Vol 32 Iss. 2

The study of the artesian basins of the USSR in recent years in connection with the widespread drilling of deep wells has been marked by major achievements. In many artesian basins, the basement underlying their sedimentary complex has been uncovered. In the basins of the European part of the Soviet Union and Eastern Siberia it is represented by granites and gneisses; in the basins of Central Asia, Kazakhstan, Western Siberia - by Paleozoic sediments of different age, genesis, composition and various eruptive rocks. For many basins their depth has been established at different points. It often exceeds 1-2, and in some cases even 3 km. For the majority of basins in the European part of the USSR sufficient data have been accumulated to construct the first tentative isohypsum maps of the basement surface. Similar maps can be constructed for the southern part of Western Siberia. The data on the age of rocks composing the basins, their composition, thickness, facies, etc. have been clarified. New data obtained as a result of studying the composition of artesian waters of deep parts of the basins, confirmed and clarified the ideas of Acad. V. I. Vernadsky about the wide distribution of saline waters and brines at depth. At the same time, Soviet scientists developed the doctrine of hydrodynamic and hydrochemical zonality of artesian basins.

Turbulent movement of groundwater is known to occur at significant cross-sections of water-conducting channels in rocks and sufficiently high groundwater velocities and gradients. More often the development of turbulent movement is observed in fractured rocks intersected by open fractures with a significant gap and in karsted rocks. In loose porous rocks, turbulent motion occurs only in highly permeable rocks such as pebbles and gravel-pebble formations, and the filtration rates and gradients at which the development of turbulent motion begins in these rocks are much higher than in fractured and karsted rocks. At present, as a result of a number of research works carried out in laboratory and field conditions, it has been established that laminar movement of groundwater often takes place in fractured and even karsted rocks. Therefore, for such rocks it is possible to use the linear filtration law (Darcy's law) and dependencies based on this law under certain conditions. In particular, groundwater movement observed in natural conditions is characterized by small hydraulic gradients and usually obeys the linear law, even in rocks intersected by large open fractures and often in karsted rocks.

The behavior of rocks under the impact of certain structures on them is determined by their geological, petrographic, physical and mechanical properties. These properties they acquire in the course of natural-historical processes of formation and subsequent change in the bowels of the Earth's crust under the influence of various factors. The question of formation of construction properties of rocks was first put forward by the founder of Soviet engineering geology, Acad. F. P. Savarensky. He and with his participation carried out the first major studies in this direction. Many geological specialists took part in the subsequent development of this issue. The works of B. M. Gumensky, N. Y. Denisov, G. S. Zolotarev, N. V. Kolomensky, G. A. Mavlyanov, V. A. Priklonsky, I. V. Popov, P. N. Panyukov, I. I. Trofimov and other Soviet scientists are devoted to the study of the peculiarities of the formation of the properties of clayey rocks. Consideration of the conditions of clay sediment formation shows that the first stage of sediment formation is the accumulation of finely dispersed material by mechanical or chemical means. Depending on the conditions of accumulation of this material, sediments of different composition, properties and state are formed.

In hydraulic engineering construction, mining, construction of subways, construction of deep foundations, etc., the method of artificial lowering of groundwater level is used more and more often. Especially widespread has found water lowering on modern grandiose hydraulic engineering construction sites, such as the Volga-Don, Kakhov hydroelectric complex, construction of hydroelectric stations near Kuibyshev and Stalingrad and others. There are also known a number of cases of sinking mine shafts and dewatering of coal and other mineral deposits with the help of dewatering plants. At the same time, when designing new dewatering installations or rearrangement of existing drainage systems consisting of variously designed dewatering wells, drainage wells, needle filters, etc., there are difficulties in calculations of the main efficiency indicators of such installations. They mean calculations of necessary level lowering in any point of the site, determination of total water inflow at different location and different design of drainage devices, determination of flow rate of separate interacting excavations, etc. For these calculations, in turn, it is necessary to have such indicators as water permeability coefficient, radius of influence and some others.

Widespread use of the method of artificial lowering of the groundwater level in the construction of foundations for hydraulic and industrial structures, as well as large high-rise buildings caused the need to develop a methodology for calculating the water inflow to excavations in different hydrogeological conditions. The present article deals with the case of water inflow to the dewatering unit of an excavation, elongated in plan form, under the conditions of pressure-unpressurized regime of aquifers opened by the excavation. Attention to this case was attracted by the construction of a lock on a navigable canal. In spite of its special character, the set task is also of theoretical interest, as it allows us to check the suitability of certain calculation schemes and formulas in specific hydrogeological conditions. The excavation of the mentioned structure has already been realized at present, and the forecast of possible groundwater level lowering, which was given in 1952 when designing the structure on the basis of the calculations given below, was mostly confirmed.

There are different methods of hydraulic calculation of groundwater flow in a homogeneous medium with a flat sloping water table. These methods are characterized by different degree of approximation. Thus, the formulas of G. N. Kamensky do not have a strict theoretical justification. The method of Acad. N. N. Pavlovsky's method is also approximate to a certain extent, since according to this method of calculation the surfaces of equal heads in the conditions of a flat problem are considered as vertical planes. The method of N.N. Pavlovsky can be considered as the most accurate at present, because it is based on a strict mathematical conclusion and its main provisions are very close to the true picture of motion when the slope of the water table and the slope of the depression surface are small. The new method proposed in this paper is also an approximation, but it is based on a fairly rigorous mathematical derivation. Determination of flow rate and construction of depression curve by this method is simpler and more convenient than by the method of N. N. Pavlovsky.

A comparative evaluation of the existing formulas for calculating the flow rate of imperfect wells in a pressurized aquifer is given on the basis of analysis of experimental data obtained during hydrogeological studies in one valley made by alluvial sediments to which the pressurized aquifer is confined. Alluvial deposits of the valley are represented mainly by multigrained sands, partly dusty and clayey, with gravel, pebbles and single boulders. The total thickness of alluvial formations overlying Tertiary sediments is 40-42 meters. The upper part of the alluvium is composed of clays and loams up to 13 m thick, which is a water-retaining roof. The head reaches 12.79 m, counting from the roof of the aquifer. The level of this horizon is subject to seasonal fluctuations. The minimum level position is observed in autumn (0.21-0.95 m below the ground surface), the maximum - in spring, when the water level rises 0.35-0.83 m above the ground surface, as a result of which some wells self-pour during this period.

To determine the flow rate of imperfect wells under pressure water conditions in hydrogeological practice, a number of formulas proposed by P. P. Argunov, G. N. Kamensky, I. Kozeny, M. Maskett and others are used. As is known, calculations using these formulas are relatively time-consuming and often difficult for average technical personnel. The proposed accelerated method considerably facilitates calculation of flow rate of imperfect wells under pressure water conditions and is quite accessible to a wide range of specialists engaged in the study of pressure water for water supply purposes. The accelerated method is based on the formula of Prof. P.P. Argunov.

Geographical position. Yan-shan ridge is located in the northern part of He-pe province of Northern China. It is located between 40-41° of north latitude and 115-120° of east longitude. This ridge separates the plateau of Inner Mongolia from the North China Plain. The Great Wall of China was built along it in ancient times. Geologic structure. The orogeny that resulted in the folding of ancient sediments in various areas of China during the Upper Jurassic and Cretaceous was called the Yanshan orogeny. No orogeny earlier than the Yanshan folding is known in North China, except for a putative orogeny of pre-Xinian time. The Sinyi system basically corresponds to Upper Proterozoic. time. Beginning in the Sinaian, down to the Jurassic, sedimentary rocks were accumulated in parallel horizontal layers. The layers in this stratum lie more often in accordance with each other, but sometimes stratigraphic disagreement is observed. The disagreement is most pronounced between Ordovician limestones and various rocks of the Middle Carboniferous. This indicates that North China was a landmass during the Silurian and Devonian periods.

Electrolevel gauge is designed to measure the dynamic water level in wells during pumping (Fig. 1). The maximum depth measured by the device is 100 m, measurement accuracy + 0.05%. The operating principle of the device is based on the closing of the electric circuit between the tip lowered into the well and water, determined by the deviation of the galvanometer arrow (Fig. 2). The depth at which the circuit is closed is determined by the length of the insulated wire lowered into the well (see article). In conclusion, it should be noted that the above described electric level gauge gives quite sufficient accuracy for practice in measuring both static and dynamic water levels in wells at single and cluster pumping.

In laboratory practice up to the present time for determination of filtration coefficient of cohesive rocks two types of devices are used: N. V. Kolomensky and PV - Znamensky and Haustov's design. But these devices are designed either for small heads expressed in fractions of atmosphere (PV) or for cores of large diameter (N.V. Kolomensky device). The device described in this article is designed and actually applied by us for determination of filtration coefficient of cohesive rocks under pressure of 2-3 atm at core diameter of 35 mm. Some features of the E. E. Kerkis device, designed for determination of the filtration coefficient of loose soils, were partially used in the construction of the device. The device for pressure filtration (Fig. 1) consists of a cylinder 5, two flanges 1 with grids 2, clamping rings 3 and rubber gaskets 4. A core with a diameter of 35 mm and a height of 20 mm is loaded inside the cylinder. The gap between the conical part of the inner surface of the cylinder and the core is filled with resin. When selecting the resin, it should be borne in mind that excessive plasticity may cause the resin to float on the bottom surface of the core, which will reduce the filtering surface. Therefore, a harder resin should be used.

Central well. When organizing experimental pumping, the dynamic water levels in the central well are usually left out of observations, as the water-lifting pipe is filled with emulsion masking the position of the dynamic level. To observe dynamic levels, a special observation well of small diameter (piezometer) in the immediate vicinity of the central well is installed, and it is called a downhole observation well. At deep occurrence of the dynamic level in the aquifer, the sinking and anchoring of the downhole well becomes difficult. It is very convenient to replace such a well with a piezometric tube lowered into the central well next to the air pipe. If the lower edge of the piezometric tube is immersed 5-10 m below the mixer, the water in it is completely free from the impact of air supplied to the central well and set at a level corresponding to the dynamic level in the central well and aquifer. It remains only to periodically measure the position of this level with a level gauge. B.P. Ostroumov's level gauge is convenient.

A large number of stadiums and sports grounds have been built and are in operation in the USSR. In addition, hundreds of new sports facilities are built annually at factories, educational institutions, collective and state farms. In the process of new construction, operation, current, preventive and major repairs of stadiums and sports grounds there is a need for objective assessment of the composition and condition of artificial soils (special mixtures). At present, a subjective method is taken as a basis for the assessment of artificial soils, the reliability of which is not always correct. So far, for the quality assessment of running tracks, athletics sectors, tennis and other sports grounds their granulometric composition, physical-mechanical and water properties are not taken as a basis. The lack of objective assessment methods is explained by the undeveloped technical requirements for artificial soils. Thus, for example, the standard project of a normal sports core states: “...the coastal track should be elastic, flexible, have a constant volume, have a level surface of the top layer and good resistance to atmospheric (rain, snow, ice, wind) and mechanical influences...”. These requirements can by no means be called technical and do not allow for an objective assessment of the composition and condition of special mixtures.

Presence of salts in the rock often creates difficulties of methodological order when studying granulometric composition and physical and mechanical properties of rocks. The methodology of analysis of saline rocks is still poorly developed. In the present work some methodical questions on preparation of rock for granulometric analysis, determination of plasticity and specific gravity are considered, which are solved in relation to carbonate-clayey rocks of Tatar layer of Permian system. The methodology and technique of determination of physical and mechanical properties of saline differences of sandy and clayey soils are devoted to a considerable number of works, mainly aimed at the study of soil preparation for analysis - the main factor affecting the results of analysis. The question of preparation of non-saline rocks for analysis is solved relatively easily and does not cause much disagreement, while the question of preparation of saline rocks turns out to be very complicated.

In the study of natural foundations of designed engineering structures, the most important indicator to be clarified is the ability of the soil to compact under the action of external load, i.e. compression properties of the soil. Laboratory tests of compression properties of soils consist in determining the compressibility of the soil loaded in the ring of the compression device under the action of the load increasing in steps. The deformation of the tested soil is judged by the change in its porosity according to the indicators. The quality of compression test results is decisively influenced by a variety of factors: the quality of the devices in which the tests are carried out, the serviceability of the levers used to compact the soil, the technique of the experiment and the methodology used to carry out the tests. Some differences in the design of existing compression instruments are not decisive for compression tests, although they differ greatly in terms of usability and speed of operation.