At present

the improvement of the horizontal bearing capacity of the piles by pre-consolidation of the soft soil foundation has been well recognized by practising engineers. However

how to estimate the increment of horizontal bearing capacity of piles during the pre-engineering process is still difficult. In this article

a practical calculation method for estimating the increment of horizontal bearing capacity of piles is established based on the Bowles[1] method and by considering the impact of pre-drainage and pre-consolidation treatment of the layered soft soil foundation. This method provides an effective way to calculate the shear strength index and pre-consolidation treatment time based on the shear strength of undisturbed soft soil by laboratory test. Meanwhile

the elastoplastic solution of the horizontally loaded pile and the calculation formula of the plastic zone depth of layered soft soil foundation are analytically derived

based on the influence of elastoplastic yielding of soils surrounding the pile. In addition

the source code for computing the horizontal displacement of the pile top and the maximum bending moment of the pile body are given. Finally

the horizontal displacement

bearing capacity and the maximum bending moment of piles in the sluice pile foundation engineering case in Zhejiang Province are calculated according to the proposed method. The results of the field tests before and after the pre-consolidation treatments are compared. It is found that the estimated results are close to the test results

which may provide a good reference for similar engineering designs.