1. Preliminary design of foundation for HEPS
China Electronics Engineering Design Institute
Preliminary design of foundation for HEPS
XU ZhaoGang on behalf of
China Electronics Engineering Design Institute

2. Outline 1. Background and Motivation
2. Simulation of Settlement for HEPS
3. Test Program of Settlement for HEPS
4. Specification of Differential Settlement
5. Discussion

3. 1. Background and Motivation
Tolerances required for Light source facility is special.
Small beam size
The beam size provided by the 4GSR light source is very small.
High requirement of beam stability
The desired stability in beam position and angle around 10%, even 5%, of the beam size and divergence, resulting in high requirement of Settlement and Vibration.
Integrated state of the art design
Including the machine slab, the ground improvement, the magnet alignment and support system, the beam position monitor mechanics and instrumentation, the stabilizing feedback systems, among others.
The machine slab and the ground improvement belong to civil engineering, one of the key points related to this two part is the settlement. This presentation focuses on this topic

4. 1. Background and Motivation
The characteristics of settlement
Long term
Settlement is a long-term phenomenon. It seems that we have enough time to take measure to compensate the influences of settlement on the beam stability.
Unrecoverable
In general, once the settlement occurs, it will never recover. Once the construction is completed, it is difficult to control further settlement. Therefore, we should take enough measures to control settlement during construction to leave enough space for auxiliary equipment to compensate the influences of settlement on the beam stability.
In general, theoretical analysis guides the test program in situ. Here, we introduce the simulation of settlement for HEPS first.
With this in mind, we should take into account the settlement issue of light source facility seriously, theoretical analysis and test in situ.

5. 2. Simulation of Settlement for HEPS
Outline
2. Simulation of Settlement for HEPS
2.1. Material parameters of soil
2.2. Basic assumptions
2.3. Simulation program
2.4. Simulation results
2.5. Conclusions

6. 2. Simulation of Settlement for HEPS
2.1. Material parameters of soil
All the data is obtained form Geotechnical investigation report

7. Standard value of bearing capacity
2. Simulation of Settlement for HEPS
2.1. Material parameters of soil
Material
Natural bulk density
Cohesion
Frictional angle
Possion’s ratio
Young’s modulus
Shear wave velocity
Standard value of bearing capacity
kN/m³
kPa 1
MPa
m/s
Artificial fill
18.5 8 10 ——
—— 
172~193
Sandy pebble soil 1
21.0 38
0.20 45
182~193
Sandy pebble soil 2 42
76.5
295~402
300~450
Sandy pebble soil 3 43 99
402~553
450~500
Middle weathered
granodiorite
27.0
8460
40.44
4100
793~888
1500~2000
All the data is obtained form Geotechnical investigation report

8. 2. Simulation of Settlement for HEPS
2.2. Basic assumptions
Soils are isotropic, each soil layer is horizontal;
The constitutive equation of soil is either elastic or Mohr-Coulomb;
The simulation objects are experimental hall and storage ring, without considering the effects of other constructions on the simulation results of settlement；
The mutual displacement between slab and ground is not taken into account.

9. 2. Simulation of Settlement for HEPS
2.3. Simulation program
Thickness of Slab m
NO.
Experimental Hall
Ring Tunnel 1
0.8
1.2 2
1.0
1.4 3
1.6 4
1.8 5
2.0
Live load
kPa
NO.
Experimental Hall
Ring Tunnel A 10
10 and 30
at interval of 4.5 degree B
5 and 10
Ground improvement
NO.
Method G0
Natural soil G2
5-meter thick layer of cemented soil G3
10-meter thick layer of cemented soil

10. 2. Simulation of Settlement for HEPS
2.3. Simulation program
Cemented soil is constructed by compacting grouting.
The Young’s modulus of the cemented soil is designed to be MPa.
With this numerical we have calculate many cases, here parts of them are shown

11. 2. Simulation of Settlement for HEPS
2.4. Simulation results: natural soil
Fig.1 The maximum settlement and differential settlement after construction with natural soil according to different combinations of thickness of experimental hall and storage ring.

12. 2. Simulation of Settlement for HEPS
2.4. Simulation results: 5-meter thick layer of cemented soil
Fig.2 The maximum settlement and differential settlement after construction with 5-meter thick layer of cemented soil according to different combinations of thickness of experimental hall and storage ring.

13. 2. Simulation of Settlement for HEPS
2.4. Simulation results: 10-meter thick layer of cemented soil
Fig.3 The maximum settlement and differential settlement after construction with 10-meter thick layer of cemented soil according to different combinations of thickness of experimental hall and storage ring.

14. 2. Simulation of Settlement for HEPS
2.4. Simulation results: Combination of Live load A
Fig.4 The maximum settlement and differential settlement after construction with different ground improvement method

15. 2. Simulation of Settlement for HEPS
2.5. Conclusions
The live load of experimental hall is 10 kPa, storage ring is 10 kPa and 30 kPa at interval of 4.5°
Combination of slab thickness
Maximum settlement after construction
Maximum differential settlement after construction
NO. m mm
μm/10m
(<10µm/10m/a)
Experimental Hall
Storage Ring
Natural
soil
5-meter thick cemented soil
10-meter thick cemented soil
10-meter thick cemented soil 1
0.8
1.2
5.0388
3.7219 47 46 45 2
1.4
3.9814
39.8
39.2
38.5 3
1.6
5.6704
4.9545
4.2386
34.5
34.1
33.5 4
1.8
5.9817
4.4932
30.5
30.3 30 5
4.5546 22

16. 2. Simulation of Settlement for HEPS
2.5. Conclusions
The fitting relationship between settlement and slab thickness
Ground improvement method
Maximum settlement after construction
Maximum differential settlement after construction
Natural soil
Y = X R² =
Y = X R² =
5-meter thick cemented soil
Y= X R² =
Y = X R² =
10-meter thick cemented soil
Y = X R² =
Y = X R² =
NOTE:
Y is the maximum settlement; X represents the combination of slab thickness
Y is the maximum differential settlement; X represents the combination of slab thickness

17. 2. Simulation of Settlement for HEPS
2.5. Conclusions
The real situation is that soil is inhomogeneity;
The accuracy of material parameters of soil employed for simulation is not the real one due to the limitation of test method;
The theoretical method of simulation is based on many assumptions;
The construction process will have significant affects on the settlement.
Therefore, the calculated settlement is just an estimated one, but not the real one.
Guide the test program of settlement for HEPS

18. 3. Test Program of Settlement for HEPS
Outline
3. Test Program of Settlement for HEPS
3.1. Purpose
3.2. Method

19. 3. Test Program of Settlement for HEPS
3.1. Objective
Based on the settlement data of preloading test in situ, to derive and predict the settlement after construction.

20. 3. Test Program of Settlement for HEPS
3.2. Method
Test method: Static loading test
The applied load should be same as the real one that applied on the slabs of experimental hall and ring tunnel.
Prediction method: Exponential curve method
The detailed scheme of static loading test will be performed together with the vibration test in situ which will be performed in the soon future.

21. Requirement of Differential Settlement
4. Specification of Differential Settlement
Summary of requirements of differential settlement
Name
Location
Emittance
Requirement of Differential Settlement
nm·rad
Experimental Hall
Storage Ring
HEPS
Beijing
0.06 ——
<10µm/10m/a
SSRF
Shanghai
3.9
For the first 3 year after construction: <350µm/10m/a
Then after: <250µm/10m/a;
<2.5µm/10m/d;
<1.0µm/10m/h
For the first 3 year after construction: <250µm/10m/a
Then after: <100µm/10m/a;
TPS
Taiwan
1.6
NSLS-Ⅱ
 USA
1.0
APS
USA
3.0
SPring-8
Japan
3.4
Diamond UK
2.74
<250µm/10m/a; <10µm/10m/d; <1.0µm/10m/h
<100µm/10m/a; <10µm/10m/d; <1.0µm/10m/h
ESRF
France
4.0
<300µm/10m/a

22. Criteria for specifying the requirement of differential settlement
5. Discussion
Criteria for specifying the requirement of differential settlement
Environmental friendly
All the measures that taken to control the differential settlement should be environmental friendly.
Economic feasibility
Choice of the method of ground improvement and the type foundation to control the differential settlement should take into account the economic feasibility.
Integrated factors
An entire life circle requirement of settlement of light source facility should be proposed based on integrated factors, such as the construction site characteristics, the ground improvement method, the foundation type, auxiliary measures, among others.

23. 5. Discussion
In general, the control requirement of settlement for civil engineering is millimeter level.
Whether the requirement of differential settlement for light source facility as micron order is reasonable for civil engineering ? ? ?

24. Thank you
for your attention