Grouting Pile Research Articles

Numerical model for the settlement of loess subgrade in operation period reinforced by rotary jet grouting pile

The problems of subgrade settlement failure and uneven settlement are quite prominent due to hydraulic migration. The loess in the natural state has the characteristics of high strength and low compressibility. Composite foundation method is to set a certain proportion of reinforcement (pile) in the natural foundation, so that the pile and soil jointly bear the load, and has the effect of compaction method and displacement method. Based on the actual case of a highway disease in Shanxi Province, this paper studies the influence of treatment measures of rotary jet grouting pile penetrating or not penetrating the loess soil on the uneven settlement of highway subgrade in loess region by means of field investigation, analysis and numerical calculation. The results found that the lateral friction resistance of rotary-jet grouting pile penetrates through the loess is small. When the rotarjet pile is long and the underlying soft layer is relatively thick (4.5 m), the settlement of the foundation also quickly enters the stable state. When the underlying loess is deep, the settlement of the foundation increases with time.

Settlement Characteristics of Split Grouting Pile Composite Foundation in Loess Areas

Loess foundations often affect the stability of superstructures due to their insufficient bearing capacities; thus, reinforcement measures are crucial for mitigating the uneven settlement of foundations. This study aims to investigate the settlement characteristics of composite foundations for loess foundations reinforced by splitting grouting piles. First, split grouting tests were carried out on loess foundations. After the test piles reached the design strength, static load tests and geotechnical tests were carried out to obtain the Q‐s curves of the test piles. The pile‐forming mechanism was analyzed via excavations at an on‐site test pile. Furthermore, the traditional settlement calculation method of composite foundations was used to calculate the settlement of split grouting pile composite foundations, and the results were compared with field test results to explore a suitable settlement calculation method of split grouting pile composite foundations. Finally, the numerical model of split grouting pile composite foundations was established according to the pile forming mechanism, and the settlement deformation characteristics of single pile and pile group composite foundations were analyzed. The relative errors of the composite modulus method and the stress correction method for calculating the settlement of the composite foundations were 6.4% and 32.8%, respectively, and the composite modulus method was closer to the test values. The calculated curves of the numerical model were in good agreement with the measured curves and relevant literature research results, demonstrating the rationality of the modeling method; the findings of this study provide theoretical guidance for designing loess foundation splitting grouting reinforcement and for predicting settlement during later construction periods.

Study on Bearing Mechanism of Split Grouting Pile Based on Finite Element Simulation

In order to realize the directional and controllable splitting of splitting grouting, the field grouting test was carried out. Using a new grouting pipe designed, the splitting direction and size of the branch vein are effectively controlled through the control of grouting pressure and grouting amount. In order to explore the bearing characteristics of split grouting pile and provide necessary parameters for the design of split grouting pile composite foundation in engineering practice, the field static load test and indoor geotechnical test of split grouting pile are designed, and the ultimate bearing capacity of single pile and necessary soil parameters are obtained. In order to make up for the limitations of field static load test, the three-dimensional finite element model of pile, soil and branch vein of split grouting pile is established by using the finite element analysis software ABAQUS. The finite element analysis results are compared with the measured values of field test, and the variation laws of pile shaft axial force, stress and displacement of branch vein at different depths, pile side friction, etc. are further explored, Through these changes, the interaction and load transfer mechanism between pile and soil are analyzed, which provides a reference for optimal design.

Experimental Study on Compaction Effect between MetroJet System Method and High-Pressure Jet Grouting Pile(DoubleTube)

Experimental Study on Compaction Effect between MetroJet System Method and High-Pressure Jet Grouting Pile(DoubleTube)

Linienkreuz U2xU5 – Tunnelbaumaßnahmen am Bauabschnitt U2/22

AbstractThe next expansion phase of the U2xU5 intersection is currently under construction in the inner districts of the City of Vienna. The construction lot U2/22 Rathaus (City Hall) takes place in the inner districts 1, 7 and 8. Three shafts are the main focus of the construction works at Friedrich‐Schmidt‐Platz, directly behind the Vienna City Hall as well as a shaft with extensive works on the building of the University of Vienna and another shaft at Josefstädter Straße. Due to difficult and changing geology, different support measures from full face tunnel excavation to tunnelling under a roof of jet grouting piles will be used. In addition, measures such as groundwater drainage, structural improvements of buildings and settlement compensations are necessary in advance.

Environmental Engineering Deformation Control of High-speed Railway Shield Tunnel Under Crossing Bridge Piles

With the continuous acceleration of my country’s high-speed rail construction, it is inevitable to cross the existing engineering structure during the construction process. During the construction of high-speed railway, the control of the influence and deformation of the existing structure is a subject that needs to be studied in environmental engineering. Hangzhou metro line 1 is designed to cross under the Hu-Hang high-speed railway. According to the design, the shield tunnel is very close (minimum distance 5.19m) to the bridge piles of the Hu-Hang high-speed railway. Therefore, how to control the deformation of the bridge piles is a big problem in the shield tunnel excavation. Before construction, the method of the bored piles coupled with the jet grouting piles was proposed. The 3D numerical model was built to study the deformation of the bridge piles with the cases of the shield tunnel excavation without soil consolidation, the construction of the bored piles coupled with the jet grouting piles and the shield tunnel excavation with soil consolidation. The results show that the method of the bored piles coupled with the jet grouting piles can control the deformation of the bridge piles in the shield tunnel excavation effectively. Then, the deformation monitoring of the bridge piles was performed in the process of construction. The monitored data were close to the calculated results, which implies that the method of the bored piles coupled with the jet grouting piles is effective.

Function mechanism and analytical method of a double layer pre-support system for tunnel underneath passing a large-scale underground pipe gallery in water-rich sandy strata: A case study

The Dongping No.1 Tunnel of the Guangdong–Foshan Loop Line Intercity Railway in China passes an existing large-scale underground pipe gallery in water-rich sandy strata through the undercutting method. During construction, controlling the underground pipe gallery deformation is difficult because the water-rich sandy strata can easily become unstable. To deal with this problem, this paper proposes a double layer pre-support system (DLPS) consisting of pipe shed and horizontal jet grouting piles, whose function mechanism is explored from the viewpoint of passive protection and active reinforcement. The deformation transferring path of the DLPS is described as follows: tunnel excavation → lower pre-support deformation → deformation of the soil between the upper and the lower pre-supports → upper pre-support deformation → underground pipe gallery deformation. Considering the influence of geological conditions, the proposed DLPS has two failure modes, namely, excessive settlement of the tunnel vault and excessive deformation of the overlying underground pipe gallery. The mechanical model and analytical method of the DLPS were established according to the theory of beam resting on elastic foundation. Comparing the computed and measured settlement values revealed that the established model is reliable because it could reflect the interaction characteristics of the upper pre-support, the lower pre-support, and the middle soil. Finally, multiple factor analysis was conducted to ascertain the influence of typical calculating parameters, and the deformation characteristics of the DLPS under different influence factors were obtained. The design suggestions for key parameters could provide reference for similar practical engineering in the future.

Numerical Study on Karst Treatment Technology of Wuhan Metro Line 6

Taking Wuhan Metro Line 6 karst crossing area as the research object, combined with on-site survey data, a reasonable karst treatment technical plan is proposed. The finite difference numerical calculation method was used to carry out numerical calculation research on the treatment effect of karst treatment technology in the study area. The research results show that after grouting reinforcement, the maximum settlement of tunnel segments is 19.5mm, which is 73% less than before reinforcement, and the treatment effect is better. The lining deformation is within the allowable deformation value after the reinforcement of the three rows of jet grouting piles. The maximum value of the stress of the jet grouting piles is lower than the design value of the shear strength of the high jetting walls, indicating that the treatment technology can play a good supporting role when completely collapsed Without destruction.

Application Research of High Pressure Jet Grouting Pile in an Underground Engineering In Vietnam

Application Research of High Pressure Jet Grouting Pile in an Underground Engineering In Vietnam

Numerical study of the performance of jet grout piles for braced excavations in soft clay

Abstract Jet grout piles (JGP) is a ground improvement method that is constructed beneath the final excavation level to prevent basal heave instability, control wall deflections and reduce the strut loads for braced excavations in deep deposits of soft clay. This paper presents the effects of JGP on the wall deflections and strut forces for deep excavations. Firstly, finite element analysis calibrated by an excavation case history improved by JGP is carried out, followed by parametric studies that investigate the effects of various JGP geometric and mechanical properties on the excavation performances. The numerical analyses indicate that increasing the number of piles and the areal extent of reinforcement area, as well as decreasing the pile spacing, can significantly reduce the wall deflections and strut forces for excavation in weak clay. Additionally, use of a thicker layer of jet grout slab without the jet grout pile system is also studied. The feasibility of reducing one level of struts for sake of construction time and costs while adjusting the jet grout piles’ layout to maintain the stability is also discussed.

A Review on the Grouting Piles with High Pressures Used for Pollution Reduction

Traditional bored drilling piles were often used in geotechnical engineering. However, its construction process is complicated, and the stability of the treated site and the bearing capacity of piles are unexpected. Importantly, the slurry produced in the construction process will cause the environmental pollution. This paper introduced the construction process, quality evaluation and bearing capacity calculation of a high-pressure grouting pile. In addition, this paper looked forward the application of the polymer materials and high strength concrete grouting piles for pollution reduction in power transmission and transformation engineer.

Jet-grouting in ground improvement and rotary grouting pile installation: Theoretical analysis

The permeation grouting is a commonly used technique to improve the engineering geology condition of the soft ground. It is of great significance to predict the permeation range of the grout so as to ensure the effects of grouting. This paper conducts a theoretical analysis of jet-grouting effects in ground improvement and rotary grouting pile installation by utilizing deformation-permeation coupled poroelastic solutions based on Biot\'s s theory and Laplace-Fourier integral transform technique. The exponential function and the intermittent trigonometric function are chosen to represent time-dependent grouting pressure usually encountered in ground improvement and rotary grouting pile installation process, respectively. The results, including the radial displacement, the hoop stress, the excess pore fluid pressure, the radial discharge, and the permeation radius of grout, are presented for different grouting time, radial positions and grouting lengths. Parametric study is conducted to explore the effects of variation of the exponent in the exponential grouting pressure-time relationship on grouting-induced responses. It is expected that the proposed solutions can be used to estimate the permeation range of grouting in ground improvement and rotary grouting pile installation.

Research on effect of ages and strength of concrete on wave speed in grouting pile integrality detection by low strain method in hydraulic engineering

Low strain method is the most common way to detect the integrality of piles in the hydraulic engineering since it has the advantages of simple operation and low condition for on-site test. In the detection of the integrality of concrete grouting pile via low strain method, wave speed is an important parameter to judge the integrity and length of pile. This paper studies the wave speed of cast-in-place concrete precast pile which is adapted in the engineering. Besides this, the relationship between concrete intensity and the wave speed of the body of precast pile at different ages is obtained. Via further verification, it is found that the relationship could be applied in the engineering piles, which renders a reference for wave speed at different ages in the integrity test of piles in the hydraulic engineering.

Three-Dimensions Modelling of a Jet Pile Construction in the Karolinka Dam

Karolinka Earth Fill dam was built on the Stanovnice river above the town of Karolinka in the region of Vsetín. Because of leakage on the downstream dam face due to bad compacting of soil during the construction stage, the reservoir was used to a limited level. There were some steps to improve safety which had been developed to reconstruct the dam after extensive surveys in 2005. The major rehabilitation was commenced in period from September 2012 till October 2013, included the remediation of central impervious core in the dam by using the diaphragm wall (I also have worked on) and jet grouting pile from self‑hardening cement‑bentonite suspension. The article presents three‑dimensional modelling of a jet pile construction, by using finite element method which is performed by Plaxis program. It is concluded that real data shows good agreement with the computed result obtained by the FEM analysis.

Site test study of pile-soil stress ratio of composite foundation in karst area

Aiming at the special geological conditions in Karst areas, the pile-soil stress ratio of composite foundation is analyzed. According to carry out the field test of composite foundation in Karst area, soil pressure boxes are arranged to measure the stress of piles and soil at the same time. As the load increased, the variation trend of the pile-soil stress ratio of composite foundation is analyzed. On the basic, the pile-soil stress ratio is compared with non-karst area. The test result showed that both the pile-soil stress ratio of PHC piles and high pressure jet grouting piles increase. The increase of the PHC piles is more obvious. The pile-soil stress ratio of PHC piles is larger than high pressure jet grouting piles. The main reason is that the strength of cement-soil mixed piles is lower. The high pressure jet grouting piles plays an important role in improving soil bearing capacity between piles and supporting the side abutment pressure of PHC piles in composite foundation. It is shown that the stress concentration is more obvious in karst area.

STUDY ON THE SETTLEMENT OF TUNNEL BOTTOM AND PRESSURE OF ROCK MASS BASED ON CURVED BEAM ON ELASTIC FOUNDATION THEORY

Tunnel invert is the weak section of curved beam on tunnel foundation, and it is easy to break down. Based on the curved beam theory on elastic foundation, the curved beam model of tunnel invert was established, the displacement equations of tunnel invert under external load were deduced, and the formulas of settlement of tunnel bottom and the pressure of rock mass were presented. By means of the calculating formulas, the distribution laws of settlement of tunnel bottom and pressure of rock mass were obtained when tunnel bottom was strengthened and not strengthened by high pressure jet grouting piles. The final formulas in the paper are precise to predict the settlement of tunnel bottom and pressure of rock mass, so they are of great value for tunnel design and construction.

Working Performance Control Technology of Underwater Grouting Pile Concrete

As an important part of concrete, the improvement effect of admixture on the performance of concrete has been paid more and more attention. In this paper, the effect of the compounding ratio of polycarboxylate liquor with different functions on the dosage sensitivity and slump retention of the admixture was studied. Foam control technology was used to improve the viscosity of concrete which was in favor of the fillability of concrete. In addition, the optimal formulation of proprietary admixture was determined by compressive strength test.

Behaviors of Wall and Ground due to T-shaped Excavation

Extensive monitoring was performed on a T-shaped site with a length of 280 m, a width of 16 m, and a maximal depth of 20.4 m. The braced excavation was performed under retaining comprised of cast-in-situ bored piles and jet grouting piles. The field databased wall performance and its influences to ground were assessed by detailed comparisons with that in other excavations. It is showed that the wall deflections, ground movements and bracing forces all exhibited a typical camelback-shaped characteristic along the length direction, and a maximum 100% reduction of which was observed due to the jet grouting. The rebar near sections with varied excavation depths was in a tension state both on the excavation and the retained sides due to the two-dimensional unbalanced force, and the corresponding bracing force was small. The maximum wall deflection δhm decreased as the partitioning excavation moved horizontally, and it was less than 0.04% of the final horizontal excavation length Le. The normalized Fσmax approximately approached to be identical with the normalized Fbmax, while most of the occurring depths for Fσmax were greater than that for Fbmax.

Comprehensive analysis of the retaining pile structure with the determining the stability factor by numerical methods

The paper highlights the results of the complex analysis of the retaining pile structure with determining the stability coefficient by numerical methods. To achieve this purpose, after designing a structure with jet grouting piles, the research of the stability coefficients of the landslide hazard slopes in the software complex “OTKOS” and its stress state in the software complex LIRA-CAD system was conducted. The relevance of the completed research is to develop rational parameters of the pile structure. A comparison of determining the stability coefficient of a slope by different methods for the existing landslide stretch for the public roadways of local significance C141017 (Lviv-Shehyni) – Sudova Vyshnia was carried out. Originality of the paper lies in the fact that to determine the stability coefficient in the model, the layeredness of the slope under study is taken into account, and the nonlinear volumetric problem is solved in the course of the numerical analysis of the stress state. The rational distance between piles in the gap and the length of the pile under a certain percentage of cement and ground was justified.

Experimental study and numerical analysis on bearing characteristics of large diameter ultra long bored piles with post grouting on the tip and side

To research the bearing characteristics of post grouting large diameter ultra long piles under post grouting on the tip and side, the load test of three test piles of a super high rise project was carried out, and the numerical analysis method was used to research the load transfer law of post-grouting large diameter ultra long bored piles. Based on this, the differences and advantages of the post-grouting on the tip and side pile versus the non grouting pile and the pile end grouting pile are analyzed. The analytical results show as follows: post grouting on the tip and side will significantly change the performance and distribution of side friction of the piles, and improve mechanical properties of soil and pile-soil interface around piles. The ultimate bearing capacity of the post grouting on the tip and side pile foundation has increased 100% and 52% more than the non grouting and pile end grouting pile foundations. The side friction of post-grouting on the tip and side pile plays a significant difference from the non grouting piles.