Trong chương trước, thủ tục đã được trình bày cho việc xác định độ dài tối thiểu của một bức tường đống tờ cần thiết để đảm bảo trạng thái cân bằng. Phương pháp này là rằng bất cứ khi nào bức tường ngắn hơn chiều dài tối thiểu, không có trạng thái cân bằng có thể, và bức tường chắc chắn sẽ thất bại. Điều này cho thấy rằng nó được khuyến khích để lựa chọn chiều dài của bức tường lớn hơn chiều dài tối thiểu, như là một thất bại của bức tường sẽ là thảm hoạ | Chapter 37 BLUM In the previous chapter a procedure has been presented for the determination of the minimum length of a sheet pile wall needed to ensure equilibrium. This method is such that whenever the wall is shorter than that minimum length no equilibrium is possible and the wall will certainly fail. This suggests that it is advisable to choose the length of the wall somewhat larger than the minimum length as a total failure of the wall would be disastrous. If the length is taken somewhat larger than required the bending moments may perhaps be somewhat reduced. A method of analyzing the deformation and bending of the wall has been developed by Blum. This method is presented in this chapter including a simple computer program. Blum s schematization If the length of the sheet pile wall is somewhat larger than strictly necessary to ensure equilibrium the passive earth pressure need not be developed over the entire length of the embedded part of the wall. It may be expected that the pressures against the wall will be of the form shown in Figure . Because of the extra length of the sheet pile wall the toe will act as a clamped edge in which the lowest part may have R Figure Blum s schematization. a tendency to move to the right building up a pressure towards the left. Together with the incomplete passive pressure towards the right this will constitute the clamping moment. Blum suggested to schematize the loads on the wall as shown in the right half of the figure. The force R the Ersatzkraft is equivalent to the pressure to the right at the extreme lower part of the wall. Its precise distribution is left undetermined. 212 Arnold Verruijt Soil Mechanics 37. BLUM 213 The toe of the sheet pile wall is now assumed to be a clamped edge and it is also assumed that at the toe the bending moment is zero but a shear force of magnitude R is allowed. In order that this force may indeed develop and that there is enough material to form a clamped boundary the actual
