**4.1 Freezing installation**

Freezing installation consists of refrigeration plant (primary system) and secondary system and it is suited for cooling calcium chloride aqueous solution to −35°C [1, 3].

Primary system includes three freezing units, so called chillers PAC SAB 283 E eco, which freezing medium is ammonia. They are cooled by cooling towers Evapco AT 18-3 M14. Refrigeration plant consist also of isolated pipes for brine transfer, brine tank, discharge tank, water treatment station, eight pumps and armature. Model of refrigeration plant is presented on **Figure 1**.

**Figure 1.** *Refrigeration plant [3].*

#### **Figure 2.**

*Freezing channel [3]. a) Freezing channel model, b) cross-section of freezing channel between refrigeration plant and shaft; c) freezing channel around the shaft; 1: Inlet pipeline, 2: Outlet pipeline, 3: Rack.*

**5**

**Table 1.**

*Parameters of freezing boreholes.*

*Optimization Directions for Monitoring of Ground Freezing Process for Grzegorz Shaft Sinking*

other one is a channel between freezing ring and refrigeration plant.

boreholes is equal 485 m (bottom 10 meters are filled with concrete) [12].

Secondary system is basically a channel used to transfer coolant from refrigeration plant to freezing boreholes. The channel consists of two main parts, one of them is a circle channel around the shaft outline (containing freezing ring), the

Freezing channel contains two pipelines with diameter of 350 mm – inlet and outlet pipelines and one venting pipeline with diameter of 65 mm. Around the shaft outline, pipelines are circle-shaped and form so-called freezing ring. Freezing boreholes' pipes are connected directly to the freezing ring. Model of secondary system of freezing installation and cross-sections of channels are shown on **Figure 2**.

For purpose of Grzegorz shaft sinking, 40 freezing and 3 control boreholes were designed and drilled. They are marked with numbers from M1 to M40 (freezing boreholes) and from T1 to T3 (control boreholes; one of them is previously drilled borehole G-8bis). Control boreholes are located on common axis, out of the freezing boreholes' circle. Their task is to inspect shape and size of frozen ground column. Depth of all

Distance between freezing boreholes varies in practice between 0,9 and 1,3 m. It

In case of Grzegorz shaft sinking distance between freezing boreholes was calculated at about 1,25 m. Parameters of freezing boreholes are presented in **Table 1**.

• 2,0–40,0 m – borehole's diameter Ø311 mm – 12 1/4″ (rotary drill bit Ø311 mm)

• 40–485 m – borehole's diameter Ø216 mm – 8 1/2″ (rotary drill bit Ø216 mm)

**Figure 3** presents arrangement of freezing and control boreholes and Grzegorz shaft's cross-section. Description of shaft's elements represents state of construction

4. Depth of freezing boreholes 485 m (including 10 m of concrete) 5. Casing pipes diameter Ø139,7 mm × 8,0 mm 6. Inflow pipes diameter Ø75,0 × 4,5 mm 7. Refrigerant CaCl2 aqueous solution

**No. Parameter Value** 1. Number of freezing boreholes 40 pcs 2. Distance between boerholes 1,25 m 3. Diameter of freezing boreholes circle 16 m

*DOI: http://dx.doi.org/10.5772/intechopen.95885*

**4.2 Freezing boreholes**

is determined according to:

• economic factors,

• time required.

• required size of frozen ground cylinder,

Construction of freezing boreholes:

at the moment of beginning of drilling.

• 0–2,0 m – lining pipe Ø508 mm (20″)

*Optimization Directions for Monitoring of Ground Freezing Process for Grzegorz Shaft Sinking DOI: http://dx.doi.org/10.5772/intechopen.95885*

Secondary system is basically a channel used to transfer coolant from refrigeration plant to freezing boreholes. The channel consists of two main parts, one of them is a circle channel around the shaft outline (containing freezing ring), the other one is a channel between freezing ring and refrigeration plant.

Freezing channel contains two pipelines with diameter of 350 mm – inlet and outlet pipelines and one venting pipeline with diameter of 65 mm. Around the shaft outline, pipelines are circle-shaped and form so-called freezing ring. Freezing boreholes' pipes are connected directly to the freezing ring. Model of secondary system of freezing installation and cross-sections of channels are shown on **Figure 2**.

#### **4.2 Freezing boreholes**

*Computational Optimization Techniques and Applications*

**4. Freezing installation and boreholes' construction**

Model of refrigeration plant is presented on **Figure 1**.

method for Grzegorz shaft sinking.

**4.1 Freezing installation**

−35°C [1, 3].

**Figure 1.**

*Refrigeration plant [3].*

Occurrence of these geotechnical zones enforced utilization of ground freezing

Freezing installation consists of refrigeration plant (primary system) and secondary system and it is suited for cooling calcium chloride aqueous solution to

Primary system includes three freezing units, so called chillers PAC SAB 283 E eco, which freezing medium is ammonia. They are cooled by cooling towers Evapco AT 18-3 M14. Refrigeration plant consist also of isolated pipes for brine transfer, brine tank, discharge tank, water treatment station, eight pumps and armature.

**4**

**Figure 2.**

*Freezing channel [3]. a) Freezing channel model, b) cross-section of freezing channel between refrigeration plant and shaft; c) freezing channel around the shaft; 1: Inlet pipeline, 2: Outlet pipeline, 3: Rack.*

For purpose of Grzegorz shaft sinking, 40 freezing and 3 control boreholes were designed and drilled. They are marked with numbers from M1 to M40 (freezing boreholes) and from T1 to T3 (control boreholes; one of them is previously drilled borehole G-8bis). Control boreholes are located on common axis, out of the freezing boreholes' circle. Their task is to inspect shape and size of frozen ground column. Depth of all boreholes is equal 485 m (bottom 10 meters are filled with concrete) [12].

Distance between freezing boreholes varies in practice between 0,9 and 1,3 m. It is determined according to:


In case of Grzegorz shaft sinking distance between freezing boreholes was calculated at about 1,25 m. Parameters of freezing boreholes are presented in **Table 1**.

Construction of freezing boreholes:


**Figure 3** presents arrangement of freezing and control boreholes and Grzegorz shaft's cross-section. Description of shaft's elements represents state of construction at the moment of beginning of drilling.


**Table 1.** *Parameters of freezing boreholes.*

**Figure 3.** *Arrangement of freezing and control boreholes and cross-section of Grzegorz shaft [1].*
