The invention relates to a trench cutter comprising a box-shaped housing, on the upper face of which a lifting apparatus can be mounted, at least one cutting wheel, which is arranged on a lower face of the housing and can be driven in rotation to remove soil material, wherein cutting teeth are arranged along the outer circumference of the cut-ting wheel at least one circumferential row, which at least one axial clearance adjoins, and at least one clearing plate, which is arranged to be fixed relative to the housing and engages in the at least one circumferential clearance on the cutting wheel to clear away soil material. According to the invention, it is provided that the at least one clearing plate is mounted on a plate holder so as to be spaced apart from the housing, wherein a passage is formed between the at least one clearing plate and the housing, through which passage soil material that has been cut out during operation can be guided upwards.

The invention provides a thermosyphon foundation, a method of calculating cold conductivity enhancement coefficient and a method of cold conductivity enhancement thereof. The cold conductivity enhancement coefficient is obtained by using parameters including freezing index, latent heat of soil thawing, thermal resistance of pre-buried hole without injection of a cold conductivity enhancement medium, thermal resistance of cold conductivity enhancement mass or the like, and by using formulas for calculating the cooling radius of the thermosyphon without injection of a cold conductivity enhancement medium and the cooling radius of the thermosyphon after injection of a cold conductivity enhancement medium. The invention determines whether to proceed with subsequent construction by using the cold conductivity enhancement coefficient, and achieves cold conductivity enhancement for the thermosyphon foundation by using the method of cold conductivity enhancement.