10.2.4 Building protection by increasing stiffness...
Theoretically，the increase of the stiffness of a retaining wall can reduce the wall deformation and the ground settlement.The methods of increasing the system stiffness of the retaining⁃strut system include increasing the stress or thickness of the retaining wall，decreasing the horizontal span of struts，increasing the stiffness of each strut，and decreasing the vertical span of struts，etc.
When the axial stiffness of the strut is not large enough，increasing the stiffness of struts（such as by cutting the horizontal span or increasing the stiffness of each strut）can effectively reduce the deformation of a retaining wall.However，when the axial stiffness of struts is already rather large，more increase of stiffness will not reduce the deformation accordingly.
Decreasing the vertical distance of struts is an effective way of reducing the deformation of a retaining wall.The reason is that cutting the vertical distance implies the increase of number of strut levels.That is to say，the rigidity of the retaining system is increased.Deformation will decrease as a result.From another perspective，since the deformation of a retaining wall is the accumulated result of the excavation stages，the cutting of the vertical distance will decrease the unsupported length of the retaining wall at each excavation stage.Therefore，deformation will also decrease.