Analysis and Research on Building Foundation Selection in Soft Soil

Area of Heqing, Yunnan Province

Fengfeng Ding

1a

and Jinyong Jiao

2,* b

1

College of Resources and Environment, Yunnan Vocational College of Land and Resources,

Yunnan, Kunming, 652501, China

2

China Power Construction Group Kunming Survey Design and Research Institute Co., LTD,

Yunnan Kunming, 650000, China

*

Keywords: Engineering Geological Conditions, The Soft Soil Foundation, Foundation Selection.

Abstract: This paper analyzes the engineering geological conditions of a building site in Heqing, Yunnan Province,

evaluates the seismic effect of the site and the uniformity of the foundation soil, and finally analyzes the

foundation selection of the soft soil foundation site.

a

https://orcid.org/0009-0008-9483-487X

b

https://orcid.org/0009-0005-0300-129X

1 INTRODUCTION

With its unique geographical environment and

geological conditions, Heqing area of Yunnan

Province brings many challenges to the foundation

selection of construction projects. Among them, the

selection of building foundation in soft land area is

particularly critical, which is directly related to the

safety, stability and economy of buildings. The

purpose of this study is to analyze the geological and

hydrological conditions of the soft soil area of

Heqing, Yunnan Province, and to discuss the

selection scheme of building foundation suitable for

this area by combining the practical engineering

experience and the existing research results.

2 PROJECT OVERVIEW

The proposed site is located in Yunhe Town, Heqing

County. Heqing County is located in the northwest

of Yunnan Province, at the southern end of

Hengduan Mountain Range in western Yunnan, east

of Yunling Mountain Range and north end of Dali

Bai Autonomous Prefecture. Its geographical

coordinates are 100°01 '-100°29' east longitude and

25°57'-26°42' north latitude. Yunhe Town is located

in the center of Heqing County, the terrain is high in

the west and low in the east. It is 129 kilometers to

the south from Dali and 42 kilometers to the north

from Lijiang. The proposed site is close to Yunxin

Road and North Ring Road, and the traffic is very

convenient. The location of the proposed site is

shown in Figure 1.

The proposed project consists of 11 buildings

with 7 floors above ground and one underground

floor. The basement is distributed in the whole site,

and the basement storey is 4.7m.

Figure 1: Location of the proposed site.

Ding, F., Jiao and J.

Analysis and Research on Building Foundation Selection in Soft Soil Area of Heqing, Yunnan Province.

DOI: 10.5220/0013573200004671

In Proceedings of the 7th International Conference on Environmental Science and Civil Engineering (ICESCE 2024), pages 45-53

ISBN: 978-989-758-764-1; ISSN: 3051-701X

45

3 REGIONAL GEOLOGICAL

CONDITIONS

3.1 Topography

The proposed site is located in Yunhe Town, Heqing

County, lake accumulation of highland mountain

intermittent basin west, east of Yunxin Road, south

of the North ring road, south of Huashu Village. The

site was originally cultivated land with flat and open

terrain. The site is a quaternary lacustrine

sedimentary landform.

3.2 Regional Structure and Neotectonic

Movement

Regionally, the site is located in the sag area of

Lijiang platform margin in Yanyuan Basin of

Yangtze platform, southwest of Lijiang fold belt.

Heqinging-xinmincun fault and Heqinging-Junying

fault are the main active faults of the site and its

adjacent areas. It can be seen that the structure of the

site is complex, faults are developed and neotectonic

activities are frequent. Heqing is an intermittent

depression basin in the plateau mountains.

3.3 Neotectonic Movement and

Earthquake

The neotectonic movement in the area where the

proposed site is located mainly shows that the

Diancang Mountain has risen strongly and the

mountain has risen strongly since the Tertiary period;

Along the main fault, there are more than ten

Cenozoic faulted basins at different heights. Folds

and fractures can be seen in the Pleistocene deposits.

The region is affected by the intermittent and

different movement of the modern crust, which

makes the ground stress complex, faults developed

and earthquakes relatively frequent.

4 SITE ENGINEERING

GEOLOGICAL CONDITIONS

4.1 Formation Lithology

The foundation soil of the site is composed of silty

clay, silt and clay of quaternary lacustrine

sedimentary origin, except the surface of the site is

filled and cultivated soil, which is divided from top

to bottom as follows:

① Layer, cultivated soil: brown gray, slightly wet -

wet, plastic state, underconsolidation, high

compressibility, mainly composed of silty clay

with a few gravel particles and a large number

of plant roots. The buried depth is 0.00-1.50m,

the layer thickness is 0.40-0.60m, and the top

elevation is between 2199.03-2201.68m.

② 1 layer, mixed fill: brown gray, brown, slightly

wet, loose state, mainly composed of silty clay

mixed gravel particles, underconsolidation,

buried depth 0.00m, layer thickness 0.50 ~

1.90m, the top elevation between 2200.53 ~

2201.98m. The side of the distribution site near

the North Ring Road is backfilled during th

e

construction of the North Ring road. The

backfilling period is greater than 3 years, and

the backfill is not rolled by

layers.

③ Layer, silty clay: brown, brown yellow, wet,

plastic state mainly, local hard plastic state,

medium compressibility, section rough or

slightly shiny, no shaking reaction, medium dry

strength, medium toughness, local even gravel

.

The

buried depth is 0.40-2.10m, the laye

r

thickness is 0.70-3.00 m, and the top elevation is

between 2198.53-2201.08m. It's distributed

throughout the field.

④ Layer, silt: gray, brown gray, wet, soft plastic -

fluid plastic state, high compressibility. The

section surface is slightly shiny, no shaking

reaction, medium dry strength, poor toughne

ss,

a little organic matter and a small amount of

shell residue inside. The buried depth is

1.20-4.90m, the layer thickness is 2.70-7.50m,

and the top elevation is b

etween

2196.18-2199.88m. It's distributed throughout

the site.

⑤ Layer, clay: gray, brown gray, wet, soft plastic

state, high compressibility. The section

surface

is slightly shiny, no shaking reaction, medium

dry strength, medium toughness, and partia

l

shell residue. The buried depth is 6.30-9.00m,

and the top elevation is between

21

91.00-2194.52m, which is distributed in th

e

whole site.

⑥ Layer, clay: gray, blue-gray, wet, soft plastic

state, local plastic state, high compressibility.

Section is slightly shiny, medium dry strength,

medium toughness, no shaking reaction. The

buried depth is 19.90-21.20m, and the top

elevation is between 2178.23-2180.78m.

Based on the comprehensive analysis of the

indoor geotechnical test and in-situ test, and

combined with the calculation of relevant norms, the

physical and mechanical index parameters of each

soil layer are obtained comprehensively (see Table 1

for details).

ICESCE 2024 - The International Conference on Environmental Science and Civil Engineering

46

Table 1: Physical and mechanical parameters of each soil layer.

Floor

numbe

r

Geotechnical

designation

natural

densityρ

（g/cm

3

）

Quick

shear

Set fast

Triaxial

（CU）

Compressio

n test mean

Double bridge

static test

standard value

Precast pile

Bearing

capacity

characteristi

c value

Cq

(kPa

)

Φq

(度

)

Ccq

(kPa

)

Φc

q

(度

)

Ccu

(kPa

)

Φc

u

(度

)

Es

1-2

(MPa

)

Es

2-3

(MPa

)

q

c

（Mpa）

Fs

（Kpa）

Standard value

of limit side

resistanceQ

sik

(kP

a)

Standard

value of

ultimate

end

resistanc

e

Q

pk

(kPa)

f

ak

(kPa)

①

Cultivated

soil

1.75* 15* 4* 3.0* 0.5 22.9

①

1

Miscellaneo

us

fill

1.70* 14* 5* 3.5*

②

Silty clay 1.78 35.0 7.4 38.5 8.9 5.43 6.84 0.77 32.7 65 130

③

muck 1.51 16.6 4.6 16.3 4.8 1.78 2.35 0.51 13.6 15 40

④

clay 1.56 17.9 4.7 32.0 6.7 2.80 3.35 0.74 15.6 25 1000 85

⑤

clay 1.55 16.8 4.7 26.8 6.6 2.94 3.67 0.84 17.9 27 1100 95

Note: Values marked with * are experience values

4.2 Bad Geological Effects and Special

Soil

(1) Bad geological effects

The proposed site is located on the west side of

Heqing Basin with open and flat terrain. According

to the on-site engineering geological survey, no

adverse geological effects and geological disasters

such as karst, collapse, debris flow and landslide

have been found in and around the proposed site.

(2) Special soil

①

Filling

Th

e filling soil in the site is formed by backfilling

during the construction of the North Ring Road and

has a large distribution range. The filling soil is only

distributed near the North Ring Road in the whole

site. The composition of the filling soil is mainly

composed of silty clay mixed gravel, partial mixed

gravel and block stone, and the backfilling period is

more than 3 years. The thickness of the layer is 0.50

~ 1.90m, which is not suitable for use as the

foundation bearing layer, and it is recommended to

remove it when the foundation pit is excavated.

②

cu

ltivated so

il

It

is mainly composed of clay soil mixed plant roots

and a few gravel particles, which is in a plastic state

and underconsolidated. This part of cultivated soil

has been soaked by farmland irrigation water all the

year round, and its property is poor. The layer

thickness is 0.40-0.60m. It is recommended to

remove all cultivated soil during foundation pit

excavation.

③

soft soil layer

I

n the site, the ③ layer of silt, ④ layer of clay and

⑤ layer of clay are in the soft-plastic and

fluid-plastic state, with high compressibility, low

bearing capacity, poor physical and mechanical

properties, and large layer thickness. It should not be

used as natural foundation. It is suggested that the

foundation should be strengthened or the building

structure should be strengthened in the project

construction, and the influence of soft soil subsidence

should be considered in the design.

4.3 Site Hydrogeological Conditions

The stable water level in the inland of the site ranges

from 0.37 to 1.93m, the water level elevation ranges

from 2198.10 to 2201.20m, and the height difference

is 3.10m. According to the characteristics of

foundation soil, ① cultivated soil and ①1 layer of

mixed fill have certain permeability, and the other

viscous soil layers are weak permeability.

Groundwater mainly exists in the silty clay (②

layer), silt (③ layer), clay (④ layer) and clay (⑤

layer) with the change of climate, but the amplitude

is small. Groundwater is fed by atmospheric

precipitation, surface water and Caohai seepage, and

discharged by atmospheric evaporation and

infiltration into Bonan River, and then deposited in

Caohai. The exploration and construction period is

in the rainy season, and the water level is greatly

affected by the season. According to the

hydrogeological data collected by our institute in

Analysis and Research on Building Foundation Selection in Soft Soil Area of Heqing, Yunnan Province

47

Table 2: Groundwater corrosivity evaluation table.

Corrosive

medium

The content in water

(mg/l)

Climate influencing facto

r

Osmotic facto

r

Corrosion

grade of

concrete

structure by

water

Corrosion

grade of steel

bar in

concrete

structure by

water

Environmental

category

Corrosion

grade

ZK1 Zk25

Ca

2+

44.89 38.48

Ⅱ weak

weak

Mg

2+

11.67 36.95

K

+

+Na

+

151.91 149.37

SO

4

2-

40.38 28.13

PH 7.00 7.01

A weak

侵蚀性 CO

2

4.40 8.80

HCO

3

-

（mol/l） 6.80 7.00

Cl

-

14.18 21.27

Comprehensive

evaluation of

corrosiveness

level

weak

Groundwater has slight corrosiveness to concrete structures in Class II site

environments and steel structures in reinforced concrete structures

this

area, 0.0-0.37m below the surface is the highest

water level in this area in recent years, and the

variation range of the highest groundwater level is

within 1m. According to the site topography,

hydrogeological conditions and the final leveling of

the elevation, it is suggested that the anti-floating

design water level should be 2201.50m, and

anti-floating treatment measures should be carried

out in accordance with relevant norms.

4.4 Analysis of Soil and Water

Corrosion

According to the relevant provisions of the Code for

Geotechnical Engineering Investigation (8th edition

of 2009) (GB50021-2001, 2009), groundwater is

slightly corrosive to concrete structures. It is slightly

corrosive to reinforcement in concrete structure.

Specific evaluation is shown in the table below in

Table 2.

According to the corrosion analysis of soil

samples taken from drilling, the PH values are 7.01

and 7.04 respectively, belonging to weakly alkaline

soil, and the site environment type is Class II.

According to the Code for Geotechnical Engineering

Investigation (GB50021-2001) (2009 edition), it is

comprehensively determined that the foundation soil

of the site is slightly corrosive to the concrete in

Class II site environment and the reinforced concrete

and steel structure in the concrete (see Table 3 for

details).

ICESCE 2024 - The International Conference on Environmental Science and Civil Engineering

48

Table 3: Soil corrosivity evaluation table.

Corrosive

medium

The content in

the soil(mg/kg)

Climate influencing

facto

r

Osmotic factor

Corrosio

n grade

of soil to

concrete

structure

Corrosion

grade of soil

to

reinforceme

nt in

concrete

structure

Environment

al category

Corrosio

n grade

Penetratio

n category

Corrosion

grade

Zk2-6 Zk37-2

Ⅱ weak A weak weak weak

Ca

2+

19.24 17.64

Mg

2+

4.86 17.50

Soluble salt

（%）

0.0216 0.0283

SO

4

2-

29.15 26.80

PH 7.01 7.04

HCO

3

-

170.86 219.67

Cl

-

21.27 28.36

Electrical

resistivity

(

Ω.m

)

60.00 60.00

Comprehensi

ve evaluation

of corrosion

grade

The soil is slightly corrosive to the concrete structure and the reinforcement in the reinforced concrete

structure.

5 ENGINEERING GEOLOGICAL

EVALUATION

5.1 Evaluation of Seismic Effect

1．seismic fortification standards

According to the 2016 edition of the national

seismic fortification intensity Code for Seismic

Design of Buildings (GB50011-2010), the seismic

fortification intensity of Heqing County is 8 degrees,

the design basic earthquake acceleration is 0.30g,

and the design earthquake is divided into the third

group. The characteristic period of the site is 0.65s.

The seismic facilities shall meet the requirements of

the local seismic fortification intensity.

2.

Venue category

The proposed site is located in Yunhe Town,

Heqing County. The site is generally Huxiang

sedimentary landform of the whole quaternary

system. The seismic fortification category of this

project is standard fortification category (Class C).

According to the wave velocity report of drilling

holes ZK17 and ZK27 under the surface of the site

at a depth of 0-20m, the equivalent shear wave

velocity is 158m/s and 159m/s respectively, and the

thickness of the covering layer of the site is greater

than 50m. According to articles 4.1.3 and 4.1.6 of

the Code for Seismic Design of Buildings

(GB50011-2010) (2016 edition), the site soil type is

determined to be medium soft soil and the

construction site category is Class III.

soft soil earthquake subsidence and sand

liquefaction

There is no distribution of saturated sand and silt

with a thickness of more than 0.5m in the depth of

20.0m in the proposed site, and there is no problem

of liquefaction of saturated sand.

According to Article 6.3.4 of the Code for

Geotechnical Engineering Investigation in Soft Soil

Areas (JGJ83-2011) (J1186-2011), the seismic

fortification intensity of the proposed site is 8

degrees, there is silt in the site, the equivalent shear

wave velocity is less than 140m/s, and the bearing

capacity is less than 100Kpa. The earthquake

Analysis and Research on Building Foundation Selection in Soft Soil Area of Heqing, Yunnan Province

49

subsidence value of the building is estimated at

150mm.

4.

Seismic section division of building site

The topography of the site is large, the maximum

height difference of the site is greater than 5.0m, the

terrain is relatively open, there is no bad geological

phenomena such as collapse, landslide, debris flow

in the drilling range, but there is soft soil in the

foundation soil, according to the Code for Seismic

Design of Buildings (GB50011-2010) (2016 edition)

4.1.1 division standard, the site is divided into

adverse seismic areas.

5.2 Site Stability and Suitability

Evaluation

The overall terrain of the site is basically flat, and

the terrain and geomorphology are complete. There

are no undesirable geological effects such as

Holocene active faults, slippage and debris flow

within the drilling range. There is weak soil layer in

the site, which can be used as the construction land

of the project after the reinforcement treatment of

the foundation or strengthening of the building

structure.

5.3 Evaluation of Foundation Soil

The foundation soil of the site is composed of silty

clay, silt and clay of Quaternary Huxiang

sedimentary origin, except the surface of the site is

filled and cultivated soil, which is divided from top

to bottom as follows:

① Layer, cultivated soil: brown gray, sligh

tly wet -

wet,

plastic state, underconsolidation, h

igh

co

mpressibility, mainly composed of silty c

lay

with

a few gravel particles and a large number

of plant roots. The physical and mechan

ical

p

roperties of this layer are poor, so it

is

recommen

ded to remove all the soil

during

co

nstruction.

② 1 layer, mixed fill soil: brown gray,

brown,

sl

ightly wet, loose state, mainly composed of

silty clay mixed gravel p

articles,

un

derconsolidated, distributed in the site near

the North ring road side, for the construction of

the North ring road backfill, backfill more tha

n

3

years, backfill has not been rolled by laye

rs.

The

soil of this layer is only produced in a lo

cal

sect

ion, the uniformity is poor, and it is

recommended to remove all the so

il.

③ Lay

er, silty clay: brown, brown yellow, wet

,

p

lastic state, local hard plastic, medium

compressibility, section rough or slightly shiny,

no shaking reaction, medium dry strength,

medium toughness, local even gravel, the whole

field are distributed. The soil of this layer has

good physical and mechanical properties, but

the layer thickness is uneven, and some parts

have been cleared after the excavation of

foundation pit, so it is not suitable for use as the

foundation supporting layer of the proposed

building.

④ Layer, silt: gray, brown gray, wet, soft plastic -

fluid plastic state, high compressibility. Th

e

sect

ion surface is slightly shiny, no shaking

reaction, medium dry strength, poor tough

ness,

a

little organic matter and a small amount of

shell residue inside. The physical a

nd

mecha

nical properties of this layer of soil are

poor, and it is strictly prohibited to use as

a

n

atural foundation.

⑤ Layer, clay: gray, brown gray, wet, soft p

lastic

state,

high compressibility. The section

surface

is

slightly shiny, no shaking reaction, mediu

m

dr

y strength, medium toughness, and partial

shell residue. The physical and mechanical

properties of this layer are better than that

of

th

e third layer, and it can be used as th

e

su

pporting layer of the pile end of the propo

sed

co

nstruction.

⑥ Layer, clay: gray, blue-gray, wet, soft pl

astic

state,

local plastic state, high compressibility

.

Sectio

n is slightly shiny, medium dry strength,

medium toughness, no shaking reaction. It

can

be

used as the supporting layer of pile end or

the underlying layer of the proposed

construction.

5.4 Evaluation of Foundation

Uniformity

There is little difference in the composition,

thickness, spatial distribution and physical and

mechanical properties of each soil layer of the

foundation, but the foundation soil of the site is

medium-high compressibility foundation, the

complexity of the site foundation is second class,

and the ratio of the maximum and minimum

compressive modulus of the layer silt is greater than

1.3. According to the current "Geotechnical

Investigation Standard for High-rise Building

Concrete" (JGJ/T72-2017 Article 8.2), it is

determined that the site is an uneven foundation.

ICESCE 2024 - The International Conference on Environmental Science and Civil Engineering

50

6 TYPE SELECTION DESIGN OF

FOUNDATION

According to the characteristics of the proposed

building and the engineering geological conditions

of the site, it is not appropriate to use natural

foundation in this project, and it is recommended to

use pile foundation or composite foundation + raft

foundation. The bearing layer of pile foundation and

composite foundation should choose ④ layers of

clay and ⑤ layers of clay. The basic form is

suggested as follows:

(1) Composite foundation + raft: The solution of

cored stirred pile composite foundation + raft

foundation can be adopted for the foundation

form of Building 1-11, Building 1 and pure

basement. The effective pile length is about

15.00m, pile diameter is 0.50m, and ④ layer

clay is used as the pile end bearing layer. The

bearing capacity characteristic value of single

pile is estimated to be 280KN, the pile spacing

is 1.5m, the rectangular pile layout is m=0.087.

The bearing capacity characteristic value of

composite foundation is estimated to be

140-160KPa. The foundation soil of the

proposed site is mainly silty clay, silt and clay

with normal consolidation, and its natural water

content is higher than 30%. Silt and clay

plasticity index is greater than 25, according to

local engineering experience, the site can be

used as a core mixing pile foundation treatment.

(2) Pile foundation: For this project, static pressure

prefabricated pipe pile and prestressed concrete

pipe pile (PC) can be used. The effective pile

length is about 20.00m, outer diameter is 0.50m,

wall thickness is 0.10m, concrete strength is

C60, and ⑤ layer clay is used as the pile end

bearing layer. The estimated bearing capacity

limit value of a single pile is about 1000KN in

Table 4 and Table 5.

Table 4: calculation results of ultimate bearing capacity of single core-mixed pile.

Soil layer

numbering

Soil layer name

Deep mixing pile

Characteristic value of soil side resistance

q

s

(kpa)

Characteristic value of bearing

capacity of pile end soil

q

p

(kpa)

Core pile segment Coreless pile section

③

muck

8 8

④

clay

13 13

85

Estimated

hole number

Pile end bearing layer

Pile dimension

d×L（m）

Core length

Standard value of vertical

ultimate bearing capacity of

single pile Q

uk

(kN)

ZK2

④clay

0.5×15.0 15 283.90

ZK25

④clay

0.5×15.0 15 284.75

Table 5: Estimation results of standard value of vertical ultimate bearing capacity (Quk) of single pile.

unit Pile shape

Hole

number

Pile

diameter(mm)

Pile

length(m)

Ultimate bearing

capacity of single

pile（kN）

Supporting

course

Building

1-11 and the

next one

Hydrostatic

prefabricated

pipe pile

Zk2 Φ500 20 1060.40 ⑤

Zk25 Φ500 20 1060.00 ⑤

Note: 1. The bearing capacity of single pile is estimated according to the table above, and the test pile shall prevail

according to the code requirements;

Analysis and Research on Building Foundation Selection in Soft Soil Area of Heqing, Yunnan Province

51

7 CONCLUSIONS AND

SUGGESTIONS

7.1 Conclusion

(1) The proposed site is located in Yunhe Town,

Heqing County, with silty clay and clay layer of

Quaternary Holocene lacustrine sedimentary

origin in addition to the soil filling and tillage

on the surface.

(2) The proposed site has complete topography,

open and flat terrain, small elevation difference,

no Holocene active faults, slippage, debris flow

and other adverse geological effects in the site,

there is soft soil in the site, divided into adverse

seismic areas, there is soft soil in the site, and it

can be used as the construction land of the

project after the foundation reinforcement

treatment or strengthening of building structure

measures.

(3) The seismic fortification intensity of the site is

8 degrees, the design basic seismic acceleration

is 0.30g, and the design earthquake group is the

third group. The site soil type is medium soft

soil, the construction site category is Class III,

and the site is an unfavorable seismic area.

(4) The seismogenic fault zones F166, F167 and

F168 pass through about 4.50Km, 3.00Km and

2.30Km away from the proposed site.

(5) There is little difference in the composition,

thickness, spatial distribution and physical and

mechanical properties of each soil layer of the

foundation, but the foundation soil of the site is

medium-high compressibility foundation, and

the complexity of the site foundation is second

class. According to the uniformity evaluation

standard of the current Geotechnical

Investigation Standard for High-rise Building

Concrete (JGJ/T72-2017), the foundation of the

site is an uneven foundation.

(6) According to the soil analysis results, it is

determined that the foundation soil of the site is

slightly corrosive to the concrete in the Class II

site environment, the reinforced concrete

structure in the concrete and the steel structure.

7.2 Suggestions

(1) The upper part of the ground water in the site is

pore diving, and the main aquifer is silty clay

and clay layer. According to the water quality

analysis results of the two groups of water

samples taken in the site, the ground water is

slightly corrosive to the concrete and the

reinforced concrete structure in the concrete

environment of the class II site. It is suggested

that the design water level of anti-floating

should be 2201.50m, and anti-floating measures

should be carried out according to relevant

specifications.

(2) The foundation type is suggested to adopt the

foundation form of pile foundation or

core-mixed pile composite foundation + raft.

The construction of core-mixed pile or pile

foundation should pay attention to the

protection of the soil at the bottom of the pit

before and after excavation to avoid disturbance

as far as possible.

(3) The foundation pit support can be carried out in

the form of moderate slope slope + steel sheet

pile or double drainage soil mixing pile

according to the actual situation. When the

foundation pit is excavated, the water inflow of

the foundation pit is large, and there should be

better water separation and precipitation

measures.

(4) The foundation pit of the proposed project is

mostly located in the soft soil layer, and near

the building, the foundation pit project is a

dangerous project, the construction unit, the

design unit, the construction unit, the

supervision unit should strictly implement the

relevant provisions of the "Safety Management

Regulations of dangerous sub-projects" ( 2011,

Ministry of Housing and Construction Order

No. 37) during the design and construction

process of the foundation pit.

(5) Because there is a thick layer of soft soil in the

site, it is suggested that the uniformity and

integrity of the building structure should be

strengthened in the design to avoid uneven

settlement.

(6) In the foundation construction process, the

foundation soil should be avoided as far as

possible by water immersion or exposure, and

the construction should ensure the drying of the

foundation pit, which is conducive to the

construction. If abnormal phenomenon is found,

please inform the design and investigation

personnel to conduct on-site inspection of the

tank, and study and solve the possible

problems.

(7) After the foundation construction is completed,

settlement observation points should be buried

in time for settlement observation.

ICESCE 2024 - The International Conference on Environmental Science and Civil Engineering

52

REFERENCES

GB50021-2001, 2009. Code for Geotechnical

Investigation, 8

th

edition.

GB50011-2010, Code for Seismic Design of Buildings,

2016 edition.

JGJ83-2011, Code for Geotechnical Investigation in Soft

Soil Areas.

Regulations on the Safety Management of Hazardous

Sub-Projects (Order No. 37 of the Ministry of Housing

and Urban-Rural Development).

Analysis and Research on Building Foundation Selection in Soft Soil Area of Heqing, Yunnan Province

53