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Một phiên bản ban đầu của các kiểm tra ba trục đã được phát triển vào khoảng năm 1938 bởi Keverling Buisman, xem hình 23,1. Trên thực tế, các thử nghiệm ba trục có thể được coi là một phiên bản cải tiến này thử nghiệm tế bào Hà Lan. Bộ máy bao gồm một container với một bức tường kính hình trụ (cell), với một màng cao su cố định, trong đó mẫu có thể được cài đặt. Áp lực nước trong tế bào có thể được kiểm soát. Ngược lại với bộ máy ba trục, trong đó áp. | Chapter 23 CELL TEST An early version of the triaxial test was developed around 1938 by Keverling Buisman see Figure 23.1. Actually the triaxial test can be considered to be an improved version of this Dutch cell test. The apparatus consists of a container with a cylindrical glass wall the cell with Figure 23.1 Cell test. a fixed rubber membrane in which the sample can be installed. The water pressure in the cell can be controlled. In contrast with the triaxial apparatus in which the cell pressure also acts on the top of the sample in the cell test the pressure in the cell only acts on the cylindrical surface of the sample because of the way of installing the membrane which is glued to the top and bottom plates of the apparatus. The usual testing procedure consists of applying a vertical load by means of a gradually increasing dead weight and to measure the vertical deformation. Note that in the standard triaxial test the rate of vertical deformation is imposed and the vertical load is measured. The cell test is stress controlled whereas the triaxial test is strain controlled. In horizontal direction there is no difference between the two tests in both the horizontal stress is controlled by the cell pressure. The size of the sample in a cell test usually is 6.5 cm diameter which is somewhat larger than the size of the samples in a triaxial test 3.8 cm . This is of minor importance however and there exist larger cells especially for tests on course material such as gravel. The original purpose of the cell test was to investigate the stresses that would occur in a loaded sample while the strains remained small without reaching failure. For this purpose the lateral deformations should be kept to a minimum close to zero. This can be accomplished approximately by filling the cell with water and to prevent volume change of this water by closing the cell. The cell pressure will then increase if the vertical stress is increased. In this classical form of the cell test the
