Pile Quality Research Articles

The Study of the Quantity of Wave Speed in Low Strain Integrity Testing of Foundation Pile

the stress wave speed is the necessary condition to make sure pile length and pile defects position in low strain integrity testing of foundation pile with the stress wave echo method. Quantifying the stress wave speed is very difficult, because it is affected by multi- factors. This has been choke point developing test technology of foundation pile. In the paper, some factors influencing the stress wave speed were analyzed according to stress wave theory and experiment results, the quantity relations of the stress wave speed in pile and time and concrete age were made sure. lastly, five brief methods to quantifying the stress wave speed in pile were presented to control pile quality for test engineers according engineering practice.

SIP공법 시공시 문제점 발생 요인 분석 및 대응 방안

현재 건설현장에서 매입말뚝공법인 SIP(Soil-cement Injected Precast pile)공법이 널리 활용되고 있다. 그러나 SIP공법 시공시 문제점 발생 요인들로 말뚝의 품질이 저하되거나 부실시공이 빈번히 발생하고 있다. 본 연구에서는 이 문제를 줄이는 방법으로 SIP공법을 중심으로 시공할 때 문제점 발생 요인 종류별로 현장 기술자들을 대상으로 설문조사를 수행하였다. 그리고 설문 분석 결과를 토대로 문제점 종류별로 자주 발생되는 문제점 요인을 분석함으로써 대응 방안을 제시하였다. 본 연구에서 제시한 문제점 요인별 대책은 향후 건설현장에서 SIP공법으로 시공할 때, 문제점을 최소화할 수 있는 효과적인 자료가 될 것으로 사료된다. Currently in construction Soil-cement Injected Precast pile of buried pile method are in wide use. But deterioration in pile quality and faulty construction can be often found these days because of problems arise in the construction field. For this study, survey was carried out by targeting construction engineers working in the field in order to identify the types and the causes of problems arise based on SIP(Soil-cement Injected Precast) method. By analyzing the causes of problems arise, countermeasures could be presented. The data and the analysis presented in the study could be effectively used for minimizing problems arise in future during SIP method construction.

Testing Methods for Rock-Embedded Foundation Pile in Karst Area

In karst area, geology condition is complex, karst phenomena develop, underground water is prolific, even underground river and channel exist, rock surface fluctuates up and down in a large level, which will seriously influence type of pile foundation, construction quality as well as pile foundation safety. Pile foundation construction is considerably difficult and severe hidden quality fault may occur. If rock-embedded end-bearing pile on hard rock or limestone can satisfy design requirement depends mainly on integrity of bedrock beneath pile end, pile body concrete quality and settled material beneath pile end, which are the key items for rock-embedded pile test. Using acoustic wave transmission method and core sample method, integrity of bedrock beneath pile end, pile body concrete quality and settled material beneath pile end can be tested, which can not only reflect quality and bearing capacity of single pile, but also assess bearing capacity of all foundation piles in the whole ground.

Analysis of Relationship between Pile Quality and its’ Bearing Capacity

Bored pile is one of the most widely used foundation forms in civil engineering. Relationship between pile quality and its’ bearing capacity is seldom been discussed. This paper introduces 8 bored piles in one storage tank project in Ningbo, of which 4 piles are done vertical load tests; the other four are done lateral load tests. Combined with their quality, the results reveal that when load is small, pile quality has much influence on pile bearing capacity. As soon as load is large enough to transfer to pile bottom, quality of concrete at pile bottom becomes the main factor that impacts pile vertical capacity, meanwhile pile horizontal bearing capacity mainly depends on pile length. Post-grouting is done to improve pile quality. It raises pile’s bearing capacity while reducing differential settlement at the same time.

기계굴착공법을 적용한 현장타설말뚝 시공시 부조화 발생요인 분석 및 대응 방안

현재 기계굴착공법인 올케이싱, 어스 드릴, 역순환공법이 널리 활용되고 있음에도 불구하고, 시공 현장에서 발생되는 부조화로 인하여 말뚝의 품질이 저하되거나 부실시공이 빈번히 발생되고 있다. 본 연구에서는 이 문제를 줄이는 방법으로 올케이싱, 어스 드릴, 역순환공법을 중심으로 현장 콘크리트타설 말뚝 시공시 발생되는 부조화 종류별로 부조화 발생요인을 현장기술자들을 대상으로 설문조사를 수행 하였다. 그리고 설문분석결과를 토대로 부조화 종류별로 빈번히 발생되는 부조화 요인을 분석함으로서 대응방안을 제시하였다. 본 연구에서 분석된 자료는 향후 건설현장에서 기계굴착공법으로 시공될 때, 부조화를 최소화 할 수 있는 효과적인 자료가 될 것으로 사료된다. Although a range of machine excavation methods are in wide use, including casing, earth drill and reverse circulation drilling, deterioration in pile quality and faulty construction can be often found these days because of trouble in the construction field. For this study, research was conducted in the form of a survey of construction engineers working in the field in order to identify the types and the causes of trouble by focusing on all casing, earth drilling and reverse circulation drilling. By analyzing the causes of trouble, countermeasures could be presented. The data and the analysts presented in this study could be effectively used for minimizing trouble in future machine excavation work during construction.

Use of large-diameter, cast–in situ concrete pipe piles for embankment over soft clay

A new method of using large-diameter, cast–in situ concrete pipe (PCC) piles for embankments over soft clay is introduced in this paper. This PCC pile method offers a relatively quick and cost-effective way for soil improvement as compared with other existing soil improvement methods. The principles and construction techniques involved in this method are described. Full-scale model tests were conducted to evaluate the quality and performance of piles and the responses of the surrounding soils. Methods that can be used to check the quality of the pipe piles are elaborated. A case study that illustrates the application of this method in a piled embankment over soft clay is presented.

Methods to improve the quality of auger piles : Brons, K F; Kool, A F Proc 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7–10 June 1988P269–272. Publ Rotterdam: A A Balkema, 1988

Methods to improve the quality of auger piles : Brons, K F; Kool, A F Proc 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7–10 June 1988P269–272. Publ Rotterdam: A A Balkema, 1988

Coal Pile Leachate—Quantity and Quality Characteristics

A detailed monitoring of an existing coal pile at Ithaca, N.Y. was performed to determine coal pile leachate (CPL) quantity and quality variations. The total quantity of CPL generated consists of two components, base flow and surface flow. During periods of no precipitation, retained moisture within the coal pile dissolves minerals that are flushed from the pile by precipitation. Following the first flush only minor concentration of minerals are carried from the pile in continuing CPL flows. This is particularly true of total iron, copper, manganese, chromium, and zinc. The CPL pH was found to be generally stable. CPL design quantity and quality parameters can be developed following the collection of sufficient monitoring data for each specific site to permit development of flow and primary contaminant hydrographs describing the flush phenomena and to permit determination of base flow rates and minimum contaminant concentrations.

Testing of drivability of concrete piles and disturbance to sensitive clay

The results reported are of an investigation of a group of thirteen 12 in. (30 cm) diameter precast concrete piles driven through 60 ft (18 m) of sensitive marine clay followed by 10 ft (3 m) of silt and sand and 13 ft (4 m) of very dense silt to end bearing in glacial till. The purpose of the test is to study the drivability of the piles through very dense soil and to measure the disturbance caused to the sensitive clay by the driving of displacement piles. Following a literature review, the paper presents the soil conditions at the site and the testing program. The test results are discussed and experience gained from the follow-up of the driving of 520 piles at the site is presented.Visual observations during pile driving, and analysis of driving records, show that a high pile quality is necessary at the site. The large driving resistance encountered in the very dense silt (150 to 300 blows/ft) would prevent low quality piles from reaching the competent glacial till and developing the needed bearing capacity.Pile loading tests showed the piles to have an ultimate bearing capacity exceeding 450 tons (4.0 MN). It was established that the shaft resistance in the clay during test loading was between 100 and 125% of the undrained shear strength of the clay as measured by field vane testing. In comparison, an uplift test to failure showed that the uplift shaft resistance along the pile in the clay was only 60% of the undrained shear strength of the clay.The pile driving developed large pore pressures in the clay which exceeded the effective overburden stresses. The excess pore pressures dissipated over a period of slightly more than 3 months. Vane testing within the pile group immediately after driving showed that a shear strength reduction of about 15% was caused by the piles. At a distance of 2 ft (0.6 m) outside the pile group, no strength reduction was found. The reduction within the group was gradually regained during the dissipation of the induced pore pressures. Laboratory testing on clay samples obtained within the pile group 75 days after pile driving showed a smaller value of the preconsolidation pressure of the clay, but no change in the compression indices.