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 2017-12-12

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

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

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.

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

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

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 45 182~193 140-350 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

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.

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

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 76.5 MPa. With this numerical we have calculate many cases, here parts of them are shown

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.

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.

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.

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

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 4.38035 3.7219 47 46 45 2 1.4 5.35425 4.667825 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 5.23745 4.4932 30.5 30.3 30 5 5.96195 5.258275 4.5546 22

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 = 0.2474X + 4.8593 R² = 0.9314 Y = -0.0006X + 0.0053 R² = 0.9871 5-meter thick cemented soil Y= 0.2325X+ 4.202 R² = 0.9502 Y = -0.0006X + 0.0051 R² = 0.9865 10-meter thick cemented soil Y = 0.2177X + 3.5448 R² = 0.9683 Y = -0.0005X + 0.005 R² = 0.9858 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

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

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

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.

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.

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

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.

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 ? ? ?

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