Prototype measurements of a new prestressed sheet-pile retaining wall

The structure consisted of the metope pile,soil shield,prestressed cables,anchorage pile and filled soil,earth-pressure cell,rebar stress metre,RC strain metre,pulling loop of cable,settlement cup,horizontal-displacements sight gauge were all placed in the structure to observe the earth pressure,moments and displacements of piles,stresses of anchorage interface,tensile forces of cables,settlements of filling.The observed results showed that when the anchorage cable was stretched,the moment of the metope pile was reduced efficiently and the negative moment in the metope pile that must be considered in the bar arrangement of the pile appeared.The new distribution of earth-pressure of the filled soil which was different from the classical earth pressure theory was found and an adapted formula was presented based on the observation results.Obvious reduction of the contact stress of the anchor segment was also found when two lines of anchorage cable were stretched,therefore the maximum stress of the anchor segment was easily ensured within the range of the allowable compressive strength of the surrounding rock and the concrete.The results also showed that the internal force of the anchorage cable could be adjusted automatically and even exceeded 40% of the design value under variatible external load.Hence it was recommended that the margin of resisting capability should be considered in design in order to utilize efficiently the tensile capability of the anchorage cable.It was also recommended that 1/5¹/4 of pile length could be adopted in the design of the anchorage length of the metope pile in stead of 1/3 in similar engineering projects in which two lines of anchorage cable were stretched and surrounding rock was hard and intact.