PURPOSE: To construct a sheet pile wall having good water-stopping property by quick construction work by a method in which a trench is excavated with a stabilizer liquid supplied to the trench being excavated, a solidifying agent is charged into cohesive sludge in the trench, and a sheet pile is driven under non-hardened condition and the sludge is hardened.

CONSTITUTION: Guide walls 1 are set along a portion to be excavated of the ground, and the soil is broken by the cutting edge 5 of an excavator 3 with a trencher 4. Large gravels are discharged through the slits 6 of the trencher 4 to the outside of the trench 2. A stabilizer liquid 8 is supplied into the trench 2 as the same time as excavation is made, and a cement-based solidifying agent is charged into and mixed with cohesive sludge. Under the condition that the sludge is non-hardened, a sheathing body such as concrete sheet pile 9 is penetrated, and the sludge is hardened. Afterwards, the front side of the pile 9 is excavated to form an adjacent sheet pile wall consisting of the pile 9 and the hardened wall 11 to obtain a revetment or underground wall. The construction work can thus be performed at low cost without the need for operation of reclaiming soil, etc., by treating residual soil at low cost.