Grouting Pile Research Articles

Evaluation of Post-grouting Bearing Capacity of Cast-in-situ Bored Pile Based on Self-balance Method

When the site conditions are complex and the building structure is sensitive to settlement, post-grouting can be adopted for bored grouting pile to improve its bearing capacity, reduce settlement and improve the safety of pile foundation. In this paper, the ultimate bearing capacity of pile foundation is tested by self-balance method, and the ultimate bearing capacity of the two test piles is improved by 95% and 33.3% respectively. The post-grouting has a good impact on the formation with poor bearing capacity and denaturation index.

Field study on post-grouting effects of cast-in-place bored piles in extra-thick fine sand layers

The post-pressure grouting technique has proven to be an effective method to enhance axial resistance. In this paper, field tests were conducted to investigate the performances of large-diameter cast-in-place bored piles for six combined side-and-tip grouting piles and two side-grouting piles in extra-thick fine sand layers. The load–displacement response, shaft resistance, and mobilization of unit base resistance were discussed. The field results indicate that compared with the piles before post-grouting both the shaft resistance and base resistance for the piles after post-grouting are significantly improved. The piles after post-grouting have higher load-bearing capacity. Meanwhile, the load-bearing capacity of combined-grouting piles is also greater than that of side-grouting piles. Additionally, the strengthening effect of the surrounding soil improvement due to side grouting on the base resistance can enhance the unit base resistance, and the unit shaft resistance can also be increased by the soil improvement at the pile tip due to tip grouting. Moreover, the distribution of the injected pressurized grout at the pile tip and side is detected by an electromagnetic wave computerized tomography (EWCT) technique. The results reveal that EWCT can detect the distribution pattern of the pile, injected grout and geotechnical interface and evaluate the diffusion range of the grout of the soil at the pile tip and side, which can be used to assess the grouting effect of grouted piles. Finally, an in situ standard penetration test is employed to evaluate the grouting effect of grouted pile by variation of the SPT N value before and after post-grouting. The research results have reference value and guiding significance for the design and effect detection of post-grouting piles.

Analysis of the Bearing Capacity of Helical Pile with Hexagonal Joints.

This study aims to improve shafts with hexagonal joints so that they will not require welding or bolts in static load tests. In order to evaluate the bearing capacity of helical piles, two sites were selected to conduct pile installation for the field test and the pile load test. For the pile load test, a static pile load test and a dynamic pile load test were carried out, and torque was measured during pile installation in a field test to compare and analyze the expected bearing capacity and thus assess the feasibility of the method for estimating the bearing capacity. The field pile load test revealed that the bearing capacity of the gravity grout pile was the same or greater than 600 kN in the static pile load test in accordance with the AC 358 code. The non-grout pile showed a bearing capacity that was the same or smaller than 600 kN, suggesting that gravity grouting is required. Moreover, the field pile load test was used to establish the bearing capacity equation considering the torque in the pile installation, and a small number of samples were used to establish the equation, which can be used as basic data.

Base stability of deep excavation in clay reinforced with grout piles

For clay reinforced with grout piles, its shear strength is not easy to determine because the overall strength characteristic of the reinforced soil is the combined result of the shear strengths of the clay and grout piles, improvement ratio, stress path, boundary condition and so on. The purpose of this study is to develop an undrained stability analysis for the base stability of an excavation when grout piles are installed. This analysis is derived by combining the circular slip mechanism and two equivalent shear strengths: (a) the axial compression undrained shear strength of clay for the slip surface outside the excavation; (b) the axial extension undrained shear strength of clay reinforced with grout piles for the slip surface inside the excavation. This study indicates that the difference between the factor of safety calculated from the proposed method and that predicted from the anisotropic bearing capacity method is limited. However, the applicability of the proposed method to excavations with a longer depth of retaining wall (D > 50·0 m) and a narrower width of excavation (B < 0·80D) is still subject to further investigation.

Theoretical computation background for transformation of foundations using pile drains

In the design of foundations for buildings and structures of various purposes, including improved risk, weak water-saturated clay soils with low mechanical characteristics are often found on a construction site. One of the possible ways of using them as a foundation is to seal them in various ways, including using pile drains of sand or rock stone material that are capable of both absorbing the load at the base and accelerating the process of filtration consolidation. This paper describes an analytical solution to the problem of interaction between the pile and the mattress with the surrounding soil of the foundation, taking into account the possibility of expanding the pile shaft. Solutions are obtained for determining the stresses in the shaft of the pile drain and in the soil under the mattress. The solution takes into account the influence of the pre-stressed state of the foundation after compaction on the formation of a stress-strain state during the erection and operation of structures. The solutions are relevant for consolidating pile drains made of rubble or for jet grouting piles, the rigidity of which is comparable to the rigidity of the surrounding soil. The paper describes the technique for determining the characteristics of the strength and deformability of the converted foundation and the results of large-scale tests at the experimental site for the construction of a large energy facility in Russia.

Performance of an Embankment Foundation with Sand over Clay: Experimental and Numerical Analyses

AbstractTo efficiently control postconstruction settlement (PCS) of a high-speed railway embankment on sand over soft clay, a study was conducted to analyze the performance of the embankment foundation treated by one of two methods; that is, only the clay was treated by jet grouting pile (JP foundation), or only the sand was treated by dynamic compaction (DC foundation). Two-dimensional coupled mechanical and hydraulic analysis was conducted using the finite-element method, and the measured and simulated results were compared. This study analyzed mainly performance of the JP foundation involving settlement during construction, PCS, and the soil arching effect related to differential settlement between the pile and soil, vertical effective stress, and the overall efficiency coefficient. Settlement of the DC foundation is also discussed. The results show that during construction, sand of the JP foundation produced a large settlement but became stable under loading of the embankment fill. Settlement of the D...

ESTIMATION OF SUBGRADE STRENGTHENING INFLUENCE USING SOILCEMENT ELEMENTS

Purpose. The aim of this work is to identify dependencies and options to strengthen the roadbed and a weak base by grouting piles. Analysis of software package SCAD to assess the effect of the selected option of strengthening the construction of spatial subgrade models. Methodology. In this paper the method of calculation of the soil mass in the software package SCAD is considered, which is a universal accounting system of finite-element analysis of structures and is focused on solving problems of designing buildings and structures rather complex structure. The finite element method is among the most modern and effective methods for the calculation of structures for various purposes. In the simulation, we get a complete picture of the stress-strain state of the study area, as well as the value of the limit load, rainfall, and so on. The spatial model based on the finite element volume, to better address the real characteristics of the soil mass, meets all the geometric characteristics of size and natural subgrade and the top structure the path that has been adopted in Ukraine. Findings. It was found that the most effective option to strengthen the roadbed, when applying grouting piles at the base of the subgrade and body, is to strengthen the five piles. At the same time there is even strengthen the soil mass at the level of 25 … 30% of the entire depth. However, even with the strengthening of the only two piles at the base of the effect of the strengthening of 14.1%. Established equation is linear and describes the decrease in strain. Taking into account the results of the research can be concluded that the consolidation is proportional to the depth with any number of piles. The dependence of the strain on the number of piles adheres to a polynomial function. Strengthening the bases of the subgrade and body depth also occurs in proportion with any number of piles. Originality. Design scheme generation algorithm for the calculation of the subgrade on a weak basis by finite element method was determined. The selection of strength characteristics of soils and the design parameters for use during the numerical simulation was completed. Load process simulation of the system by rolling stock was grounded. Practical value. Analysis of stress-strain state of «weak base-subgrade» allows you to see the basic laws work the soil and take the necessary measures to enhance the cross-section profile of jet-grouting elements.

RESEARCH OF CEMENT ADDITIVES INFLUENCE ON THE PROPERTIES OF SOILCRETE

The article analyses a possibility of replacing a part of cement with fly ash in jet grouting piles, because the received strength of cement treated grout is much higher than it is necessary for these piles. The paper presents the problems of fly ash utilization, overviews experimental and theoretical works and analyses laboratory tests on the samples of cement treated grout. The conducted experiments involved manufacturing cylindrical cement treated grout samples containing different additives when the diameter of the cylinder is 35 mm, and its height is 70 mm. The experiments on the samples comprising the additives of fly ash were made in sand and clay soils. 25% to 75% of cement was replaced with fly ash in cement treated grout samples tested under compressive strength following 7 days hardening in air.

Deflection Measurement of Bored Pile Body With Steel Bar Meters in the Lateral Load Test

Abstract This paper presents a lateral load test conducted with a service bored grout pile. In this test, 15 pairs of steel bar meters were mounted in the pile body. The equipment not only measures the section moments of the pile body, but also measures the deflections and rotations of the pile body, which are measured by inclinometers traditionally. A comparison between the deformation near the pile head measured by the steel bar meters, and the one measured by four dial gauges proved that it is valid to use steel bar meters to measure the lateral deformation of pile body during lateral loading tests. Moreover, the results are very precise before the lateral load exceeds the elastic limit, which was determined as 120 kN in the present study.

In-Situ Study to Assess the Quality of Pre-Drilled Embedded Geotextile Gravel Grouting Pile

In-Situ Study to Assess the Quality of Pre-Drilled Embedded Geotextile Gravel Grouting Pile

Application of Water-Proof Curtain with High-Pressure Injection Concrete Piles in Foundation Pit

This paper introduces a design program for supporting of deep foundation pit through the actual example for Beijing Moisten the world Center project to solve the difficulties of high water content in foundation soil, sensitiveness to surroundings, and difficult control of quick sand and flowing mud in the process of supporting of foundation pit. This program adopts a supporting system with upper soil nailing wall and lower pre-stressed anchor pile and a comprehensive water-proof curtain (Retaining piles + Long spiral high pressure jet grouting & mixing piles) to effectively solve the above difficulties. It is indicated through actual monitoring that displacement and settlement of foundation pit meet the specification and design requirements with excellent water-proof effect. The successful application of this program provides a reference for foundation pit engineering with rich underground water, especially for engineering at hard soil layer and stratum with sand and gravel that are apt to the formation of cement-soil grouting and mixing piles, as well as engineering with limitation on dewatering of foundation pit.

NUMERICAL ANALYSIS ON THE EFFECT OF JET GROUT PILES ON AN EXCAVATION LOCATED IN AN URBAN AREA

The development of infrastructure in limited land space is a challenging scenario. Infrastructure in limited land space regions (e.g. Singapore) does not provide freedom to develop at favourable locations instead forces the engineer to design at the possible locations. Clay with high organic content, commonly referred as Peaty clay is predominant in coastal areas. This clay being highly acidic (PH>7) and possessing very low shear strength is a critical factor to the design of infrastructure in the vicinity. Ground improvement adopted weak strata will have varying effect and may not be able to achieve the required strength. This paper discusses the effect of ground improvement (Jet Grout Piles) on the sloped excavation predominantly in Peaty clay. A 15m deep excavation which is 60 m wide is used for the Finite element modeling. Impact study on a tunnel located 40m from the excavation is presented (The study is carried out for various achieved Jet grout piles strengths of 100, 200, 300, 400 and 500 kPa). The stability of the slopes for the various strengths is also discussed (GeoSlope was used as the medium to perform the geotechnical analysis).

Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

The slurry wall bored grouting has some defects. The pile-base post grouting technique can effi- ciently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain refer- ence value for theoretical research and technical application of the technique.

Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.

The Thermal Behaviour of Three Different Auger Pressure Grouted Piles Used as Heat Exchangers

Three auger pressure grouted (APG) test piles were constructed at a site in Richmond, Texas. The piles were each equipped with two U-loops of heat transfer pipes so that they could function as pile heat exchangers. The piles were of two different diameters and used two different grouts, a standard APG grout and a thermally enhanced grout. Thermal response tests, where fluid heated at a constant rate is circulated through the pipe loops, were carried out on the three piles, utilising either single or double loops. The resulting test data can be used to determine the surrounding soil thermal conductivity and the pile thermal resistance, both essential design parameters for ground source heat pump systems using pile heat exchangers. This paper uses parameter estimation techniques to fit empirical temperature response curves to the thermal response test data and compares the results with standard line source interpretation techniques. As expected, the thermal response tests with double loops result in smaller thermal resistances than the same pile when the test was run with a single loop. Back analysis of the pile thermal resistance also allows calculation of the grout thermal properties. The thermally enhanced grout is shown to have inferior thermal properties than the standard APG grout. Together these analyses demonstrate the importance of pile size, grout thermal properties and pipe positions in controlling the thermal behaviour of heat exchanger piles.

Mixing Pile and Rotary Jet Grouting Pile New Monitoring Technology Research and Application

Construction of buildings on soft ground, key issues need to improve the bearing capacity on soft ground. The cement mixing pile and high pressure rotary grouting pile technology are widely applied in road soft foundation consolidation engineering. However, due to the impact of various factors of construction technology, machinery and equipment, geological conditions, such as the quality of the construction team, quality control has great difficulty. This paper presents three indicators - SPT blow count, and core samples described and unconfined compressive strength of cement mixing pile quality evaluation, which SPT blow count based, core sample description, followed by anti-supplemented unconfined compressive strength. According to certain standards of each score, and assign different individual scores are weighted average weights to obtain weighted score of three indicators of the quality.

Discussions on the Construction Technology of the Vibrating Inserting Rod Long Auger Bored Pile-CFA

The vibrating inserting rod Long Auger Bored pile is a new technology of pressure grouting pile based on the development in the long spiral drilling. On the basis of introducing the method of traditional slurry drilled pile, this paper analyzes advantages of the vibrating inserting rod Long Auger Bored pile, the construction process and key points in detail, summarizes the causes of common quality defects of the vibrating inserting rod Long Auger Bored cast-with-pressure and their solutions.

New Construction Machinery Developed in Ultra-Deep High Pressure Jet Grouting Pile

High pressure jet grouting pile has been widely used in engineering application, with the increase of depth, demand for construction machinery will increase, also the difficulty of the construction quality control. Through the deep soft soil area in southeast coastal areas in fujian actual engineering example, we have improved ultra-deep Yet Grouting Pile machinery to meet the construction requirements.

Application of High Pressure Jet Grouting Pile with Undrained Open Caisson Combined Construction Technology in the Protection of Yangtze River Levee

It is easy to cause Yangtze River embankment soil slip or even collapse to have a deep foundation pit construction adjacent to Yangtze River outside embankment，with lots of risk . A new combined construction technique for large caisson is presented. The construction technology, the earthwork excavation of deep high pressure jet grouting pile combined with undrained open caisson construction technology, with data monitoring for the open caisson excavation control is adopted. This study mainly summarizes the advantages of deep high pressure jet grouting pile combined with undrained caisson combined construction technology engineering application, and describes the process of the combined construction and measures of deviation correction.The new combining construction technique has made a relatively effective protection for the Yangtze River levee and its ecological environment,having great engineering application value to some similar engineering.

Construction Quality Control and Inspection Measures of Ultra Deep Jet Grouting Pile

High pressure jet grouting piles have a wide range of application in the engineering field. However, nowadays the increasing construction depth leads to an increasing difficulty of construction,which involves that the quality of construction is much more difficult to control. In this paper, some examples are given of the Luoyuan ultra-deep high pressure jet grouting piles. These examples are described with the used construction quality control methods and preventive recommendations for work construction quality detection methods. That is why this paper has an important guiding significance for similar projects.