In Japan, there are many man-made sandy strata of hydraulic fill in recent years. But little is known about the mechanical properties of the undisturbed samples of these sands at present. Density measurements and triaxial compression tests have been performed on undisturbed specimens of sand in order to determine the mechanical properties of hydraulic fill. Undisturbed samples of sands have been taken from block samples at Ichikawa and core samples by freezing at Chiba. Both hydraulic fills are poorly-graded fine-sands on the basis of boring logs and sieve analysis. Dry densities from small specimens of these sands show much irregular variation with the depth. Avdrage dry densities of sand of hydraulic fills are over 1.4g/cm3 that is nearly those of middle Pleistocene deposits. Relative densities of hydraulic fills are the same or slightly smaiier than those of Holocene deposits. The stress-strain curves for undisturbed and disturbed (remolded) samples by triaxial compression tests are compared as follows. The axial strain at failure for undisturbed sand is lower than that Jor disturded sand. The maximum deviator stress, the maximum compression of volumetric strain and the secant modulus for undisturbed sand are higher than those for disturded sand. Characteristics of dilatancy by triaxial compression tests on sample Ichikawa B from hydraulic fill is as follows. Here, the value of stress dilatancy κf is defined as a ratio of effective stress ratio to dilatancy factor at failure. The value of κf for disturbed samples increases with increasing confining pressure. For the undisturbed sands, a minimum value of κf is found at a confining pressure of about 0.2kg/cm2. In the range of confining pressures lower than about 0.2kg/cm2, the value of κf increases with decreasing confining pressure, the trend being contrary to that of disturbed sand. And these similar results are found in samples from Quaternary sand deposits which have unconfined compressive strength. However, sample of Ichikawa B has no unconfined comressive strength when saturated. In spite of the fact that the sand from hydraulic fill has not passed ten years yet, some difference in triaxial compressive properties exists between undisturbed and disturbed samples. And the triaxial compressive properties of undisturbed samples from hydraulic fill are like those from Quaternary deposits.
In the present paper, geological and topographical characteristics of the upper stream of the Kurobe River, (one of the representative river basins in the high mountains of Central Japan), are decribed and the relationship between the fluvial topographic changes and climatic changes since the latest Pleistocene is discussed. The stratigraphical and topographical relationships between old gravel beds, a huge accumulation of detritus, and andestic lava flows which issued from the Jijidake volcano are important in estimating the fluvial topographic change in this area. The gravel beds, which are found in the old river bed, have a maximum thickness of 80 meters and are fairly well stratified. Trey can be divided into roughly four characteristic rock facies, i. e. from Lg4 to Lg1 (bottom to top). These are unconformably overlain by the andestic lava flows. The age of activity of the Jiiidake volcano may be correlated to the third stage of the Tateyama volcano, viz. 32, 000-40, 000 y. B.P. Consequently, the depositional period of the old gravel beds may be assigned to the Altwürm Stadial (Wv3). Large deposits of small-sized gravels indicates a cool/cold climatic condition during that period. The dissected lava flows are overlain by detritus deposits which are widely distributed along the main stream of the Kurobe River and and the Iwagokekodani (a branch of the Kurobe River) and which form very broad, gentle slopes. The maximum thickness of the deposits is more than 100 meters. The period of a large accumulation of detritus may be correlated to the maximum phase of the Wurm Ice Age (Wh2), around 20, 000 y. B.P. Lowering of the timber line and a decrease in precipitation accompanied by a very cold climate might have accelerated the production and accumulation of detritus. There was heavy river erosion both before and after the detritus accumulation period. The erosion before this period is estimated to have started within the Göttweigel Interstadial. This estimation is based on the large-scale erosion that took place and that resulted in the formation of wide river beds. The erosion that occurred after the detritus accumulation period is assigned to the Holocene. Original depositional form of detritus has been subjected to intense river erosion by running water and has formed remarkable topography that looks like river terraces. Generally speaking, the fluvial topographic changes occurring since the latest Pleistocene in the upper stream of the Kurobe River coincide quite closely with the climatic changes.
Some applications of the geophysical logging for civil engineering are discussed as follows: (1) Typical records of the intensity-log in the sonic logging which is an useful investigating method for cracks in bedrock and uniformity of geologic conditions are showed. (2) It is considered that the formation resistivity factor is more effective data than the true resistivity for investigation on the quality of bedrock. (3) The modulus of deformation of bedrock is estimated accurately by the multiple regression from the modulus of dynamic elasticity and R.Q.D.. (4) The principal component analysis are applied in the paper on 19 variates of the geophysical logging data and the other. 54% of the informations are represented by the first and the second components.
This paper reports on the classification for the types of the water pressure (P) versus the flow rate (Q) curves (P-Q curves) that obtained by the borehole permeability tests, and the consideration on the causes for these types. In these tests, the relation between the flow rate (Q) and the water pressure (P) is expressed in general equation as Q=KPα therefore, the types of the Q curves can be classified by the value of α, as follows α=1-the normal type (N type) α>1-the increase type (I type) α<1-the decrease type (D type) The causes for these types and subdivision can be so considered as follows N type (α=1) -by the laminar flow I type (α>1) I-a type-by the percolation I-b type-by the progressive increase of the permeable cross section. I-c type-by the piping D type (α<1) D-a type-by the closed fissure or the beeing impervious D-b type-by the limit of apparatus D-c type-by the turbulent flow
The seepage through dam foundations and abatments reduces the capacity of storage and, furthermore, might cause the failure of dam. It costs very much to reduce seepage by grouting and other water tight procedures. Lugeon test method is common practice for measuring rock mass permeability in the field of dam construction. However, there was no standard test procedures nor interpretation methods. Therefore, the Ministry of Construction defined tentatively the Manual of Lugeon Test in 1977. Some test procedures are as follows; (a) the borehole diameter should be 66 mm, (b) test section length should be 5m, (c) the maximum pressure at the test section should be over 10kg/cm2 unless ground breaks.