	填土	1.5～6.5	-	-	-	-	-	30.0	0.30	-	-	-
②	粉质粘土	0.5～2.0	27.4	18.0	0.94	0.168	0.78	30.0	0.30	12	31.5	2
③	淤泥质粉质粘土	2.5～6.9	34.7	17.2	1.18	0.241	0.84	22.5	0.35	12	29.8	2
④	淤泥质粘土	8.4～10.0	48.6	17.0	1.43	0.383	0.55	18.0	0.35	9	18.9	2
⑤	粉质粘土	5.0～8.1	34.2	18.2	1.03	0.244	1.01	45.0	0.35	12	28.3	2
⑥	粉质粘土	2.4～4.8	22.5	19.9	0.71	0.131	2.34	60.0	0.35	15	30.1	2
⑦₁	粉质粘土	9.4～13.1	29.9	18.9	0.84	0.101	11.44	70.0	0.30	21	29.8	2
⑦₂	粉砂	23.0～27.5	27.1	19.1	0.76	0.125	23.75	80.0	0.30	25	34.0	2

分区	开挖深度／m	地下室层数	面积／m²	支撑类型及标高
Z1	15.7	3	10 000	地面标高-1.000 m
Z2	?	?	11 000	第1道砼支撑-2.200 m
Z3	?	?	8 300	第2道砼支撑-7.800 m
?	?	?	?	第3道砼支撑-13.300 m
Z4	11.5	2	650	地面标高-1.000 m
Z5	?	?	543	第1道砼支撑-1.600 m
Z6	?	?	636	第2道钢支撑-4.900 m
Z7	?	?	574	第3道钢支撑-9.100 m

开挖基坑	起始时间	结束时间	持续时间／d
Z1	2014-03-15	2014-07-02	109
Z2	2014-10-20	2015-01-03	75
Z4	2014-11-30	2014-12-24	24
Z3	2015-04-17	2015-06-21	65
Z6	2015-06-11	2015-06-21	10
Z7	2015-09-17	2015-09-27	10

项目	类型	特点	测点
地下墙	A类	位于分隔带上的外墙	P26～P30，P32～P34 P36～P39，P41～P45
?	B类	位于分隔带上的隔墙	P11～P12，P22～P24
?	C类	分隔带外的隔墙	P07～P10，P18～P19
?	D类	分隔带外的外墙	P01～P06，P13～P17 P20～P21
坑后土体	E类	分隔带外侧，有分区	DB9～DB12
?	F类	无分隔带，有分区	DB4～DB8
?	G类	无分隔带，无分区	DB1～DB3

类型	（d_h／H）／％
类型	最大值	最小值	平均值
A类	0.39	0.02	0.16
B类	0.48	0.23	0.36
C类	1.04	0.35	0.69
D类	0.99	0.46	0.76