Climate warming and the heat conditions of bases in northern cities

This article considers trends of climate change in circumpolar regions and evaluates its effect on the heat conditions of bases in northern cities (Noril'sk, Dudinka, etc.). The technogenic effect connected with industrial development of northern territories, which causes a number of negative phenomena in the bases of structures (a rise in the level of groundwater, salinization, a rise in temperature), is also evaluated. A conclusion is drawn about the predominance of the technogenic effect, and effective methods are suggested for controlling the thermal status of bases, which help to raise the stability of buildings and structures in northern cities.Noril'sk Branch of the Scientific Research Institute of Foundations and Underground Structures. Scientific Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 27–30, September–October, 1993.     

Experimental investigation of the distribution of stresses in large bored situ-cast piles

Conclusions 1. Diagrams were obtained of the distribution of specific skin friction of bored situ-cast piles with a diameter of about 1 m and length of 18 m and of their transformation as a result of flooding the soils and successive loading of the pile with gradual involvement of shearing resistance forces in a downward direction.2. Before the long bored situ-cast piles broke loose, the specific skin friction in homogeneous soil is practically constant over the length of the pile, which confirms the correctness of the concept used in [3].3. On flooding soils at the base of the piles, when the external load is equal to zero and there is still no slumping of the soil layers under their own weight, substantial normal stresses occur in the cross sections of long bored situ-cast piles, as a result of which they are additionally loaded by the soil hanging on them.4. The foot of long bored situ-cast piles penetrating loose layers of loam soils and supported on a layer of loam with =0.662 carried no more than 10% of the total load applied to the pile prior to breaking loose. Thus it behaves as a friction pile before breaking loose.5. After the pile breaks loose, the normal contact stresses on its foot increase in direct proportion to settlement. It follows from this that to increase the point resistance before breaking loose it is necessary to preliminarily compact the bottom of the hole of the bored situ-cast pile.Scientific-Research Institute of Bases and Underground Structures (NII Osnovanii). Research Department, All-Union Planning, Surveying, and Scientific-Research Institute (Gidroproekt). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 11–13, May–June, 1980.     

Technology of forcing in piles for reconstruction of operating enterprises and in constrained construction conditions

This article discusses the technology and equipment for forcing in piles in the construction of pile foundations in constrained conditions of the construction site and during reconstruction. Ways of development and creation of new, specialized, highly productive, compact equipment, and technologies for reinforcing foundations by forcing-in and final pressing of piles in the basement part of a building are considered.Scientific Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 13–16, January–February, 1993.     

The question of assigning a bed coefficient in calculating rigid airport pavements

It is suggested that the bed coefficient be considered as a characteristic of the contact interaction of rigid pavement and the soil base. Equations are derived for the relationship between the bed coefficient and the modulus of elasticity of the soil base for reinforced-concrete and metal pavements. They are compared with the results of experimental investigations, indicating sufficiently good correspondence of these values. Patterns of operation of pyramidal piles in swelling soils are given: the dependence of their rise on the cone angle, length of the pile, and transmitted load. The authors studied layer-by-layer displacements of soil around a pile and give their dependences on the depth of the layer's location. Formulas are given for determining the coordinate of the neutral point, according to which the rise of an unloaded pile is found.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 16–18, July–August, 1993.     

Performance characteristics of horizontally loaded piles located near a trench

Conclusions 1. The excavation of a trench (pit) in the vicinity of a pile diminishes its ability to resist horizontal loading. This reduces the depth of pile embedment in the soil and depends on the depth of the trench and its distance from the pile.2. The above-described method of testing piles for horizontal loading with strain gages can be used to determine the design depth of pile embedment in a soil.3. The upper layer of soil of thickness d exerts no significant influence on the performance of horizontally loaded piles due to the formation of a gap between the pile and soil during its backfilling and can therefore be disregarded in their disign.Scientific-Research Institute of Industrial Buildings and Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 13–14, May–June, 1976.     

Method and results of testing piles tamped into holes drilled in soils classed as type II in terms of proneness to slump-type settlement (in order of discussion)

Conclusions 1. Piles that are tamped into predrilled holes cutting through soils classed as type II in terms of proneness to slump-type settlement, which have expended tips supported on clayey soils and clays that are not prone to slump-type settlement and that are situated above the water table under conditions prevalent in Zaporozhe, have low (with respect to type-I soils), but, in many cases, completely adequate bearing capacity, and can be used to build many structures.2. The load friction in soil classed as type II in terms of proneness to slump-type settlement amounts to 30–35 kN/m² along the lateral surface of a pile in Zaporozhe.3. The allowable design load on a pile in soils classed as type II in terms of proneness to slump-type settlement should be determined, as a rule, from pile tests in an experimental trench where the soil develops slump-type settlement under its own weight.4. A smaller load friction acts on a pile whose lateral surface is covered with three to five layers of elastic sheathing than on the unprotected piles.Scientific-Research Institute of Bases and Underground Structures. Dnepropetrovsk Civil-Engineering Institute. Ukrainian State Design Institute for Special Construction. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 7–10, May–June 1984.     

Stock test sounding pile

A new design is suggested for a stock sounding pile that makes it possible to separately determine the bearing capacity and deformation characteristics of layers of engineering-geological elements (EGE) on the side surface and tip of the test pile. From these data, any piles sunk into a base with different thicknesses of the EGE can be calculated.Vorkuta Branch of the "Komigrazhdanproekt" Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 15–18, November–December, 1993.     

Investigations of negative skin friction on piles and suggestions on its calculation

Conclusions The investigations showed that negative frictional forces appear at the time of occurrence of continuous settlement of the soil relative to the pile, but for their maximum development this settlement should be relatively large, of the order of 5 cm and more. In addition, it was established that the negative frictional forces act only during active displacement of the soil surrounding the pile as a result of its consolidation or other causes. After this displacement stops the negative frictional forces practically disappear.The established physical characteristics of the effect of negative frictional forces permitted taking the presence of an excess of the rate of soil settlement over the rate of pile settlement as the criterion of their occurrence. The suggestions on calculating piles worked out with consideration of this criterion allows in a number of cases disregarding the negative frictional forces in the effective design load or taking them to be considerably less than by the previously known calculation methods.Scientific-Research Institute of Bases and Underground Structures. State Planning Institute for General Construction and Sanitary-Engineering Planning of Industrial Establishments, Kiev. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 11–15, July–August, 1974.     

Evaluation of pile bearing capacity by dynamic tests

Conclusions 1. In determining the bearing capacity of piles, dynamic resistance should be understood to mean that maximum value of soil reaction which is generated during the hammer blow. However, this concept should not be confused with the resistance obtained from the results of dynamic pile tests.2. Upon the delivery of a dynamic blow, as pile penetration proceeds, an increase in soil reaction occurs which reaches the limiting and then the critical load values as obtained from static tests. Therefore, the results of dynamic tests if the latter are correctly performed should coincide with the critical load obtained from static tests. Experience has shown that for this condition to be fulfilled, the total refusal of piles due to a single blow should be not less than 10–15 mm and the residual part of the refusal should be not less than 2 mm.3. The results of the dynamic tests enable the static pile resistance to be determined for the soil condition at the given instant. As is shown by graphs of the dynamic and static tests, the limiting pile resistance depends not on the type of test but on the condition of the soil and the degree of its thixotropic recovery.4. The determination of pile bearing capacity by the dynamic method, taking their "resting" into account, should be based on the results of the initial blows.Scientific-Research Institute of Foundations. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 11–13, March–April, 1975.     

Analysis of settlements of bored-cast-in-place piles in collapsible soils

Conclusions 1. The proposed method of analysis makes it possible to investigate the behavior of bored-cast-in-place piles interacting with collapsible bases for different complex cases of "soaking" of the soils.2. The sequence in the "soaking" of the soil base and the application of the load to the pile exerts a determining effect on their settlement.3. The loading force of "negative" friction depends on the soil base "soaking" scheme, the "soaked" soil layer thickness, the collapsible soil properties, and other factors.4. The additional pile settlements caused by the "negative" friction forces developed as a result of hanging of the collapsing soil from the pile can be significantly larger than the pile settlements under the load in the absence of collapse.5. "Soaking" of the collapsible soil base from the bottom in parallel layers is more dangerous for bored-cast-in-place piles than "soaking" from the top.Scientific-Research Department of S. Ya. Zhuk Gidroproekt Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 14–17, January–February, 1987.     

Design of laterally loaded piles in a nonlinearly deformable bed

Conclusions 1. The computational method that we have proposed makes it possible to study the performance of the "pile-soil" system in the elastoplastic stage and investigate the behavior of piles and pile frames in all stages of loading — right up to failure.2. Allowance for shear strains in the cross section enables us to reflect the stress-strain state of the "pile-soil" system more precisely and provide high serviceability to the pile beds.Astrakhan Technical Institute, RPKh. Far East Scientific-Research Institute for the Design and Planning of Marine Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 9–11, July–August, 1980.     

Procedure for compiling tables for practical calculations of frame tunnel constructions

This article considers frames used as the calculation schemes for tunnels and channels of typical constructions. For symmetrical loads, an algorithm is given that makes it possible to tabulate the forces at nodes of the frame depending on their initial parameters. The inaccuracy of approximate calculations is evaluated.Central Scientific Research Institute of Industrial Buildings. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 27–29, November–December, 1993.     

Results of evaluation of the strength of concrete placed in the shafts of cast-in-place piles

Conclusions 1. Application of the method of underwater concreting with the use of a container is inexpedient in connection with the presence of a large number of flaws detected in the shafts of cast-in-place piles formed by this method; concreting of holes by the VAT method is preferable.2. The strength of concrete in the shafts of cast-in-place piles increases, reaching a maximum at a depth of 0.4–0.5 the length of the shaft. Variation in strength along the shaft is explained primarily by the percentage of coarse aggregate contained in the concrete.3. The quality of pile concrete should be monitored during all stages of pile installation, and, primarily during the stage of concreting, i.e., when there is a chance of correcting an observed defect.All-Union Institute for the Design and Planning of Health Resorts. Scientific-Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 14–17, September–October, 1976.     

Interaction of cast-in-place piles with soil under type II collapsibility conditions

Conclusions 1. Under the given and similar hydrogeologic conditions, the settlements of piles fully cutting through the collapsible mass and sunk 2–12 m into the noncollapsible soils, when the pile bearing capacity under the external load is satisfied, are practically equal to the ground surface settlements in the pile site.2. For long-term soaking of the soils from the top, the low position of the depth at which soil compression starts under the action of the dead weight of the mass (it is in the range 14–16 m), and the development of compression deformations in the noncollapsible layers, which prevents detachment of the upper soil zone from the piles, are essential under the given conditions.3. For increase in the pile length from 24 to 31 m and support on denser soil layers (alluvial clays), the soil base resistance and the additional load caused by the soil mass action increase correspondingly, but the pile settlements remain practically unchanged.For substantial reduction of the possible absolute pile settlements with prolonged soaking of the soils under the given hydrogeologic conditions, the pile length should be increased by about 20 m. However, for establishment of the foundation dimensions it is extremely important to compare the allowable and possible differential settlements of adjacent foundations, which are comparatively small under the given conditions.Scientific-Research Institute of Bases and Underground Structures. TISI. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 14–17, March–April, 1986.     

Technicoeconomic basis for selection of pile and pile-foundation designs

Conclusions 1. In addition to the factors enumerated at the outset of this paper, the character of the given external effects should be considered in selecting a pile design.It is expedient to use large-diameter (60–120 cm) predrilled-and-rammed piles in cases where the piles should sustain large (100 kN and greater) horizontal loadings, and driven or predrilled-and-rammed piles with a pedestal where the piles should sustain large vertical loads.2. The advantage of one pile design over another should be weighed from both the cost indicators, and the material-outlay indicators for the pile and pile-foundation design, taking into account the resources of the construction organizations as a basis for a variant design.State Institute for the Design and Planning of Beds and Foundations. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 13–16, January–February, 1976.     

Results of investigations of the process of consolidation of drained multilayered peaty bases (joint Soviet-Finnish experiment)

Results are given from many years of experiments to reveal efficient technology and compaction of a multilayered peaty base with the help of various drains: factory-made (the "geodrain" type), and sand ones made directly on the site, with cylindrical (round) and flat cross sections of equal area.Scientific Research Institute of Foundations and Underground Structures. Planning, Design and Technological Institute, St. Petersburg. Central Asian Scientific Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 18–23, September–October, 1993.     

Investigation of the bearing capacity of piles driven in plastic frozen soil

Conclusions The bearing capacity of a pile lowered into a borehole whose cross section exceeds the cross section of the pile for the possibility of filling in with slurry (frozen-in, friction, bored-sunk piles) is close to the calculated, but has a greater settlement under a standard load in comparison with a bored-drive pile.The bearing capacity of piles driven by the VMS-1 vibratory hammer into plastic frozen soil (bored-drive piles) is on the average 1.6 times greater than the calculated. Such an excess of the bearing capacity of the piles can be explained by the formation of a new structure and frost texture of the soil within 30–50 mm around the pile skin. A characteristic feature of the newly formed zone of soil is a considerably greater homogeneity and density of the soil than under natural conditions and absence of ice lenses and interlayers directly contacting the pile.The settlements of the pile tested under a standard load were less than the allowable deformations for the bases of the majority of buildings and structures.The cross-sectional area of the pilot hole should be equal to 0.65–0.75 of the pile section in the case of driving it at the time of the maximum depth of thawing of the soil and 0.95 at the time of seasonal freezing of the soil.Restoration of the contact bonds between the soil and pile during its freezing-in after driving into soil with a temperature of -0.5°C and higher can continue for several months.Deceased.Central Scientific-Research Institute of Transport Construction (TsNIIS). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 19–20, January–February, 1979.     

Introduction of rectangular pyramidal piles in Belorussia

Conclusions 1. The investigations corroborate the results of well-known theoretical and practical studies on the effect of the geometric shape of piles on their bearing capacity. A computational analysis and model and full-scale pile tests established some quantitative relationships between the bearing capacity and shape of driven piles currently being used in construction.2. Investigations and construction experience indicate that there is no "universal" pile which is optimal for all structures and all types of soil conditions. According to the results of investigations of short driven piles, and from design and construction experience, it can be concluded that for loose and medium-density, homogeneous sands and clay soils having a consistency ranging from semistiff to soft/plastic, it is expedient to adopt rectangular pyramidal piles for large-scale construction in the conditions in Belorussia, instead of the prismatic type, as they have shown that, under the above conditions, the volume of pile work is reduced 1.6 times, and labor consumption and costs are reduced commensurately.Belorussian Polytechnical Institute (BPI). All-Union State Trust of Enterprises for Manufacture of Construction Machinery (Stroimekhanizatsiya). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 8–10, January–February, 1980.     

Provision for bearing capacity of permafrost soils in conditions of climate warming

Results are given from numerical calculations of the change in temperature conditions of the permafrost layer and its strength properties with possible warming of the air temperature by 2–4°C in the next 60 years. The effect of these changes on the bearing capacity of permafrost soils and the associated stability of structures erected in the permafrost zone is evaluated. Measures that provide for stability of these structures by using the natural cold of the North are discussed. It is taken into account that the natural temperature of the permafrost layer changes in a meridional direction from north to south, and that, in connection with this, the sensitivity of permafrost soil to a thermal action also changes.Moscow State Construction University. Production and Scientific Research Institute of Construction Engineering Surveys. Leningrad Zonal Scientific Research Institute of Standard and Experimental Design of Residential and Public Buildings. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 2–6, November–December, 1993.     

Effect of oblique extracting forces on single piles

Conclusions 1. Under the effect of an oblique extracting load on a pile there occurs some increase of the bearing capacity in comparison with the case of a vertical load. This increase depends on the angle of application of the load and elastic characteristics of the pile and soil.2. When calculating the effect of oblique extracting forces on a pile the bearing capacity of a single pile can be determined at load application angles from 0 to 10° (from the vertical) for pure extraction without consideration of horizontal forces and from 10 to 40° with consideration of the simultaneous effect of vertical and horizontal forces.Togliatti Polytechnic Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, p. 15, September–October, 1975.