A method of constructing a ground anchor, wherein: - there are provided tendon and a boring machine that comprises: - a boring tool that is rotatable about a longitudinal axis, the boring tool being provided with a deployable mixer device that presents a retracted position and a deployed position, the mixer device in the deployed positioned presenting a diametral span that is greater than its diametral span in a retracted position; and - a device for injecting at least one fluid into the ground; the method comprising: - performing an introduction step for introducing the boring tool into the ground along a boring axis parallel to the longitudinal axis so as to form a top portion having a first diameter, a first height, and extending to a first depth, the mixer device being in the retracted position during the introduction step; then - performing a mixing step during which the mixer device is taken to the deployed position and the boring tool is driven in rotation with the mixer device in the deployed position while moving the boring tool axially along the boring axis and while injecting the fluid so as to perform mechanical in-situ mixing of the ground in place with the fluid, thereby forming a bulb in the ground under the top portion, which bulb has a second diameter that is greater than the first diameter; characterized in that: - making a borehole (K, K') in the bulb along the boring axis and having a third diameter less than the second diameter; characterized in that: - filling the borehole with a bonding grout; and - performing an insertion step during which the tendon is inserted in the bulb, the tendon being inserted into the borehole (K, K') before or after filling the borehole with the bonding grout, whereby a ground anchor is obtained. - there are provided tendon and a boring machine that comprises: - a boring tool that is rotatable about a longitudinal axis, the boring tool being provided with a deployable mixer device that presents a retracted position and a deployed position, the mixer device in the deployed positioned presenting a diametral span that is greater than its diametral span in a retracted position; and - a device for injecting at least one fluid into the ground; - a boring tool that is rotatable about a longitudinal axis, the boring tool being provided with a deployable mixer device that presents a retracted position and a deployed position, the mixer device in the deployed positioned presenting a diametral span that is greater than its diametral span in a retracted position; and - a device for injecting at least one fluid into the ground; - performing an introduction step for introducing the boring tool into the ground along a boring axis parallel to the longitudinal axis so as to form a top portion having a first diameter, a first height, and extending to a first depth, the mixer device being in the retracted position during the introduction step; then - performing a mixing step during which the mixer device is taken to the deployed position and the boring tool is driven in rotation with the mixer device in the deployed position while moving the boring tool axially along the boring axis and while injecting the fluid so as to perform mechanical in-situ mixing of the ground in place with the fluid, thereby forming a bulb in the ground under the top portion, which bulb has a second diameter that is greater than the first diameter; characterized in that: - making a borehole (K, K') in the bulb along the boring axis and having a third diameter less than the second diameter; characterized in that: - filling the borehole with a bonding grout; and - performing an insertion step during which the tendon is inserted in the bulb, the tendon being inserted into the borehole (K, K') before or after filling the borehole with the bonding grout, whereby a ground anchor is obtained.