The deformation process of clay siltstone under loading is a cumulative process of energy. Therefore, in order to clarify the deformation process of clay siltstone in compression by plate- bearing test, it is advisable to employ the method of energy analysis.
In this paper, the reversible and irreversible energy in the deformation process is calculated from stress-deformation curves. The relationship between the deformation and the time of application of load to clay siltstone is investigated.
Circular steel bearing plate is applied in testing, The plate has a thickness of 5 cm and a diameter of 32 cm, Its area is about 800 cm%,
Three tests, that is, tests (a), (b) and (c), were conducted, In test (a), the deformation of rock is measured immediately after each class of load is applied to it, and then it is read off the scale in every three minutes, It is taken as a controlling standard that the difference between two successive readings in every three minutes is not beyond 1/100 mm, This is called the controlling method of deformation, Tests (b) and (c) are carried out by what is called the controlling method of time, But each is slightly different from the other, In test (b) its deformation is measured after ten minutes of loading and then the next class of load is appliea at once but in test (c) the interval is three minutes, It holds true both in loading and in unloading. At this point these three tests are the same, Tests (a) and (b) arc all single cycle of loading and unloading, while test (c) is multi cycle loading unloading, Other technological requirements and experement conditions, for instance, clean and flat rock surface, accuracy of installation of loading system, rating of measurement instruments and so on, are all the same.
When testing is carried out, the natural water content in clay siltstone is 3.1%, testing cavern temperature is between 18.2° Ct and 20°C, uniaxial compressive strength of clay siltstone is 211 kg/cm2.
The stress-deformation curves of test(a), (b) and(c) are obtained by means of the plate-bearing test, as shown in Fig,1 ~ Fig,3,hencc corresponding moduli of elasticity and deformation, as shown in Table 1, In order to make a comparison between them, results in laboratory and normal test in situ in the same testing cavern, where the, area of the plate is 2000 cm2, are shown in Table 2.
From Table 2 it can be seen that even if the fissure is not developed in clay siltstone and it is more uniform rook, the range of variation of its deformation parameter is very evident as well,
(Figure in full paper)
The curve was obtained under a single process of loading and unloading as shown in Fig. 4. The reversible and irreversible energy in the deformation process is calculated by measuring areas in the stress-deformation diagram. Total deformation energy u,' applied to the rock mass by an external load is divided into two parts.
