Settling of large buildings and structures erected on clay loess grounds

Conclusions 1. Some 60% of foundation settling in clay grounds of the type considerered here takes place during the construction period. The settling continues for 10 years, and then for an additional 20–25 yr at a very low rate.2. The II-B.5–67 scheme of pile foundation, proposed by the SNiP from the analysis of deformations, is substantiated by the actual settlings.3. Settlings calculated by different methods differ but little among themselves and are in fair agreement with the actual settlings. The single instance of great discrepancy between the theoretical and actual data evidently is due to changes in ground facies and the rate of compactions.4. The published data [1, 2] on a marked discrepancy between the theoretical and actual data on settleling for the large structures should be regarded as anomalies associated with foundations in sandy grounds and acted upon either only by the static loads (minor settlings) or by the combined static and dynamic ones (large subsidences).5. Observations of settling should start with the construction, at loads not exceeding the operational, with accurate records kept on loads transmitted to the foundation.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 29–31, September–October, 1971.     

Evaluation of pile bearing capacity from results of static penetration tests using a probabilistic approach

Conclusions 1. Based on a probabilistic approach taking into account the natural heterogeneity of the soils in the engineering-geologic elements and the depths at which they are located, the analytical value of the pile bearing capacity was obtained (for the specified probability of unfailing operation) from the static penetration test results.2. The analysis of the factual material indicates a possible increase, by 16–25% (for R=0.95) in comparison with the SNiP II-17-77 Norms (since January 1, 1987 with the SNiP 2.02.03-85 Norms) of particular values of the limit resistance of the pile at the penetration point.Soyuzgiprovodkhoz. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 7–9, July–August, 1987.     

Determination of the bearing capacity of piles in permafrost by static penetration

Conclusions 1. The tests that we conducted demonstrated the technical feasibility of the static penetration of plastically frozen soils with temperatures of 0 to –0.4°C by series-produced type SP-59 and SP-72 apparatus.2. According to penetration data, computation of the bearing capacity of piles in plastically frozen soils using the method proposed by Ladanyi indicate good convergence with data derived from the field testing of piles.3. Penetration makes it possible to determine the bearing capacity of piles in plastically frozen soils with a temperature above –0.3°C on which there are no data for the computation in SNiP II-18-76, and the increase their bearing capacity by 25–30% as compared with the SNiP for soils with temperatures of –0.3 to 0.4°C.4. Further research on the development of a technology and methodology for static penetration of plastically frozen soils of different lithologic composition and temperature, and also a more precise definition of a number of parameters , n, and m, which are used in computations of pile bearing capacity, are necessary.State Institute for the Design and Planning of Beds and Foundations. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 18–20, March–April, 1986.     

Optimal design of foundations of short piles with a monolithic grillage for rural construction

Conclusions 1. For the more effective use of short piles it is necessary to continue investigations and to supplement Tables 1, 2, and 6 of SNiP II-B.5-67* with consideration of the possibility of using piles with a depth less than 3 m.2. It is necessary to revise the instructions in point 9.4 [2] with respect to the minimum distance between piles 3d and to allow reducing it in cases when this is justified by the incomplete use of the bearing capacity of the piles and economic considerations.Petropavlovsk Rural Construction Administration. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 21–24, September–October, 1975.     

Tests of driven piles in slump-prone soils under the effect of horizontal and elastic loads

Conclusions 1. Flooding of a soil base leads to a substantial increase in deflection of piles under the effect of horizontal loads.2. Fixing the piles at the level of their head leads to a decrease of deflection and increase of their bearing capacity.3. An increase of reinforcement compared to series 1.011-6 has little effect on deflection of piles at the first stages of loading, but has a considerable effect on their ultimate bearing capacity.4. For horizontal loads of 15 kN per pile its deflections in flooded soils of type I slump-proneness do not exceed 10 mm, which is permissible for the given type of buildings.Trust for the Organization of Construction Technology, Main Administration for Construction in North Caucasian Regions (Orgtekhstroi Glavsevkavstroya). Kharkov Design and Scientific-Research Institute of Industrial Construction (Promstroiniiproekt). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 14–15, May–June, 1980.     

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.     

On the rational range of application of different designs of pile foundations for residential construction in weak soils

Conclusions 1. At the present time, sectional driven piles of continuous square cross section are economically the most expedient for foundations supporting large-panel 9- and 16-story apartment houses built on weak soils of considerable thickness (more than 12–16 m).2. Of the square sectional pile designs employed in the USSR, the most technically rational and economically effective design is the sectional driven pile with a socket splice.3. A material-technical base now exists for the widespread use of square sectional piles. General-contracting organizations maintain pile-driving equipment in their inventory, all reinforced-concrete-products plants produce square driven piles, and an effective and reliable splice design has been developed.4. To increase the installation efficiency of pile foundations for buildings constructed on weak soils of considerable thickness, it is necessary to develop working drawings of type designs for square sectional piles, type plans for the foundations of apartment houses which are constructed of square sectional piles, estimated norms for their embedment at the construction site, and recommendations for the range of their rational application.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 23–26, March–April, 1977.     

Maximum permissible values of nonuniform settlements of agricultural buildings

Conclusions 1. For single-story agricultural buildings with a complete framework and yielding-type attachment of panels to the frame, it is recommended to adopt, at the next revision of Construction Norms and Regulations (SNiP) II-15-74, a maximum differential settlement of 0.01 mm.2. In designing agricultural buildings, provision should be made for yielding connections between the panels and the framework, adoption of a joint gap of not less than 20 mm between reinforced-concrete panels and 40–50 mm between asbestos-cement panels, and filling of the joints with easily compressed thermal containers.Central Scientific-Research Institute of Experimental Design in Agricultural Construction (TsNIIEPsel'stroi). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 6–8, September–October, 1979.     

Piles injected into predrilled holes in soils prone to slump-tyre settlement

Conclusions 1. Drill-and-inject piles of increased bearing capacity with a diameter of 250–400 mm and more and a depth of up to 50 m and more, which are embedded into underlying soils not prone to slump-type settlement can be used in loess soils classed as type-II in terms of proneness to slump-type settlement.2. The use of washing mud based on sodium silicate, which eliminates slump-type settlement of the soils during pile fabrication and reduces the friction against their lateral or surface by 10–15% within the limits of the stratum prone to slump-type settlement, lowering the negative loads on the pile, is effective when piles are injected into predrilled holes in soils prone to slump-type settlement.3. Drill-and-inject piles 250–400 mm in diameter and up to 50 m long have a design bearing capacity of from 0.50 to 2.50 MN and can be recommended for the installation of new, and the strengthening of existing foundations for civil and industrial projects in soils prone to slump-type settlement.4. A special set of equipment, which makes it possible to ensure the continuous production of work that includes the drilling of holes, assembly of reinforcing cages, and the filling of the holes with a hardening grout, should be used for the installation of these piles."Soyuzgidrospetsstroi." Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 18–20, January–February, 1988.     

Discussion of SNiP 2.02.04-88 Norm "bases and foundations on permafrost soils"

From the Editors: The complexity of construction on permafrost soils, as well as numerous cases of deformation of structures constructed on such soils, calls for an especially careful design and construction approach. The preparation of all editions of the SNiP Norms for design of bases and foundations on permafrost soils (including the last edition 2.02.04-88 of the SNiP Norms), has always been carried out with the participation of many different organizations, and their discussion is of a wide nature. However, after edition of the latest SNiP Norms and their approbation in the engineering practice, continuation of this discussion is highly desirable.For this reason, on publishing the present article without any evaluation of the recommendations contained in it, the Editors ask the specialists in the field of foundation construction on permafrost soils to express their opinions about the questions considered in the article as well as about other criteria of the SNiP 2.02.04-88 Norms.Vorkuta Branch of the "Komigrazhdanproekt" Institute. PechorNIIproekt Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 30–32, March–April, 1993.     

饱和黏性土地基中现浇大直径管桩水平振动响应解析解

基于经典的平面应变假定,将土体假设为若干个相互独立的薄层,对饱和土地基中现浇大直径管桩水平振动频域特性进行了理论研究。首先通过引入势函数对土体动力固结方程解耦,采用Laplace变换和分离变量的方法求得了桩周土及桩芯土频域响应解析解,进而利用桩土完全耦合的条件得到桩振动响应解,给出了桩顶复阻抗解析表达式。将本文解完全退化到实心桩的解与已有理论解对比,验证了本文解的合理性并阐明两解的区别。通过参数分析,得到了桩长以及桩半径等参数对复阻抗特性影响的规律。     

Design values of strength characteristics of frozen saline soils

Based on a large number of personal tests and analysis of results of investigations of other authors, the writers comment upon the design values recommended in the SNiP 2.02.04-88 Norms for the strength characteristics of frozen saline soils.NIIOSP Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 27–29, March–April, 1993     

Computing the settlements of foundations placed on beds with layers of weak clayey soils

Conclusions 1. In designing natural foundation beds with layers of weak clayey soils, the final settlements of the foundations and the settlements with time can be computed using the theories of elasticity and seepage consolidation in accordance with the method outlined in the paper. This is confirmed when additional (over and above the natural) pressure p₀ 5c are applied to the top of the weak clays, where c is the minimum specific cohesion of the clayey soils as determined with allowance for the possible reduction in cohesion with time. When p₀ > 5c, including pressures on the roof of the weak clays equal to the design pressures given in Section 3.62 of SNiP II-15-74, there are only isolated cases of building construction from which it is impossible to judge laws governing bed deformation.2. In conformity with Section 1, the method of computation clarifies the computation of settlements as compared with SNiP II-15-74, simplifying the design of beds with layers of weak clayey soils.Scientific-Research Institute of Bases and Underground Structures (NIIosnovanii). Estonian Institute of Industrial Design and Planning. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 15–18, July–August, 1981.     

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.     

Construction on loess soils

Conclusions 1. Inadmissible settlements and tilts of several multistory buildings in Volgodonsk are the result of collapse of the soils under external loads owing to disregard of the requirements for elimination of the collapsibility within the limits of the entire deformable zone under shallow foundations.2. The cause of the possible settlements of structures on pile foundations fully cutting through the collapsible mass lies in development, under soaking from the top, of deformation phenomena with compaction not only of the collapsible layers but also of the underlying non-collapsible soils, which was first mentioned in [9].The concept that the most hazardous situation for a pile foundation, in this regard, occurs when collapse takes place under the weight of the overlying mass with the GWL rising from bottom to top is erroneous and is not confirmed by construction experience.3. In the development of deformation phenomena, it is important to distinguish between the active period and the settlement attenuation period, since differential settlements occur only during the active period for all practical purposes.4. It is possible to eliminate completely the possibility of substantial settlements of structures under severe Type II collapsibility conditions either by construction of deep founations carried to 40–50 m so that they will rest on solid material, or by elimination of the possibility of soaking of the soils. These highly uneconomical solutions can be used only in especially important cases. On the other hand, in the massive construction practice it is justifiable to correctly fulfill the SNiP requirements, taking into account the possible additional settlements caused by compression of the underlying noncollapsible soils.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 24–27, January–February, 1991.     

Design of beds and foundations for rural buildings framed with three-hinge mill bents

Conclusions 1. Until more modern methods of computation are developed, it is recommended that the bearing capacity of beds for rigid rectangular foundations of agricultural buildings framed from three-hinge mill bents with a relative embedment 0.5h/B1 and angles of incline of the resultant of external loads 20<<45° from the vertical be determined by the method outlined in ICR 0.1–76. The method described in SNiP II-15-74 should be used when the relative embedment of the lower surface is less than 0.5 and the angles <.2. It is recommended that the long side of rectangular foundations be placed in the direction of the shearing force.3. As has also been noted by other investigators, determination of the effective width of a foundation in accordance with the Gersevanov method leads to excessive safety factors in estimating the bearing capacity of a foundation bed. The need has arisen to develop more accurate procedures that take into account the configuration of the lower surface of the foundation, the relative embedment of the lower surface, and other factors.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 14–16, November–December, 1982.     

饱和及非饱和粉土中扩底桩极限上拔承载力大尺寸模型试验研究

 通过采用大比例尺模型对饱和度为49%的非饱和粉土及饱和粉土中埋深比(桩埋深与扩底直径之比)为1,2,3和5的扩底桩进行试验研究,揭示饱和度、埋深比对扩底桩极限上拔承载力及其破坏模式的影响。试验结果表明：土体饱和度从49%增加至100%,扩底桩的极限上拔承载力降低至原来的30%～50%;扩底桩埋深比从1增加至5,非饱和及饱和土中桩的极限上拔承载力分别增加8和12倍;扩底桩的上拔破坏模式随埋深增大由桩周土体倒圆锥台形破坏变为扩底圆周土体局部破坏。     

Possibility of reducing the duration of static pile tests

Conclusions 1. The experiments, carried out under different conditions, did not show substantial differences in the limit strengths of prismatic piles tested at the standazd loading rate and by the accelerated method when it is considered that attenuation of the settlement has been reached when it has a rate of 0.1 mm in 15 min. The tests performed by continuous increase in the load over a period of 10–15 min led to overestimation of the limit strengths by 20–30%.2. Under conditions in which the settlements are not the object of special studies, accelerated pile tests (with a settlement stabilization criterion of 0.1 mm in 15 min), in place of standard prismatic piles applicable under the most widespread soil soil conditions (for example, in alluvial, deluvial, and similar deposits). In this case, it is advisable to use the pile limit strength for settlements which are smaller by a factor of two than for the standard tests.NIIpromstroi Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 9–12, January–February, 1987.     

Analysis of foundation installation for old buildings in downtown Saint Petersburg

Basic types of foundations supporting old buildings in Saint Petersburg are reviewed. Fundamental relationships between the width and depth of embedment of the foundations and the number of stories are analyzed on the basis of field observations. Average pressures against the lower surfaces of the foundations are compared with design strengths adopted from modern standards for bed soils.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 13–15, September–October, 2004.     

Settlements of experimental plates on plastic-frozen soils

Conclusions Plastic-frozen soils can develop perceptible creep settlements, which can exceed the limits of permissible values. The data of long-term experiments thereby confirm the validity of the requirements of SNiP II-18-76 concerning the need to calculate bases composed of plastic-frozen soils not only with respect to strength but also deformations. In this case it is necessary to take into account both settlement due to consolidation and settlement due to creep.To calculate settlements from the data of field tests one can use Eq. (8) or (10), and with consideration of a variable load or time-varying temperature — Eq. (7).Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 26–29, September–October, 1978.