Table 2 Properties of the soil, grouting and pipe material used in the experiment

Soil

 Dry density

DIN EN 13286-1 (2003)

ρ_d

1.71

g cm⁻³

 Grain density

DIN EN ISO 17892-3 (2015b)

ρ_s

2.67

g cm⁻³

 Porosity

DIN EN ISO 17892-2 (2015a)

Ф

~ 36

%

 Hydraulic conductivity

DIN EN ISO 17892-11 (2019)

K

1 × 10^–8

m s⁻¹

 Thermal conductivity (Sat.)

Drefke et al. (2017)

λ

2.3

W m⁻¹ K⁻¹

 Liquid limit

DIN EN ISO 17892-12 (2020)

W_L

23.5

%

 Plastic limit

DIN EN ISO 17892-12 (2020)

W_P

21.3

%

 Plasticity

DIN EN ISO 17892-12 (2020)

I_P

2.2

%

Grout

 Suspension density

VDI 4640-2 (2019)

ρ_s

1.47

g cm⁻³

 Marsh funnel time (4.76 mm)

DIN EN ISO 10414-1 (2009)

t_f

51

s

 Water bleeding (24 h)

VDI 4640-2 (2019)

3

%

 Uniaxial comp. strength (56 d)

DIN 18141-1 (2014)

C_u

5.47

N mm⁻²

 Hydraulic conductivity

DIN EN ISO 17892-11 (2019)

K

< 1 × 10^–11

m s⁻¹

 Hydraulic system conductivity (FTC₀)

VDI 4640-2 (2019)

K

7.0 × 10^–10

m s⁻¹

 Hydraulic system conductivity (FTC₆)

VDI 4640-2 (2019)

K

2.8 × 10^–9

m s⁻¹

 Thermal conductivity

Manufacturer data

λ

> 2

W m⁻¹ k⁻¹

Pipe

 Pipe material

Manufacturer data

Polyethylene PE 100-RC

 Outer/inner diameter

Manufacturer data

d_o/d_i

32/26

mm

 Wall thickness

Manufacturer data

s

3.0

mm

 Surface roughness

Manufacturer data

R_t

1.86

µm

 Thermal conductivity

Manufacturer data

λ

0.40

W m⁻¹ K⁻¹

 Coefficient of thermal expansion

Manufacturer data

α

180 × 10^–6

K⁻¹