Ways to reduce metal consumption in the construction of sunken shafts

Conclusions 1. A number of positions taken in active documents regulating questions concerning the computation and design of sunken shafts embedded without a thixotropic jacket are highly conditional and require more precise definition. This applies primarily to the computation of wall failure during hang-up of the lower section of the shaft and the soil pressures on circular shafts possessing diameters to 16 m with allowance for their actual curvature.2. The method recommended in the present paper for the design of circular sunken shafts with diameters to 16 m and depths to 10–12 m makes it possible to reduce significantly (by 25–30% on the average) the amount of reinforcement in the upper section of the shaft wall as compared with its consumption for type designs without impairing the strength of the structures.3. It is expedient to disseminate construction experience acquired with lightly reinforced sunken shafts in Vyaz'ma, Leningrad, and Moscow for structures of similar dimensions under various engineering-geologic conditions using the manual of structural solutions and technological schemes for work production developed by the Leningrad Division of the State Institute for the Design and Planning of Beds and Foundations.4. In sinking lightly reinforced shafts, it is necessary to follow especially carefully the conditions set forth in the plan for work production, particularly the excavation of soil in the blade segment, prohibiting their skewing so as to ensure uniform pressure between the shaft walls and ground.Main Administration for Special Foundation Construction. Leningrad Division of the State Institute for the Design and Planning of Beds and Foundations. All-Union Scientific-Research Institute of Hydraulic and Sanitary Engineering. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 8–9, November–December, 1979.     

Effect of boring method on bearing capacity of short cast-in-place piles

Conclusions 1. Bored-hole/cast-in-place piles 4–10 m long tend to retain a constant value of the unit bearing capacity, irrespective of soil moisture. Driven piles, and piles cast in punched holes, undergo a loss unit bearing capacity (up to 20%) as their length is increased.2. With the saturation of high-porosity collapsible soils, the unit bearing capacity of bored-hole/cast-in-situ piles up to 10 m long diminishes two to three times, on average. For cast-in-place piles installed in a punched hole, and for driven piles, this reduction ranges up to only 30%. This trend is characteristic of soil layers whose collapsibility properties diminish with depth, from 2–3% to 1–1.5%.3. The unit bearing capacity of cast-in-place piles installed in punched holes is equal to that of driven piles, both for saturated and dry soil conditions.4. Following soil compaction, the unit bearing capacity of concrete cast-in-place piles installed in punched holes is higher than for bored-hole/cast-in-place piles, in the ratio of up to 2 for slightly moistened soils and 3–3.5 for saturated soils.5. All other conditions being equal, the unit bearing capacity is greater for driven piles, and somewhat smaller (by 10–15%) for piles cast in punched holes. The smallest unit bearing capacity is observed in bored-hole/cast-in-place piles (1.5–2 times less than for driven piles).Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 14–15, July–August, 1979.     

Bearing capacity of cast-in-place piles on construction sites of the volgodonsk heavy machine-building plant

Conclusions 1. The behavior of large-diameter (a shaft diameter of 1 m, a pedestal diameter of 2.2 m, and a length of up to 25 m) cast-in-place piles subject to an increasing crushing load in a stratum of wetted loess soil is characterized, as with small-diameter piles, by a clear-cut transition from an elastic to a plastic state with small settlements (up to 12 mm).2. Pile settlement owing to compression of the shaft is a significant part (0.6) of the total settlement experienced by the pile within the loading range from 0 to P_ul.3. Computations of the bearing capacities of piles performed in accordance with an approximate solution of the problem of limiting equilibrium [4, 5] are in good agreement with data obtained from static pile tests in all cases under consideration; this made it possible to use them in designing the Nos. 1 and 3 frames of the plant with a savings of 1.5 million rubles.4. Computations of pile bearing capacities, which are performed in accordance with the plan outlined in Chapter II-17-76 of the Construction Norms and Specifications should be defined more precisely.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 13–16, March–April, 1977.     

Experience with construction of cast-in-place slag-soil-cement pile foundations in Zaporozhe

Conclusions 1. The simple technique for construction of slag-soil-cement pile foundations makes it possible to build piles with widened tips or thickened shafts at any level.2. It is recommended that as fill material use be made of any hardening mix meeting the strength and operation requirements of the structures, including blast-furnace slags.3. Maximum mechanization of the zero-cycle (substructure) work is attained.4. Maximum utilization of the fill material is achieved and the lowest cost per 10 kN of bearing capacity of the piles is obtained, for high-quality, reliable foundations.Zaporozhe Branch of the BV Section of the Scientific-Research Institute of Bases and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 6–7, March–April, 1985.     

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.     

Construction of deep pile-columns at the Noril'sk combine

Conclusions 1. For design loads of up to 300 tons on piles it is convenient to use Type-NSF-40 precast piles, while for large loads and depths of over 24 m it is convenient to use bored piles with diameters of not less than 800 mm.2. It is important to take into account the fact that for bored piles it is necessary to apply careful techniques, especially in connection with continuous concreting and with mixing of the concrete with antifreezing chemical admixtures.Noril'sk. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 11–12, March–April, 1973.     

Means of increasing the effectiveness and quality of foundations constructed of cast-in-place piles

Conclusions 1. The type SO-2, SO-1200, and MBS-1.7 apparatus currently used to drill holes for cast-in-place piles provide for high drilling productivity, but do not permit complete cleaning of the base of the hole. It is necessary to fit their working devices with attachments to clean the hole bottoms and taper sections.2. The condition of the face of the hole prior to placement of the concrete should be inspected and corected. For this purpose, it is necessary to develop attachments or devices to check the condition of the hole bottoms.3. In developing plans for the production of work, it should be stipulated that the concrete be delivered into the hole directly from transit-mix trucks.4. In dry stable soils, holes can be concreted by the free-fall method with concrete having a slump of 10–12 cm and a cement factor of 250–300 kg per 1 m³ of concrete.Scientific-Research Station of the All-Union Lenin Order S. Ya. Zhuk Scientific-Research Institute for Design and Exploration (NIC Gidroproekta). Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 10–14, November–December, 1976.     

质量控制点在钻孔灌注桩施工中的应用

质量控制点是土木工程施工中对质量进行事前控制的常用方法。本文在钻孔灌注桩施工中,通过事前对其过程进行分析,确定其关键工序和薄弱环节并设置质量控制点,提出了保证施工质量应采取的预控措施。通过质量预控,灌注桩的质量全部满足工程桩的要求,表明质量控制点的设置是准确的,质量预控措施是有效的。     

Bored/cast-in-place piles employing soil compaction of hole bottom,for the "Atommash" Plant

Conclusions 1. Compaction of the soil at the bottom of deep holes of 1-m diameter as described, raised the bearing capacity of piles at their ends, under the Volga-Don ground conditions, by three to five times.2. In view of the fact that the toe of long (exceeding 15 m) floating bored/cast-in-place piles of usual construction contributed only to a weak extent (up to 10% of the total resistance, under Volga-Don conditions) to the performance of the pile, right up to its failure, it is expedient and economically efficient to install such piles only in holes previously rammed at their ends. Under ground conditions of type II in regard to collapsibility, this measure is particularly important in order to avoid inadmissible pile settlements resulting from negative friction following soil collapse under the weight of its own thickness. Cast-in-place piles placed in prerammed holes were introduced in the construction of Section 5 of the Volga-Don "Atommash" Plant, and are recommended for buildings of a substantial number of stories in Volga-Don.Scientific-Research Institute of Bases and Underground Structures. (NII Osnovanii) Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 10–13, November–December, 1980.     

Analytical model for evaluating XCC pile shaft capacity in soft soil by incorporating penetration effects

The derivation of a new analytical model for predicting the soil displacement of X-section cast-in-place concrete (XCC) piles installed vertically into soft clay as well as for predicting limit shaft resistance during loading phases is presented in this paper. The analytical model is formulated by assuming that the XCC pile penetration process is an X-shaped cylindrical cavity expansion process. Based on the theoretical framework of the Strain Path Method (SPM), the strain, displacement and stress induced by X-shaped cavity expansion can be obtained. The proposed analytical model is validated by comparing the degenerate solution of this study with that of conventional circular (cylindrical) cavity expansion theory. Analytical model-based design methods are then proposed for evaluating soil displacement and XCC pile shaft capacity. Theoretical predictions are compared with field test measurements to verify the suitability of the proposed design method. The proposed new analytical model reveals the fundamental penetration mechanics of XCC piles and gives improved design methods for determining XCC pile shaft capacities.     

大直径随钻跟管桩竖向抗压承载性能试验研究

随钻跟管桩是一种桩侧后注浆的非挤土PHC管桩桩型,是近年研发出的新型大直径桩基础。为了研究这种新桩型的竖向抗压承载性能,对现场5根直径1m的随钻跟管桩进行静载和高应变承载力试验。研究结果表明：以静载试验结果为校核标准,高应变承载力检测误差可控制在±10%以内;嵌岩0.5m的随钻跟管桩极限承载力可达到20000kN,比同等直径泥浆护壁灌注桩的承载力经验计算值大13%～23%;桩侧后注浆工艺和桩端嵌岩深度能有效提高随钻跟管桩的侧阻力发挥,实测值比灌注桩的规范计算值大28%以上;虽然现场4根随钻跟管桩均嵌入中风化花岗岩0.5m,但端阻比小于30%,呈现摩擦型桩的承载性状。试验成果有助于进一步揭示随钻跟管桩的竖向抗压承载机理,可为其工程设计与工艺优化提供依据。     

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.     

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.     

Experience with use of pile foundations in rural construction in Kazakhstan

Conclusions 1. The introduction of short-driving and cast-in-place piles is technically and economically justified under conditions of residential, school, and agricultural construction.2. For a more rational application of pile foundations, it is recommended that soils be probed statically with an S-979 apparatus, and the results combined with data of engineering-geologic surveys and dynamic pile tests.Petropavlovsk Rural Construction Administration, Petropavlovsk. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 9–11, May–June, 1975.     

后压浆灌注桩的实际应用

灌注桩后压浆技术解决了桩底沉淤和桩身泥皮影响灌注桩承载力的问题,使桩底、桩侧土得到了加固,从而大幅度提高了灌注桩的承载力,降低了桩的沉降量。本文通过对某高层住宅大直径后压浆灌注桩和普通钢筋混凝土灌注桩的设计及静载对比试验,说明了后压浆灌注桩是一种承载力高、经济效益显著的桩型,在太原市地质条件下,值得推广应用。     

现浇混凝土夹芯桩(空心桩)成桩工艺的研究

介绍了等效于现浇混凝土空心桩的几种现浇混凝土夹芯桩及其施工方法.在桩体安装好的钢管内,灌入余土制成的砂石混合泥浆,在紧后的拔管过程中,令管内砂石混合泥浆及时填补拔管留下的空间,并对新浇的混凝土桩身内筒壁进行有效护壁,拔管后即形成了连续施工的现浇混凝土夹芯桩.由于夹芯桩等效于空心桩,故解决了现浇混凝土空心桩无法连续施工的...     

湿陷性黄土中大直径扩底桩垂直承载性状的试验研究

本文根据湿陷性黄土中桩侧和桩底均埋有测试元件的４根大直径扩底桩的现场实测数据，分析了浸水湿陷对桩垂直承载力的影响，得出了负摩阻力的变化规律，最后提出浸水湿陷全过程中大直径桩荷载传递机理的《三阶段分析法》。     

Use of radioisotopic measurements to control the quality of concrete placement within the bodies of cast-in-place piles

A procedure is proposed for rapid quality control of concrete placement in the bodies of cast-in-place piles; this procedure includes assessment of body density, continuity, and strength, based on the processing of results of radioisotopic measurements in holes preliminarily installed in the body of the pile. It is demonstrated that the procedure is rather simple to implement and effective, and can be recommended for broad use in construction practice. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 22–25, March–April, 1998.     

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.     

不稳定场地上桩基的施工与试验

通过近1000根桩基的施工,分析工程的土质特点、存在矛盾,对需堆载预压（尤其是较大厚度）的回填爆破石渣场地上,灌注桩桩型及冲孔钻孔成孔工艺的可行性进行分析。对目前电力工程选址及对类似土质的处理及施工经常遇见的现象提点经验,供借鉴。