Vízügyi Közlemények, 1981 (63. évfolyam)
2. füzet - Szepessy József: Vízépítési földművek talajainak diszperzitás-vizsgálata
238 Szepessy József Автор излагает типы трещин (и возможности предупреждения возникновения таковых), поскольку считает, что наличие трещин является исходным условием к эрозионному разрушению земяных сооружений (глава 3). В целях предупреждения прорывов дамб предлагается: 4.1. Исследование связных грунтов методом иглоукаливания. 4.2. В случаях наличия дисперсности грунта устройство дамб сложных профилей (например с применением фильтров). 4.3. Систему фильтров проверять на лабораторных модельных установках. * * * Dispersivity tests oil soils in hydraulic earth structures by Dr. J. Szepessy Using data published in the professional literature and the results of tests performed, the methods suggested for determining the dispersivity of soils have been compared. Instructions have been compiled for the method of measurement suggested and the drawings of the equipment required have been prepared (Section 1). Dispersivity is a property of cohesive soils, which the conventional soil mechanical tests fail to predict and indicate. Investigations in Australia and the United States have found the highly dispersive soils to be susceptible to erosion. Internal tunnelling erosion was responsible for the failure of over hundred small dams and flood levees, which occurred in each case at an uncontrollably fast rate. The investigations into this phenomenon were warranted by the frequent occurrence in Hungary of soils with a high Na content indicating susceptibility to dispersion, as well as by the observed base seepages and leakages which give rise to internal erosion. The investigations into the causes of the failure or the left-hand levee of the Berettyó River on July 26, 1980 have revealed that the base seepage initiated by other factors deteriorated because of the high dispersivity of the soil into a failure, which occurred two hours after seepage was observed without possibility of corrective measures. The systems of internal forces in colloidal soils, the structure of such soils and the factors affecting these are described. In the light thereof the various methods of testing are examined and the process of erosion itself is examined (Section 2). This problem has not received attention thus far in Hungary. On the other hand, the phenomenon of soil liquefaction has been studied for many years. Now we have succeeded in demonstrating that the two phenomena can be traced back to the common cause of dispersivity and that the same soil will erode, or liquefy depending on the forces acting on it. The primary cause of erosion failure is the development of cracks in earth dams, 'the process of cracking and the potential preventive methods are described (Section 3). In order to prevent levee failures the following approach is suggested (Section 4): 4.1. Cohesive soils should be tested for dispersivity by the pinhole test. 4.2. Levees of dispersive soil should be built with a compound (e.g. filtered) cross sections. 4.3. The filter zones should be determined by model tests.
