NOVELTY - The steel sheet pile (120) has an accommodating unit (124) that is provided in a steel sheet pile substrate (122). An accommodation space (124b) is formed in inside of the steel sheet pile substrate and extended to the longitudinal direction. A heat exchange piping (126) is accommodated in the accommodation space, for circulating the heat medium. An outbound path pipe (126a) and an inbound path pipe (126b) are accommodated in accommodating unit. The end of outbound path pipe and end of inbound path pipe are connected by a connecting pipe (126c).    USE - Steel sheet pile of geothermal heat exchange piping system (claimed) for performing heat exchange of seawater utilization heat pump installed in underground of building e.g. terrestrial building. Can also be used in road and park.    ADVANTAGE - The production of noise and vibration at the time of installation work of geothermal heat exchange piping is reduced. Since the contact area of the steel sheet pile and underground earth and sand is increased, the heat transfer efficiency between the steel sheet pile substrate and accommodating unit is improved. Hence, the geothermal heat of high temperature is utilized effectively. Since the steel sheet pile is inserted and removed respectively, the rebuilding of terrestrial building is performed easily. Since the installation of the countermeasure against liquefaction and geothermal heat exchanger is performed simultaneously, the installation expense of the heat exchange piping is reduced.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a geothermal heat exchange piping system; and    (2) an installation method of geothermal heat exchange piping.    DESCRIPTION OF DRAWING(S) - The drawing shows the perspective and sectional views of the steel sheet pile.    Steel sheet pile (120)    Steel sheet pile substrate (122)    Accommodating unit (124)    Accommodating space (124b)    Heat exchange piping (126)    Outbound path pipe (126a)    Inbound path pipe (126b)    Connecting pipe (126c)